A comparison of MODIS, NCEP, and TMI sea surface temperature datasets

The monthly average sea surface temperature (SST) datasets of MODIS (Moderate Resolution Imaging Spectroradiometer), NCEP (National Center for Environmental Prediction) and TMI (Tropical Rainfall Measuring Mission (TRMM) Microwave Imager) are compared for the period March 2000 to June 2003. Large discrepancies (0.5 K->1 K) are found over extensive areas: the tropical Atlantic, tropical western Pacific, Bay of Bengal, Arabian Sea and the storm tracks. Many of these discrepancies are related to the biases inherent in the infrared and microwave retrieval methods. Probable causes for these biases include cirrus contamination, insufficient corrections for water vapor absorption and aerosol attenuation in infrared retrieval as well as uncertainty in surface emissivity in microwave retrieval. The SST difference patterns bear close resemblance to the patterns of distribution of aerosols, cirrus, atmospheric water vapor and surface wind speed at certain regions. Correlations between SST difference and aerosol optical depth, column water vapor and surface wind speed in some areas are high (>0.75). These biases have to be adjusted in order for the SST datasets to be more useful for climate studies.