Working Group Summaries
The three working groups focused on (1) environmental models, (2) atmospheric effects, and (3) sensors and weapon systems. This chapter covers the salient topics and ideas that arose during the discussions of the working groups.
ENVIRONMENTAL MODELS
Ninety percent of the Navy's strike missions have been adversely affected by weather in the past three years. Strike missions are a significant component of naval air operations and, consequently, the Navy needs a weather-based system to aid in configuring aircraft weapons and sensors. The Navy is continuing its vigorous pursuit of greater vertical and horizontal resolution of environmental parameters, particularly with coupled atmospheric and oceanographic models. The Navy's goal is to obtain a 2-kilometer horizontal resolution by the end of the decade, which raises the question: Where should the Navy's environmental models be run? Ship-installed and -operated oceanic and atmospheric prediction systems using high-resolution models would rely on boundary conditions transmitted from shore sites. Thus, even with shipboard modeling capabilities, ships would need to rely on communication with shore facilities.
The present limitation on communication speeds in the battle group, as well as between shore and ship, constitutes one of the major reasons for running high-resolution models aboard ship. To obtain the minimum data volume regarding boundary conditions in a timely manner, it is imperative that naval communication speed and bandwidth be improved dramatically. Presently, it can take hours to measure and execute strike warfare planning actions, whereas other types officer environmental data products and forecasts (e.g., activities related to ship self-defense) can be produced in minutes. Hardware and software system designers must take into account the time constraints under which the METOC staff must operate. A fleet forecaster has only minutes from the time environmental data are received to assess and review the data and formulate a forecast for the ship captain or task force commander.
As the Navy increases its emphasis on littoral zone warfare, environmental modeling must more accurately account for the small-scale processes that affect coastal ocean and atmospheric conditions. Oceanographic and atmospheric conditions change much more rapidly in the littoral area, therefore, there is a practical limit to the forecasting of conditions at small scales. This issue reflects the
importance of rapid assimilation of in situ data, as well as the need to increase data collection and to determine the impact of observed data on coastal model performance. Although most of today's tactical decision aids are not dependent on distance, most of the world's littoral areas are oceanographically and meteorologically heterogeneous. It must be noted that, by focusing solely on model resolution, one might be misled into believing that a model is accurately predicting environmental conditions. Forecast quality control and verification of observational data are conducted in earnest at the Navy's Fleet Numerical Meteorology and Oceanography Center. Similar procedures will have to be established and installed for shipboard environmental models.
In evaluating the Navy's capabilities for providing tactical environmental support, the Office of the Oceanographer of the Navy is confronted with the following fundamental question: Should planning forecasts use coupled individual (ensemble) forecasting techniques or should the Navy strive for one very high resolution megamodel? Although ensemble forecasting is valuable, such systems may offer too many choices to forecasters, thereby compounding the problem imposed by limited time. A separate but important issue is whether stochastic or deterministic methods would best solve the Navy's environmental forecasting needs (given today's level of technology and forecasting expertise). The Environmental Models Working Group suggested that the Navy pursue modeling techniques in which individual processes are turned on and off via toggle switches, depending on the littoral area conditions for which forecasts are desired.
Toggle-switched modeling techniques would allow individual scientists to focus their research on specific METOC processes. A modeling research panel (similar to the ongoing Special Sensor Microwave Imager [SSM/I] algorithm research panel) could then meet on a regular basis to discuss the merits of the computer program written to model each process. The Navy must remain open to innovative modeling ideas, whereas the purveyors of these ideas must keep in mind that models need to be stable to consistently support fleet operational users.
The working group cautioned the fleet regarding the recent trend in requests for increased forecast precision. For example, wind and sea forecast updates will soon be expected every 3 hours versus the present synoptic 6 hour schedule. The fleet has also voiced the desire that quantitative constraints be placed on forecasts. For example, a prediction of “15- to 20-knot winds today” may soon be replaced with a more difficult forecast of “19-knot winds from 1300 to 1400 [hours], decreasing to 17-knots from 1400 to 1500 [hours].”
The working group noted that emphasis must be placed on the need to seek and foster feedback from tactical users regarding which environmental parameters are most critical. The academic members of the working group conveyed the opinion that the modelers are rarely aware of the most significant environmental features for operational or simulator use. It was obvious from the briefings provided by fleet operators at the symposium that few, if any, METOC parameters are presently used in strike warfare training (i.e., few METOC parameters are recorded as part of the Strike Warfare Center's [STWC] computer stored engagement).
The members of the working group agreed that the Navy should strive to use METOC data in a diagnostic mode during training and simulation in order to determine the possible impact of environmental factors on an actual engagement. The go/no-go METOC criteria for a given engagement need to be understood by both operators and the METOC community. The Navy should characterize the METOC conditions under which past engagements occurred in order to better understand the potential impact of environmental factors on future engagements.
The Navy appears to be reaching a general awareness of the risk associated with developing any system (e.g., ship, aircraft, weapon, sensor) without first understanding how METOC conditions will affect its performance. The METOC community must do a better job of demonstrating its support for METOC modeling to program managers and associated members of the acquisitions community. Program managers for instrument systems must be convinced that their investments will be offset by future savings in program funds. They must be shown the potential for environmental impact on their program early in its development, instead of trying to work around environmentally induced operational shortfalls after the program has been completed. An excellent example of this situation is reflected in the Navy's investigation of the use of the SPY-1 radar as a potential weather radar.
Most METOC customers in the fleet are interested in obtaining practical information about weather phenomena (i.e., predictions of cloud base, visibility). The need to generate this type of weather output was evident to all panel members, and the opinion was voiced that the initial focus should be on moisture (i.e., clouds, cloud bases, visibility, aerosols, rain rates) in the atmosphere. Moisture in the lower atmosphere has the potential to impact both strike warfare and ship self-defense operations in significant ways.
METOC data must also be configured for direct integration into Navy fire control systems. A future goal should be for each weapon and/or radar to have continuous and automatic access to METOC data for local and target areas, as well as with enroute environments and forecasted operational effects electronically passed into the systems.
ATMOSPHERIC EFFECTS
The Atmospheric Effects Working Group postulated that numerous factors could promote improvements in the capabilities of tactical METOC. High-resolution mesoscale models are needed that accurately describe atmospheric effects (i.e., refractivity, visibility, clouds) and that are tuned to the specific needs of operators in a specific region and environment. System developers are reaching beyond the historic "all-weather" concept to a series of "adjective" weather terms such as “standard,” “adverse,” and “severe.” In addition, aviators make a critical mission distinction between “flying through the weather” and “flying over the weather.” Consequently, the Navy's precision strike study defined adverse weather with 4 parameter values, including a cloud ceiling of less than 1,500 feet, visibility of less than 3 nautical miles, precipitation greater than 4 millimeters per hour, and absolute humidity greater than 18 grams per cubic meter. Modelers must be able to quantify the variance of atmospheric parameters and develop predictions of geographic controls on means and variances for such parameters as winds and gusts, cloud coverage, and refractivity fluctuations.
Four-dimensional data assimilation techniques also are needed to support strike warfare, including better sensor-to-model integration and better data dissemination. These improvements require airborne radiometers and satellite imagery (e.g., UAVs and satellite remote sensors, including lidars), geographically tied to the NAVSTAR GPS. Additionally, there is a need for the ability to conduct analyses from remotely sensed data (including higher-order moments) and for the use of new representation techniques for turbulence-scale phenomena that affect signal propagation.
METOC capabilities should include improved environmental observations. More proficient models that produce near-surface forecasts should be developed from improved datasets. The capability to perform data and model uncertainty assessments is a critical link in the formulation of new models. The ability to perform simultaneous RF and electro-optical (EO) assessments is highly desired. Finally, it is imperative that available data be used more effectively for briefing and debriefing.
Mission-inhibiting conditions described during the symposium focused on offensive threats that could be obscured from detection by the environment. Concern was expressed about the adverse impact that environmental factors may have on the sensing of sea-skimmer cruise missiles, mines, and periscopes. Detection of mobile missile-launcher platforms also may be hindered by an obscuring atmosphere. The ability to forecast cloud formation and movement is therefore, particularly important. Real-time METOC information should provide input to a visualization scheme that will allow warfighters to place assets in the best position, under the best conditions. Warfighters should have the ability to fight and operate sensors and fire control systems using the most up-to-date data available.
There are specific areas of science and technology that, if made available to the Navy, would advance the tactical use of meteorology and oceanography. Small-scale environmental predictability and the identification of predictability limits are possibly the most important challenges facing the Navy. Therefore, an improvement in the measurement of variables (i.e., cloud cover, refractivity, visibility) to support small-scale environmental models would constitute a significant accomplishment. In addition, efforts must be made to fully exploit the space-based collection of atmospheric and oceanic data. The collection and assimilation of conventional and unconventional environmental data (such as GPS) would improve modeling capabilities. To exploit the sea-skimming cruise missile environment for tactical ship self-defense, models will have to be tuned specifically for characterization of the complex, coupled ocean-atmosphere, near-surface layer.
SENSORS AND WEAPON SYSTEMS
There is a significant overlap between civilian and Department of Defense weather observations, thereby permitting the transfer of technical knowledge from one sector to the other. Military METOC forecast applications, however, are vastly different from civilian applications. Civilian-marketed environmental forecasts are designed for fixed geographical areas and regular time intervals; military tactics demand flexibility in terms of variable locations and time periods. Military applications often have less tolerance for degradation of METOC product accuracy and timeliness.
Priorities for METOC applications were identified by the Sensors and Weapon Systems Working Group for strike and ship self-defense missions. The working group concluded that, to support strike warfare, the METOC community should focus its attention on (1) environmental conditions at the target area, (2) environmental conditions at the launch platform (both carrier and tactical aircraft), and (3) environmental conditions along a target's route. The need for increased effort in these areas is driven by the technologies used in seeker-based, stand-off missile systems.
These systems are used during aircraft launch and during the rapid transition from target acquisition to fire control and bomb damage assessment that occurs as part of an actual strike. Environmental parameters of concern to the METOC community include the determination of cloud ceiling height, as well as EO and IR visibility. These parameters can determine go/no-go decision points. Therefore, if conditions deteriorate at a target area while strike aircraft are enroute, such conditions can force a decision to abort the mission. Similarly, target appearance to imaging IR seekers may suffer various stages of precision degradation owing to environmental conditions. Finally, knowledge of wind profiles is critical to the performance of free-fall weapons and submunitions.
To support ship self-defense, the METOC community must become proficient in describing conditions at and around the surface ship, including 3 important zones: 100 kilometers from shore, 100 kilometers inland, and a radius of 100 kilometers around the ship. Similar to the rapid pace of events in strike warfare, ship self-defense operators must detect, acquire, target, and engage sea-skimming targets that are masked by environmental clutter. To reduce the threat represented by sea-skimming targets, knowledge of the RF, EO, and IR refractivities is vital to increasing detection ranges. Sea-surface characterization in terms of wave spectrum, currents, and temperature can assist in determining the masking potential of the ocean-atmosphere interface environment. High-resolution vertical atmospheric profiles of temperature, pressure, and humidity increase the ability to target and engage incoming missiles.
METOC model products are derived from global weather information which, in turn, is derived from surface ship observations, drifting and moored buoys, and polar and geosynchronous orbiting weather satellites. Unfortunately, this broad array of weather data sources, tools, and resources is still inadequate to collect the data necessary to support mesoscale models and detect certain specific environmental events. Exploratory projects developed to address this shortfall are presently under way at the Applied Physics Laboratory (APL), the Naval Research Laboratory (NRL), and the Stennis Space Center. The APL is developing a ship-board sensing system called SEAWASP. The NRL is focusing its efforts on small dropsondes for UAVs, as well as small on-the-ground systems used to increase data collection in areas of low data density. Other options are being explored, including the delivery of sensors from chaff launchers on operational tactical aircraft.
Cloud base is an example of an important observational parameter for which improved data collection is needed. The Navy's fleet forecasters cannot rely on the single data point provided by an enroute radiosonde. Satellite data cannot provide accurate information regarding cloud base. The large-array multiple spectral bands on the sensor suite of the new Geostationary Orbiting Environmental Satellite (GOES) may be capable of providing this cloud base information. It would be tactically prudent to perform cloud base measurements with a small dropsonde or another small unit. This issue is of such great importance that the Advanced Research Projects Agency (ARPA) has circulated a Broad Area Announcement to solicit ideas.
In general, aircraft-mounted sensors do not have the capacity to collect the METOC data required to support strike warfare. Future remote-sensor suites needed for environmental characterization must combine multiband microwave and stereographic imagery. Shipboard support infrastructure for imagery already exists on aircraft carriers.
The weapons development community needs to examine how the environment affects emerging systems prior to selecting any sensor or sensor array. For example, the use of an infrared-seeking sensor may not be appropriate for an “all-weather” weapon. There are circumstances where the METOC community will not have the ability to solve questions posed by the platform and subsystems acquisition communities, owing to limitations imposed by the physics of the natural system. It is imperative that such limitations be known and communicated. In addition, it is equally important to communicate to the fleet or users that a problem limited by physics is unlikely to be solved in the near future.
One approach to solving questions involving weapon sensors would be for the Office of Naval Research to sponsor a survey of available historical databases of the military services. This survey would emphasize forecasting capabilities and how they might be used to employ weapons more effectively. The needs of weapon sensor systems could also be addressed by making automated weather observation systems available on all ships. When automated shipboard systems were originally proposed, there was concern that they might not be properly or easily maintained. Coastal automated weather stations and drifting buoys, however, have demonstrated that commercially available sensors and communications have the ability to withstand the rigors of the marine environment. Similarly, meteorological data collected by sensors suites presently operating onboard ships of the University-National Oceanographic Laboratory System (UNOLS) fleet indicate that moderate improvements and additions to sensor suites used on Navy surface vessels could result in better quality data. It is important to have sensor systems either in place around areas of future military interest or available for immediate deployment if necessary. A significant time frame (days to weeks) is needed to place satellites over an area of interest. The likelihood of having six months to prepare for military action, such as in Operation Desert Storm, is low.
Environmental sensor technology can address the METOC needs for both strike warfare and ship self-defense. As alluded to earlier, three-dimensional measurements of temperature, pressure, relative humidity, ocean currents, wave spectra, and sea-surface temperature are needed in the vicinity of ships and aircraft. This can be accomplished in situ, using a combination of radiosonde, unattended ground sensor, drifting instrumented buoy, dropsonde, and nephelometer assets. Environmental microsensors, small enough to fit in a watch case, can be appended or dispersed from aircraft and UAVs. In situ measurements can be supplemented by lidar and improved exploitation of environmental satellite sensor suites. A new approach is emerging that utilizes existing ship sensors as environmental sensors in off-cycle times (e.g., using the AEGIS radar as a doppler weather radar).
Future directions for technology used for environmental support of fleet operations center around increased precision, data density, and timeliness. Quantitative knowledge of the influence of sea state on RF and IR sensor clutter and masking is needed. The environment must be described using microscale characteristics. Future METOC needs include system integration to provide operators and forecasters with an easily recognizable and comprehensible awareness of the environment. This may include sensor data assimilation with mesoscale models that are adapted to, and integrated with, sensor management.
METOC data resolution requirements envisioned for these fleet activities were defined during the symposium. Temperature and humidity profiles need to resolve (vertically) 15-foot
intervals between 30 and 500 feet above the sea-surface, 25-foot intervals between 501 and 2,000 feet, and 100-foot intervals between 2,001 and 20,000 feet. The horizontal resolution required between profiles is on a 5-mile grid, in a region with a radius of 65 miles (~100 km) around a ship. Sea-surface temperature must be described for the upper 3 inches of the sea-surface (i.e., not by using simple seawater injection temperatures), measured on the same 5-mile grid and over the same horizontal space as the vertical profiles. Data accuracy needs are projected as follows:
It is unknown whether sensor and weapon systems should be designed to directly measure or remotely sense important parameters. Both methods have advantages and disadvantages in terms of accessibility, timeliness, covertness, and affordability. It is important that modeling be used to help determine data sampling strategy (i.e., where and how to measure and or remotely sense). Although initially easier, it is expensive to measure all parameters and extract small data subsets (e.g., virtual temperatures derived directly from GPS data).
Affordability may be a limiting factor in expanding environmental sensing. Direct measurement by balloons, dropsondes, and rocketsondes can cost tens to hundreds of dollars for a given operation. Operating budgets may not allow ships to carry sufficient disposable sensors or perform the maintenance optimally required for expanded METOC support through in situ measurements. The unit cost of environmental satellites has risen, and continues to rise rapidly, promoting interagency agreements such as that of the Department of Defense and Department of Commerce that merged the efforts of the Defense Meteorological Satellite Program (DMSP) and the National Oceanic and Atmospheric Administration's (NOAA) polar satellites. Intergovernmental agreements also are becoming necessary to make satellite systems more affordable (e.g., the inclusion of French assets in the National Polar Orbiting Satellite System [NPOSS]). Concern has arisen regarding the planning of an absolute minimum number of spacecraft, with no backup satellites in orbit. Furthermore, questions remain about the participation of governments that reserve the right to deny data access.
As fleet communications capabilities have grown, so has the need to transmit more environmental data and products. Bandwidth has been a limitation for decades. Although the U.S. Navy has large communications conduits, METOC community communications cannot fit within the bandwidth allotted, even during peace time. For example, with the present communications system, 30 percent of the environmental products do not make it to the customer, and 30 percent of the ships and aircraft do not have the equipment to receive any products. Furthermore, in times of crisis or national emergency, operational and tactical message traffic volume increases rapidly, further reducing the capacity for transmission of environmental data.
Efforts to distribute products of the Fleet Numerical Meteorology and Oceanography Center (FNMOC) via super high frequency (SHF) communications systems were viewed by symposium participants as appropriate. High-frequency facsimile communication is now considered obsolete, even though the equipment is inexpensive and small enough to be placed on any small vessel or accompany mobile meteorology teams. These user groups are not scheduled to receive SHF receiver equipment and they need access to data. The decrease of combatant ships in a reduced fleet, combined with an increase in the number of areas in which the Navy is potentially active, results in an increase in the number of independent ship operations. The number of vessels accompanying aircraft carriers has been reduced, in some instances to one or two. The large carrier-centered battle group, in which the carrier's meteorological staff passes environmental products to accompanying ships, has become very rare. All future sensor solutions must be affordable, to allow installation on as many ships as possible.
