NASA Scatterometer (NSCAT) will measure wind speeds and directions over at least 90% of the ice-free global oceans every 2 days - under all weather and cloud conditions. Winds are a critical factor in determining regional weather patterns and global climate. At present, weather data can be acquired over land, but our only knowledge of surface winds over oceans comes from infrequent and sometimes inaccurate reports from ships. Since oceans cover approximately 70% of Earth's surface, NSCAT data will play a key role in scientists' efforts to understand and predict complex global weather patterns and climate systems.

NSCAT is a specialized microwave radar designed to measure winds over the oceans. NSCAT will use an array of antennas that radiate microwave pulses at a frequency of 14 GHz across broad regions of the Earth's surface. This array of six, 3-m-long antennas will scan two 600-km bands of ocean; one band on each side of the instrument's orbital path, separated by a gap of approximately 330km. Obtaining backscatter and wind vector information nearly continuously, NSCAT will be able to make 190,000 wind measurements per day; more than 100 times the amount of ocean wind information presently available from ships.

Scatterometers use a highly indirect technique to measure wind velocity over the ocean. These instruments transmit microwave pulses and receive backscattered power from the ocean surface. Changes in wind velocity cause changes in ocean surface roughness, modifying the radar cross section of the ocean and the magnitude of the backscattered power. Multiple, collocated, measurements acquired from several direction can thus be used to solve wind speed and direction simultaneously.

Ground computers will process wind measurements within 2 weeks of receiving raw NSCAT data from the ADEOS spacecraft through the 3-year mission. NSCAT data products will include global backscatter data; 50-km resolution ocean wind vectors in the measurement swaths, and spatially and temporally averaged, gridded, wind field maps.

Studies using NSCAT data are expected to lead to improved methods of global weather forecasting and modeling - and possibly to a better understanding of environmental phenomena (such as El Nino) that greatly affect world economies.

Wind Velocity	2m/s(rms) : 3-20m/s 10% : 20-30m/s
Wind Direction	20deg.(rms): 3-30m/s
Spatial Resolution	25km : 0deg. Cell 50km : Wind Cells
Location Accuracy	25km(rms) : Absolute 10km(rms) : Relative
Coverage	90% of ocean every 2days
Mass	300kg
Power	275W
Data Rate	2.9kbps