Appendix B
The Role of Environmental Information in Naval Warfare

INTRODUCTION

As discussed throughout this report, the use of environmental information by U.S. Naval Forces evolved dramatically during the past 100 years. The rapid evolution in observation and prediction capabilities has reinforced the rapidly expanding need for one infrastructure driven by evolving naval tactics and weapons systems. Naval operations represent a complex interplay of a variety of missions; thus the meteorological and oceanographic (METOC) system must be flexible enough to meet a variety of demands on many timescales, driven by the specific objective of a given operation.

The various actions undertaken by different components of the fleet are grouped into mission warfare areas. These areas generally center on actions or assets with a common theme and include, among others, aviation and strike warfare, submarine and antisubmarine warfare, surface warfare, naval special warfare, and amphibious warfare (see Table 2-1).

Targeting Information and the Weather

The need for accurate targeting information is as important as being able to hit the target once it has been identified. Fixed targets can be located ahead of time by using satellite imagery or manned and unmanned reconnaissance aircraft. Again, the need for advanced weather information in the theater area is clear. Furthermore, it will be important to be able to locate enemy forces in real time. To best manage resources and plan tactics it will be necessary to be able to more accurately predict and identify current weather conditions in the search areas.



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Appendix B The Role of Environmental Information in Naval Warfare INTRODUCTION As discussed throughout this report, the use of environmental information by U.S. Naval Forces evolved dramatically during the past 100 years. The rapid evolution in observation and prediction capabilities has reinforced the rapidly expanding need for one infrastructure driven by evolving naval tactics and weapons systems. Naval operations represent a complex interplay of a variety of missions; thus the meteorological and oceanographic (METOC) system must be flexible enough to meet a variety of demands on many timescales, driven by the specific objective of a given operation. The various actions undertaken by different components of the fleet are grouped into mission warfare areas. These areas generally center on actions or assets with a common theme and include, among others, aviation and strike warfare, submarine and antisubmarine warfare, surface warfare, naval special warfare, and amphibious warfare (see Table 2-1). Targeting Information and the Weather The need for accurate targeting information is as important as being able to hit the target once it has been identified. Fixed targets can be located ahead of time by using satellite imagery or manned and unmanned reconnaissance aircraft. Again, the need for advanced weather information in the theater area is clear. Furthermore, it will be important to be able to locate enemy forces in real time. To best manage resources and plan tactics it will be necessary to be able to more accurately predict and identify current weather conditions in the search areas.

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Battle Damage Assessment Finally, it is important to perform battle damage assessment on targets that have been attacked. The scheduling of reconnaissance flights or satellite imagery to provide this postattack assessment will also be dependent on knowledge of current and predicted weather conditions in theater. ENVIRONMENTAL INFLUENCES ON AVIATION AND STRIKE WARFARE Aviation and strike warfare depend critically on accurate environmental assessments and forecasts, from winds for carrier operations to humidity, clouds, and haze effects on electrooptical sensor performance. Carrier Operations Carrier operations require a minimum of wind across the deck for safe take-offs and landings. Deck-level wind is the combination of atmospheric wind and the ship’s forward velocity. Continuous in situ measurement of wind speed and direction is required for flight deck operations. Additionally, accurate forecasting of deck-level wind speed and direction is essential for vectoring the carrier, especially in geographic regions where maneuverability is constrained. Radar Many systems are directly affected by the atmospheric environment. Anomalous radar propagation due to humidity-dependent refractive index effects was noticed early in World War II. Radar range was highly variable, sometimes reaching over the horizon, due to refractive “ducting.” Although the dependence of radar refractivity on air temperature, humidity, and pressure is known exactly, accurate prediction of these parameters is a continuing goal. Optical Sensors and Lasers Conditions common in the marine atmosphere limit the effectiveness of laser target designating systems (on both the laser designator and the optical sensor that acquires the laser beam energy) through refraction and scintillation (“twinkling”) of the light beams. Obviously, fog, clouds, and marine aerosols are obscurants, and their prediction at the target is desirable. As naval operations focus on coastal regions, smoke and dust can also have a detrimental impact on the successful use of laser designators and optical sensors.

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Present-Day At-Sea Data Collection Good environmental information depends on good measurements and good forecasts. Typically, naval operations are at a disadvantage compared to land operations because of the lack of observations and the remoteness of operating areas. Ships give routine weather reports at synoptic times, but the instruments and information transmitted have not changed much since the sailing age. Ship-relative wind is obtained from a mechanical anemometer; true wind is calculated via a nomograph slide rule and logs of the ship’s speed and heading. Temperature and humidity are measured with handheld wet-and-dry bulb psychrometers and bulk sea temperature from cooling intake seawater or a bucket sample. Pressure is from aneroid mechanical barometers in the wheel house, which are ported and manifolded to the outside (port and starboard). Sometimes aerographer’s estimates of wind speed are obtained from the Beaufort scale of sea state appearance, which admittedly is judgmental but avoids distortion of the wind by the ship’s structure. Wave data are by visual estimates. In contrast to the in situ measurements, frequent detailed satellite pictures are available to assist the METOC officer in evaluating the environmental scene. Forecasting the weather has evolved considerably from Crick’s case study method of comparing synoptic charts, Bjerkne’s discovery of fronts, and Rossby waves to numerical integration of the governing equations on supercomputers. Numerical forecasting is, of course, the method used at the Fleet Numerical Meteorology and Oceanography Command (FNMOC) and has improved steadily. There is still a “person in the loop” in monitoring the model outputs, and the models are semiempirical and contain a wealth of experience from analysis of previous forecasts, data analysis, and results of focused experiments. The models rely on primitive shipboard data for initialization. Because the governing equations are extremely complex, they cannot be solved exactly, and errors due to inexact physical assumptions and/or inaccurate initial data propagate and can grow to unacceptable levels with increased forecasting time. Key Problems The environmental issues relevant to aviation and strike warfare cover a wide range. For situ ship data, the basic instrumentation on most ships is archaic. More complete systems for civilian use can be bought for less than $1,000. There has been no systematic study of the effect of the accuracy of routine ship observations on resulting forecasts. Weather centers such as FNMOC toss out “erroneous” data by a filter/comparison technique, thus pointing out the obvious distrust of the data and communications scheme. However, history is rife with examples of bad forecasts due to suppression of data simply because they did not fit a normal distribution. The proposed SMOOS upgrade to ship instrumentation is an improvement but does not address basic issues such as sensor location.

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While the actual relative wind across the deck of a carrier is important for flight operations, wind and other measurements away from the flow blockage of the ship are required for numerical model input. Smart Weapons Systems Precision-guided munitions (PGMs) or “smart weapons” have an expanded role in modern warfare, especially in the past decade. Their value in warfare became evident during Desert Storm even though they accounted for only a small portion (approximately 7 to 9 percent) of the ordnance expended. This view was furthered in the Bosnian and Kosovo conflicts because of the increased percentage (70 percent of ordnance) of smart weapons used. These new weapons have been lauded for their accuracy, defined as a low circular error probability (CEP). Table B-1 shows the dramatic decrease in CEP in the past 60 years. This improvement in performance has increased our ability to damage the adversary’s equipment and warmaking capability while decreasing casualties on both sides. Because precision bombing can result in a significant reduction in civilian collateral damage and casualties (compared to previous wars), their use relative to conventional or dumb bombs has expanded significantly and can be expected to continue to grow. However, the very systems that make these weapons more precise also make them, in some instances, more sensitive to environmental conditions. Development of Laser- and Operator-Guided and Terrain Mapping Weapons Systems The first techniques (1976) made use of laser designators to illuminate the target and a laser seeker in the bomb to track and guide the weapon. Another approach (1985) uses TV (visible or infrared) to send signals back to a weapons TABLE B-1 Improvement in Accuracy of Air-Delivered Weapons Since World War II War Weapon CEP (m) World War II Gravity bomb 1,000 Korea Gravity bomb 300 Vietnam Gravity bomb 100 Desert Storm Laser-guided bomb 8   Tomahawk Block II 10 Bosnia Laser-guided bomb 8   Tomahawk Block III 3

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system operator to remotely guide the bomb. Cruise missiles such as the Tomahawk use terrain-matching techniques en route to the target and digital optical matching for final target identification and acquisition. Current and Next-Generation PGMs The performance of many PGMs is highly dependent on weather factors, such as cloud cover, rain, smoke, and wind effects. The current generation of guided bombs and cruise missiles still depends on either an ability to visualize the scenes on the way to the target, the target itself, or both. New generations of guided bombs, such as the Joint Direct Attack Munition (JDAM) and cruise missiles such as the Tomahawk IV, will use the Global Positioning System (GPS) as well as inertial measurement units to provide higher accuracy in adverse weather conditions. The use of GPS can bring the CEPs down to 13 m in adverse weather conditions for either JDAM or the Tomahawk Block IV weapons. However, the ability to obtain CEPs of 3 m or less will still rely on favorable local weather conditions in the target area and electrooptical visualization methods upon reaching the target. Optimizing the Performance of Weapons Systems In order for the Navy (and land forces) in theater to be able to optimize the performance of their weapons systems, it will be necessary to (1) make use of all relevant weather data without regard to source and (2) be able to generate a continuous picture of weather in the theater in terms that are relevant to the war-fighters and their smart weapons. This weather picture should be based on the same data and shared in a common format to all forces in the theater. Use of Other (non-Navy) Weather Information The Navy should be using data and contributing data to databases that are being used by the other services. Clearly each service will have its own way of manipulating and mapping data to support its own needs and weaponry. But insofar as they are operating in a common environment with similar or the same weapons, decisions and performance expectations should be based on the same weather picture. Weather Data Dissemination Data and data analyses should be available to all users via the Internet. This can be accomplished through ground-based or wireless networks depending on location and platform. The utilization of widespread and rapidly evolving

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commercially developed and supported infrastructures and infrastructure technologies should be exploited to the greatest extent possible commensurate with security needs. Consideration should be given to common networks and enterprise-level database and storage management technologies that are shared by the services. Each service or user can tailor products to its specific needs, but all of the most current data are made available to all. Environmental Influences on Antisubmarine Warfare Systems Acoustic Propagation Because acoustic propagation, especially at low frequencies, is dictated by the nature of the physical environment, knowledge of the environment is fundamental to the performance of antisubmarine warfare (ASW) systems. Much of the existing knowledge is quite mature and is incorporated into the training of Navy sonar operators. A number of texts are available that summarize this knowledge. Consequently, this discussion focuses on topics where environmental knowledge, or lack thereof, has impacted operational sonars and the development of more advanced systems. Furthermore, the environmental influence can be subdivided according to the surface water column (or volume) and the seafloor. Acoustic Propagation at the Surface Sonar performance is impacted by the sea surface, which is moving and can be rough primarily due to wind. Surface motion imparts Doppler shifts to a signal. An active system generates long narrowband signals to move a Doppler-shifted signal out of the clutter. The surface imparts a Doppler spreading that degrades performance. Doppler effects are particularly important for fixed systems where platform motion is mostly eliminated and Doppler is the primary observable parameter. Surface roughness becomes important when the Rayleigh number, which scales according to the RMS (roughness to wavelength), becomes high. At this point the surface can no longer be treated as a simple reflector. The roughness leads to angular spreading and ray/mode coherence. This angular spreading can be measured by the large-aperture systems now in use. The ray/mode coherence is a fundamental issue in ranging systems that exploit vertical multipath. Again, these issues are more important for fixed systems. Additionally, surface roughness impacts the performance of wake detection systems. The same surface processes, such as wave breaking and wind/wave interaction, are also important sources of ambient noise. Bubble processes are a very important component of the surface. Very small fractions of bubbles lead to significant changes in sound speed, which modulates

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the reflection/refraction properties of sound near the surface. Moreover, bubbles are both efficient scatterers and sources of ambient noise. While there is still much to do with regard to modeling acoustic interaction with the surface, environmental drivers of surface effects according to region and time of year are important predictors of modeling sonar performance. Acoustic Propagation in the Water Column The sound speed profile (SSP) of the water column is one of the fundamental quantities needed for predicting propagation of an acoustic signal. All the basic features associated with this are well known and are tabulated in operational databases. There are, however, significant gaps in these databases for operationally important regions. Long-range detection systems of Cold War vintage exploited SSP data extensively. Since these were primarily low-frequency, deep water, low-resolution systems, the databases were usually adequate for coarse predictions. Nevertheless, internal waves that led to scattering could be a factor. Over the years important processes such as seasonal surface duct formation and focusing effects were understood. However, environmental questions do remain for long-range systems. These include the impact of internal waves and mesoscale eddies on the coherence of multipath/signals. Specification of fronts and eddies is also important for long-range predictions. Sonar detection ranges are now much shorter because of advances in reducing ship noise (referred to as “quieting”). Thus, ship detection is generally regarded as possible at distances of tens versus hundreds of kilometers. SSPs remain important because of the significant role they play in ranging algorithms used to interpret acoustic signals. While these can usually be measured in situ, it is still important to know the general characteristics of an area for a specific time of year. Probably, the most important volumetric aspect concerns littoral waters. First, they are very dynamic with short scales. A range curtain governed by interaction of the SSP and the geoacoustics of the seabed effectively limits sound propagation ranges. Moreover, many of the processes, including internal waves, soliton generation, propagation across slopes, and regions of rapidly changing bathymetry, require better environmental information than is currently available. Acoustic Propagation at the Seabed One of the most important aspects of acoustic propagation is whether a path is bottom interacting. The seabed is a loss mechanism that can, during reflection, change the frequency of and/or attenuate the emitted sound wave. Current knowledge of the bottom at specific locations is inadequate for state-of-the-art predictions. The models used lead to prediction ranges that can vary by a factor of 3. While we have detailed charts of the bathymetry of the deep ocean, such knowl-

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edge for important littoral areas is lacking. Moreover, at low to medium frequencies, where there is significant geoacoustic interaction, the models and database simply do not give useful predictions. Many of the data are gathered by normal-incidence, high-frequency probing, while the concern is with low grazing angle, low-frequency regimes. Transmission loss measurements are made; however, the data reduction often fails to capture important features and it is next to impossible to get at the original data. Geoacoustic data are absolutely necessary for predictions in littoral environments because acoustic interaction with the bottom is unavoidable. Detailed bathymetry and subseabed geoacoustics are imperative. Roughness and coherence scales are needed for input to predictive models. Understanding of the controls that the environment places on acoustic properties is certainly one of biggest factors now missing. Effects of Active Acoustical Transmissions on Marine Mammals Another area in ASW where environmental data and support are important is related to the effects of active acoustic transmissions on marine mammals. This is a highly emotional issue driven in most cases not by science but by the media and nongovernmental organizations’ recent outcry over the potential for harm to marine mammals by active sonar transmissions. The intensity of this opposition is highlighted by a recent lawsuit by the National Resources Defense Council and several other nongovernmental organizations against the Littoral Warfare Advanced Development program at the Office of Naval Research. It is also significant that the SURTASS-LFA program at SPAWAR has been prohibited from conducting sea tests for the past six years because of public opposition to sonar transmissions in the oceans. Environmental activists have also targeted active operational sonars as being deleterious to marine mammals. More studies and data are needed to assist the Navy in understanding and explaining the effects of active transmissions on marine mammals. The effect of active transmissions (as a function of frequency and source level) on marine mammal physiology, migration patterns, feeding habits, and general well-being must be determined. As a part of this requirement, environmental data are also needed to facilitate detection of marine mammals in areas where active sonars are to be used. Passive and active scenarios are both used to detect marine mammals. Environmental data to support these efforts consist of basic acoustic parameters such as propagation loss, ambient noise detection threshold, and source level. Environmental Influences on Naval Special Warfare and Amphibious Warfare Amphibious warfare and naval special warfare (NSW) are the areas of naval warfare most prominently involved in recent shifts in emphasis on shallow water

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(or “brown water”) naval operations. Both areas focus activities from shallow waters through the beach to inland areas, both operate at short time- and space scales, and both are heavily affected by many aspects of the coastal environment. While they can share a common battlespace, differences in their mission focus and style suggest separate discussion of each problem and their METOC sensitivities. In particular, NSW emphasizes clandestine operations by small groups to achieve specific limited objectives while amphibious warfare operations typically involve much extensive and more overt troop activities. Naval Special Warfare (NSW) and METOC Since their creation in 1970, the SEALs of NSW have developed and maintained a reputation as an elite and effective force for special operations. Typically working in teams of 16 members (platoon) or squads of 8, their missions are usually characterized by the need to operate stealthily and remain undetected from insertion through extraction. When compromised, SEAL units are capable of demonstrating a show of force out of proportion to their small numbers through intense, often unexpected, violence of action. Swimmer operations figure strongly in the mission profile, and the METOC role is of critical importance in forecasting environmental conditions necessary for planning. In 1997 a tactical oceanography symposium initiated a dialogue between academic oceanographers and NSW operators. Much of the material from this section is extracted from the report of that meeting (National Research Council, 1997). NSW Mission The small, highly trained nature of NSW forces is conducive to a range of missions. These include counterterrorism, counterproliferation, special reconnaissance, psychological operations, direct action, foreign internal defense, civil affairs, information warfare, and unconventional warfare. In addition, NSW is involved in a range of collateral activities, including combat search and rescue, counter-drug, counter-mine, and humanitarian assistance. Mission Planning Although the specifics of mission activities vary enormously, they all involve the five phases of insertion, infiltration, actions at the objective, exfiltration, and extraction. Mission planning occurs on a 96-hour countdown to operation. METOC information most strongly influences infiltration and exfiltration.

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Amphibious Warfare Amphibious operations involve assault from the sea of an enemy-held coastal region and securing the subsequent Logistics-Over-The-Shore capability for re-supply of ongoing operations. While the element of surprise is important, operations are not usually clandestine and often involve combat. There is a necessity for speed and particularly in-stride mine-sweeping capability. However, troop sizes generally include thousands of Marines, and transit is by armored and substantial vehicles rather than the swimmer operations of the SEALs. Thus, environmental factors such as water temperature are not as directly important while other factors such as visibility, wave height, and electromagnetic ducting may be more important. Mission Planning Mission planning cycles for amphibious operations can be substantially longer than the 96-hour SEAL time line due to the greater logistical complexities required. However, METOC information can clearly stop a mission, and up-to-date METOC information is required right up to the final go/no go decision. Role of the Environment The required resolution of environmental knowledge in the littorals is substantially finer than for traditional open-ocean purposes and increases with proximity to the beach. At the extreme, for example, the surf zone contains rip channels that may offer safe gaps for landing vehicles but deadly countercurrents for swimmers. These features are only tens of meters wide but are sufficiently stable to make 24-hour reconnaissance data useful for planning. Because of the required fine granularity of predictions and the generally changeable nature of the nearshore environment, METOC information must be current and of high resolution. To achieve this purpose requires quantitative use of remote sensing data (ground truthed with some in situ data, if possible) fused with numerical models for complete battlespace characterization. METOC Variables for Nearshore Operations Discussions at the 1997 tactical oceanography symposium led to the development of a full list of important METOC variables for nearshore operations, their level and nature of impact, and the state of scientific understanding or capability for their estimation. Major environmental factors include: Bathymetry—of pervasive importance with either direct impact (obstacle) or indirect impact (e.g., cause of wave shoaling and breaking). Shelf life of data is short in surf zone, longer offshore.

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Waves and surf—major impact on all operations as described by operational limits. Refraction can lead to substantial along-coast variability that can be used to an advantage. Currents—major impact on swimmer operations, less so for amphibious vehicles. Can be modeled, given reasonable bathymetry data. Tides—affects clearance over shoals and obstacles, workable depth. Tidal currents can be strong in some sites. Water temperature—major impact on swimmer operations. Can be predicted or remotely sensed. Turbidity—useful for clandestine swimmer operations but can hinder navigation or obstacle (and mine) search. Bioluminescence—major impact on clandestine SEAL operations. Wind—direct effect on parachute operations, indirect effect through waves. Precipitation—visibility effect (potentially positive) with other impacts on fatigue and discomfort. Atmospheric visibility—effect can be positive or negative. Humidity—affects electromagnetic ducting and fatigue in warm climates. Environmental Influences on Mine Warfare and Mine Countermeasures Since the refinement of sea mines and sea-mining strategies during World War I, naval mine warfare has figured prominently in all major conflicts involving U.S. Naval Forces. Indeed, since the Korean War (1950-1953), sea mines have been responsible for more U.S. ship casualties than all other forms of attack combined (Avery, 1998). Mine Warfare The importance of mine warfare (MIW) in both offensive and defensive operations lies in the efficiency of mines as force multipliers: Mines are inexpensive and can be technologically simple to build; the simplest forms of sea mines rely on 19th-century technology that is still effective (National Research Council, 2000b). Mines can require very little maintenance. Once deployed in the marine environment, mines can persist as active threats for years. Mines are easily deployed from almost any platform. Swimmers or divers, small boats, large ships, submarines, or aircraft are capable of mine-laying operations. Mines are small and stealthy; the small size of mines combined with their frequent deployment in shallow water marine environments makes their detection and neutralization difficult.

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redeposition of sediments and mine scour or burial. Opposing river outflow currents and tidal currents may result in very turbulent flow and mixing of water masses with quite different temperature and salinity characteristics, and these can impact the performance of acoustic and optical sensors used for mine detection. In the surf zone, powerful currents generated by breaking waves can affect transport and redistribution of mines or transport large quantities of sediment, resulting in mine burial on a variety of timescales important to MIW operations. In addition, the surf zone is an environment where extreme turbulence and bubble saturation in the water column renders acoustic or optical detection systems useless. Thus, physical conditions in the surf zone water column continue to pose very challenging problems for MIW and MCM operations. In very shallow water and shallow water environments, wind-driven currents are somewhat more predictable than in the surf zone, but their impacts on MIW are no less profound. Strong currents cause significant scour around bottom mines or mine moorings and greatly affect the distribution or track of drifting mines. Alternatively, strong shelf currents or bottom-feeling waves can transport sediment, resulting in mine burial, which makes detection difficult. Water clarity is inversely related to turbidity or opacity. Water clarity affects both MIW and MCM operations by affecting the performance of optical sensors (divers or other optical sensing devices) and their capability to detect mines or accurately map bottom features and bathymetry. In riverine/estuarine settings, water clarity can vary from clear to opaque, and vice versa, on timescales of less than an hour due to rapid resuspension and settling of sediments induced by tidal flow and water mass mixing. In the surf zone, water is typically rendered nearly opaque to optical sensors as a result of breaking waves and consequent bubble saturation and sediment suspension in the water column. In shallow and very shallow water zones, water clarity may vary seasonally according to variations in primary productivity, incursion/excursion of various water masses, and fresh-water and sediment outflow from coastal rivers or estuaries. In deep water zones, optical properties of water are controlled primarily by abundance and type of plankton. Plankton abundance may vary diurnally to seasonally, with associated impacts on visual recognition of drifting or moored mines. Temperature and salinity are critical environmental parameters affecting MIW and MCM activities in a variety of ways. Temperature and salinity variations may impart stratification to the water column with concomitant influences on the acoustic properties of the water column and the performance of acoustic sensors used for mine detection. Temperature and salinity variations in riverine/ estuarine and coastal settings may result in density fronts in the water column that affect acoustic sensor performance. Suspended sediments may become trapped on these fronts, resulting in turbid horizons in the water column, or mixing of water with different salinities may induce flocculation of very fine-grained sediments, resulting in settling as loose aggregates on the seafloor as mud or fluid mud deposits. In shallow and deep water zones, oceanographic fronts and water

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column stratification related to temperature and salinity differences affect acoustic properties of the water column and thus the performance of acoustic sensors. Waves are of critical concern in the surf zone through the shallow water zone because of their capacity to generate strong currents (e.g., in the surf zone), scour and redistribute bottom sediment (surf zone through shallow water), induce turbulent mixing in the water column that may affect both optical and acoustic properties of the water column, and affect nearshore MIW and MCM operations. In the surf zone, breaking waves render the environment opaque to acoustic sensors. Breaking waves generate strong longshore and rip currents capable of redistributing mines, creating scour around mines, or transporting sediment and burying mines on dynamic temporal scales. In shallow and very shallow water zones, bottom-feeling waves may induce scour around mines or affect sediment transport, resulting in mine burial. In deep water, white caps or rough sea surface conditions with large or confused wave patterns may make visible detection of drifting mines very difficult. The acoustic environment of the ocean is very complex, especially in littoral settings where MIW activities are most prevalent. Nearshore environments (riverine/estuarine, surf zone, shallow water, and very shallow water) are characterized by high reverberation, high ambient noise, and both vertical and horizontal water column heterogeneities, all of which affect acoustic properties of the ocean environment. As such, any physical, chemical, biological, or geological phenomena that affect the water column have potential impacts on its acoustic properties and the performance of acoustic sensors used for mine detection. Environmental Influences on Biochemical/Environmental Warfare Biological Weapons Biological weapons include bacteria, viruses, and toxins that are spread deliberately in the air, food, or water to cause disease or death to humans, animals, or plants. Examples include plague, smallpox, and anthrax. Biological agents tend to be persistent and can have a delayed effect extending for days or weeks. Biological weapons are attractive to so-called rogue states or nonstate actors such as terrorist groups because they provide a means of waging asymmetric warfare against an adversary with superior military capabilities. They are easy to acquire, since agents occur in nature as the causative agents of disease. Depending on the biological agent, small amounts are capable of creating significant disruption, fear, and a number of deaths. Chemical Weapons Chemical weapons would likely be dispersed in the air for the purpose of rapidly debilitating or destroying humans, animals, or plants. Examples include

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mustard gas, sarin, and napalm. Chemical agents are usually volatile (although some can be persistent). It takes a large volume of chemicals and thus a large number of aircraft to deliver chemical agents to their targets (i.e., to attack a city, seaport, or battle group). For this reason a chemical attack would likely be more obvious than a biological attack and easier to defend against. Scenarios One scenario might be a single biochemical attack against a single U.S. naval vessel or naval base that does not result in large casualties or affect the viability of military operations (USS Cole-type scenario). An opponent might consider such an attack as a propaganda medium and a way to demoralize U.S. military personnel. A second scenario might be an aggressor who decides that chemical/ biological warfare may diminish the willingness or capability of the United States and its allies to intervene. In this case, the aggressor might try to use such weapons to kill significant numbers of U.S. and allied military personnel and to raise the cost of defending against aggression well above what it would be otherwise. Role of Environmental Information The environment (air and water pathways) is the transmission medium for biochemical weapons of mass destruction. Environmental pathways should be addressed and modeled by the METOC community. Some examples are: A dispersion zone of influence forecast might be a worthwhile product for special forces and other forward-deployed forces. Mesoscale modeling and forecasting. Urban terrain and dispersion. Distributed sensors to feed mesoscale transport models. METOC should take a role similar to the role meteorologists have taken for air pollution issues. This should include establishing siting criteria for biodetectors on ships and determining the type and number of sensors required to estimate the duration of a shipboard chemical attack. Important Parameters in Air Environmental parameters important for airborne dispersal of biological or chemical warfare agents are temperature and humidity; wind speed; wind direction; turbulence parameters for urban or rural environments; solar insolation, photooxidation, and/or decay; and precipitation and precipitation rate.

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Important Parameters in Water Environmental parameters important for dispersal of biological or chemical warfare agents in water are currents, temperature and salinity, waves, and turbidity. Environmental Influences on Multi Mission Operations Multi mission naval operations are those that incorporate elements of power projection, air-sea dominance, and deterrence of hostile actions into a complex 4-D battlespace, often to be coordinated with operations of other armed forces of the United States or coalition partners. By their very nature, multi mission operations conducted by naval forces will require maximum utilization of navy METOC assets in such a way that the full spectrum of naval METOC products will be required throughout the mission time line. Multi Mission Scenario A hypothetical multi mission scenario might include requirements for environmental information relevant to (1) naval special warfare activities, (2) suppression of enemy air defenses, (3) tactical strike warfare, (4) time-critical strike warfare, (5) MIW and MCMs, (6) naval amphibious warfare, (7) naval surface warfare (primarily ship self-defense), and (8) submarine and anti-submarine warfare. Clearly, requirements for environmental information in support of each of the operational elements of the multi mission scenario above are diverse. In addition, it will be necessary to disseminate relevant environmental information to a broad spectrum of fighting forces across a number of armed services. As such, interoperability and compatibility of environmental data or data products are overriding requirements for successful execution of multi mission objectives. A brief summary of the range of environmental information that might be required for successful conduct of multi mission operations is presented below. This summary is intended to serve as an illustration of the complexity of METOC requirements for this type of mission and is not necessarily a comprehensive review of all potential information needs. Instead, the review below is intended to stimulate exploration of strategies to achieve the desired sensor and information coverage within the multi mission battlespace necessary to meet the needs of the various warfighters. Naval Special Warfare Naval special warfare (NAVSPECWAR) operations typically involve covert deployment of SEAL teams in hostile territories. As the name implies, SEALs may be deployed from the sea (submarines, swimmer delivery vehicles, fast

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TABLE B-3 General Summary of Environmental Data Needs for NAVSPECWAR Operations Deployment Style Environmental Information Needs Sea Ocean temperature, currents, tides, winds at sea, surf/sea state (period, height, wavelength, direction, steepness, “groupiness”), salinity, water optical properties, bioluminescence, dangerous marine organisms, ocean or other environmental toxins, near shore acoustics, bathymetry, lunar phase/ illumination, biofouling, bottom character Air Surface winds, winds aloft (speed, direction), EM ducting (effects on radar propagation/detection and communications), temperature and humidity, temperature and humidity profiles with altitude, cloud cover, lunar phase/ illumination, visibility, aerosols (type and quantity), EO properties of atmosphere, atmospheric boundary layer dynamics, terrain, vegetation, precipitation forecasts Land (amphibious) Winds at sea, surf/sea state (period, height, wavelength, direction, steepness, “groupiness”), bathymetry, beach trafficability, terrain, vegetation, EM-EO ducting, slant range visibility, aerosols, temperature, humidity, precipitation, lunar phase/illumination   SOURCE: National Research Council (1997). surface vessels, swimming through open water), air (fast-rope helicopter insertion, parachute drops from any altitude), or land (amphibious landing). Environmental information needs for each of these deployment strategies are different, and a general summary is provided for each in Table B-3. Suppression of Enemy Air Defenses Suppression of enemy air defenses (SEAD) will typically be accomplished using various strike warfare tactics and weapons systems. Increasingly, there is a need for precise target identification and location for these missions, and often PGMs such as cruise missiles or other “smart” weapons (e.g., Joint Direct Attack Munition), radar-homing weapons (e.g., HARM), electrooptical weapons (e.g., Maverick), and various gliding ordnances will be utilized in addition to potential use of close air support aircraft (A-10, AV-8, A-6, F/A-18, AH-1F, AH-1W, AH-64, RAH-66). At least some of the weapons systems used for SEAD will depend on NAVSPECWAR operators in the theater providing targeting intelligence and laser designation of targets. Use of these weapons platforms for SEAD operations will require a variety of METOC forecast products as well as more specific environmental data needs (summarized in Table B-4). Again, the list presented in Table B-4 is not comprehensive but is intended to provide a sense of the diversity of environmental data needs for SEAD operations.

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TABLE B-4 General Summary of Environmental Data Needs for SEAD Operations SEAD Weapons Systems Environmental Information Needs Cruise missile Digital terrain model, complete forecast along flight path and for duration of flight, winds aloft, winds at target, aerosols, slant range visibility, cloud cover, precipitation, precise target identification and location, space weather (if relying on direct GPS communication), vertical wind shear, atmospheric turbulence EM-targeting weapons EM ducting, winds aloft, winds at target, vertical wind shear, atmospheric turbulence, aerosols, precipitation, precise target identification and location EO-targeting weapons Atmospheric refraction, refractive index, visibility, aerosols, slant range visibility, winds aloft, winds-at-target, precipitation, cloud cover, precise target identification and location Gliding ordnance Precise target identification and location, winds aloft, winds at target, vertical wind shear, atmospheric turbulence, precipitation, space weather (if relying on direct GPS communication) Close air support Precise target identification and location, winds aloft, winds at target, vertical wind shear, atmospheric turbulence, precipitation, space weather (if relying on direct GPS communication), slant range visibility, lunar illumination, weather fronts and severe weather systems, cloud cover, cloud ceiling   SOURCE: National Research Council (1996b). Tactical and Time-Critical Strike Warfare Strike warfare involves the use of combat aircraft, cruise missiles, and (as recently demonstrated in Afghanistan) armed unmanned aerial vehicles (UAVs) to (1) penetrate an adversary’s defenses from the air, (2) deliver precision ordnance on either fixed or mobile targets, and (3) assess battle damage while ensuring a safe return to the base of operations. In the context of naval strike warfare, this means air operations from aircraft carriers or ship-launched cruise missiles. Increasingly, there is recognition that many strike missions (especially those targeting mobile or opportunistic targets) have a time-critical dimension such that weapons systems must be selected and delivered precisely on target with a very short decision cycle. Such time-critical assaults require near real-time environmental information from battlefield sensors, and these data must be processed and disseminated from the sensors to the weapons system within minutes. Such rapid target identification, location, and destruction place extraordinary demands on METOC capabilities. Factors affecting tactical and time-critical strike missions are summarized in a general way in Table B-5. It is important to note that a significant proportion of naval strike missions continue to

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TABLE B-5 General Summary of Environmental Data Needs for Tactical and Time-Critical Strike Operations Tactical/Time-Critical Strike/ Warfare Systems Environmental Information Needs Combat aircraft, cruise missiles, unmanned aerial vehicles Precise target identification and location. EM-EO ducting, winds aloft, winds-at-target, vertical wind shear, atmospheric turbulence, aerosols, humidity, precipitation, slant-range visibility, cloud cover, cloud ceiling, precipitation, weather fronts, severe weather, icing conditions aloft (for UAVs), space weather (if relying on direct GPS communication), atmospheric refraction effects, atmospheric scintillation, forecast along flight path and for duration of strike operations, precipitation rate, characteristics of surface and near-surface clutter   SOURCE: National Research Council (1996b). be adversely affected by weather. (National Research Council, 1996b, reports that 90 percent of strike missions from 1992 to 1995 suffered from weather effects.) Mine Warfare and Mine Countermeasures Technologies for deploying, concealing, and activating mines are becoming increasingly sophisticated, and MIW and MCM in multimission scenarios greatly complicate efficient execution of these missions. In the worst cases mines may cause significant loss of naval assets (e.g., ships, submarines, amphibious assault craft) and personnel. In less severe cases, the presence of mines requires a significant dedication of assets for detection, sweeping, and neutralization while at the same time impeding progress of offensive operations, removing the element of surprise, and exposing U.S. combat forces to hostile action for longer periods of time. MIW Battlespace The MIW battlespace ranges from the littoral zone (coastal rivers and estuaries, beaches, and surf zone) to deep water settings offshore continental margins, island margins, and narrow seaways. Environmental parameters critical to MIW and MCM operations vary among these zones (see Table B-6) but are generally divided between processes and phenomena related to the seafloor and processes and phenomena related to the overlying water column. As a general rule, these processes become more complex and dynamic with decreasing water depth and

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TABLE B-6 Most Common Oceanographic Parameters Used for Nearshore MIW Operations and Their Importance in Different Water Depth Zones as Defined by the Navy   Riverine/ Estuarinea Surf Zone Very Shallow Water Shallow Water Deep Water Seafloor Bathymetry H H H H M Sediment grain size H M H H M Seafloor clutter density M M H H L Bottom roughness M M H H L Mine burial H H H H L Water column Currents H L/Hb H H M Water clarity M L H H M Temperature and salinity H L M H H Waves L H H M L Acoustic properties H N/A H H H aRiverine and estuarine environments pose unique problems not addressed in National Research Council (2000b). bWithin the surf zone, information on wind-generated currents is of low priority as these currents are generally overwhelmed by wave-generated currents. H = High, a parameter that is essential for MIW in this depth zone. M = Medium, a parameter that is useful for MIWin this depth zone. L = Low, a parameter that is of little use for MIWin this depth zone. SOURCE: National Research Council (2000b). proximity to shore. An understanding of the dynamic oceanographic conditions in each MIW zone is an important component of evolving MCM strategies and techniques. Naval Amphibious Warfare Naval amphibious warfare involves assaults from the sea to land occupied by hostile forces, clearing land of those forces, securing a forward-operating base, and preserving capability to move additional warfighters and warfighting equipment across the beach. Amphibious warfare shares many similar environmental needs with NAVSPECWAR operations, though amphibious operations are typically overt rather than clandestine. Warfighting equipment and personnel are usually transported from sea to land in air cushion vehicles, amphibious landing craft, and amphibious armored vehicles. Oceanic, atmospheric, and geological

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TABLE B-7 Environmental Parameters Impacting Amphibious Warfare • Currents • Tides • Winds at sea • Surf/sea state ○ Period ○ Height ○ Wavelength ○ Direction ○ Steepness ○ “Groupiness” ○ Bioluminescence • Bathymetry • Coastal geology • Terrain • Beach trafficability • Vegetation • Offshore obstructions (reefs, rocks, etc.) • Lunar phase/illumination • Cloud cover • Cloud ceiling • Fog • Aerosols • Horizontal visibility • Radar-frequency propagation • Atmospheric refraction • EM-EO ducting • Precipitation features of the environment can affect the performance of these platforms. Some of the environmental parameters affecting amphibious operations are listed in Table B-7. Surface Warfare (Ship Self-Defense) Surface warfare may involve direct engagements against enemy vessels but more commonly will be focused on ship self-defense, especially in the littoral zone. Increasingly, ship self-defense is defense against airborne threats—either aircraft or missiles and sea-skimming missiles. As such, environmental parameters of importance to ship self-defense are very similar to those of importance to tactical and time-critical strike warfare. Indeed, ship self-defense might be reasonably categorized as a form of time-critical strike warfare because of the (usually) very short time to detect, acquire, and neutralize incoming sea-skimming missiles. Table B-8 provides an overview of environmental parameters important to ship self-defense.

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TABLE B-8 Environmental Parameters Impacting Ship Self-Defense • Winds at sea • Surf/sea state ○ Period ○ Height ○ Wavelength ○ Direction ○ Steepness ○ “Groupiness” • Bioluminescence • Lunar phase/illumination • Cloud cover • Cloud ceiling • Fog • Aerosols • Horizontal visibility • Radio-frequency propagation • Atmospheric refraction • EM-EO ducting • Precipitation Submarine and Antisubmarine Warfare Whereas submarine warfare remains a significant component of U.S. naval doctrine, threats to U.S. naval assets from enemy submarines have greatly diminished since the demise of the Soviet Union in the late 1980s and early 1990s. Nonetheless, ASW skills perfected by U.S. naval forces throughout the Cold War era are necessary elements of the capability to conduct multi mission operations. Submarines still serve as stealthy platforms to conduct covert reconnaissance or launch conventional cruise missiles and to stand guard as a nuclear deterrent force. However, the nature of submarine warfare and ASW in the littoral regions of the world brings with it a set of environmental parameters to which naval METOC functions are unaccustomed. These include the greater degree of spatial and temporal environmental variations in the littoral zone and their effects on the performance of submarine and antisubmarine sensors. Table B-9 provides some indication of the environmental parameters of importance to submarine warfare and ASW.

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TABLE B-9 Environmental Parameters Impacting Submarine and Antisubmarine Warfare • Winds at sea • Waves/sea state (period) ○ Height ○ Wavelength ○ Direction ○ Steepness ○ “Groupiness” ○ Surface roughness • Bioluminescence • Ocean fronts • Shelf currents • Shelf bathymetry • Seafloor acoustic properties • Salinity variations • Ocean temperature variations (lateral and vertical) • Bubbles in the water column • Ocean acoustic ducting • Littoral zone ocean climatologies • Seafloor type • Acoustic transmission losses • Subseabed geoacoustics