Ta b! e Y^i. _ 5p ac e '- b p r ne_ Ocean' Sens in g~ T e c h n j cju es_ 



Altimeter . A pencil beam microwave radar that measures the distance 

 between the spacecraft and the earth. Measurements yield the topography 

 and roughness of the sea surface from which the surface current and average 

 wave height can be estimated. 



Color Scanner . A radiometer that measures the intensity of radiation 

 emitted from the sea in visible and near-infrared bands in a broad swath 

 beneath the spacecraft. Measurements yield ocean color, from which 

 chlorophyll concentration and the location of sediment-laden waters can be 

 estimated. 



Infrared Radiometer . A radiometer that measures the intensity of radia- 

 tion emitted from the sea in the infrared band in a broad swath beneath the 

 spacecraft. Measurements yield estimates of sea-surface temperature. 



Microwave Radiometer . A radiometer that measures the intensity of radia- 

 tion emitted from the sea in the microwave band in a broad swath beneath 

 the spacecraft. Measurements yield microwave brightness temperatures, 

 from which wind speed, water vapor, rain rate, sea-surface temperature, 

 and ice cover can be estimated. 



Scatterometer . A microwave radar that measures the roughness of the sea 

 surface in a broad swath on either side of the spacecraft with a spatial 

 resolution of 50 kilometers. Measurements yield the amplitude of short 

 surface waves that are approximately in equilibrium with the local wind and 

 from which the surface wind velocity can be estimated. 



Synthetic Aperture Radar . A microwave radar similar to the scatterometer 

 except that it electronically synthesizes the equivalent of an antenna 

 large enough to achieve a spatial resolution of 25 meters. Measurements 

 yield information on features (swell, internal waves, rain, current 

 boundaries, and so on) that modulate the amplitude of the short surface 

 waves; they also yield information on the position and character of sea ice 

 from which, with successive views, the velocity of ice flows can be 

 estimated. 



2-5 



