Sea Surface Temperature Retrievals in Heavy Precipitation From AMSR-2 Microwave Measurements

The first satellite microwave sea surface temperature (MSST) estimates were provided from TRMM Microwave Imager radiometer on board of Tropical Rainfall Microwave Mission in 1997. Since then the MSST became on of one of most sought after parameters for new microwave missions in both operational and research communities. In that respect the WindSat, AMSR-E, ASMR-2 and GMI instruments all empployed either C- or X-band channels or both in order to provide the SST measurements. While the resolution of MSST is relativly course due to utilization of the low frequency channels, the main advantage of the MSST is in its ability to fill the gap in observations in cloud covered regions. While However the SST coverage is still spars heavy clouds and precipitation areas. To maximaze utility of MSST for operations we investigated different combinations of microwave brighntess temperatures that minimize precipitation effect on measurements and maximaze its sensitivity to SST. Guided by this goal we developed a statistically based algorithm that relies on three empirical quantities utilizing linear combinations of 6, 10 and 18GHz vertically and horizontally polirized channels. This approach allowed us to come up with the unique, first of a kind MSST product from AMSR-2 microwave ocean observations that provides SST estimates even in the heavy precipitation areas such as one observed within Tropical Cyclones. Utilization of higher frequency channels had an added advantage of increasing the the MSST resolution relative to products that utilized only 6 or 10GHz measurements. Another added advantage was substantially minimized sun glint areas that were traditionally excluded from measurements swaths and resulted in substantially reduced coverage in the southern hempisphere. The measurement technique, validation results and data availability will be discussed and presented.