WindSat

ars_thumbThe wind vector 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. Furthermore, accurate wind vector data aids in short-term weather forecasting, the issuing of timely weather warnings, and the gathering of general climatological data. WindSat is a satellite-based multifrequency polarimetric microwave radiometer developed by the NRL Remote Sensing Division, the Naval Center for Space Technology for the U.S. Navy, and the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Integrated Program Office (IPO). WindSat was designed to demonstrate the capability of polarimetric microwave radiometry to measure the ocean surface wind vector from space.

In addition to providing the Navy with badly needed ocean surface wind vector measurements, WindSat also measures other environmental parameters such as sea surface temperature, total precipitable water, integrated cloud liquid water, and rain rate over the ocean. An important goal of the WindSat mission was to provide risk reduction for the NPOESS Conically-scanned Microwave Imager and Sounder (CMIS), which was to be the future operational microwave imager tasked with supplying ocean surface wind data. With the restructuring of the NPOESS program this capability will now be provided to the Defense Weather Satellite System (DWSS) by the Microwave Imager/Sounder (MIS) instrument.

CPI was tasked to develop (in collaboration with NRL) a robust Ground Data Processing System (GDPS) for WindSat. CPI developed and implemented the WindSat GDPS to process 100% of the available downlink data (approximately 200 MB of data per orbit, or 3.0 GB per day) up to the calibration level. This involved exhaustive testing of the software under adverse data conditions and environmental conditions such as corrupted input data, radio-frequency interference, closeness to coastlines, satellite attitude irregularities, etc. CPI also completed extensive analysis of both the temperature data and environmental retrievals to perform repeated recalibrations, assisted NRL in ongoing environmental retrieval development, and implemented the environmental retrieval for ice concentration that is currently being generated and used by the National Ice Center and by an ice group at the Oceanography Division, NRL, Stennis Space Center, Mississippi.

WindSat Sea Surface Winds in Southern Pacific Ocean

Examples of the WindSat environmental data products can be found on the NRL WindSat web site. Shown above is one example of the sea surface winds retrieved by WindSat from its 840-km low earth orbit (LEO) passes over the Southern Pacific Ocean for February 9, 2006. Below is another image showing the WindSat retrieved wind speed when Hurricane Katrina was in the Gulf of Mexico on August 28, 2005, as well as a rotating Earth globe animation showing the wind speed on this day for the WindSat orbit passes (rollover image for 360° view).

Hurricane Katrina

Although WindSat was not intended to be an operational satellite, the successful development of the WindSat GDPS has resulted in WindSat becoming an operationally usable resource. CPI provided technical support for all components of the WindSat GDPS in the areas of algorithm development, maintenance configuration management (CM), and data processing.