Current satellite based infrared and microwave sensors provide extremely complementary information for determining the sea surface temperture (SST). To best utilize this information, however, the source of the differences between SST retrievals from the two sensors must be fully understood. To examine these differences, a detailed comparison is performed between infrared AVHRR-based skin and bulk SST products and a microwave bulk SST product from the TRMM Microwave Imager (TMI). These differences are evaluated as functions of wind speed, water vapor, residual cloud effects, and the bulk-skin temperature difference. By including both infrared skin and bulk SST products, it is possible to look at the potential effect of the bulk-skin temperature difference in detail.

To enable these comparisons, a new AVHRR skin SST product for NOAA-14 was first derived from radiative transfer simulations and a globally representative set of over 2000 radiosonde profiles. Comparisons with multiple in situ skin SST measurements demonstrate the accuracy of this new algorithm. Differences between the infrared and TMI SST products were computed over the Pacific basin throughout the year of 2000. These differences are presented both over short time periods and as seasonal averages. To examine the dependence on wind speed and water vapor, the differences are binned using coincident wind speed and water vapor retrievals from TMI. Residual differences are then compared with predictions of the bulk-skin temperature difference to determine if there is any significant correlation. Based on these results, recommendations are made concerning how to best combine data from the different sensors into a blended SST product.