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9 Future Naval Forces and the Operating Environment Introduction Effective Navy and Marine Corps operations of all types require a comprehensive knowledge of the operating environment and, in turn, an understanding of the impact of those operations on the environment. The tools for characterizing the operating environment include longand short-term weather forecasting and mapping and modeling of ocean and littoral waters, including positions of submarines, ships, and mines. Readily available supercomputing-scale computational power (see Chapter 2, Computation), combined with high-resolution, pervasive sensor information (see Chapter 4, Sensors), increasingly sophisticated sensor fusion and filtering of data, and improved data display and assimilation tools (see Chapter 3, Information and Communications), will provide Navy and Marine Corps decision makers with access to accurate and predictive battle space environment information. Public awareness of the impact of commercial and military maritime operations on the ocean environment is growing, and new restrictions on ocean dumping have been placed on ships. Recent Marine Pollution (MARPOL) Annex V regulations include a total ban on plastics discharge anywhere at sea and restrictions on the discharge of other solid waste materials in specially designated areas. Restrictions will likely become more pervasive in the future with the international regulation of atmospheric emissions from ships scheduled to begin in 1999. Tomorrow's naval forces will have to be able to reduce the sources of waste and to safely dispose of waste in a more efficient manner than currently fielded technology now allows.
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Terrestrial Weather and Climate Prediction Recent advances in remotely acquired data, mainly from satellites, are providing a wealth of information about the ocean and atmospheric environment not previously available. The Navy complements such remote sensing with ship-based measurements of ocean depths, temperatures, salinities, and other parameters and has good historical data sets derived from more than 100 ship-years of dedicated time. New distributed sensors will provide real-time data at high resolution representing large areas, with deployment possible in remote or otherwise inaccessible regions as needed. A major thrust for the future will be the enhancement of environmental data through the use of increasingly sophisticated models of the ocean/atmosphere system. Assimilation of these data into the Coupled Ocean-Atmosphere Dynamic System (COADS) model will be enabled by the rapid advances in computational power and modeling and simulation technology. The real-time weather prediction made possible by this combination of massive database modeling and computational power will allow tactical users to anticipate events in real time and strategic planners to more accurately predict seasonal weather. Meteorological Thrusts On the meteorological side, the current major emphasis of Department of the Navy research conducted at the Naval Research Laboratory, Marine Meteorology Division, at Monterey, California, is on data assimilation for the Navy Operational Global Atmospheric Prediction System (NOGAPS) and the Navy Operational Regional Atmospheric Prediction System (NORAPS) models. The data being assimilated includes those from both surface- and space-based platforms, data from the latter including the remotely sensed measurements of the ocean-surface wind speed, precipitation rates, and total vertical column moisture. A new NASA scatterometer (NSCAT) was successfully launched on a Japanese satellite in August 1996 and is delivering accurate wind speed and directional data spanning the world's oceans. Future instruments, called SEAWINDS, are scheduled for launch on Japanese platforms in 2002 and 2007. These and other satellites will provide a major new critical data set for naval open-ocean operations. They are expected to revolutionize boundary-layer modeling for upper-ocean environmental changes as well as provide a complete array of electromagnetic surveillance of the battle-group environment. The wind is the basic parameter that determines the vertical structure of all atmospheric variables below the cloud base. Currently, these data are available only in a delayed mode; future naval operations will require real-time data acquisition from U.S. spacecraft. In all likelihood, planners soon can expect to see significant development of very-high-resolution weather prediction models, such as the Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS), which is the planned
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successor to NOGAPS and NORAPS. COAMPS will provide data on a 5-km grid. Higher-resolution models will be necessary, however, for precision tactical warfare purposes. Expected increases in computing power, high-density data storage, and real-time sensor data will allow the necessary increases in both spatial and temporal resolution, with a concomitant increase in prediction reliability for such phenomena as localized rainfall, cyclone tracking, ocean wave height and direction, and coastal mesoscale issues. Forecasting ability has improved continuously since 1970, and expectations are that this trend will continue beyond the year 2000.1,2 These expectations are based on data that do not take into account the high-resolution satellite data now available, which should significantly increase cyclone predictability. Local forecasting of rainfall conditions was performed by a special group of the National Weather Service using IBM and other supercomputers for the 1996 Atlanta Olympics.3 The availability of this type of information allowed the organizers of the Olympics to manage their multiple widely separated venues effectively. The application of similar real-time or near-real-time information to battle-group operations should be straightforward. Data and Data Assimilation Thrusts The Department of the Navy has provided a great service by making available large amounts of extremely valuable data, such as the global digital bathymetric database (DBDB). A gridded 5-arc-minute product from these data is publicly available and widely used. In the aftermath of the Cold War, efforts to declassify data that are most useful for understanding emerging environmental issues (e.g., global warming, fisheries, pollution) are increasing, along with the development of technology to assist the user with assimilating large amounts of data through the use of graphical representations and other visualization means. The focus is on how such data may be enhanced by combination with mathematical models, for both reporting current conditions (best estimate of current state of the environment) and forecasting. Such a combination has been accomplished successfully in meteorology, which has been driven by commercial interest and which is currently more advanced than ocean modeling. This combination of models and data will be a major area of research in the atmospheric as well as 1 Anthes, Richard, A. 1995. ''Tropical Cyclones: Their Evolution, Structure, and Effects," Journal of the American Meteorological Society , 19(41):1–203. 2 Foley, G.R., H.E. Willoughby, J.L. McBride, R.L. Elsberry, I. Ginis, and L. Chen. 1995. "Global Perspectives on Tropical Cyclones," WMO Report, TCP-38, R.L. Elsberry, ed.. Secretariat for the World Meteorological Organization, Geneva, Switzerland. 3 Skinrud, E. 1996. "Georgia on Their Minds: Olympic Weather Team Pushes the Limits of Forecasting," Science News, 150:29, July.
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ocean sciences in the near future, especially with the greatly expanded current databases and new types of data available from remote sensing. Computing and Oceanography Thrusts Modeling of such complex systems as the oceans, the atmosphere, and their interactions requires massive computational power. The world oceans have major circulation features such as the Gulf Stream and associated eddies that require horizontal grid resolution of a few kilometers and many vertical levels to adequately resolve important features. For example, to address the entire global ocean, including the effects of these small-scale but energetic features, which may be critically important, requires a computational grid of at least 100 million points. Assuming a typical time-step size of about 5 minutes and about 250 operations per grid point per time step, this translates to about 10 million-billion operations to calculate 1 year of activity. This does not include coupling of models for the ocean and the atmosphere, which is even more computationally intensive. Thus, the High Performance Computing Initiative's (HPCI) minimum computing allotment to the DOD would not be enough for serious climate studies. For regions of special naval force or other environmental interest, it may be desirable to use nested grid approaches in which ultrahigh-resolution regional grids are nested within coarser grids to reduce the computational load. Nesting has the major advantage of providing physically consistent open boundary conditions. This technology is particularly promising for shipboard computing applications. For example, it allows a ship-based computer to assimilate local observed data into a resident regional model in which the boundary conditions are provided via communications from a large-scale model center, as depicted in Figure 9.1. This approach avoids the transmission of information that may compromise strategic advantage and decreases the need for large-bandwidth shipboard communications. Improved nesting approaches will be a major area of technology development for the foreseeable future. Goals of the Ocean-Atmosphere Weather Modeling Effort In the near term (3 to 5 years), planners can expect to achieve high-resolution weather modeling and prediction using HPCI facilities, including 3- to 5-day forecasts of mesoconvective rainfall, cyclone tracks and intensity, ocean waves, and coastal mesoscale phenomena. In the medium term (5 to 10 years), it should be possible to provide mesoand microscale weather information to users in the field, improved weather models with ocean/atmosphere interactions, high-resolution forecasts for battle-group and field users supported by high-resolution local observations via deployable sensors, correlation of local sensor data with atmospheric and ocean models to
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FIGURE 9.1 Schematic representation: A future battle-group weather forecast. provide accurate automatic target recognition and acquisition, and 6- to 7-day forecasts of large-scale weather systems such as cyclones. In the long term (10 to 20 years), ships should be provided with local high-performance computing with massive stored databases for autonomous high-resolution, small-scale weather reporting of current environmental conditions and lower-resolution, larger-scale 30-day weather forecasts displayed multi-dimensionally and multisensorially. Space Weather Prediction The space environment around Earth, known as the magnetosphere/ionosphere system, can have adverse effects on naval communications, navigation, and weapons systems. The ONR and NRL conduct research on space phenomena, but the Department of the Navy generally does not field operational sensors that collect environmental data that can be used in space weather forecasting. The U.S. Air Force 50th Weather Squadron at Offutt Air Force Base, Nebraska, has responsibility for monitoring space weather for all of DOD. The Air Force employs a full suite of modeling and prediction tools, but because the space environment is so large and complex, these models and tools are necessarily
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limited. In terms of forecasting, the most important variables are the interplanetary magnetic field orientation and the density and speed of the solar wind. NRL is now intimately involved in the Solar Heliospheric Observer (SOHO) mission that provides a point measurement of the solar wind density and speed. Observations from more than one platform are crucial to providing adequate temporal and spatial characterization of the parameters that ultimately determine the state of the space environment. With respect to satellite operations that support naval interests, satellites in geosynchronous and semisynchronous orbits are exposed to a flux of high-energy particles. Electronics on orbiting space platforms are affected by the radiation dose and the naturally occurring variations in these energetic particles. Charging of dielectrics to several thousands of volts under certain space environment conditions can occur with subsequent discharges and permanent damage to sensitive electronics. Energetic particles may emanate from regions that involve huge volumes of space that cannot reasonably be sampled in situ. Recent efforts supported by a consortium of civilian and governmental institutions have shown some promise in remotely imaging this vast magnetosphere using space platforms. Continuing efforts in magnetospheric remote sensing is needed if the DOD and the Department of the Navy are to have reasonable lead time in forecasting disturbed conditions in space. The value of specifying the state of the on-orbit space environment in real time cannot be overstated. Every operational spacecraft should carry basic particle- and field-sensing equipment to characterize the local radiation environment. Equipping new spacecraft with compact environment sensor packages would be the space equivalent of collecting atmospheric and sea surface measurements by the surface fleet. Scintillation The ionosphere is often viewed as the cooperative medium that makes over-the-horizon communications possible, but the ionosphere is also the largest source of error in civilian GPS4 navigation and can cause communication problems, notably those arising from the phenomenon of scintillation. At sunset, the ion and electron content of the ionosphere near the equator becomes irregular. These irregularities cause significant rapidly varying phase and amplitude distortions in communication signals. Radio waves appear to scintillate, causing uncertainty in geo-locating the satellite transmissions. At high latitudes the auroras cause similar effects. Scintillation is more widespread and intense during the maximum portion of the 11-year solar cycle, such as the upcoming period from 1998 to 2003. 4 Ionospheric effects on military GPS systems are partially mitigated through the use of two frequencies.
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Mid-latitude areas, where most weapons systems are deployed, are not normally affected by large regions of ionospheric scintillation, but the low- and high-latitude regions that are affected may extend to 40 percent of Earth's surface. The occurrence, extent, and impact of ionospheric scintillation needs to be better understood, along with the physics of scintillation forecasting, if increasing geo-positioning accuracy with the GPS satellite system is to be achieved. To understand the extent of scintillation, surveys must be made worldwide. Inexpensive sensors need to be fielded at both shore locations and on ships that collect data in HF, UHF, and GPS frequencies. After data collection and analysis to correlate the frequency of occurrence of scintillation with weapons-system interference, the Department of the Navy should examine its options for implementing scintillation mitigation measures. Finally, 24- to 72-hour forecasts of ionospheric scintillation could be generated if the DOD developed an operational computer model of the sun and interplanetary space, with a corresponding sensor suite to drive the model in real time. The output of the solar/interplanetary model could be used as input to radiation models that forecast the condition of the magnetosphere and to those models that produce background and scintillation forecasts of the ionosphere. Deep-Water Modeling NRL is a world leader in modeling the world oceans for aspects critical to naval operations. It routinely calculates ocean currents, fronts, and eddy locations (in hindcast mode) using daily surface weather fields including those obtained from the European Forecasting Center. Despite this excellent capability, naval forces in the future must have real-time access to the output of a global model driven by current input data on (1) surface wind fields, (2) surface sea level, and (3) the internal variability of thermal fields. Wind data may be obtained from scatterometers on polar-orbiting satellites, such as NSCAT. Two satellites are required to give the Navy the coverage needed to monitor all remote areas. Altimeters mounted on the Navy GEOSAT and NASA TOPEX-POSEIDON satellite have demonstrated the ability to measure the shape of the ocean surface. Given an accurate geoid and tidal model, such data can be assimilated into ocean models to provide an estimate of ocean currents, front location, and eddy location. Measuring the internal variability of thermal fields is more difficult because the information comes from the midwater (on the order of 500- to 2,000-m) ocean thermal structure. The two technical systems that are candidates for future development are acoustic tomography and drifting smart floats that measure current and temperature and maintain position in a constant water density. Both systems have been tested by the academic community, and both show promise. The global acoustic monitoring of ocean thermometry (GAMOT) project, for example, has demonstrated that the feasibility of deploying very inexpensive drifting passive sonar buoys capable of measuring
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deep-water travel time using fixed-sound-source acoustic transmission and data uplink to satellites. Such measurements allow the development of models of the upper 1,000 m of a 4- to 5-km-deep ocean. The other 80 percent is below the level of most conceivable naval operations. Because the ocean is stratified, slow moving, and, consequently, hydrostatic, almost all of the fundamental environmental information that is time dependent is transferred to the deep ocean through conservation of mass and momentum. Since the atmosphere cannot be accurately forecast more than 1 to 2 weeks in advance, accurate upper-ocean forecasts cannot be obtained because the ocean is forced by the wind. Fortunately, the ocean structure changes relatively slowly, so that current ocean reports will be viable for a week or more, which is long enough for most critical naval operations. Littoral-Water Modeling The ocean's response to the atmosphere, radiant energy, and tides may be characterized according to its local depth. The domains are the deep ocean (depths greater than 1,000 m), the continental slopes (depths from 2,000 m to 200 m), the continental shelf (depths from 200 m to 20 m), and the near-shore littoral zone (depths shallower than 50 m). The overlap in depths accounts for different configurations of shelf-slope geometry around the world. For example, off Peru, one might find water depths of 100 m within 100 m offshore, whereas near deltas off the southern United States, depths of only 10 to 20m might be found 10 km from shore. A thorough understanding and modeling of near-shore littoral waters is critically important for future naval forces. A physical understanding is reasonably well established, but this zone also encompasses much greater variability in current, sediment transport, visibility, salinity, and so on, than the deeper regions of the ocean. The deep ocean is quite variable in many regions, but the time scale of variation is generally longer than that for shore waters, and, as discussed above, high-resolution real-time data are not as critical for many naval operations. The physical variability, the acoustic environment, and the visibility of the littoral zones are not well modeled. Each region on Earth is affected differently primarily because of variations in bottom topography, water runoff, climate, and bottom composition. There are, however, well-understood (except for turbulence) physical principles to assist in characterizing each regime. If appropriate data are acquired and retrospective studies performed, it is possible to anticipate the physical state of the littoral zone that might be encountered in naval operations. Multimodality sensor systems that provide real-time data are being developed for this highly variable environment.
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Physical Modeling of the Littoral Zone Near-shore waters are driven by the sun, tides, winds, and land runoff of fresh water and sediments and by off-shore currents. The actual shape of the bottom and its capacity to reconfigure are also significant. Tomorrow's naval forces will have access to large-scale ocean models capable of accurately predicting off-shore currents needed for boundary conditions and will have accurate large-scale weather modeling for atmospheric boundary values of such phenomena as wind stress, heat flux, and solar radiation. For each threat region, a local, portable physical model could be created that could accurately simulate the physical state of a littoral zone under various scenarios of weather, both typical and extreme (typhoons, tsunamis, climate variability, etc.). Model scenarios for each potential area could be developed and validated. Codes, climatologies, topographic configurations, and the like, can be stored in a modern high-speed, large-memory workstation. Modern data assimilation protocols (either variational adjoint or Kalman-Bucy filtering) can be overlaid on the basic model database. Either in anticipation of actions or during an event, all data gathered in the region can be assimilated to produce the most probable physical environment needed for surface, underwater, acoustic, and countermeasure operations. The data output from these physical models is time dependent and three dimensional. Shipboard personnel generally do not have the technical back-ground to interpret the complex environmental fields. A solution is to develop four-dimensional graphical visualization systems to be used to identify patterns such phenomena as currents, temperature fronts, and low-visibility regions. Such software is not currently available except in primitive form but is under development. Mapping the shape of the bottom is currently straightforward, but visualization of the flow in the water volume is difficult because of the enormous databases involved and the inherent problem of mapping a four-dimensional picture onto a two-dimensional computer screen. Workstations of the future will have enough cycle power, memory, and storage to handle the computations, but new visualization techniques have to be developed, such as four-dimensional virtual reality systems. Within 10 years, it should be possible to provide on shipboard modest-sized virtual-reality sites for naval personnel to see the present and evolving underwater physical environment. Shallow-water Acoustics The physics of acoustic phenomena in the open ocean is well understood. Given a source location, a receiver, and information on such things as water density and the shape of the bottom, the behavior of sound can be calculated. But in most littoral zones, this is almost impossible because the temperature and
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salinity of the water change with season and weather conditions. Moreover, surface sea waves change quickly and frequently and the behavior of the bottom reflectivity and absorption changes within waters. Thus, reliable interpretation of acoustic transmission in near-shore waters is technologically challenging. Unfortunately, foreign navies are investing in electric submarines that are relatively small and quiet. These, along with inexpensive and plentiful mines, pose serious threats to naval forces in shallow water. Special attention needs to be directed toward pattern recognition and signal recognition of moving and stationary objects in shallow water. Extensive simulation of acoustic systems must be carried out with the various scenarios predicted by the physical modeling system. For example, high-frequency active sonar may be effective for mine detection in shallow water but not have enough range for ASW in deeper water. Modeling will provide the information necessary to make informed choices of sensor-system deployment and enable the development of protocols to identify interdicted structures not encountered in tests of the anticipated acoustic environments. Visibility Various manned and unmanned operations in the littoral zone are affected by changing visibility conditions. Intense storms can reduce underwater visibility by moving silt, and the typical clear waters seen by divers on tropical shelves during pleasant weather do not characterize the visibility on most continental shelves. Fog, rain, and sandstorms can affect atmospheric visibility. To offset these problems, physical models of the visible environment under a variety of conditions should be developed. Such simulations can be used for training personnel on the conditions and hazards to be experienced in naval operations. Near-shore Currents In many littoral zones, strong unpredictable currents, such as storm surges, rip tides, turbulence, and breaking waves, can occur. These shallow energetic currents can create havoc for surface or underwater transportation of people and equipment. Databases need be developed for climatologies and probabilities of strong near-shore currents. Beaches must be characterized by their physical properties and ability to support energetic events. It is currently technically feasible to predict storm surges up to a day or two in advance, since strong atmospheric storms are very well predicted on that time scale.5 In the United States, a priori storm-surge prediction is typically used to determine coastal building codes, for example. Hurricane storm surges predicted when 5 O'Brien, James J. 1996. "Changes to the Operational Early ETA-Analysis/Forecast System at the National Centers for Environment Protection," Weather and Forecasting, 11(3):391–413.
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a storm arises are based on empirical information, not accurate modeling. The Navy Department could benefit from the models being developed by the academic community, not only for naval bases but also for potential action locations. Shipboard Waste and Pollution Management Cost-effective, environmentally sound, and technically feasible methods for handling solid and hazardous waste will continue to be a vital concern for the Navy, particularly with regard to the unique logistical constraints associated with shipboard operations. Increasing restrictions placed on ship discharge by the international community also drives the need for efficiency improvements on board Navy ships. Although the Navy is currently exempt from the MARPOL 73/78 Annex V Regulations for the Prevention of Pollution by Garbage from Ships, these guidelines are applicable to all classes of ocean-going ships and the U.S. Congress has indicated that the Navy will have to comply with Annex V at some point in the future. In this document, only those waste and pollution management problems unique to ship operation are considered. Waste management alternatives such as waste minimization, pollution prevention, recycling, and waste use and reuse, when used in conjunction with innovative technological advances, can offer a variety of options to ensure the effective management of the Navy's shipboard solid, liquid, gaseous, and hazardous waste. Several recent reports by the National Research Council6,7 on shipboard waste management summarize currently available and near-term waste management technologies. As pointed out in the Guidelines for Implementation of Annex V of MARPOL 73/78, education of personnel is an important component of any waste management system. Adapting existing technologies or developing new technologies to help manage shipboard waste requires knowledge of the types and quantities of waste produced during naval operations. The types of waste streams typically generated on U.S. Navy vessels can be categorized as (1) solid (e.g., metal, glass, plastics, food waste, paper, cardboard, medical waste); (2) liquid (nonoil waste such as blackwater [sewage] and graywater [shower/laundry/dishwashing discharges] and oily waste such as bilge cleaning and derusting fluids, antifouling paints, and waste oils); or (3) gas (air emissions from marine vessel diesel or gas turbine engines and on-board incinerators). The ideal waste management system would be completely closed where waste are used as feedstocks for useful products or energy, preferably on board 6 Naval Studies Board. 1996. Shipboard Pollution Control; U.S. Navy Compliance with MARPOL Annex V, National Academy Press, Washington, D.C. 7 Marine Board. 1995. Clean Ships, Clean Ports, Clean Oceans, National Academy Press, Washington, D.C.
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Closed-cycle systems would be necessarily complex, heavy, and bulky and therefore not suitable for shipboard use. Partial systems for recycling some materials such as metals, plastics, and water and converting waste paper into energy are in use on shore. Waste Minimization A primary goal of any waste management system that must operate in a closed and contained environment, such as in Navy vessel operations, is to have a logistics system in place that minimizes the production of waste. To help facilitate this goal, all shipboard supplies and maintenance procedures should be evaluated in terms of the types and quantities of wastes generated, and a thorough study should be conducted to see if other options such as process changes, engineering design changes, product or packaging specification, or substitution can accomplish the same goal while simultaneously reducing the waste stream. For example, a significant portion of the space on a logistics support ship is occupied by soda cans. Substitution of the cans with bulk soda syrup and water carbonation systems would increase logistical-support ship capacity and decrease waste while not significantly affecting quality of life aboard ship. A similar product and process design philosophy is being used by the automobile8 and personal computer9 industries in their design-for-recycling programs. Because of serious space limitations, the absence of at-sea replenishment, and limited air supply to support incineration, submarines have developed effective (albeit labor-intensive) waste minimization practices. An example of waste minimization is the Plastic Removal in Marine Environments (PRIME) program that focuses on source reduction of plastic materials aboard Navy ships. By changing the packaging specifications for supplies, PRIME has reduced the annual amount of plastics brought on board by 475,000 pounds.10 This is approximately 10 percent of the total 4.5 million pounds of plastic estimated to have been discharged each year until 1988. PRIME eliminated another 62,000 pounds of waste (per ship per year) by using paper instead of polystyrene drinking cups. This amounts to about 8 million large, 14-oz.styrofoam cups or over 10 million small cups. Such programs can be expanded to produce significant additional savings at little additional cost. Managing potentially hazardous substances can best be accomplished by ensuring that the materials are consumed. A current example of hazardous waste 8 Ashley, S. 1993. "Designing for the Environment," Journal of Mechanical Engineering, 115(3):53–55. 9 Sheng, P., and J. Sutanto. 1995. "Environmental Factors in Parametric Design of Computer Chassis," Journal of Electronics Manufacturing, 5(3): 199–216. 10 Marine Board. 1995. Clean Ships, Clean Ports, Clean Oceans, National Academy Press, Washington, D.C.
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minimization Consolidated Hazardous Material Re-utilization and Inventory Management Program (CHRIMP), a computer-based inventory system based on the concept of centralized control and cradle-to-grave management of hazardous materials and waste such as paint, solvents, and cooling agents. Nonminimizable hazardous materials such as those generated by various cleaning and industrial operations are stored on board in drums until docking, where they are transported to landfills or land-based incinerators. Identifying and/or developing technologies that could minimize, clean and reuse, or detoxify these waste materials on board the vessel while at sea should be an important research priority. Another approach is the development of nontoxic, environmentally benign alternatives, particularly for cleaning operations. The use of citrus-based cleaners instead of chlorofluorocarbons for degreasing in the semiconductor industry is a good example of the latter. Waste Treatment A major roadblock in developing effective waste treatments is generally a separation process. For example, recycling of metal cans has been proven to be economically feasible because there are cost-effective methods of separating steel and aluminum cans with the resulting materials easily recycled. Similar arguments can be made for plastics, paper, solvents, and waste water of all kinds. Ultrafiltration is being used in the food-processing and paint industries but needs further development for the complex mixtures encountered on Navy vessels. In current use are ceramic membranes for concentrating oily waste and polymeric membranes for blackwater and graywater. The discharged filtered water has waste concentrations below 15 ppm, within the current acceptable discharge limit. The removed dried solid material may be incinerated, eliminating the ocean discharge of the food waste, graywater, and sewage streams. Plastics, a major waste management concern on ships, are currently treated for disposal by shredding the material and then thermally compressing it into flat disks for storage until off-loading at port. Shredding plus thermal compression yields a volume reduction of almost 50 percent. The resultant disks are composed of several types of plastic, usually contaminated by food and other container contents, thereby significantly limiting their ability to be recycled. More than 200 types of plastic now exist in waste streams, and these should be separated for effective recycling. Commercial recyclers are developing infrared techniques for identifying different types of plastic, which can then be sorted for recycling. Currently, seven types can be distinguished in this manner. Such technology may not be feasible for shipboard use, however. A more practical solution may be to limit the number of plastic types on board and sort by use. The use of biodegradable plastics would not eliminate the disposal problem but would allow such plastics to be treated as food or paper waste. Biodegradable plastics
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would be particularly useful for forms such as plastic film that are readily contaminated. Shredding and pulping are efficient methods for the treatment of food and paper waste. Pulpers are able to treat up to 600 lb/h of waste, and the resulting slurry can be mixed with seawater and dumped overboard in permitted regions. The slurry presumably does not adversely affect plant and fish life. This technology can have significant benefits as food and paper waste constitutes approximately 60 percent of shipboard solid waste by weight. Additional reduction in weight can be achieved by biological treatment, but more compact systems need to be developed for Navy shipboard use. To meet future, more stringent, discharge requirements, the biologically treated slurry would have to be dewatered and stored or oxidized. After all possibilities for minimization, recycling, and reduction are exhausted, residual concentrated carbon-based waste may be pyrolyzed and oxidized to produce volatile oxides with minimal solid residue. Compact, efficient incineration or alternative pyrolysis/oxidation processes specifically adapted for use aboard U.S. Navy ships should be developed. Some of the methods now in various stages of development are supercritical water oxidation, high-pressure hydrothermal processing, electrochemical oxidation, semiconductor photocatalysis, ozonation, electrohydraulic cavitation, plasma arc thermal conversion, pulsed-power cold plasma reactors, and advanced incinerator designs. In addition to factors such as process efficiency and throughput and emissions that must be considered for any disposal technique, other factors unique to Navy vessels that must be considered include power requirements (a net power producer, if possible), size (small), infrared signature (low), EMI (little or none), reliability (under normal and battlefield conditions), and the need for operator expertise. Although the Navy is exempt from MARPOL regulations for the time being, it is still required to achieve zero plastic discharge. Because restrictions on ocean dumping will only increase, it is prudent for the Department of the Navy to continue development of adequate waste disposal systems. The two alternatives appear to be (1) storage of compacted separated waste for port recycling and disposal, and (2) adaptation of current cruise ship or similar systems involving biological pretreatment and incineration of wastes except for plastics, glass, and metal, which are stored and recycled on land. In either case, properly packaged waste could be retrograded to combat logistics support ships after offloading supplies. Both of these options require significant on-board storage space. For waste destruction, near-term development should concentrate on compact, low-power, low-signature, high-reliability incineration systems. Air Pollution The main source of air pollution in any navy are propulsion and auxiliary power systems burning fossil fuels. In fact, restrictions on nitrogen oxides (NOx),
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unburned hydrocarbons, carbon monoxide, and particulate matter will be imposed on new marine diesel-powered vessels by 1999. The most direct method, therefore, of reducing air pollution from naval operations is to develop alternative energy sources (see Chapter 8, ''Electric Power and Propulsion") for most, if not all, shipboard energy needs. At present, nuclear power is the cleanest power source available for ship use with regard to air pollution. Although disposal of spent nuclear power plant waste is a serious problem, it is not one that is unique to ship operations. Fuel cells for clean oxidation with few environmental byproducts and solar cells for direct electrical energy production are two alternative energy sources that have been under development for several decades. Compact, high-density fuel cells, based on immobilized enzymatic redox reactions for power storage, should be available in the near term. Similar advances in solar cells have occurred regularly over the past decade. Certainly, increasing the efficiency of ships' engines and their distribution systems will reduce reliance on nonrenewable and potentially embargoed oil resources. The centralization of power sources possible with the electric ship would enhance the development of more efficient engines. For the near term, however, air pollution from chlorofluorocarbon (CFC) refrigerants is a much more serious problem because of the deleterious effect of CFCs on atmospheric ozone. Under the auspices of the Copenhagen Amendments to the Montreal Protocol, the production of ozone-depleting fluorocarbon refrigerants has been banned since December 31, 1995. The Navy currently has approximately 850 CFC-114 chilled water air-conditioning plants that provide mission-critical electronics cooling on surface ships and submarines. It has therefore been necessary for the Navy to identify a suitable refrigerant alternative to CFC-114 and to develop and qualify suitable backfit modifications for shipboard CFC-114 air-conditioning plants. Currently, 12 different Navy shipboard CFC-114 air-conditioning plant designs are in effect—ranging from 125 to 363 tons in cooling capacity—all of which require backfit modifications. Noise Pollution An issue of critical importance to today's naval forces, and almost certainly to be important to 21st-century forces, is the growing concern about the possible harmful effects of certain underwater sounds on marine life, and the restrictions this might place on the use of sonar systems and other naval activities that generate underwater sounds, including weapons and hull-integrity tests. In point of fact, the Navy Department has had to seek permits to conduct ship-shock tests (using explosive sources) and tests of prototype sonar systems, as well as for exercises to develop tactics and strategies for employing low-frequency active sonars. Weapons-testing in the Gulf of Mexico has been constrained. The Navy has to prepare extensive environmental impact studies for
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these operations and in some instances has altered venues and test plans. In all instances, delays have been incurred, and the expense in dollars and manpower has been significant. Largely as a result of an increasingly aware, vocal, and powerful environmental movement that is demanding compliance with marine mammal and endangered-species protective laws, recent naval practices have been called into question—specifically, the low-frequency active acoustic ASW development programs, which are based on very-high-intensity sonars operating in the vocalization frequency bands of many marine mammals, especially whales. The steady, historical reduction in submarine-radiated noise in all submarine variants—nuclear, diesel, and air-independent—has reduced the effectiveness of passive ASW and necessitated the development of active methods. Over the next several decades the proliferation of quiet, capable, and effective submarines through foreign sales and indigenous manufacture may result in even more reliance on active acoustics. As a result, the issue of compliance with environmental laws will almost certainly be a major problem for the future naval forces unless mitigation measures are undertaken. Therefore, it is entirely possible that the Department of the Navy will be prevented from developing and fielding the systems it requires to execute its future missions, unless a rational basis for mitigating risk to marine populations is developed. The Navy Department must pursue the R&D necessary to develop sufficient understanding of the issues to enable rational, informed decisions. Recommendations Battle-space awareness, communications, target identification, navigation, weapon guidance, and tactical planning all require real-time understanding and forecasting of the atmospheric, space, and sea environments of operation. Global weather models with improved satellite data on winds, temperature, solar inputs, and so on will permit the generation of accurate weather forecasts. Space weather forecasting of solar disturbances, scintillation phenomena, and other disturbances will be modeled based on real-time satellite data. The Department of the Navy must support the development of this modeling capability. With respect to terrestrial weather and climate prediction, the panel presents the following recommendations: To take advantage of the vast quantities of new environmental data from an increasing array of remote-sensing devices—in space, in the upper atmosphere, on land, and on and under the sea—the Department of the Navy should pursue the development of shipboard computational and data communication systems coupled to land-based high-performance computers. Emphasis should be placed on developing the higher-resolution climate prediction models that are necessary for tactical warfare operations.
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R&D emphasis should be placed on the high-performance hardware, algorithms, and memory storage required to enable real-time applications under realistic battle-space conditions. With respect to space weather prediction, the panel presents the following recommendations: Greater emphasis should be placed on educating naval personnel about the effects on weapon systems of interference caused by electromagnetic disturbances and energetic particles in the space environment. Greater R&D emphasis should be placed on technologies for mitigating or eliminating adverse effects owing to space weather, such as the scintillation phenomena, on communication and weapons systems. The Department of the Navy should monitor and contribute to the development of space-based remote sensors, such as magnetospheric imagers, and Earth-based sensors that monitor the sun and the ionosphere to provide reasonable lead times in forecasting disturbances in space weather. Development of a robust computer model of the sun and interplanetary space, driven by real-time sensor data, should be a high priority within the DOD, and should be encouraged by the Navy Department, to permit reasonably accurate forecasts of ionospheric scintillation. With respect to deep-water modeling, the panel presents the following recommendations: To take advantage of the vast quantities of new data from an increasing array of remote-sensing devices and thus be able to accurately forecast ocean currents, fronts, and eddy locations and behaviors, the Department of the Navy should pursue the development of multidimensional, on-board data retrieval and analysis systems involving high-performance models. Deployment of at least two additional remote-sensing satellites may be required to permit complete monitoring of the ocean's surface. Greater R&D emphasis should be applied to obtaining thermal profiles of depths ranging to 1,000 m, a critically important element in ocean forecasting. With respect to littoral-water modeling, the panel presents the following recommendations: Greater attention should be paid to the dynamics of near-shore environments, including such phenomena as shallow-water acoustics, variable visibility, and strong, near-shore currents, which at present are not well understood. Databases should be developed that sufficiently describe near-shore phenomena,
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including beach characteristics, that can lead to accurate forecasting of littoral conditions. To enable naval personnel to use such databases, graphical interface technologies need to be developed, including on-board, multidimensional, multisensorial virtual-reality systems capable of representing real-time and evolving underwater physical environments near shore. With respect to shipboard waste and pollution management, and management of noise pollution, the panel presents the following recommendations: To mitigate risks to the environment and to shipboard personnel, greater emphasis in reducing and handling a variety of waste streams associated with naval operations is a pressing need. Where possible, successful land-based applications of waste minimization and treatment technologies should be adapted for shipboard operations. Emphasis should be on curbing waste at its source and treating waste as a renewable resource or useful energy source. Increased R&D on subsurface noise propagation and its effects on marine populations must be conducted. There are few data currently available on an issue that is likely to pose serious impediments to a host of naval operations.
Representative terms from entire chapter: