Insights gained from a TRMM microwave and infrared Sea Surface Temperature comparison

A detailed comparison of Sea Surface Temperatures obtained from one year of infrared and microwave satellite observations was performed on data from the VIRS and TMI sensors, both onboard the Tropical Rainfall Measurement Mission (TRMM). Using VIRS radiances, we developed daily maps of infrared SSTs and compared them to microwave SST daily maps derived from TMI. The intercomparison aims at identifying and minimizing errors in each dataset. Results from the analysis of the correlation of SST differences and possible sources of error (i.e., high winds, diurnal variations of skin layer temperature, atmospheric water vapor, undetected clouds, satellite maneuvers and calibration errors) are discussed. The intercomparison of four tested IR algorithms and the TMI SSTs facilitates the choice of the optimal IR algorithm for use in future data processing. We investigated how co-located MW observations of water vapor help IR SST retrievals by improving the cloud detection algorithm. In addition, the MW retrievals can benefit from the comparison with IR observations, which highlights the effects of land contamination in the TMI retrievals.