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Proceedings of the Symposium on Coastal Oceanography and Littoral Warfare
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PROCEEDINGS OF SYMPOSIUM ON COASTAL OCEANOGRAPHY AND LITTORAL WARFARE (Unclassified Summary)
Fleet Combat Training Center Tactical Training Group, Pacific San Diego, CA August 2-5, 1993
Navy Committee Ocean Studies Board National Research Council
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NATIONAL ACADEMY PRESS 2101 Constitution Avenue, N.W. Washington, DC 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the panel responsible for the report were chosen for their special competencies and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with the general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce Alberts and Dr. Robert M. White are chairman and vice-chairman, respectively, of the National Research Council. The work was sponsored by the U.S. Department of Defense under Grant No. N00014-92-J-1636. Such support does not constitute an endorsement of the views in this report by the sponsors. Copies of this report are available from Ocean Studies Board National Research Council 2101 Constitution Ave., NW Washington, DC 20418 Copyright 1994 by the National Academy of Sciences. All rights reserved. Cover art by Terry Parmelee, a Washington, D.C. artist represented by the Jane Haslem Gallery in Washington, D.C. Printed in the United States of America.
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NAVY COMMITTEE Kenneth Brink, Woods Hole Oceanographic Institution, Woods Hole, MA, Chairman Robert Cannon, Jr., Stanford University, Palo Alto, CA Robert Detrick, Woods Hole Oceanographic Institution, Woods Hole, MA Eileen Hofmann, Old Dominion University, Norfolk, VA William Kuperman, Scripps Institution of Oceanography, La Jolla, CA Arthur R. M. Nowell, University of Washington, Seattle, WA Project Staff Mary Hope Katsouros, Study Director Stewart B. Nelson, Consultant Mary Pechacek, Project Assistant
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OCEAN STUDIES BOARD William Merrell, Texas A&M University, Galveston, TX, Chairman Robert Berner, Yale University, New Haven, CT Donald Boesch, University of Maryland, Cambridge, MD Kenneth Brink, Woods Hole Oceanographic Institution, Woods Hole, MA Gerald A. Cann, Independent Consultant, Rockville, MD Robert Cannon, Stanford University, Stanford, CA Biliana Cicin-Sain, University of Delaware, Newark, DE William Curry, Woods Hole Oceanographic Institution, Woods Hole, MA Rana Fine, University of Miami, Miami, FL John E. Flipse, Texas A&M University (ret.), Georgetown, SC Michael Freilich, Oregon State University, Corvallis, OR Gordon Greve, Amoco Production Company, Houston, TX Robert Knox, Scripps Institution of Oceanography, La Jolla, CA Arthur Nowell, University of Washington, Seattle, WA Peter Rhines, University of Washington, Seattle, WA Frank Richter, University of Chicago, Chicago, IL Brian Rothschild, University of Maryland, Solomons, MD Thomas C. Royer, University of Alaska, Fairbanks, AK Lynda Shapiro, University of Oregon, Charleston, OR Sharon Smith, University of Miami, Miami, FL Paul Stoffa, University of Texas, Austin, TX Staff Mary Hope Katsouros, Director Edward R. Urban, Jr., Staff Officer Robin Peuser, Research Associate David Wilmot, Research Associate Mary Pechacek, Administrative Associate LaVoncyé Mallory, Senior Secretary Curtis Taylor, Office Assistant Stewart B. Nelson, Consultant
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COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES M. Gordon Wolman, The Johns Hopkins University, Baltimore, MD, Chairman Patrick R. Atkins, Aluminum Company of America, Pittsburgh, PA Edith Brown Weiss, Georgetown University Law Center, Washington, DC Peter S. Eagleson, Massachusetts Institute of Technology, Cambridge, MA Edward A. Frieman, Scripps Institution of Oceanography, La Jolla, CA W. Barclay Kamb, California Institute of Technology, Pasadena, CA Jack E. Oliver, Cornell University, Ithaca, NY Frank L. Parker, Vanderbilt/Clemson University, Nashville, TN Raymond A. Price, Queen's University at Kingston, Canada Thomas C. Schelling, University of Maryland, College Park, MD Larry L. Smarr, University of Illinois, Urbana-Champaign, IL Steven M. Stanley, The Johns Hopkins University, Baltimore, MD Victoria J. Tschinkel, Landers and Parsons, Tallahassee, FL Warren Washington, National Center for Atmospheric Research, Boulder, CO Staff Stephen Rattien, Executive Director Stephen D. Parker, Associate Executive Director Morgan Gopnik, Assistant Executive Director Jeanette Spoon, Administrative Officer Sandi Fitzpatrick, Administrative Associate Robin L. Allen, Senior Project Assistant
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CONTENTS
A. B. C.
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CONTENTS
EXECUTIVE SUMMARY 1
1. INTRODUCTION AND OBJECTIVES 5
2. WORKING GROUP SUMMARIES Harbors and Approaches Straits and Archipelagoes Surf Zone Continental Shelf 9 11 26 30 37
APPENDIXES Symposium Program Symposium Attendees List of Acronyms 49 51 59 65
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CONTENTS x
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EXECUTIVE SUMMARY
1
EXECUTIVE SUMMARY
Littoral warfare is the use of combined forces, designed for operations in the sea-land-air environment, to influence, deter, or contain and defeat a regional threat through the projection of maritime power. It is an extremely complex and dynamic part of naval warfare. To be waged successfully, it demands long-term commitment to research and development, acquisition, threat assessments, tactical and operational analysis, training, education, and realistic fleet exercises. On August 2-5, 1993, the third in a series of classified symposia on tactical oceanography was held, with a focus on coastal oceanography and littoral warfare. The symposium was organized by the Navy Committee of the National Research Council's Ocean Studies Board, and was jointly supported by the Oceanographer of the Navy and the Chief of Naval Research. The Navy's new focus is on the littoral regime, examined herein as four subdivisions: harbors and approaches, straits and archipelagoes, the surf zone, and the continental shelf. Symposium participants discussed the meteorological and oceanographic forcing factors that have an impact on military operations. The symposium brought together knowledgeable individuals from the operational Navy (specialists in oceanographic research and development, and data acquisition) and from academia with the following goals: • Addressing timely operational problems, fleet mission needs, and other requirements for which research and development assistance and inputs are sought by naval leaders and program managers. • Enhancing communication and understanding among basic and applied scientists, and between these scientists and U.S. naval personnel. • Enabling an extended group of researchers to become familiar with challenging naval issues applicable to the littoral regime.
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EXECUTIVE SUMMARY
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The symposium was preceded by a littoral war game designed to provide insight into the critical role that oceanography plays in achieving and maintaining battle space dominance. The war game emphasized the impact of decisions forced upon warfare commanders and gave insights about the timing involved in developing environmental assessments and predictions for influencing combat decisions. The symposium began with several presentations by Navy personnel to set the context for subsequent discussions. Participants were divided into working groups focused on the four emphases of the symposium: harbors and approaches, straits and archipelagoes, the surf zone, and the continental shelf. The working groups summarized their findings in plenary session, emphasizing the present status and future directions of research in each area. A recommendation that emerged from several of the working groups was that physical regions (e.g., estuaries and straits) should be categorized in standard classification systems so that the research results from accessible regions can be extrapolated during combat situations to relatively unstudied environments in the inaccessible territorial waters of hostile nations. An intriguing proposal that emerged from the symposium concerned the conduct of one or more field experiments in the littoral zone, much like the open ocean measurements conducted in the mid-Atlantic Ocean during the 1970s. These experiments would include observations and modeling of coastal marine, atmospheric, and land environments. Such exercises could be used to transfer academic capabilities and expertise to the applied and operational communities supporting littoral warfare. The Harbors and Approaches Working Group discussed the information needs, research directions, and potential technological developments related to littoral warfare in estuarine areas. The discussions of the working group focused on three scientific topics: tides and currents, acoustic and electrical properties of the water and the sediment, and the transport of materials and other properties having scalar distribution behavior. The working group recommended the development of a classification system for estuaries, based on hydrodynamic properties, that will allow simplified prediction of warfare-relevant environmental characteristics from a few measured parameters. The Straits and Archipelagoes Working Group recommended that a number of issues be addressed as the Navy prepares for future littoral warfare. First, like the previous working group, they recommended that a classification system be developed for the straits of the world. Existing information about straits should be compiled and published for scientific review. Process-oriented studies of straits must be designed to understand the key processes that control flow, temperature,
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EXECUTIVE SUMMARY
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and salinity in straits. A variety of strait types, identified according to the new classification system, should be studied to permit extrapolation of the information to other straits that have not been studied in detail. Archipelagoes are, in essence, series of straits, so that studies of straits are fundamental to understanding the more complex situation in archipelagoes. The Surf Zone Working Group made recommendations about research and development needs related to improving our abilities to measure and understand the processes controlling nearshore bathymetry, waves and currents, shelfwide propagation of surface gravity waves, acoustical properties, sea level variations, and “trafficability” through the surf zone. The working group noted that several instruments now used in academic research could be used by the Navy to improve littoral zone environmental prediction, and thus Navy operations. Examples include bottom-mounted pressure sensors and remote sensing techniques that allow characterization of wave features and variability. The working group also recommended that the Navy pursue an empirical approach to understanding the evolution of nearshore systems by studying a set of archetypal beaches. The Continental Shelf Working Group identified a number of cross-cutting issues that are important for operations in the littoral environment. These issues included the need for sufficient characterization of coastal regions to permit advanced planning, a better understanding by naval personnel about how to use nonacoustic environmental information for making tactical decisions, information about the accuracy of sensors under any combination of environmental conditions, limiting risk to Navy personnel by using more remote methods and predictions, the need for real-time sensors of environmental properties, and new approaches for data handling, archiving, and dissemination. The working group also noted relevant problems in mine countermeasures, antisubmarine warfare, special warfare, and amphibious operations that could benefit from increased research effort.
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EXECUTIVE SUMMARY 4
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INTRODUCTION AND OBJECTIVES
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1 INTRODUCTION AND OBJECTIVES
Littoral warfare is the use of combined forces, shaped for forward operations in the sea-land-air environment, to influence, deter, or contain and defeat a regional threat through the projection of maritime power. It is an extremely complex and dynamic part of naval warfare. To be waged successfully, it demands long-term commitment to research and development, acquisition, threat assessments, tactical and operational analysis, training, education, and realistic fleet exercises. A primary need for amphibious operations, made obvious by recent actions, is to detect, locate, and either avoid or clear mines and obstacles from shallow water approaches to and through the craft landing zones. The primary current shortfall is the time it takes for high-confidence Mine Countermeasures (MCM) to be completed. MCM capabilities are required in three categories: (1) rapid reconnaissance and assessment of the mine threat; (2) organic detection and avoidance and/or other means of protecting Carrier Battle Group and Amphibious Task Force assets; (3) clearance of sea mines, including rapid breakthrough at choke points. Operational maneuver from the sea is the desired tactic for present and future maritime power projection ashore. Whenever possible, it is initiated from a position at sea that threatens a large part of the enemy's littoral area. Current counter-mine/ obstacle technology limits our capability to conduct operational maneuvers from the sea across beaches defended by both mine and obstacle barriers. On August 2-5, 1993, the third in a series of classified symposia on tactical oceanography was held, with a focus on coastal oceanography and littoral warfare. The symposium was organized by the Navy Committee of the National Research Council's Ocean Studies Board, and was jointly supported by the Oceanographer of
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INTRODUCTION AND OBJECTIVES
6
the Navy and the Chief of Naval Research. The Navy's new focus is on the littoral regime, examined herein as four subdivisions: harbors and approaches, straits and archipelagoes, the surf zone, and the continental shelf. Symposium participants examined the meteorological and oceanographic forcing factors that have an impact on military operations. The symposium had several objectives. • To address timely operational problems, fleet mission needs, and other requirements for which research and development assistance and inputs are sought by naval leaders and program managers. • To enhance communication and understanding among the basic and applied research communities, and between these communities and our naval forces. • To enable an extended group of researchers to become familiar with challenging naval issues applicable to the littoral regime. The symposium was preceded by a simulation of a warfare situation in the littoral zone (war game). Fifty academic and military personnel participated in the war game. Staff from the Tactical Department of the Training Center interacted with war game participants for one day, with the goal of emphasizing the decisions that are forced upon commanders by rapidly changing littoral environmental conditions. The war game simulated conditions in the Persian Gulf. The war game focused on the following issues: Navy platforms (i.e., aircraft, surface ships, and submarines), tactical use of meteorology and oceanography data, tactics, communications, procedures, equipment capabilities and limitations, weapons, and acoustic and nonacoustic systems. The war game was also useful for motivating discussions during the remaining sessions of the symposium. The symposium began with a number of introductory presentations to prepare symposium participants for subsequent discussions. RADM John Chubb (Commander, Naval Oceanography Command) provided an overview of the challenge of collecting and analyzing data in the littoral environment (from the shelf break to the surf zone and beyond) to provide useful products to warfare commanders. He challenged symposium participants to identify ways to collect environmental data in a real-time tactical environment, to improve and apply satellite capabilities, to find ways to develop prototype models rapidly, and to correct deficiencies in our present high-resolution modeling efforts. COL Michael Patrow (U.S. Marine Corps, Office of Chief of Naval Operations, Expeditionary Warfare Division) provided an overview of the shift in emphasis (i.e., resources) by the Navy toward the littoral environment based on
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INTRODUCTION AND OBJECTIVES
7
changes in the international arena. The discussion included a summary of the Navy reorganization to sustain the new focus on littoral warfare, a definition of expeditionary warfare, a review of the threats that U.S. forces face, a review of some systems and initiatives for upgrading them now under way, and several real-world “walkthrough” examples. CAPT R.C. Mabry (Commander, Naval Special Warfare, Group One) provided an overview of Naval Special Warfare from World War II through the current operations in Somalia, focusing on the mission, organization, and capabilities of special forces in the littoral environment. The discussion included planning considerations and data needs prior to entering the theater of operations, as well as a summary of meteorology and oceanography data requirements (i.e, essential elements of information in oceanic, land, riverine, and other operating environments). RADM Geoffrey L. Chesbrough (Oceanographer of the Navy) provided an overview of operational oceanography from multiple perspectives, including preparation for executing the strategy set forth in the internal Navy document entitled From the Sea. He also discussed the global changes from World War II to today, use of the Naval Expeditionary Forces, multiple littoral threats, joint operations required for success, command and control in a vast battlespace, and the need for tailored meteorology and oceanography data products.
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INTRODUCTION AND OBJECTIVES 8
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WORKING GROUP SUMMARIES
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2 WORKING GROUP SUMMARIES
Symposium working groups were set up to cover four geographic subdivisions of the littoral region: • • • •
Harbors and Approaches Straits and Archipelagoes Surf Zone Continental Shelves
Each working group was asked to focus on the following questions, to stimulate and focus discussion. 1. What environmental information is needed to support special operations mine warfare, antisubmarine warfare, and amphibious operations? What are the important technical issues? 2. Why is the environmental information needed and how is it currently applied operationally? Is there additional environmental knowledge that can be applied, immediately or over the next three years? 3. How is this environmental information currently acquired? 4. What are the central environmental research issues? a. Database issues b. Collection methods and priority issues c. Modeling and simulation issues d. Applications issues
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WORKING GROUP SUMMARIES 10
5. What research and development is needed that will have direct impact on these problems? What are the environmental research issues and warfare issues? 6. List novel, high-risk, “far-out” ideas that could be applied. Be creative, not critical.
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WORKING GROUP SUMMARIES
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REPORT OF THE HARBORS AND APPROACHES WORKING GROUP Dr. David Jay, University of Washington, Chair CAPT R.C. Mabry, SWG1/NSWG, Cochair LCDR Anthony Negron, SWG1/NSWG, Assistant CAPT Charles Mauck, USNR/FNOC, Assistant The operational aspects considered were counter-mine warfare (CMW), special forces (SF), amphibious operations (AO), and antisubmarine warfare (ASW), the first three being of greatest importance in the context of harbors and approaches. The Environment Harbors and approaches are almost always identifiable as estuaries. An estuary can be defined as “a semienclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water derived from land drainage” (Cameron and Pritchard, 1963). Familiar North American examples include New York Harbor, a coastal plain estuary with several adjacent tidal straits; San Francisco Bay, a river-estuary attached to a fault-formed embayment; and Puget Sound/Strait of Juan de Fuca/ Straits of Georgia, a complex of river deltas, straits, and fjords. We may usefully extend the definition quoted above to include (1) tidal rivers landward of salinity intrusion to the head of the tide (e.g., the Columbia River to Portland); (2) hypersaline negative estuaries, where evaporation exceeds the sum of precipitation and river inflow (e.g., Houston's harbor and Galveston Bay); and (3) the estuarine plume outflow area, usually into an open coastal environment, where buoyancy-driven flows and stratification have a major influence on circulation and sedimentation processes (e.g., the mouth of the Amazon). These additions reflect both operational needs and the research methodology of the estuarine oceanography community. There are undoubtedly some harbors (e.g., on arid islands) that meet the quoted definition only to the extent of being “semi-enclosed.” As a practical matter, however, the conduct of littoral warfare in these exceptional harbors would require the same information concerning tides and currents as its conduct in more typical estuarine harbors and approaches. Moreover, the presence of even small sanitary and/or industrial sewer outfalls will raise the same issues concerning
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WORKING GROUP SUMMARIES
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pollution and acoustic and electrical properties of the water column and sediments that are pertinent in estuarine harbors and approaches. The estuaries that make up the numerous harbors and approaches of the world are characterized by a great diversity of physical conditions and processes. This is true not only because there are many types of estuaries (ranging from shallow, tropical lagoons to deep, ice-bound fjords), but also because conditions within individual estuaries are extremely variable in both time and space. Salinity in a fjord may vary, for example, from zero to oceanic values across the main halocline over a few meters in the vertical direction. Salinity variability of the same magnitude may occur over a tidal cycle at a single point in space as a result of tidal advection in a saltwedge estuary. Turbidity in a river-estuary may vary over a few hours by a factor of more than 103 because of a storm or freshet. Thus, the circulation and the electrical and acoustic properties of the estuarine environment are more diverse than those of almost any other marine environment. Fortunately, much of this variability is concentrated at a few dominant frequencies. Circulation in river-estuaries, fjords, and many other systems is controlled by tides and/or fluvial input leading to dominant tidal daily, tidal monthly, and seasonal time scales. While the influence of river flow can be unpredictable in harbors with small tributary drainage basins, river flows in large drainage basins, and particularly in those having a substantial ratio of dam storage capacity to river flow, generally follow well-defined seasonal patterns. In contrast, the atmospheric forcing that dominates many large embayments (e.g., tropical lagoons and the Ob estuary in Russia) is predictable in a statistical sense only, e.g., storms are more frequent in some seasons. How should the oceanographic diversity of the strategically important harbors of the world be handled? It is clearly impossible to study all of them; they are too numerous, and most are within the coastal waters of nations that restrict research access. It is imperative, therefore, to make good use of available information concerning dominant time and space scales of forcing. Process-oriented studies must be carried out in representative and accessible systems that are analyzed in detail. These results must then be extrapolated in a conceptually sound manner to the many important, poorly known, and inaccessible systems of the world. Coordination with other programs that seek systems-level understanding of estuarine and coastal environments would also likely be productive. These include the Land Margin Ecosystem Research program funded by the National Science Foundation and the upcoming Land-Ocean Interactions in the Coastal Zone (LOICZ) initiative of the International Geosphere-Biosphere Program.
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WORKING GROUP SUMMARIES
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The variability of estuarine physical environments is reflected in biological processes. Supplies of nutrients and/or organic matter in many estuarine systems are very large relative to open-ocean values, allowing high biological productivity, a factor that strongly influences acoustic properties of water and sediment. Furthermore, estuarine biological communities are commonly, though not universally, structured by physical forcing and geochemical constraints rather than by biological processes such as competition or predation. Thus, the ecosystems that have evolved in river-estuaries, for example, are made up largely of organisms that can survive in an advection-dominated environment where the residence time of an average parcel of water (typically a few days) is much less than the generation time of most invertebrates and salinity is variable. For example, the Chesapeake Bay's ecosystem has been forced to adjust within the past several hundred years to summer anoxia imposed by high nutrient loadings. Although certain opportunistic species may appear in infrequent and unpredictable blooms, most estuarine biological populations respond to the patterns of physical variability discussed in the previous paragraph. This again points to the importance of understanding certain representative systems in some detail. We should not, as a consequence of a pressing need to deal with the short time scales directly pertinent to naval operations, lose track of the place of estuaries in recent geological history. This context is necessary to understanding the structure and evolution of estuarine ecosystems, their sedimentology, and (to the extent that channel morphology controls circulation processes) even their physics. Most estuarine ecosystems are young and rapidly evolving, because they have existed in their present form only since stabilization of global sea level about 5,000-6,000 years ago. Sedimentation rates are typically much greater than those in open-ocean environments. Estuaries on tectonically active coasts may change morphology rapidly enough to render bathymetric and tidal information obsolete within a few decades. Large expanses of bare tidal flats may become vegetated within a few years. A food chain based on large amounts of detritus exported from marshes may disappear and be supplanted by one based on river-borne detritus, with important consequences for water clarity and acoustic properties. Finally, because much of the world's population lives adjacent to estuaries, anthropogenic change is extremely important in determining the features of interest to naval operations. Estuaries are the part of the marine environment that is most accessible and susceptible to human manipulation. The direct effect of harbor dredging and construction in the form of jetties, channels, and breakwaters on tidal properties is the most obvious type of alteration. Entering the Columbia River (once the “graveyard of the Pacific”) through the maintained 48-ft navigation channel is a very different problem, for example, from that of navigating the former shifting, natural channel that had a controlling depth of 20 ft in a good year. Less direct but equally potent alterations must also be considered. Construction of the
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Aswan Dam, for example, utterly changed circulation, acoustic properties, and the sedimentation and ecosystem structure in the Nile delta. Industrial and sewage pollution in an estuary may cause a system to have completely different acoustic properties from those of nearby, unimpacted systems that would, in the absence of human population, be quite similar. Moreover, these anthropogenic changes are rapid relative to most natural changes-except perhaps those induced by tectonics. The possible use of flow regulation as a defensive weapon cannot be ignored altogether. Nationalist forces in China used dike breaches and subsequent flooding to immobilize and drown the invading Japanese during World War II, though at great cost to the native population. Artificial floods could also be used to increase stratification, decrease water clarity, and bury mines. Numerous possibilities for offensive use exist. Working Group Discussion The charge to the working group consisted of two primary tasks. The first concerned environmental information: What information is needed for littoral warfare operations, how is it presently acquired, and how can this process be improved? For the Harbors and Approaches Working Group, this issue served as a means to focus further discussion on the second topic, identification of research and development (R&D) priorities for littoral operations. Discussion in the first topic area resulted in the development of a list of information types (see Table 1). Review of this table suggested that consideration of research and technological priorities should be organized into three unifying topic areas, as follows: 1. Tides and currents 2. Acoustic and electrical properties of the water and sediment 3. Pollutant and other scalar transport. Bathymetric data serve as a good example of how a specific type of data fits into the overall topics listed above. Bathymetric data are needed for modeling of tides and currents in support of all four types of operations (ASW, AO, CMW, and SF). Such data would also play an important role in evaluating acoustic, electric, and pollutant properties of the water and sediment for CMW, ASW, and SF operations, whether this evaluation was carried out through numerical modeling or more qualitative methods. The most systematic and intensive need for these bathymetric data would, however, come from numerical circulation modeling programs. Thus, we associated bathymetric data acquisition and database storage with the first research area, tides and currents. Each of the other information
Navigation, planning, mine burial MCM Detection, sonar performance, NSW counter detection
GFMPL = Geophysical Fleet Mission Program Library NSW = Naval Special Warfare SeaWiFS = Sea-Viewing Wide Field Sensor
Bottom composition and transport Acoustic Properties
Table 1. Oceanographic Parameters for Littoral Warfare: Harbors and Approaches Why and How Used Parameter Currents Mission planning, operations, maneuvering Tides (heights) Mission planning, operations Pollution Mission planning, protective gear, effects on swimmers, clutter density Turbidity and color of water MCM - visual identification, NSWSubmersible operations Bathymetry Navigation, planning, rehearsals Remote sensing, SeaWiFS, LANDSAT Laser, LANDSAT, better resolution needed NRL's Remote Survey Systems
Transmissometers, laser prototypes Charts, surveys, notice to mariners In situ during operations surveys, charts MCM Sonar Performance model, data acquired on site
Additional Information Available Availability of barotropic models
Current Means of Acquisition Sailing directions, pilots GFMPL, tide data base Not available, intelligence
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WORKING GROUP SUMMARIES 15
Magnetic field specification Navigation, density effects SDV operations (Covert), MCM maximum ranges Covert swimmer operations, safety, sonar performance Navigation, safety, covert, MCM operations Planning, parachute operations (winds critical), boat, ship navigation, safety Planning, detection, counter detection Planning, detection, navigation, night vision equipment Navigation, planning
IREP = Interactive Refractivity Environmental Prediction System MCM = mine countermeasures NAVO = Naval Oceanographic Office NODDS = Naval Oceanographic Data Distribution System SDV = swimmer delivery vehicle
Ice
Atmospheric Refractivity Solar/Lunar
Waves Meteorology
Ambient Noise Bioluminescence, Biologics
River Flows
Satellite, intelligence
“OA” Division, NODDS GFMPL, PC-based Tables
Not available Not used NAVO equipping ships to collect bioluminescence “OA” Division Limited applicability, resolution “OA” Division NODDS
Intelligence, Army Terrain Analysis Center, surveys
Range dependent IREPS needed
Remote sensing (airborne) Require higher resolution models
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WORKING GROUP SUMMARIES 16
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types can similarly be assigned to one or more of the three topics listed above. The remainder of this report is organized, therefore, in subsections focused on these areas, followed by a section presenting our Summary and Conclusions. It is important to note the considerable overlap of the above three topics with the traditional research agenda of the estuarine oceanography community: there is both good and bad news here. The good news is that the present state of knowledge in estuarine oceanography will allow rapid improvement at low cost insome areas, particularly the prediction of barotropic tides and currents. The bad news is that certain problems in estuarine oceanography have not been resolved by several decades of research and are of considerable fundamental difficulty. Transport of pollutants, sediments, and other materials is in this category. Consider as an example the transport of suspended matter that determines the optical properties of the water column and, in many environments, the character of the seabed itself. Existing sediment transport models uniformly fail to consider the effects of horizontal gradients in suspended sediment concentration. The rheology of liquid mud (a nonNewtonian fluid), the erosion and deposition properties of cohesive sediments, and the kinetics of particle aggregation as a function of shear, biological activity, and stratification are all poorly understood. Clearly, a sustained research effort will be required if functional models of estuarine suspended sediment transport are to be developed. Tides and Currents Improvement of knowledge in the area of tides and currents was the subject most thoroughly treated by the Harbors and Approaches Working Group. Ideas for improved prediction of tides and currents were separated into four categories: planning, operations, research problems, and desirable technology. An important conclusion for both planning and operations was that substantial improvements could be made in the near future with a relatively low investment of funds, on the basis of the existing understanding of estuarine circulation and of present models of barotropic tides and currents. There are two primary needs on the planning level. First, an estuarine classification system based on hydrodynamics should be developed that would allow division of most of the harbors and approaches of the world into about a dozen categories (e.g., lagoons, river-estuaries, weakly stratified and partially mixed bays, tidally forced fjords, and weakly forced fjords). A small suite of parameters (e.g., ratio of semidiurnal to diurnal forcing, tidal range to depth, river flow to tidal velocity, and estuary length to tidal wavelength) would then be used to place estuaries in these categories and a slightly larger number of subcategories. Representative estuaries from around the world would be classified as to category and subtype. Additional systems could be added as they became operationally important for new or potential operations. This categorization could be used focus
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research into types of estuaries deemed to be of strategic importance and would be useful for operational purposes. This classification system would be very useful in identifying the primary sources of variance in the velocity and surface elevation, and would (as discussed below) provide additional information concerning density structure and scalar transport processes. Following is an example of the practical utility of such a system. Suppose that the barotropic tidal models discussed in the following paragraphs have been run for a particular harbor of interest, but that the river-flow and bathymetric data used in the model were of poor quality, and therefore the predicted tides and currents were of dubious validity. How much effort should be put into improving these predictions? Improvement options might include processing of remote-sensing data, covert installation of pressure gauges (not possible now, but certainly feasible in the near future), and on-site intelligence operations. If, on the one hand, we know that the system is a macrotidal river-estuary, then further efforts might well be merited, because 60 to 90 percent of the total velocity variance in such systems is normally associated with tides and river currents. If, on the other hand, the system is categorized as a hypersaline, microtidal tropical lagoon, where typically 60 to 90 percent of the current variance is related to atmospheric forcing and density currents, then further refinement of a bathymetric tidal model would likely be pointless, but modeling of wind and density-driven circulation might be imperative. A considerable improvement in the tide and current predictions presently available for many estuaries could be made by systematic application of existing tidal models on various scales. The methodology has been well proven in systematic tests in the North Sea [see Waiters and Wemer (1991) for a review]. In practice, a largescale, regional, barotropic tidal model would be run for an entire area of possible operations. Such a regional model would usually cover at a low resolution an area the size of the North Sea, or the coastal ocean from Northern California to the north end of Vancouver Island. This regional model would then be used to formulate the open boundary conditions for models of individual estuaries or related groups of them. Examples of riverestuary systems suitable for regional models would be the Rotterdam Waterway and the Puget Sound/Strait of Juan de Fuca/Straits of Georgia complex. The smaller-scale models may be either two- or three-dimensional, and adapted to the character of the particular estuary; such models might include, for example, wetting and drying of tidal flats, fluvial forcing, and sophisticated turbulence predictions, as appropriate. Given reasonable bathymetric data and proper boundary forcing, existing barotropic tidal models can predict tidal
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elevations within a few percent and barotropic tidal currents within plus or minus 10 percent. For many harbors and approaches, barotropic currents account for the bulk of the total velocity variance. In other cases--for example, river-estuaries-nonlinearities related to time variations in the density field create internally forced modes that greatly modify the barotropic tide. These differences again emphasize the importance of a classification system: it would allow identification of systems for which existing barotropic models are, or are not, adequate for current prediction of currents. A rather different modeling approach is needed within an actual theater of operations. The analogy to oilspill modeling is appropriate here. Model predictions must not only be accurate and timely, but the modeling system must be relatively easy to use and needs to be capable of being run with assimilation of observations in near real time. Experience with oil-spill cleanups suggests that if operational models do not have these characteristics, they will be ignored in favor of tide tables and seat-of-the-pants reasoning. Theater operational models should also be relatively small scale, and should run on microcomputers or work stations. They would be connected to large, regional planning models through a network. As data are acquired in the course of an operation, they should be incorporated into a geographic information system (or other similar) database and used to improve model predictions. Relevant data might include bathymetry, velocity profiles from shipboard Acoustic Doppler Current Profilers (ADCP), tidal elevation from moored pressure gauges, and information concerning sediment type and bottom roughness. These data should also be sent by network back to the regional planning center so that the larger regional model could also be modified as data were acquired. Prediction of tides and currents is straightforward for harbors and approaches only in the absence of strong interactions with other flow processes such as river flow, wind waves, and atmospherically-forced currents. If both tides and one or more of these factors are important in a system, the resulting interactions raise fundamental, unresolved questions in estuarine oceanography. Estuaries with both strong tides and strong river flow, for example, have time-varying stratification that drives substantial, nonlinear circulations that are poorly understood at present. Interactions of tidal currents with swell can substantially modify the tidal current and greatly increase wave amplitude. Prediction of these wave-current interactions is still an imprecise art. Better turbulence models that account correctly for mixing due to free-shear layer instabilities and internal wave interactions are essential to the construction of improved models of stratified tidal flows that could properly represent the nonlinear processes mentioned above. Analyses of time series of current and pressure observations need, furthermore, to be improved in light of recent advances related to nonstationary
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processes. Abrupt nonlinear transitions in stratification lead to major reorganizations of the tidal and residual circulations in many estuaries. The advection of a plume by storms and other coastal ocean processes leads to highly intermittent internal tides. These and other examples of forcing of tidal currents by a time-varying density field indicate that tidal currents cannot be treated as a stationary process in many systems. Conventional harmonic analysis programs can be modified to add any arbitrary number of frequencies (literally hundreds of them), but this does not lead to either conceptual understanding or predictive capability. It would be far more productive instead to use rapidly emerging methodologies for nonstationary time series; these go under the names “discrete wavelet transforms” and “short-term Fourier analysis.” Optimum use should also be made of large ADCP data sets in which the observations are distributed in space and time in such a way that they do not form proper time series. Here partial analogies to tidal analysis via satellite altimetry and other geophysical inverse problems should be kept in mind. Some methods of satellite data analysis may be directly pertinent to ADCP data. Existing harmonic analysis methods all minimize least-squared errors of predicted relative to observed currents. Because ADCP data are inherently noisy, this optimizes the fit to data plus noise. It would be better to follow the example of other areas of geophysics (Constable et al., 1987) and optimize some combination of leastsquared errors and smoothness. Finally, scalar data from harbors such as data on salinity, temperature, sound speed, and turbidity can be subjected to tidal analysis, although the available data will rarely be available as traditional time series. The art of modeling also needs improvement in several areas. Most presently available assimilative models, for example, make compromises in representing nonlinear processes that are unacceptable in estuaries with multiple forcing processes (e.g., tides plus river flow or wind stress). Better methods need to be developed to use numerical models to identify optimal locations for data collection. The cost of data acquisition in a theater of war is likely to be very high; thus, sensitivity analyses of models should be used to determine which data are most crucial. The working group also had several suggestions for improved technology. The single item most frequently mentioned was a pressure gauge that could be covertly deployed (e.g., from the air) and that would periodically transmit data to a satellite. A low-cost, expendable conductivity temperature-pressure-optical backscatter profiler would also be highly useful. It is worthwhile remembering that temperature and salinity gradients are a factor of 102 to 104 greater in estuaries than in deep ocean environments. Thus, cheap sensors may not be difficult to develop because they would need to discriminate among small changes in
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temperature and salinity. Such sensors would also be highly useful for underwater vehicles and drifters. Acoustic and Electrical Properties of the Water and Sediment Determination of the acoustic properties of seawater and various substrates is of vital importance to ASW and CMW because of their reliance on sonar. SF operations and AO depend on sonar to a lesser degree. The magnetic properties of the water column and seabed are a dominant consideration for CMW and are of some importance to ASW. Acoustic and magnetic detection methods are important for detecting mines as well as for detecting other bottom obstacles that may be “false targets” and, in some cases, can distinguish between the two. Acoustic properties of “blue water” environments relevant to the cold war ASW in past decades are entirely determined by the thermal structure of the water column. This is not the case in littoral environments in general, and particularly not in harbors and approaches. Salinity stratification and the presence of suspended sediment exhibit variability on a variety of time scales and may have a significant effect on water-column transmission and scattering of sound. Sediments in estuarine environments are also much more diverse and variable in time and space than they are in open-ocean environments. Just as salinity stratification may change radically over a tidal cycle as a result of advection on salt wedge, deposits of liquid mud may appear and disappear tidally, and their character may change over the tidal month and seasonally. This variability is reflected in sedimentary records from numerous coastal and estuarine environments that exhibit “varves” (sediment layers) indicative of tidal daily, tidal monthly, or seasonal variations. Sand waves, moreover, may form and disappear, or bury a mine in a single tidal cycle. At the other extreme, more quiescent estuarine environments (fjord basins, for example) may exhibit little or no variability over years or decades. Thus, it is vitally important to determine the likely time and space scales of variability for acoustic and electrical properties, exactly as was the case for tides and currents. Any sensible estuarine classification system based on hydrodynamics must deal directly or indirectly with the time scales of variability of the scalar fields that determine water-column acoustic and electrical properties. Existing estuarine classification systems do not, however, consider the relationship of flow properties to the character of the substrate. Sedimentological properties are more difficult to classify than are those of the water, because of the strong roles of regional geology and biology in determining the former. For example, we can expect a strong degree of commonality in circulation processes in river-estuaries around the world, but the same cannot be said for their substrates. Some large river-estuaries with strong
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tides are sand-bedded, because bed stresses are too high to allow muds to be permanently deposited. This is not the only possible sedimentary regime, however, for a strongly forced river-estuary. If the system is deep enough or the fine sediment load large enough, then very large concentrations may accumulate in the estuary. Density stratification induced by the suspended field reduces bottom stresses, and the seabed will consist primarily of silts and clays rather than sands. The realization that understanding acoustic and electrical properties of the water column and seabed in harbors and approaches overlaps substantially with traditional estuarine research objectives led to identification of a number of research issues. The importance of the estuarine density field in the tidal circulation was discussed in the previous subsection. Our understanding of estuarine sedimentology and sediment transport is less mature, however, than is that of tidal processes. While the present state of knowledge provides a basis for future research, it also emphasizes that sustained funding will be required to improve the present state of the art substantially. Cohesive sediment transport is particularly important, and is discussed below in the subsection on scalar transport. Here it suffices to note that sedimentary information acquired during the course of operations (e.g., from helicopter-towed sidescan sonar used in ASW) should be, along with hydrodynamic data, recorded in a database and assimilated rapidly into hydrodynamic models. The mine warfare tactical environmental display system (MTEDS) database was mentioned by the working group in this regard. Basic research is also needed on the low-angle acoustic scattering by sediments as a function of composition, porosity, degree of bioturbation, bedform character, and presence or absence of active sediment transport. The impact of sediment and water column geochemistry on aggregate seabed physical properties is as yet poorly understood, as are water column aggregation processes that play a vital role in the settling of organic material to the seabed. This material may be the result of in situ productivity, aquatic productivity elsewhere in the river-estuary system, agriculture in the tributary watershed, or industrial pollution. Moreover, recent research has emphasized the high numbers, diversity, and productivity of microbial populations in estuarine turbidity maxima. These bacteria play a major role in aggregation, and thus settling, of particles in many estuaries. Several potential R&D projects were also identified by the working group. These included development of a Doppler penetrometer and variable-frequency (“chirp”) sonars for seabed characterization. The latter would emulate dolphin sonar and would assist in the detection of buried mines that cannot presently be detected acoustically, except by dolphins. Tomographic methods analogous to those now used in medical imaging might also be adapted to mine detection.
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Pollutant and Other Scalar Transport Scalar transport is important to littoral warfare in several respects. Detection of pollutants (e.g., oil, fecal bacteria, and dissolved toxics) and predicting their likely transport are vital issues for SF operations, as was demonstrated in the Persian Gulf war. They are also an important considerations in the use of dolphins for mine detection. As discussed above, suspended sediment transport plays an important role in determining water column and seabed properties of interest to CMW and ASW. Several areas of recent estuarine research are relevant here. Studies of estuarine and shelf transport of both cohesive and noncohesive sediments have concentrated heavily on the deposition and erosion properties of sediment grains and aggregates. Aside from the influence of sediment stratification on turbulent mixing, little attention has been paid to the effects of circulation nonlinearities on the fate of sediments. Oil spill models are highly specific to petroleum products. Other pollutant transport investigations have tended to focus on the initial dispersion of pollutants from a source rather than on the long-term disposition of the materials in question. Investigations of scalar transport have focused on the relationship between wave transport of scalar wave variations (e.g., at the dominant tidal frequency) and the Stokes drift transport of the scalar mean field. These studies have shown that the frequencies at which transport occurs are strongly dependent on the scalar in question and on the type of estuary. In narrow tidal channels where vertical rather than horizontal shear is the dominant agent of dispersion, salt is transported landward both by the tides and by the mean, two-layer flow. Scalar transport is in general not chaotic for this case, although, of course, turbulent mixing adds a chaotic element to scalar dispersion. The direction and magnitude of scalar transport (e.g., of salt or sediment) is extremely sensitive, however, to shear in the velocity field and stratification of the scalar being transported. In contrast, scalar transport in broadly influenced, shallow embayments with complex topography exhibits, like other chaotic processes, an acute sensitivity to initial conditions. Even though it is deterministic, scalar transport cannot be predicted very far into the future in such systems, because the initial conditions cannot be specified with sufficient accuracy. Studies of these chaotic processes have considered (to date) only vertically uniform transport of conservative scalars. Theoretical understanding of scalar transport in more complex environments (e.g., fjords) that are both stratified and topographically complex is inadequate. Thus, several decades of research by scientists and engineers have brought about only a preliminary understanding and, in most cases, a rather rudimentary ability to predict scalar transport. The large number and diverse character of the world's harbors and approaches means that research efforts must focus on process studies in carefully chosen, representative systems. Again, the use of a hydrodynamically-based classification system is necessary for choosing
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representative systems for intensive, process-oriented studies. Pollutant transport is also an issue of importance in the Navy's Environmental Program. Sediment transport merits particular mention because of its importance in all aspects of littoral warfare. Recent advances in fluvial transport of mixed-grain, noncohesive sediments provide a solid base of knowledge for construction of sediment transport models for sand-bedded systems. Suspended-sediment transport is subject to the aforementioned flow nonlinearities, plus the complexities of deposition, erosion, aggregation, compaction, and (for liquid mud) a non-Newtonian response to imposed surface stresses. There are at present no adequate models of sediment transport, either of sand or cohesive sediments, in the estuarine environment. Shelf sediment transport models have elaborated in considerable detail the influence of wave-current interactions and sediment self-stratification on bed stress. They emphasize the exquisite level of detail required for successful treatment of deposition and erosion--about 50 model levels per decade in the vertical direction down to the roughness scale length for a total of 300 to 400 levels in all. This detailed representation has been accomplished, however, through the total neglect of lateral transport and its complexities. In contrast, estuarine sediment transport models have focused on horizontal transport processes and lack both sufficient vertical resolution and adequate turbulence models. Development of a capability to predict the transport, erosion, and deposition of fine sediments is vital, and will require sustained effort over perhaps a decade. Models of noncohesive transport could be achieved on a shorter time scale, because of the better level of fundamental understanding available at this time. Two R&D issues were also mentioned in working group discussions. Field detection kits for use in SF operations should be developed for selected pollutants. Pollutant detection capabilities should also be added to remotely-operated underwater vehicles. Summary and Conclusions Most of the harbors, approaches, and straits of the world are estuaries. As such, they are complex, extremely diverse environments subject to abrupt natural and anthropogenic alteration. Prediction of the properties of interest for naval operations will require an ecosystems approach that considers the couplings between biological, geochemical, and physical processes, and the ways in which alterations of these processes change the operational environment. Because of the diversity and large number of estuarine systems, a key element of a successful strategy for littoral warfare over the coming decades is to define an estuarine classification system based on hydrodynamics that will allow determination of
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basic properties of these diverse systems from a few external parameters. This classification system would provide a basis both for operational decisionmaking relative to environmental factors and for choosing productive research directions. Discussion of information needs, research directions, and potential technological developments to assist in the Navy's littoral warfare mission in harbors and approaches led to the definition of three primary topical areas that unified the previously identified information needs and served as a basis for further discussion. The three areas were tides and currents, acoustic and electrical properties of the water and sediment, and pollutant and other scalar transport. Research needs in these three areas overlap considerably with the traditional research program of estuarine oceanography. Substantial, short-term improvements can be made at relatively low cost in the prediction of barotropic tides and currents through systematic use of existing, robust numerical models. In some types of estuaries, barotropic tidal currents are either not important or are strongly modified by other processes, e.g., atmospheric forcing, time-varying vertical mixing processes, and surface waves. Practical prediction of currents in these types of estuaries requires substantial work. This is also true in the areas of acoustic and electrical properties and scalar transport; several decades of research have defined an agenda but have not resolved the major technical issues. A sustained, long-term research effort is required. References Cameron, W. M., and D. W. Pritchard. 1963. Estuaries. In: M.N. Hill (ed.), The Sea, Vol. II. John Wiley and Sons, New York, pp. 306-324. Constable, S. C., R. L. Porker, and G. C. Constable. 1987. Occam's inversion: a practical algorithm for generating smooth models from electromagnetic sounding data. Geophysics 52:289-300. Waiters, R. A., and F. E. Wemer. 1991. Nonlinear generation of overrides, compound tides and residuals. In: B.B. Porker (ed.), Tidal Hydrodynamics. John Wiley and Sons, New York, pp. 297-320.
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REPORT OF THE STRAITS AND ARCHIPELAGOES WORKING GROUP Dr. Michael Gregg, University of Washington, Chair LCDR Timothy Sheridan, Office of Naval Research, Cochair CAPT George Heburn, USNR/NRL(S), Assistant The constricted topography of straits often produces fast and variable currents and sharp changes in water masses. Consequently, flow through straits is usually characterized by (1) hydraulic controls in constrictions and over sills, (2) strong steering in channels changing direction, (3) density currents throughout the water column, and (4) focusing of surface waves both by the bathymetry and by winds steered by local topography. Intense human activity further complicates naval operations, particularly with shipping, fishing, and installation of cables and pipelines. Archipelagoes are yet more complicated, with many intersecting channels. Major Research Issues Synthesis of the Literature About Straits The existing literature on straits should be synthesized in a thorough review article published in a refereed scientific journal. This effort should include an attempt to classify straits using known parameters, including the following: • Geometry, straightness or crookedness, depth or shallowness, and relative importance of sills and constrictions • The importance of Earth's rotation, that is the internal Rossby number • Flow modulation, seasonally and tidally • The importance of hydraulic controls, given by Froude numbers, in constrictions and over sills • Hydrography, sources, and nature of water masses and types • Atmospheric forcing, importance of wind stress, and the surface buoyancy flux In addition, reviews should be done on particular straits where extensive work has been carried out--for example, Gibraltar.
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Process-Oriented Studies of Straits The goal is to understand the major processes controlling flow, temperature, and salinity in straits. So many straits are potentially important for naval operations that only a subset can be studied, and access for research is likely to be denied to some. Consequently, once a particular strait is identified during a crisis, predictions for naval operations must rely on available data and models incorporating processes known or likely to dominate that strait. Straits and processes chosen for further study should be chosen on the basis of the reviews recommended above, but several issues are apparent now. a. Internal bores and solitary waves are often generated when hydraulic control is lost as flow decreases--for example, every 12 hours in the Strait of Gibraltar when tidal outflow changes to inflow. Similar features are often found on continental shelves, propagating in from the sea. Although it is shown to be strongly turbulent, the rate at which they decay has not been determined. b. Bottom stress is likely to be a major factor in flow dynamics but is difficult to measure and was omitted completely from the Gibraltar Experiment. Later estimates obtained with Expendable Current Profilers (XCPs) and expendable dissipation profilers outside Gibraltar in the outflow plume disagreed by a factor of 3. c. How surface waves are generated and focused in straits has not been studied. This is important during minesweeping, as estimates of bottom pressure are used determine the likelihood that other factors can trigger mines. d. Secondary circulations. Most straits have strong secondary flows, across or counter to the main flow. Sometimes accurately described in local pilots, these features are likely to be important to the dynamics of the strait, but are poorly known and have not been studied systematically. e. Bottom morphology and sediment dynamics strongly affect bottom stress, acoustic propagation, and mine warfare. It needs to be known whether there are general scientific issues other than those about bottom features in general. Modeling Issues Modeling flow through straits has not received the attention given to modeling ocean basins and continental shelves. Several general issues should be addressed: (1) How should flow be modeled in a channel connecting two water bodies without simultaneously modeling those bodies? (2) What scale of bathymetry should be included to describe the dominant flow, and what numerical schemes are needed to model abrupt changes in depth? (3) How can subgrid-
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scales processes be included, as they differ greatly from those in the open ocean? (4) How can models be adapted to predict stochastic variability instead of dealing only with deterministic flows? Instrumentation Issues Available instruments are not adequate for either academic or naval measurements; the same type of instrument needs are common to other coastal regimes. Short space and time scales require making measurements at many places and times. Existing capabilities need to be available in packages that are smaller, cheaper, easier to operate, and in some cases capable of covert deployment. Nearshore salinity often dominates both density and sound speed profiles. It is essential, therefore, that naval forces measure salinity when conducting antisubmarine operations or sweeping mines. Adding a dipping conductivity-temperature-depth (CTD) package to minesweeping helicopters is one step that appears feasible with minimal development. Valuable data are being lost when minesweeping helicopters fail to record output from their sidescan sonar. When coupled with positions from the Global Position System (GPS) receiver, these data can be used to characterize the detailed bathymetry and bottom type. Process studies are limited by the difficulty of measuring bottom stress. ADCPs with standard beams oriented 45 degrees from vertical usually do not return useful data from within the lower 15 percent of the water column. ADCPs with beams oriented at 20 degrees from vertical can measure within 6 percent of the bottom, and sophisticated processing can further improve resolution. Nevertheless, full resolution of the bottom boundary layer requires mounting sensors on the bottom or dropping XCPs, which are presently too expensive for the spatial and temporal resolution required. Archipelagoes All issues about straits apply to archipelagoes. No less important to the Navy, archipelagoes are much more complex. Consequently, the working group believes that further progress in research on straits should contribute to the understanding of flow behavior in archipelagoes. Summary and Conclusions The Straits and Archipelagoes Working Group recommended that a number of issues be addressed as the Navy prepares for future littoral warfare. First, they
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recommended that a classification system be developed for the straits of the world. Existing information about straits should be compiled and published for scientific examination. Process-oriented studies of straits must be designed to understand the key processes that control flow, temperature, and salinity in straits. A variety of strait types, identified according to the new classification system, should be studied to permit extrapolation of the information to other straits that have not been studied in detail. Processes that are particularly important to study in straits include the generation of internal bores and solitary waves, the effect of bottom stress on flow dynamics, how surface waves are generated and focused, how secondary circulations develop incidental to the main flow, and the effect of bottom morphology and sediment dynamics on bottom stress and acoustic propagation. The working group identified several other studies related to modeling flow through straits and the information needed to study straits. Archipelagoes are, in essence, series of straits, so that the study of straits is fundamental to understanding the more complex situation in archipelagoes.
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REPORT OF THE SURF ZONE WORKING GROUP Dr. Stephen Elgar, Washington State University, Chair LTCOL John Cassady, SWDG, Cochair CDR Harry Selsor, USNR/NRL(S), Assistant Introduction For Navy purposes, the surf zone encompasses the region from about 10-m depth to the dune crest on the beach, an area called the nearshore by the academic community. This harsh and rapidly changing environment must be exploited to full advantage by naval forces operating in the littoral region. One objective of the Surf Zone Working Group was to determine whether academics, primarily in the basic research (6.1) program funded by the Office of Naval Research (ONR), could help provide solutions to practical Navy problems. The working group concluded that academics could help. This report contains recommendations for assisting naval forces both immediately and in the long term. Short-term solutions should be passed directly to the technology arm of ONR for quick implementation, whereas the longer-term recommendations may influence the direction and scope of 6.1 research programs. This working group report starts with brief descriptions of the nearshore from academic and Navy points of view. There is considerable overlap between the processes studied by academics and the environmental information needed by the Navy. The most critical environmental needs and possible approaches to meeting these needs are discussed next, followed by a summary of the working group recommendations. The Nearshore from an Academic's Point of View The three-dimensional circulation in the surf zone is driven primarily by breaking waves. Sediment movement associated with oscillatory and quasi-steady currents often are strong enough to produce rapid (on time scales of a day or less) and significant changes in the seafloor morphology. The changing bathymetry in turn affects the three-dimensional nearshore circulation both by creating spatial variability in the intensity of wave breaking and by modifying the bottom roughness. A long-term objective of ONR 6.1 research is to understand the feedback between complex topography, waves, and the three-dimensional circulation. Significant progress has been made toward understanding important aspects of the fluid dynamics of the nearshore. The detailed evolution of normally incident waves propagating over plane parallel contours toward the breaking region has been successfully modeled with the Boussinesq equations. The wave height
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and mean alongshore and cross-shore currents in a surf zone with planar bathymetry can be predicted accurately by existing models initialized with wave fields measured just outside the breaking region. Ongoing research is directed toward extending these predictions to include waves approaching the beach from several different directions and to include beaches with complicated bathymetry. Additionally, wave breaking, swash processes, bottom boundary layers, and the generation of infragravity and far infragravity waves are subjects of ongoing 6.1 research efforts. The response of sediment to fluid forcing is less well understood than the fluid forcing itself. However, recent ONR 6.1 programs have focused on small-scale nearshore processes, especially on the details of sediment suspension and transport in response to nearshore waves and currents. Other 6.1 programs are studying the evolution of bedforms and the overall beach morphology. The development of a predictive capability for the coupled fluid-sediment nearshore system, spanning a range of scales from the suspension associated with the passage of individual waves to the seasonal migration of large sandbars, is a long-term research effort. The Nearshore From an Operational Point of View Operational naval forces require knowledge of surf zone processes occurring on time scales ranging from hours to months. On time scales of a few hours, the bathymetry and wave field often does not evolve significantly, and thus only a snapshot view of the environment is needed. On the other hand, for longer-term planning, an understanding of the evolution of the nearshore system, including the coupling between waves, currents, and bathymetry, is needed. The choice of assault site requires information about both large and small spatial scales. On the larger scale (greater than 1 km) there can be extreme variations in waves and currents along the coast, often due to changes in coastline orientation or offshore bathymetry, and methods to predict this variability are needed. On smaller scales, natural beaches often show strong flow and bathymetric variability over several hundred meters. Since assault corridors are much narrower than this, small-scale variability as megaripples to bar migration, can cause rapid (hours to days) mine scour, redistribution, or burial. Environmental Data Needs The working group discussed the following environmental factors and processes identified by the Navy as relevant to nearshore operations:
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WORKING GROUP SUMMARIES
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Bathymetry from 10-m depth to the high-tide line Waves and currents across the nearshore Shelfwide propagation of surface gravity waves Acoustical properties Sea level (tides, shelf-scale waves, storm surge, wave setup) Trafficability information Optical clarity
The working group discussions (summarized below) focused on ways of significantly improving existing capabilities rather than meeting predetermined levels of accuracy, and included long- and short-term approaches and both direct measurements and modeling of environmental parameters. Bathymetry The nearshore bathymetry influences many surf zone processes important to amphibious operations, including the spatial distribution of wave breaking and wave-driven steady currents. Beaches with low-tomoderate wave energy (which are the most likely landing sites) exhibit alongshore variability on many scales, often roughly 250 m. Wave heights, currents, beach slopes, and overall bathymetry may thus be somewhat “selectable” within a rather small alongshore stretch of coast. The movement of bedforms over an area can result in scour followed by deep burial of surf zone mines. Knowing when and where these bedforms occur and how they evolve may thus help assault planning. No reliable models exist for predicting surf zone bathymetry and its evolution, and thus the bathymetry must be measured, at present by SEAL hydro-reconnaissance teams (a difficult and dangerous task). Several alternative techniques were discussed. Blue-green lasers appear to be useful for bathymetric measurements when water in the surf zone is clear enough, and presumably will continue to be developed in the more applied (6.2 and 6.3) ONR research programs. Land-based video imagery is presently being used to estimate the surf zone width, gross nearshore morphology (location of submerged sandbars and rip channels), and wave celerity (directly related to depth in shallow water). Further refinement of these techniques, and adaptation to airborne or even high-resolution satellite platforms, appears possible with a short to mid-term effort. Additional suggestions were made by the working group for techniques using autonomous underwater vehicles (AUVs). For example, a small, bottom-following AUV could ease the logistics and danger of bathymetric reconnaissance. Suggestions were also made for better instrumentation (e.g., GPS and pressure sensors) to improve the quality of SCUBA-based bathymetric measurements. Finally, synthetic aperture radar (SAR) and electromagnetic bathymetric survey methods were mentioned, although the working group lacked expertise in this area.
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Present models for the evolution of nearshore bathymetry are inadequate for operational use. A continuation or increase in the efforts of the 6.1 program to understand bathymetric evolution was recommended as the best long-term approach to providing predictive capabilities. To provide a shorter-term solution, the working group suggested that beaches worldwide be classified, and representative U.S. beaches be selected as analogs or archetypes. These analog beaches could then be studied intensively to determine the typical patterns of bathymetric evolution and the associated waves and currents. The use of analogs appears to be the approach used in the Mine Warfare Pilots, although most academics have never seen these publications. The development of beach archetype systems would be severely hampered by the very poor spatial coverage of the outdated data set of worldwide nearshore bathymetries (which apparently is not available in a computer database). Waves and Currents Wave and current estimates based on SEAL reconnaissance provides only a gross estimate of conditions. Moreover, fixed-instrument deployments from many sites show that estimates of wave height or current based on very short time periods are not useful because conditions can fluctuate greatly in a few minutes (e.g., wave grouping may cause large sets of waves every several minutes). The deployment of instruments across the nearshore at the site of operations is rarely feasible, and thus predictive models, initialized with offshore measurements, must be used. The current Surf Forecast model accurately predicts the wave height transformation across the zone on unbarred, alongshore homogeneous beaches. Specific goals of the present 6.1 research program include extending models for waves and currents to beaches with complex bathymetry, studies of wave breaking, and the inclusion of low-frequency flows in model predictions. Technologies for measurement of the wave field outside the surf zone are readily available. Robust, easily deployed single pressure sensors can provide wave data for initializing models for wave heights in the surf zone. Wave directional data necessary for predicting alongshore currents can be acquired by small arrays of a few pressure sensors that have been successfully deployed for over a decade. Working group discussion of new techniques for acquiring measurements within the surf zone largely centered on remote sensing, including SAR, interferometric SAR, video, radars (including X-band Doppler), and active acoustic Doppler imaging of the nearshore current. However, none of these has yet been used extensively in academic research.
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Shelfwide Propagation of Surface Gravity Waves Models predicting surf zone waves and currents are now routinely initialized with wave data obtained just seaward of the breaking region. Initializing the models for many possible landing sites requires a prohibitively large number of observations. However, given measurements of the wave field at a few representative deepwater locations, models for wave propagation across the shelf could provide estimates of the wave field over the entire shelf and near the surf zone. The processes important to surface wave evolution across the shelf are probably different from those in very deep and shallow water depths, and are yet not well understood. Some development and testing of shelfwide wave models is ongoing. Acoustical Properties Although acoustical techniques may be useful in the nearshore region, much research is needed to evaluate the environmental parameters necessary for their use. There is large variability of acoustical propagation on short and long time and space scales in the surf zone. The stochastic refractive properties of the nearshore need to be determined. Environmental factors affecting acoustical propagation include attenuation owing to breaking-waveinduced bubbles, suspended-sediment concentrations, and the presence of organisms. Scattering from the bottom and the surface also need to be investigated, as well as the physics of propagation in water depths less than onehalf wavelength. Sea Level Existing constituent models for tidal elevation need sea-level data of only a few weeks' duration to predict the barotropic tide at a new site. Such data may be available from satellites or could be collected by the clandestine deployment of submerged pressure sensors (which would also provide very useful wave data). Lowcost pressure sensors are available commercially, and could be configured to collect wave and tide data in a submerged package that would pop to the surface to transfer the data via satellite. Additional nearshore sea-level fluctuations as large as 1 m can be caused by shelf-scale processes (e.g., shelf waves, eddies, large-scale currents, and storm surge), and should be incorporated in planning. Trafficability A saturated slurry region is often observed at the base of the swash zone of steep beaches, and alongshore variability of geotechnical properties has been observed on the scales of beach cusps (25 m) and beach rhythmicity (250 m). Although these observations may be relevant to beach trafficability, the academics scientists in the working group had little experience with beach trafficability, and this problem is not part of the current 6.1 research program. Suggestions were made regarding the use of passive and active acoustics and SAR to investigate
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processes relevant to beach trafficability such as soil properties, sand depth, and moisture content above the water line. Optical Clarity Water clarity, important for operation of several instruments that obtain nearshore environmental data (e.g., bathymetry), is determined by a suite of factors ranging from biological productivity to freshwater runoff. The working group did not have sufficient expertise to make recommendations concerning this complex and multidisciplinary subject area. Working Group Recommendations Recommendations for increased Navy use of nearshore science and technology to meet operational needs, discussed in the previous sections, are summarized and expanded upon here. Some of the recommendations were developed during postmeeting discussions. Instruments Amphibious and SEAL operations do not utilize modern instrumentation adequately. A number of technologies commonly used in university research could be transferred rapidly into Navy use. One of most important is the incorporation of bottom-mounted pressure sensors (and associated telemetry systems) for measurement of wave height and direction. Additionally, several remote-sensing technologies could be transitioned within roughly two years, including video estimation of sandbar morphology, beach face slope, and surf zone width. Radar and SAR are promising techniques for very wide area coverage of wave properties. With suitable packaging, GPS and pressure sensors could probably be combined into a SEAL-borne bathymetric profiling system with much greater accuracy than available with the present system. Surf Zone Bathymetry and Currents An empirical approach to understanding the evolution of the nearshore system can be initiated through the study of archetypal beaches. The bathymetric data required to begin such a study should be acquired through an immediate increase in the surveying of beaches in appropriate locations. However, although bathymetric data alone are valuable, they will not meet the long-term goal of developing a full modeling capability that includes waves, currents, and the bathymetric response. This goal is being pursued in the 6.1 research program. Presently, most field investigations of fluid motions on a three-dimensional beach and the sediment/bathymetric response are largely restricted to the Army Corps of Engineers Field Research Facility in Duck, North Carolina, the only U.S. field site with the tools--that is, the sophisticated survey systems, four-wheel drive forklifts
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and amphibious vehicles, boats, beach-based electronics labs, exclusion of surfers, and so forth--needed for the research. There are many beach types in the continental United States, some of which could serve as suitable archetypes and help generalize the research conducted in North Carolina to other sites. Continuing nearshore research programs could be conducted at assault exercise sites (e.g., Little Creek, Virginia and Camp Pendleton, California), in coordination with landing exercises, allowing fuller evaluation of the environmental conditions during the exercises. Moreover, these secure sites are ideal for studying mine burial and scour, presently unpredictable even when the waves, currents, and bathymetry are fully known. Although extremely variable over alongshore distances of a few kilometers, coastal wave heights can be predicted by combining a few wave observations in deep water with meteorological information and wave models. However, the existing models have not been well validated. Efforts should be focused on the development and validation of models predicting the regional-scale variability of surface gravity waves. Summary and Conclusions The Surf Zone Working Group made recommendations about research and development needs related to improving our abilities to measure and understand the processes controlling nearshore bathymetry, waves and currents, shelfwide propagation of surface gravity waves, acoustical properties, sea level variations, and “trafficability” through the surf zone. The working group noted that several instruments now used in academic research could be used by the Navy to improve littoral zone environmental prediction, and thus Navy operations. Examples include bottom-mounted pressure sensors and remote sensing techniques that allow characterization of wave features and variability. The working group also recommended that the Navy pursue an empirical approach to understanding the evolution of nearshore systems by studying a set of archetypal beaches.
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REPORT OF THE CONTINENTAL SHELF WORKING GROUP Dr. Susan Henrichs, University of Alaska, Chair CAPT Franklin West, Jr., U.S. Navy (Ret), Cochair Mr. Philip Vinson, CNO (N096), Assistant Environmental Information Needed to Support Special Operations, Mine Warfare, Antisubmarine Warfare, and Amphibious Operations Several groups of experts have already listed the environmental information needed to support littoral operations. With a few additions by the working group, these are summarized in Table 2. An asterisk (*) in the table marks environmental characteristics identified by the working group as particularly important research topics with respect to the continental shelf. Table 2. Environmental Factors That Affect Naval Operations in the Littoral Zone Atmospheric • Weather
• Sun glint/glare
- Clouds, fog - Precipitation - Wind speed and direction - Air temperature
* Marine boundary layer properties - Temperature - Humidity - Refractivity - Evaporative duct height - Aerosols
• Particulate matter • Ambient light Biologic • Ambient noise • Scatterers and false targets • Optical scattering * Bioluminescence
• • • •
Reefs, kelp, etc. Biofouling Hazardous animals Fish and marine animal behavior
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Oceanographic • Tides
* Optical properties (vertical and horizontal) * Absorption (dissolved and particulate organic matter)
-Effects of local wind stress • Internal Waves * Currents -Surface -Subsurface
• • • •
Turbidity Bottom pressure Ice conditions Bubbles
• Water temperature * Salinity/conductivity -Freshwater run-off • Sea state • Wave height and direction • Surf conditions Bathymetric and Topographic • Bottom and beach slope • Beach composition • Bathymetric features
• Rivers and estuaries • Harbors • Coastal terrain
- Reefs - Bottom obstructions
- Soil types - Vegetation types
Acoustic * Scattering and reverberation * Sound speed profile
• Ambient noise * Transmission loss
Geophysical/Magnetic * Bottom roughness • • • • •
Bottom type Sediment property gradients Clutter (acoustic and magnetic) Sediment conductivity Sediment gases
• Geoacoustic properties * Bottom strength and stability • Pressure wave transmission (Shock wave propagation) • Ambient magnetic background * Ambient electrical background
Anthropogenic * Pollution • Noise
• Obstructions • Bottom clutter
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Littoral Operations Requiring Environmental Data, Data Presently Available, and Additional Data Requirements Cross-Cutting Issues Cross-cutting issues affect all, or at least more than one, type of naval operations in the littoral zone. Environmental or data-gathering issues that are more specific to mine countermeasures, antisubmarine warfare, special operations, or amphibious warfare are discussed in separate sections below. Sufficient characterization of coastal regions is needed to permit advance operational planning. For example, the range of weather conditions, currents, water temperature and density, or bottom conditions that might be encountered could be provided, along with information on probabilities of encountering environmental conditions within that range. Such information should indicate correlations or cause-and-effect relationships among environmental variables. For example, a change in wind direction could lead to changes in sea surface currents and in temperature and salinity distributions. At present there is a limited understanding by naval personnel of nonacoustic environmental information and how it could be used in making tactical decisions. For example, the appropriate tactical response to information on the distribution of bioluminescence, suspended particulate matter, or zooplankton and nekton is not clear. Research to provide more and better environmental information is a vital first step, but this must be coupled to education of naval personnel in the use of the data. There is a general need for performance prediction and assessment for all sensors deployed in naval operations, but in particular for sonar and radar. The availability of information on the accuracy of sensors under any given set of environmental conditions is one key aspect. Also, important, of course, is the availability of the necessary environmental data. Another priority is the minimization of risk to naval personnel, which in general also means that an increased capability for assessment and prediction of environmental conditions is needed. In addition, new remote or robotic approaches to operations such as covert data gathering and mine detection and neutralization must be developed. One of the most difficult problems in environmental prediction and assessment is the conditions encountered by advance personnel such as special forces and amphibious forces. By their nature, these forces must enter areas that have not recently been accessible for study except by remote sensors. Workshop participants indicated a need, in general, for instruments that can measure key environmental properties during naval operations and provide useful
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information in real time. Ideally these instruments would be small, rugged, and compatible with a variety of platforms, including helicopters, surface ships, submarines, and AUVs. Both passive and active sensors should be considered. Expendable or highly portable instruments would be especially valuable to advance forces. Because of the spatial and temporal variability of the littoral zone and because of rapidly increasing datagathering efforts and capabilities, data handling, archiving, and dissemination will require new approaches. It simply will not be possible for the Navy to retain all the data that will become available. The high temporal and spatial variability of the continental shelf will require assimilation of different data sources, with different spatial and temporal resolution, into databases. Assimilation of data, with varying resolution, into models and “nesting” of high-resolution littoral models into lower-resolution oceanic models also pose significant problems. Issues that must be addressed include these questions: (1) What kinds of data are needed, at what spatial or temporal resolution? (2) What quality-assurance and quality-control procedures should be implemented? (3) What is the required spatial and temporal resolution of models? (4) What is the required accuracy of model predictions? (5) How can data or model predictions be provided to naval personnel, rapidly and in the most useful form? Mine Countermeasures Mine burial prediction models, including the processes of burial due to impact, scour, migrating sand ridges, and deposition, require development or improvement. At present, impact models are the only type available, and they do not provide sufficiently accurate predictions. A better fundamental understanding of benthic boundary layer hydrodynamics and sediment transport is essential. Data needed to constrain such models is also lacking; new, high-area-coverage remote-sensing techniques to gather the required data are needed. Mine detection and classification, especially for buried mines, remains a challenge. Acoustic techniques have promise, but environmental information is essential for developing and predicting the performance of these sensors. Such information is needed on the following subjects, for example: spatial and temporal coherence of the medium; ambient noise from breaking waves, bubbles, organisms, or precipitation; volume scattering due to bubbles or suspended particles; and the shock wave propagation mechanism in sediments. For high-frequency mine classification, information on density, microstructure, and internal waves is needed. The potential of magnetic and electrical sensors needs further evaluation.
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For all mine detection, classification, and neutralization operations, there is need for a package of selected environmental sensors that can be deployed by various platforms and which will operate unattended for several days. This capability would provide information about the temporal variability of the selected parameters. The suite of sensors would need to include magnetic and acoustic sweeping gear and output detectors for determining whether the sweeping gear was operating up to specifications. The package should be deployable from iron surface ships, helicopters, submarines, and Sea, Air, and Land (SEAL) special warfare units, or installed on AUVs. Antisubmarine Warfare Both passive and active sonar performance prediction and assessment capabilities in shallow water are essential, even if extensive local databases are not available. For low-frequency detection, in the range 20 to 200 Hz, bottom loss and reverberation must be better understood to yield improved range predictions. Hydrophones on the bottom will respond to various interfacial waves that travel on or near the water-sediment boundary. Will this phenomenon provide useful information, or should the hydrophones be deployed above the bottom to reduce this signal? Shallow-water acoustic ducting, when it exists, is critically important to submarine detection and localization. There is a need for more historical and synoptic knowledge of when and where such ducting might occur. Ships or submarines may stimulate organisms to emit acoustic signals. Understanding of this phenomenon could lead to a new means of passive detection. For active sonars at medium frequencies, measurement and prediction of reverberation are important problems. If the sound speed profile is neither positive nor strongly negative, the sound field will depend on bottom reflection and scattering coefficients, which depend on bottom composition and roughness. These could be determined experimentally in selected areas. Another key environmental characteristic is the distribution of organisms in the water column. A means of covertly assessing volume scattering is needed, as well as predictive models. It is not known whether shallow-water acoustic field calculations using 2.5-dimensional models will be sufficiently accurate or whether three-dimensional models will be required. High-frequency volume attenuation in shallow water will limit or enhance certain acoustic detection techniques. There is need for more historical and synoptic knowledge of such attenuation values at frequencies of 25 to 300 kHz. Single acoustic probes should be evaluated for collecting essential data in remote areas. For example, can an approximate sound speed profile and bottom reflection and scattering coefficients be obtained from a single explosive charge
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WORKING GROUP SUMMARIES
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and receiver? Also, useful information might be obtained by means of active sonar devices, for example, expendable “pingers.” Passive or relatively undetectable atmospheric sensors for forward data collection would be useful. Sensors capable of measuring vertical temperature and humidity profiles along a path to a potential target have particular application to ASW, allowing prediction of evaporative duct height or submarine electronic sensor module capability and vulnerability. Such sensors could also allow range-dependent Radar/radar sensor module performance predictions. Aerosols impact the performance of infrared, visual, and laser systems. Vertical total wind profiles are needed to predict aerosol distributions. Sea surface roughness affects the performance of radar and optical sensors. A potential new approach to assessment is the use of over-the-horizon radars, modified from those now used for drug interdiction. Special Warfare and Amphibious Operations Assessment and prediction of subsurface currents is a particular need for the Naval Special Warfare Command, although they are also important to other aspects of littoral warfare. Hull-mounted or bottomdeployed (and upward-looking) ADCPs can provide extensive current data over depth profiles of up to about 300 m, although there are two practical limitations to widespread use, cost and data management, that must be overcome. Prediction, especially of high-frequency variations in currents, will require an improved fundamental understanding of shelf dynamics. Density fields and variations due to processes such as internal waves are important to special operations. These affect activities such as exit of divers from submarines. Assessment of density is straightforward, but, again, prediction of temporal and spatial variations will again require improved understanding of fundamental physical oceanographic processes. Marine life is much more abundant in the littoral zone than in the open ocean, and thus biological factors have more influence on littoral naval operations than those in the open ocean. However, present knowledge of several important biological phenomena is inadequate. For example, bioluminescence stimulated by turbulence can either be a useful tool for tracking hostile vessels or a dangerous “marker” of the Navy's assets. In either case, at present the distribution of bioluminescent organisms in space and time is unpredictable. There are no strategies available for avoiding or mitigating bioluminescence, or, on the other hand, for exploiting it. Other biological phenomena with potential operational significance include biological obstructions such as reefs and kelp beds, alteration of bottom-sediment physical properties and stability by benthic organisms,
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WORKING GROUP SUMMARIES
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biofouling of mines to avoid detection, and biofouling and resulting impaired performance of deployed sensors. Pollution is of concern to special forces and amphibious operations from several perspectives. For example, divers or amphibious personnel may be exposed to hazards due to poor water quality. Diseases such as cholera can be contracted by swimming in sewage-contaminated waters, and some coastal waters may be contaminated with highly toxic industrial wastes. On the other hand, negative impacts on public opinion can result if naval operations cause environmental damage. Research Needs Overview The environment of the littoral zone is distinct from that of the open ocean, and it presents many special challenges to naval operations. For example, radar, sonar, and other sensors developed for use in the open ocean are less effective in the coastal ocean. To adapt these to use in continental shelf regions, more and better information on the environmental factors that govern sensor performance is needed. Development of new sensors, or sensors newly applied to Navy problems, could be of great value. However, in some cases, research to characterize the environment is an absolute prerequisite to sensor development. Research to understand better the fundamental oceanographic processes responsible for key environmental variables must underpin research targeted on specific problems such as sensor performance in a particular region. More and better environmental data from littoral zones is needed, but it is even more important to place these data in a context of research that will lead to an understanding of the processes which yield and interrelate atmospheric, oceanic, and seafloor properties. Research effort should initially concentrate on the collection of data required for better understanding of shelf processes and for the development of modeling capabilities. Work can then proceed to the development and validation of coastal ocean prediction systems, which incorporate enhanced models with the capability to assimilate environmental data. Sufficient knowledge of the littoral environment to predict the usefulness of new or improved sensors must be obtained before substantial effort is expended on sensor development. Although many examples of this need could be given, the working group discussions focused on underwater electromagnetic field measurements and remote sensing of salinity.
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Electromagnetic Field Measurement One of the more promising shallow-water surveillance and mine countermeasure technologies is based on the detection of the electromagnetic fields produced by ships and submarines. These fields are generated by corrosion-electric currents due to the dissimilar metals used in the hull and shaft/screw, and may be enhanced by passive and/or active anticorrosion efforts, for example, by the use of sacrificial anodes. The electromagnetic signatures of ships and submarines, which typically have characteristic frequencies in the 0.1-to-0.001-Hz range, have characteristic shapes that can yield direction information and are detectable at ranges of several kilometers on the shelf. In addition, the corrosion current dipole can be modulated by the rotating shaft to produce higherfrequency signals that can propagate even farther. Electromagnetic (EM) signals are enhanced in shallow water as compared to those in the deep ocean, and their attenuation with range is substantially weaker. The Navy is investing substantial sums in improving EM sensors and devising rapidly deployable systems utilizing these technologies. Signal processing schemes are also being devised. These efforts are being conducted in the virtual absence of basic information on the ambient EM environment. What are the natural sources of EM fields, what are their coherence scales, and what are their magnitudes? This information is essential for devising physics-based noise cancellation procedures and determining the level of sensor performance that is needed, compared with what is achievable. In the absence of basic information on the EM environment, there is a real danger of prematurely discrediting the EM method due to improper consideration of the physical problem. What is needed is a basic effort to characterize the sources of EM fields in typical shallow-water environments. The most important generating mechanism is hydrodynamic, that is, the Hall effect. The possible sources, such as surface waves and internal waves, are both numerous and spatially variable. A series of focused array experiments in diverse environments, utilizing EM sources together with measurements of variables related to the hydrodynamic sources, is essential. This will lead to a predictive capability that feeds back into sensor and system design and to quantitative prediction of performance. The Navy should not expend extensive efforts on improving sensor sensitivity in the absence of information on environmental noise. The capability of EM systems is not sensor-noise-limited, but rather environmental-noise-limited. Remote Sensing of Salinity New approaches to remote sensing of key environmental variables need to be explored. For example, salinity is much more variable spatially and temporally in the littoral zone than in the open ocean. Although it is readily measured from surface ships using conductivity sensors, there is no technique for remote
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WORKING GROUP SUMMARIES
45
measurement from aircraft or satellites. However, there is a potential approach to remote sensing of salinity that involves measurement of the fluorescence or light absorbance of dissolved organic matter (DOM). This is possible because most rivers contain larger quantities of DOM than seawater does, and fluvial organic DOM absorption and fluorescence spectra differ from those in a marine environment. The fluvial DOM signature could also provide a remotely detectable tracer for surface-water circulation in the coastal zone. Some basic environmental data are needed to evaluate the potential of this technique. Correlations of salinity versus DOM concentration and absorbance/fluorescence spectra should be determined for a variety of rivers. Also, the sensitivity of the DOM signal to salinity variations needs to be established. Based on the optical properties of fluvial and marine DOM, sensors could be developed to optimize their discrimination. Important General Issues for Future Navy Operations in the Littoral Regime Fundamental Differences Between the Littoral and Oceanic Environments Must Be Recognized. In the past, large environmental databases and predictive models have served an important purpose in naval operations in deep-ocean basins. In contrast, in the dynamic shelf environment, the extent to which such approaches will be useful is not clear. The danger in using approaches suited to less dynamic, open-ocean systems is that such models could “invent” an average shelf environment which is far from reality at any particular time or place. An important, first-order task for mine countermeasures and antisubmarine warfare in shelf areas is to identify the environmental properties that can in principle be mapped or predicted and those that cannot. A refinement would be to assign accuracy estimates or confidence levels to predictions. Certainly, predictive capabilities can be increased with gathering of more or more accurate data and with improved models. However, in a dynamic area such as the shelf, the time and space scales of variability are such that many environmental characteristics will not be predictable in the long term, either by amassing a large, retrospective database or by modeling. A new paradigm is needed that recognizes the temporal and spatial variability of the shelf and leads to innovative scientific and engineering approaches to the support of naval operations. Oceanographic Processes of the Shelf Must Be Understood. Basic research is needed to improve predictive capabilities for shelf circulation features relevant to the Navy's littoral warfare mission. Effort should focus initially on existing dynamic modeling capabilities, used in conjunction with
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WORKING GROUP SUMMARIES
46
existing data sets, with the ultimate goal of constructing a three-dimensional, time-dependent coastal ocean prediction system that can be applied in a series of verifying field experiments. Research must be designed with awareness of the high degree of spatial variability on the shelf. Relevant issues are as follows: a. Given limited measurements, how well can we model or predict oceanographic variables relevant to littoral warfare? At present, some predictive capability exists for tides, surface waves, and lowfrequency alongshore velocity, but there is no corresponding predictive capability for cross-shore flow and the three-dimensional density structure over the continental shelf. Also, the existing understanding of mean flow, over time scales of days to weeks is more complete, than of higherfrequency variations such as those due to tides. b. Understanding of the basic temporal and spatial correlation scales as a function of shelf regime is required. c. Increased understanding of the behavior of the surface and bottom turbulent boundary layers on the shelf is needed. In particular, the bottom boundary layer is a key region because of resuspension of sediment and its effects on water clarity and mine burial. d. What is the best way to assimilate data obtained by air-deployed and/or covert underwater sensors into fully three-dimensional, time-dependent shelf circulation models? This is essential for construction of a coastal ocean prediction system that should eventually include biological and suspended-sediment submodels for addressing water clarity. It is essential to evaluate model systems and prediction with a sequence of field experiments on several types of continental shelves, perhaps most usefully in conjunction with Navy exercises. e. The Navy research effort should initially concentrate on important shelf circulation processes using existing modeling capabilities and data sets, then proceed to coastal ocean prediction systems that incorporate both models and observations. The recommended research will facilitate the transition of academic expertise to the applied and operational communities concerned with littoral warfare. Sensor performance is dependent on multiple processes occurring on different time and length scales. Is there a correlative relationship between larger-scale and small-scale patterns? The time and length correlation scales for a variety of frequencies need to be determined. A database approach may be successful for large-scale processes and low-frequency acoustics but is unlikely to be usable for mesoscale and small-scale processes and higher frequencies. To use medium-high and high-frequency sensors, a first-principle understanding of the link between
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WORKING GROUP SUMMARIES
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oceanographic processes and sensor performance is needed. For example, research is needed to determine how wave fields and sediment properties interact to produce bottom roughness, and how bottom roughness is related to sound reverberation and scattering. Multidisciplinary Field Experiments Should Be Conducted. One or more field experiments in U.S. waters are needed to assess the abilities and performance of existing and developing technologies to support littoral warfare in water depths from 40 to 1,000 meters. Both observations and modeling conducted in connection with such an experiment should include marine, atmospheric, and coastal land environments. An important goal of this experiment should be to transfer academic capabilities and expertise to the applied and operational communities supporting littoral warfare. This exercise could also be a test of the proposal to establish “regional oceanographic experts” within the operational community. Another key goal should be to “calibrate” the ASW/MCM capability of tactical units and surveillance assets under a variety of well-characterized environmental conditions. These field experiments could also be used to test performance-prediction models for acoustic or nonacoustic sensors. Ideas for Collection and Use of Environmental Data for Operations in the Littoral Environment The working group assembled a list of ideas for naval operations, or environmental data collection or utilization in the littoral environment: • Sensor Performance Assessment - Assess passive and active sonar performance in situ. • Sensor Confusion - Confuse enemy acoustic sensors by deploying acoustic decoys--for example, devices that emit submarine or ship noises at a point distant from the actual location of the asset or that disguise active sonar as ambient noise. • Environmental Assessment - Expand environmental data collection by naval and research vessels operating in the littoral zone, and assimilate that data into a littoral database; combine sidescan sonar with a chirp sensor in order to obtain information about bottom roughness and volume heterogeneity; use radar reflection as a means to obtain information about surface currents over large areas from ships; and measure bioluminescence and light transmission remotely using satellite or aircraft-borne sensors or an in situ (deployable) sensor.
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WORKING GROUP SUMMARIES
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• Assessment or Prediction of Hostile Activities - Use covert sensors to detect hostile mine-laying operations; locate mines or submarines via the fluorescence of synthetic organic chemical components; predict mining tactics--for example, “seeding” of currents with floating mines; and use a remotelyoperated vehicles to survey activities off known submarine ports. • Environmental Databases and Their Exploitation - Develop a process-oriented database that is verified by fleet and academic data collection; maintain a person knowledgeable about environmental conditions and effects aboard all fleet assets, and provide that person with appropriate data and training. Working group participants were struck by the contrast between the substantial naval expertise and data availability in meteorology and the much smaller utilization of oceanographic expertise and data. Summary and Conclusions The Continental Shelf Working Group identified the set of environmental factors of most importance to Navy operations in the littoral zone. The working group also identified a number of cross-cutting issues that are important for operations in more than one of the four littoral areas examined in the symposium. These issues included the need for sufficient characterization of coastal regions to permit advanced planning, a better understanding by naval personnel about how to use nonacoustic environmental information for making tactical decisions, information about the accuracy of sensors under any combination of environmental conditions, limiting risk to Navy personnel by using more remote methods and predictions, the need for real-time sensors of environmental properties, and new approaches for data handling, archiving, and dissemination. The working group also noted relevant problems in mine countermeasures, antisubmarine warfare, special warfare, and amphibious operations that could benefit from increased research effort. Finally, this working group listed a set of key research needs to improve operations in the littoral zone, highlighting the need to acquire basic environmental knowledge before sensor development is pursued. The discussions and recommendations of the Continental Shelf Working Group often reiterated the theme that the continental shelf is extremely dynamic, with a high degree of variability in space and time. New approaches, not just more data, are needed to characterize this environment. However, it should also be emphasized that the continental shelf is bounded by the open sea, and much of our present and developing understanding of the shelf region builds upon the research results and research techniques of basin oceanography.
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APPENDIXES
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APPENDIX A
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APPENDIX A SYMPOSIUM PROGRAM
SYMPOSIUM ON COASTAL OCEANOGRAPHY AND LITTORAL WARFARE AN EVENT SPONSORED BY THE OCEANOGRAPHER OF THE NAVY CHIEF OF NAVAL RESEARCH NATIONAL ACADEMY OF SCIENCES (OCEAN STUDIES BOARD) AUGUST 2-5, 1993 FLEET COMBAT TRAINING CENTER TACTICAL TRAINING GROUP, PACIFIC 200 CATALINA BOULEVARD SAN DIEGO, CA Littoral Warfare is an extremely complex and dynamic extension of naval warfare, and it demands longterm commitment to research and development, acquisition, threat assessments, tactical and operational analysis, training, education and realistic fleet exercises. Littoral warfare is the use of combined forces, shaped for forward operations in sea/land/air environment, to influence, deter, or contain and defeat a regional threat through the projection of maritime power.
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APPENDIX A
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A primary need, emerging from recent actions, is to detect, locate and either avoid or clear mines and obstacles from shallow water through the craft landing zones ahead and in support of amphibious operations. The primary shortfall is in the timeliness with which high confidence Mine Countermeasures (MCM) can be completed. MCM capabilities are required in three categories: (1) rapid reconnaissance and assessment of the mine threat; (2) organic detection, avoidance and/or other means of protecting the Carrier Battle Group and Amphibious Task Force assets; (3) clearance of the sea mine threat, including rapid breakthrough at choke points. Operational maneuver from the sea is the desired tactic for present and future maritime power projection ashore. Whenever possible it is initiated from a position at sea that threatens a large part of the enemy's littoral area. Current counter-mine/obstacle technology limits our capability to conduct operational maneuvers from the sea across beaches defended by both mine and obstacle barriers. OBJECTIVES OF THE SYMPOSIUM • ADDRESS TIMELY OPERATIONAL PROBLEMS, FLEET MISSION NEEDS, AND OTHER REQUIREMENTS WHERE RESEARCH AND DEVELOPMENT ASSISTANCE AND INPUTS ARE SOUGHT BY NAVY LEADERS AND PROGRAM MANAGERS. • ENHANCE COMMUNICATION AND UNDERSTANDING AMONG THE BASIC AND APPLIED RESEARCH COMMUNITIES, AND BETWEEN THESE COMMUNITIES AND OUR NAVAL FORCES. • ENABLE AN EXTENDED GROUP OF RESEARCHERS TO BECOME FAMILIAR WITH CHALLENGING NAVAL ISSUES OR STRONGLY APPLICABLE TO THE LITTORAL REGIME.
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APPENDIX A
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SYMPOSIUM ON COASTAL OCEANOGRAPHY AND LITTORAL WARFARE FLEET COMBAT TRAINING CENTER TACTICAL TRAINING GROUP (TTG) PACIFIC 200 CATALINA BLVD. SAN DIEGO, CA August 2-5, 1993 Monday, August 2 0700 Buses Depart Sheraton Harbor Island (East Tower) and Admiral Kidd BOQ 0730-0830 Security Check-In/Registration Continental Breakfast 0800-1700 LITTORAL WARGAME 0830-1130 Tactical Oceanography Briefings CDR Peter Bishop, Fleet ASW Training Center, Pacific Mr. Thomas Little, Naval Oceanographic Office 1130-1300 Speaker and Lunch RADM John Chubb, Commander, Naval Oceanography Command “Operational Needs in Oceanography” 1300-1700 Conflict Simulation Adjourn/Buses Depart for Sheraton Hotel and BOQ 1700 Tuesday, August 3 0700 Buses Depart Sheraton Harbor Island (East Tower) and Admiral Kidd BOQ 0730-0830 Security Check-In/Registration Continental Breakfast SYMPOSIUM - PLENARY SESSION I Mine Warfare Moderator: Dr. James Andrews, Office of Naval Research Welcoming Remarks 0830-0900 CAPT J.A. Burke, Commanding Officer, TTG, Pacific RADM G. Chesbrough, Oceanographer of the Navy Dr. Kenneth Brink, NAS Ocean Studies Board
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APPENDIX A
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Tuesday, August 3 0900-0945 0945-1030 1030-1100 1100-1145 1145-1315
1315-1345 1345-1415 1415-1445 1445-1600
1600 1630-1830 1830
The New Threat - Regional Instabilities COL Michael Patrow, USMC, Office of Chief of Naval Operations Mine Warfare - WWII to Present Dr. T. Moser Melia, The Naval War College Break Mine Warfare in the Persian Gulf CAPT F. West, Jr., USN (Ret.) Speaker and Lunch “Focus and Needs in Naval Special Warfare” CAPT R. C. Mabry, Commander, Naval Special Warfare Group One PLENARY SESSION II Joint Littoral Warfare Moderator: Dr. Curtis Collins Oceanographic Support of Littoral Warfare RADM Geoffrey Chesbrough, Oceanographer of the Navy Environmental Parameters for Mine Countermeasures CAPT F. West, Jr., USN (Ret.) Break The Role of Ocean Science and Technology in the Navy of Today and the Future Dr. Arthur Bisson, ONR Dr. Bruce Robinson, ONR Mr. Robert Winokur, Office of the Oceanographer of the Navy Buses Depart TTG for Reception at Submarine Base Officers' Club (“Ocean View”) Reception/Submarine Tours Buses Depart Officers' Club for Sheraton and BOQ
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APPENDIX A
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Wednesday, August 4 0700 Buses Depart Sheraton Harbor Island (East Tower) and Admiral Kidd BOQ 0730-0800 Continental Breakfast PLENARY SESSION III The State of Science, Technology and Environmental Data Bases Moderator: Dr. Kenneth Brink, Woods Hole Oceanographic institution 0800-0900 Overview of Inner Shelf Dynamics Dr. Robert Guza, Scripps Institution of Oceanography Dr. Steven Lentz, Woods Hole Oceanographic Institution 0900-1000 Coastal Modeling Dr. John Allen, Oregon State University 1000-1030 Break 1030-1100 Ocean Prediction System Dr. Kenneth Brink, Woods Hole Oceanographic Institution 1100-1145 Navy Environmental Data Bases, Coastal Modeling, and Operational Support CDR David Martin, Naval Oceanographic Office 1145-1315 Speaker and Lunch “Technology and State of Mine Warfare” RADM John Pearson, Commander, Mine Warfare Command 1315-1630 WORKING GROUPS (Concurrent) • • • •
1630 1700
Harbors & Approaches Straits & Archipelagoes Surf Zone Shelves
Working groups will discuss science and technology/R&D aspects of the three fold process of detection, localization and neutralization of targets within the four environments. Working groups will also discuss how each environment requires special handling, special sensors and specific equipment to meet the littoral warfare challenge expeditiously. A formatted set of questions will be provided to working group chairs. Buses Depart TTG for Naval Air Station, North Island Officers' Club (“Island Club”) Aircraft Displays and Aircraft Trainer Demonstrations
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APPENDIX A
1830 2100
Reception/Dinner at “Island Club” Buses Depart Officers' Club for Sheraton and BOQ
Thursday, August 5 0700 Buses Depart Sheraton Harbor Island (East Tower) and Admiral Kidd BOQ 0730-0800 Continental Breakfast 0800-1145 WORKING GROUPS Reconvene (Concurrent) 1145-1315 Demonstration and Lunch “Tactical Decision Aid” 1315-1515 PLENARY SESSION IV Presentations by Working Group Chairs Moderators: Dr. James Andrews and Dr. Kenneth Brink 1515-1545 Break 1545-1715 Navy Panel Mr. Robert Feden, Office of Naval Research CAPT F. West, Jr., USN (Ret.) Dr. William Moseley, Naval Research Laboratory Dr. Steven Ramberg, Office of Naval Research 1715-1730 Closing Remarks Dr. James Andrews Dr. Kenneth Brink 1730 Adjourn Buses Depart TTG for Sheraton and BOQ 1730
NOTES: 1) This symposium is an invitation-only event. For information call: Mary Hope Katsouros or Mary Pechacek, NAS Ocean Studies Board, (202) 334-2714. 2) Unless otherwise noted in the program, all activities will be held at the Tactical Training Group (TTG), Pacific. TTG, Pacific telephone numbers are a) Voice: 619-553-8341 or 8337 b) FAX: 619-225-9449
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APPENDIX A
3) TTG Pacific is a secure facility with very limited and restricted parking. All symposium attendees are encouraged to use the shuttle buses. 4) The Littoral Wargame on Monday, August 2, is limited to 50 selected participants. 5) Symposium registration fee is $125, payable to the “National Academy of Sciences/Ocean Studies Board.” Advance payment is appreciated. 6) Symposium Steering Group: Ocean Studies Board Dr. Kenneth Brink, Woods Hole Oceanographic Institution Dr. Stewart Nelson (Consultant) Office of Naval Research Dr. James Andrews Dr. Thomas Kinder CDR Peter DeVries Office of the Oceanographer of the Navy Mr. Robert Winokur CAPT Dieter Rudolph Mr. Philip Vinson ENS Cynthia Viernes
7) Uniform for military personnel is khakis.
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APPENDIX A 58
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APPENDIX B
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APPENDIX B SYMPOSIUM ATTENDEES
Last Name Allen Andrews Arends Bacon Balon Barth Bassett Benz Bisson Boesch Bonnstetter Bradley Brand Brink Brown Campbell Case Cassady Cataldo Chave Chesbrough Ching Chubb Church Clark
First John S. James E. Christopher Jeffrey L. Michael J. John A. Robert M. Raymond Arthur E. Donald F. Terrence J. Mohsen Sampson Kenneth Brian B. Colin L. James F. John M. Edmund F. Allan D. Geoffrey Wallace K.L. John E. John C. Robert L.
Title Dr. SES LTJG LCDR LT Dr. LCDR Dr. Dr. LT Dr. LT Dr. LtCol Dr. RADM RADM LCDR CDR
Company/Activity Oregon State University Office of Naval Research Naval Oceanography Command Facility, San Diego Naval Oceanography Command Facility, San Diego Mine Warfare Command Oregon State University Naval Oceanography Command Facility, San Diego Naval Special Warfare Command Office of Naval Research University of Maryland U.S. Naval Reserve Office of Naval Research Naval Research Laboratory Woods Hole Oceanographic Institution Naval Oceanography Command Facility, San Diego Naval Oceanography Command Facility, San Diego University of California, Santa Barbara Surface Warfare Development Center SONALYSTS, Inc. Woods Hole Oceanographic Institution Chief of Naval Operations, N096 Office of Naval Research Commander, Naval Oceanography Command Naval Research Laboratory Naval Oceanography Command Facility, San Diego
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APPENDIX B
Clendening Coble Costa Cote Culver Dalrymple DeVries Delgado-Medina Dewar Dimento Douglas Dunn Elgar Feden Fisher Freilich Frieman Gaines Garrett Gilbert Gilroy Goodman Gottshall Gregg Guza Hale Hall Harding Hawkins Hayes Heburn Henrichs Hickey Hill Hillyer Hinchey
60
Michael Paula G. Daniel P. Johanne L. Richard L. Robert A. Peter J., Jr. Mario J. William K. John Brenton L. Stanley E. Stephen L. Robert Alvan Michael H. Edward A. William A. J.C. Kenneth E. Michael J. Louis Eric L. Michael C. Robert T. Kevin R. Adron F. John M. Harold L. Richard M. George W. Susan M. Christopher Paul Richard S. Patricia S.
LCDR Dr. Dr. LT Dr. CDR AGCM Dr. LT Dr. Dr. Dr. Dr. CAPT COL Dr. LCDR Dr. Dr.
CAPT Dr. Dr. CAPT
Naval Oceanography Command University of South Florida Office of Naval Research Naval Oceanography Command Facility, San Diego Penn State University, APL University of Delaware Office of Naval Research Naval Oceanography Command Facility, San Diego Florida State University Naval Oceanography Command University of California, Santa Barbara Florida Atlantic University Washington State University Office of Naval Research Naval Research and Development Oregon State University Scripps Institution of Oceanography Scripps Institution of Oceanography USMC Camp Pendleton, CA Pennsylvania State University Submarine Group One Office of Naval Research Tactical Training Group, Pacific University of Washington Scripps Institution of Oceanography National Research Council Naval Oceanographic Office Naval Research Laboratory Office of Naval Research Chief of Naval Operations U.S. Naval Reserve University of Alaska Marine Corps Intelligence Act. Dalhousie University Space and Warfare Systems Command SONALYSTS, Inc.
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APPENDIX B
Holman Houston Howard Howd Hsueh Jackson Jay Jenkins Jumars Kalcic Kammerer Katsouros Kendall Kinder Kuperman Lee Lentz Luettich Lynch Mabry Mango Markham Martin Martin Mauck McCluskey McDonnell Melia Miles Miller Morrison Morrison Negron Nelson Nelson Oltman-Shay Orcutt
61
Robert A. Brian H. Michael D. Peter A. Ya George A. David A. Scott A. Peter A. Maria T. John G. Mary Hope Robert L. Thomas H. William A. Hau Steven J. R. A., Jr. James F. Robert C. Stephen A. David G. David L. Sanford M. Charles J. William J. Sheila L. Tamara A. M. Ronald Carl W. John M. Michael F. Anthony J. Stewart B. Joan M. John
Dr. Dr. Dr. Dr. Dr. Dr.
Dr. Dr. Dr. Dr. Dr. CAPT CDR CDR CAPT Dr.
LCDR
Dr.
Oregon State University Naval Research Laboratory Marine Corps Intelligence Act. Duke University Florida State University Texas A&M University University of Washington Office of Naval Research University of Washington Naval Research Laboratory Naval Surface Force, Pacific National Research Council U.S. Naval Reserve Office of Naval Reserve Scripps Institution of Oceanography University of California, Santa Barbara Woods Hole Oceanographic Institution University of North Carolina Woods Hole Oceanographic Institution Special Warfare Group One Fleet ASW Training Center Space and Warfare Systems Command Naval Oceanographic Office Coastal Systems Station U.S. Naval Reserve Office of Naval Research Naval Research Laboratory The Naval War College NRL Det., Stennis Space Ctr Naval Oceanography Command Naval Air Warfare Center Naval Command, Control & Ocean Surveillance Center Naval Special Warfare Command Marine Expeditionary Force National Research Council Northwest Research Associates Scripps Institution of Oceanography
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APPENDIX B
Orr Pastore Patrow Patterson Pearson Pechacek Ramberg Ramsdale Ranelli Richardson Richter Robinson Robinson Roth Sawin Schaeffer Schroeder Sheridan Simmons Spaulding Spinelli Spinrad Stern Streed Suender Thornton Tiedeman Tooma Van Norden Viernes Vincent Vinson Weinstein Weller
62
Marshall H. Michael Michael Wayne L. J. D. Mary C. Steven E. Dan J. Peter H. Michael D. Juergen H. Bruce B. Russell H. Julie K. R. M. Henry J. William W. Timothy F. Richard H. Malcolm L. Julia M. Richard W. Richard D. H. Gary E. Edward B. Paul R. Samuel G. Maxim F. Cynthia D. Charles L. Philip S. Alan
Dr. COL RADM
CDR Dr. Dr. LCDR LTJG LT Dr. Dr. LT LCDR QM2
ENS Dr. Dr.
Naval Research Laboratory Naval Research Laboratory Chief of Naval Operations (N085) Naval Command, Control & Ocean Surveillance Center COMINEWARCOM National Research Council Office of Naval Research Naval Research Laboratory Space and Naval Warfare Systems Command Naval Research Laboratory Naval Command, Control & Ocean Surveillance Center Office of Naval Research COMSUBFORCE Pacific Fleet Naval Oceanography Command Facility Marine Expeditionary Force SONALYSTS, Inc. Naval Research Laboratory Office of Naval Research Naval Oceanographic Office Naval Research Laboratory Naval Oceanography Command Office of Naval Research Penn State - Applied Physics Lab Patrol Wings, U.S. Pacific Fleet Naval Oceanography Command Facility Naval Post Graduate School PEO (USW/ASTO) Undersea Warfare Naval Research Laboratory Naval Oceanographic Office Chief of Naval Operations (N096) U.S. Army Waterways Experiment Station Chief of Naval Operations (N096) Office of Naval Research
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APPENDIX B
Wenzel West Wheatcroft Winokur Yamamoto Zankofski
63
Diana B. F. G., Jr. Robert A. Robert S. Tokuo Deborah A. CAPT Dr.
Dr. LCDR
Naval Western Oceanography Center National Research Council Naval Research Laboratory Chief of Naval Operations (N096) University of Miami Defense Mapping Agency
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APPENDIX C 64
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APPENDIX C
65
APPENDIX C LIST OF ACRONYMS
ADCP AO ASW AUV CMW EM GFMPL IREP kHz MCM MTEDS NAVO NODDS NSW SeaWiFS SDV SF XCP
acoustic Doppler current profiler amphibious operations antisubmarine warfare autonomous underwater vehicle counter-mine warfare electromagnetic Geophysical Fleet Mission Program Library Interactive Refractivity Environmental Prediction System kilohertz (cycles per second) mine countermeasures mine warfare tactical environmental display system Naval Oceanographic Office Naval Oceanographic Data Distribution System Naval Special Warfare Sea-Viewing Wide Field Sensor swimmer delivery vehicle special forces expendible current profiler
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APPENDIX C 66
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APPENDIX C 67
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APPENDIX C 68
NATIONAL ACADEMY PRESS
The National Academy Press was created by the National Academy of Sciences to publish the reports issued by the Academy and by the National Academy of Engineering, the Institute of Medicine, and the National Research Council, all operating under the charter granted to the National Academy of Sciences by the Congress of the United States.
