Satellite Microwave Retrieval of Total Precipitable Water Vapor and Surface Air Temperature Over Land From AMSR2

An approach for deriving atmosphere total precipitable water vapor (PWV) and surface air temperature over land using satellite passive microwave radiometry from the Advanced Microwave Scanning Radiometer 2 (AMSR2) was developed in this study. The PWV algorithm is based on theoretical analysis and comparisons against similar retrievals from the Atmospheric Infrared Sounder (AIRS). The AMSR2 PWV retrievals compare favorably with AIRS operational PWV products (R² ≥ 0.80 and rmse: 4.4-5.6 mm) and independent PWV observations from the SuomiNet North American Global Positioning System station network, with an overall mean rmse of 4.7 mm and more than 78% of absolute retrieval errors below 5 mm. The PWV retrievals were then applied within an AMSR2 multifrequency brightness temperature algorithm for deriving atmosphere-corrected surface air temperatures. The estimated temperatures agree favorably (R² > 0.80 and rmse <; 3.5 K) with independent weather station daily air temperature measurements spanning global climate and land cover variability. The resulting PWV estimates increase surface air temperature retrieval accuracy in our algorithm scheme. The AMSR2 algorithm is readily applied to similar microwave sensors including the AMSR for EOS and provides suitable performance and accuracy to support hydrologic, ecosystem, and climate change studies.