Analysis of alternatives: atmospheric measurements supporting naval operations
Document ID: 189
Philbrick, C. Russell1
Clark, Richard D.2
Willitsford, Adam H.3
1 Professor of Electrical Engineering, Applied Research Laboratory Senior Scientist, Penn State University
2 Professor of Meteorology, Chair, Department of Earth Sciences, Millersville University
3 PhD Candidate, Penn State University, Electrical Engineering
Prepared for SPAWARSYSCEN CHARLESTON
Abstract
As combinations of factors bring about the necessity to make changes and take advantage of the next generation of technology, we arrive at the point where major improvements can be made in our ability to monitor atmospheric variables to better understand the influence of the environment when performing complex missions, as well as the day-to-day tasks in the operational Navy (see the description in http://www.nwdc.navy.mil/Concepts/Sea_Strike/SeaStrikeM.aspx). The traditional use of balloon sonde expendable instrument packages has served well as the source for atmospheric data profiles, but cannot provide the time resolution of atmospheric changes to meet the needs of the present and future naval systems. However, major improvements in remote sensing technologies now make possible several opportunities for extending our ability to measure and define the atmospheric conditions. Instead of two per day sonde releases with data products two hours later, the atmosphere can be continuously profiled using Raman lidar techniques, which provide real time data products of the primary data on temperature, density, and water vapor profiles. In addition to these, new data products available from lidar include profiles of optical extinction, range resolved visibility, cloud height – and most important for the forecaster or the operations planner, the profiles are updated every few minutes to resolve rapid changes in the parameters. Water vapor and temperature profiles are used in real-time calculations of the RF-refraction that is needed for radar interpretation. The profiles of the meteorological properties, the electro-optical (EO) environment and the electromagnetic (EM) environment can be obtained simultaneously using a single instrument. Other remote sensing techniques can add further important information. For example, microwave radiometers can be used to receive the path integrated brightness temperature from the microwave emission of molecules. The microwave brightness temperature can be used to select the most appropriate atmospheric model to represent the current conditions. By entering the microwave data into a model such as COAMPS, an appropriate model representation for the atmospheric conditions can be selected. Another technique that can add information on the low altitude wind velocity is an SODAR, or sound detection and ranging. The Doppler shift in the frequency of an acoustical wave is used to measure the range resolved radial wind component. Current SODAR systems use phased-array transmitters to point the sound wave and determine the total wind vector from the surface to above 1 km. While preparing this document, we have considered three additional points which are important regarding the development of the Navy’s capabilities for conducting future operations. The first has to do with the importance of distributive data processing and data/model availability for local support/forecasting during deployment, the second is the recognition of the value in a multisensor capability to support naval operations, and third is the potential contribution of the TAGS ships.
- The COAMPS model was developed to provide a high resolution mesoscale model for local prediction of atmospheric conditions within an operating region, and it uses the regional boundary from the global NOGAPS model. The importance of distributive processing has been demonstrated in many ways, but the current plan appears to be to depend on a center, such as FNMOC, receiving data products from the local area, processing it and preparing a model to distribute back to the deployed unit. A better approach appears to be installing a dedicated microprocessor cluster computer (ballpark cost $50k) on one of the ships in a battle group so that the local data can be assimilated, and the COAMPS model can be locally run for battlespace forecasts. This approach would avoid problems in distant communications and provide the best support for the commander.
- The atmosphere is a complex fluid medium and no single instrument or system can measure all of the key properties. In particular, no single sensor is able to provide measurements of its particular parameters at all times. For these reasons, the most logical approach is to develop an operational plan that would allow the selection of data from several different sensors. It should be possible to develop an operational approach that could obtain measurements using Raman Lidar, microwave radiometer, MRS balloons and SODAR. All have added value at different times in support of different missions.
- The T-AGS ships provide valuable mission support in defining the oceanography and the undersea stratigraphy (https://www.navo.navy.mil/pao/other/about_us.htm). The mission for these ships could be expanded to include the function of providing: (1) a suite of atmospheric sensor measurements (lidar, radiometer, balloon sondes, SODAR), (2) assume a role gathering the data from other ships and assets deployed in the area, (3) facilitate the assimilation of the data into forecasting models by communicating it back to FNMOC, and (4) running the regional COAMPS model for local forecasting. A cluster computer could be dedicated to ingest the local data, gather the NOGAPS regional boundary model updates, and provide the local model for operational forecasting.
| Citation: | "Analysis of alternatives: atmospheric measurements supporting naval operations", Philbrick, C. R., R. D. Clark, A. H. Willitsford, U.S. Navy, 2007, pp. 1 - 71 |