The inversion and quality validation of FY-3C MWRI sea surface temperature

Sea Surface Temperature (SST) is an important physical parameter in the field of marine and climate research. Passive microwave remote sensing has the advantage of completing all weather observations that disregard cloud interference, which has received increasing attention. FY-3C satellites, which carry a Microwave Radiometer Imager (MWRI) onboard, were successfully launched on December 23, 2013. Therefore, using the FY-3C MWRI to retrieve the SST is crucial. The FY-3C MWRI SST uses statistical algorithms. First, MWRI precipitation and sea ice products were used to remove the precipitation and sea ice data. Second, the MWRI brightness temperature was matched with the buoy SST using a temporal window of 0.2 h and a spatial window of 0.2°. The matchup with land within 100 km was excluded. Third, the descending and ascending statistical relationship, which was divided into four latitudes and 12 months, between the buoy SST observation and MWRI bright temperature was established. In addition, 4 × 12 × 2 regression coefficients were obtained, and corresponding regression coefficients were used to estimate the SST. The daily SST was obtained using a 0.25° × 0.25° equal latitude and longitude projections. The quality flag is set to 51 when the FY-3C MWRI SST minus a 30-year monthly mean SST is greater than 2.5 K, thereby indicating that these pixels were distributed on the edge of the land and high wind-speed region. The quality validation of the FY-3C MWRI SST after excluding the pixels with a quality flag of 51 shows that the precision of the ascending orbit SST is -0.02±1.22 K and that of the descending orbit SST is -0.15±1.28 K in comparison with the global buoy data. The precision of the ascending daily SST is 0.00±1.03 K and that of the descending daily SST is -0.09±1.08 K in comparison with the global analysis field OISST. The ascending orbit is more accurate than the descending orbit considering the non-uniform heating of the ocean surface during the day (the descending orbit). The Kuroshio Current, Gulf Stream, Western Pacific Warm Pool, and La Nina are included in the monthly SST, thereby suggesting that this SST is applicable to climatology investigation. The results of the quality validation of the FY-3C MWRI SST include the FY-3C quality control system. The SST precision is influenced by the performance, calibration, and positioning accuracy of the MWRI, precipitation and sea ice detection accuracy, land interference, and high wind speed. The improvement of the precision of the SST with a wind speed that is higher than 12 m/s is the emphasis of the next step. The buoy SST and global analysis field OISST cannot be considered a completely true value. Therefore, the triple collocation method will be utilized in the future to improve the comprehensive analysis of the error characteristics of the SST. © 2018, Science Press. All right reserved.