Sea surface temperature observation through clouds

Sea surface temperature (SST) is an important parameter used in many applications, such as fisheries, weather forecasting as boundary condition, and monitoring of climate changes. In these applications, SST is necessary under both fine and cloudy conditions, which can be made by passive microwave radiometers in particular under cloudy condition. To measure SST by microwave radiometers, frequencies below 10GHz are necessary, but measuring SST colder below around 10C becomes difficult using 10GHz. The frequency 6GHz is necessary for measuring SST in global oceans. The Advanced Microwave Scanning Radiometer -2 (AMSR2) aboard the Global Change Observation Mission – W (GCOM-W) of the Japan Aerospace Exploration Agency is one of such sensors, and began SST observation since July 2012. AMSR-2 is a successor sensor of AMSR-E aboard the NASA AQUA satellite, whose SST observation was made from July 2002 to October 2011. Algorithms retrieving SST from AMSRs should be developed by keeping minds of several points: (1) wind effect corrections on brightness temperature for both wind speed and direction, (2) removal of radio frequency interference from several sources, (3) accurate calibration of brightness temperature of AMSRs, (4) removal of sea ice area, and (5) removal of land contamination. In this paper, those techniques developed for AMSR SST retrieval will be presented.