Cross-Calibration of the Himawari-9 Thermal Infrared Data by Applying a Physical Sea Surface Temperature Method

We developed a cross-calibration method to improve sea surface temperature (SST) retrieval from remotely sensed thermal infrared data from space. The cross-calibration method is based on a physical SST method that determines SST by solving the infrared radiative transfer equation. We calibrated the thermal infrared data from Himawari-9, a Japanese geostationary meteorological satellite, using the developed method and the reference observation obtained with the Second-generation Global Imager (SGLI) onboard the Global Change Observation Mission-Climate (GCOM-C) satellite. As a result, the bias and the standard deviation of Himawari-9 SST were improved from $-$0.63 to $-$0.028 K and from 1.2 to 0.73 K, respectively, compared to the buoy data. Consistency between the Himawari-9 SST and SGLI SST was also improved after this calibration. Meanwhile, negative bias remained in the Himawari-9 SST, which was determined using 3.9 mu m data if the observation zenith angle was larger than 50 degrees. This article discusses the cross-calibration method and the validation results of SST retrieved from the calibrated Himawari-9 data.