Radiometric Cross-Calibration Between the Thermal Infrared Data of MODIS and Tiangong-2 WIS for Monitoring Sea Surface Temperature

摘要

Following the radiometric cross-calibration procedures between the Tiangong-1 hyperspectral imaging spectrometer and the Moderate Resolution Imaging Spectrometer (MODIS) infrared bands, the thermal infrared bands of Wide-band Imaging Spectrometer (WIS) on the Tiangong-2 space station are calibrated and further used to monitor the Sea Surface Temperature (SST). Quasi-simultaneous MODIS thermal infrared images acquired in winter and spring of 2017 and 2018 are collected as the calibration reference. A linear radiance correction equation between the two data sets of MODIS and WIS is established, and the Tiangong-2 WIS thermal infrared data is calibrated by the radiance correction equation. The calibrated WIS thermal infrared data is further used to retrieve the SST of coastal waters. The results show that the thermal infrared bands of Tiangong-2 WIS are highly correlated to the 32nd band of MODIS. Credited to the high spatial resolution of WIS thermal infrared images, the SST anomalies caused by natural or human disturbance are clearly shown, e.g., the warming plume of cooling water from coastal power plant, the apparent temperature of tidal flat and the underwater tidal ridges.