SMAP Observations of the Fourth Stokes Parameter At L-Band

Measurements are reported of the fourth Stokes parameter as observed from space by the SMAP polarimetric radiometer. The SMAP radiometer has a digital back-end that provides fully polarimetric processing, including the direct measurement of the third and fourth Stokes parameters. The data provide a first look at the fourth Stokes parameter from space at L-band. Features are reported that can be associated with RFI and the characteristics of the antenna pattern. With processing to remove such effects, features associated with the surface, such as snow/ice over Greenland and land vegetation canopy have also been observed.