Book excerpt: A multiband microwave polarimetric scanning radiometer (PSR) has been constructed for airborne observations from the NASA DC-8 airborne platform. The primary application of the PSR is the development of optimal spaceborne bard ware configurations and retrieval algorithms for passive wind. vector sensing over the ocean surface. Four radiometers, operating at 10.7, 18.7, 37, and 89 GHz, each measure the first three modified Stokes' parameters (T(sub upsilon), T(sub h), and T(sub u). A gimbaled mechanism allows observations at any incident angle within a cone of 700 half angle around nadir. The PSR's four radiometers and two axis scanning capability will provide unique polarimetric data for microwave emission studies of both ocean and land surfaces, as well as atmospheric clouds and precipitation.