WindSat Space Borne Polarimetric Microwave Radiomenter: Mission Overview and Sensor Performance

The global ocean surface wind vector is a key parameter for short-term weather forecasting, the issuing of timely weather warnings, and the gathering of general climatological data. In addition, it affects a broad range of naval missions, including strategic ship movement and positioning, aircraft carrier operations, aircraft deployment, effective weapons use, underway replenishment, and littoral operations. Through its Integrated Operational Requirements Document (IORD) 1, of 14 March 1996, the National Polar-orbiting Operational Environmental Satellite System (NPOESS) program is required to provide, over a period of at least ten years, real-time global and regional environmental data in support of Department of Defense (DoD) and Department of Commerce (DoC) operational requirements. An important element of that capability is the accurate measurement of the ocean surface wind vector. Based on the aforementioned results and studies, NPOESS has opted to fulfill the wind vector measurement requirement using polarimetric microwave radiometry. The NPOESS Conical Microwave Imager and Sounder (CMIS) -- the NPOESS replacement for the DMSP SSM/I instrument -- will incorporate this polarimetric capability. This allows the global ocean wind vector, along with the many other environmental parameters now obtained by SSM/I, to be obtained with a single instrument. WindSat is a satellite-based multi-frequency polarimetric microwave radiometer developed by the Naval Research Laboratory for the U.S. Navy and the NPOESS Integrated Program Office (IPO). It was designed to demonstrate the capability of polarimetric microwave radiometry to measure the ocean surface wind vector from space. The sensor provides major risk reduction for the CMIS development, which is planned to provide wind vector data operationally on the first NPOESS satellite. The WindSat program has developed techniques for characterizing antenna and receiver systems for polarimetric radiometers. In addition, lessons learned from WindSat problem areas are being incorporated into CMIS. Lastly, the WindSat program has provided actual polarimetric radiometer data from space. The WindSat data are being used for forward modeling, algorithm development and sensor sensitivity analyses. This talk will describe the WindSat program and provide examples of WindSat risk reduction for CMIS.