Analysis of PSR Microwave Observations during SMEX04

The Polarimetric Scanning Radiometer (PSR/CX) was flown on a P-3B aircraft as part of SMEX04. PSR/CX has been successfully operated during several previous airborne campaigns. The primary objectives of PSR/CX during SMEX04 are: 1) Contribute to the calibration and validation of AMSR observations over different parts of the globe and to check for the presence of Radio Frequency Interference (RFI), 2) Explore the potential for the development of soil moisture retrieval algorithms using C-band imagery in diverse landscapes (Arizona and Sonora, Mexico), and 3) to develop retrieval algorithms to estimate soil moisture over areas of topographic variability and vegetation. The dominant landuse classes in the different SMEX04 domains are: 1) Arizona - semi-arid climate with sparse vegetation and moderate topography, and 2) Sonora, Mexico - moderate vegetation with strong topographic gradients. SMEX04 consisted of about 84 flightlines at high altitude resulting in 21 mapping domains flown during August, 2004 (11 over Arizona and 10 over Sonora). Each mapping domain is about 75 km x 50 km, providing an excellent area for calibration and validation of AMSR-E observations. Some areas of the SMEX04 domain received heavy localized precipitation as a result of convective activity during the experiment. These resulted in interesting brightness temperature patterns with strong brightness temperature gradients. The presence of these diverse conditions will help address questions relating to scaling of spaceborne microwave observations. Results of comparison between PSR and AMSR and the use of microwave remote sensing to estimate soil moisture over wide range of vegetation and soil moisture conditions are also presented.