Land Surface Temperature Retrieval From Channel Resolution Enhanced FY-3D/MWRI Observations

Land Surface Temperature (LST) is a critical parameter in meteorology, hydrology, and environmental science. Compared to thermal infrared remote sensing, passive microwave (PMW) remote sensing for LST retrieval offers advantage under cloudy conditions. In this study, we utilized the Channel Resolution Enhanced (CRE) Microwave Radiation Imager (MWRI) brightness temperature data from the Chinese FengYun-3D (FY-3D) polar-orbiting meteorological satellite as the primary input to obtain global LST. Two physics-based PMW retrieval methods were introduced: the three-channel method (18.7, 36.5, and 89.0 GHz) and the PWV-CLW method, which integrates the 18.7 GHz and 23.8 GHz channels with precipitable water vapor (PWV) and cloud liquid water (CLW). The results indicate that both methods have generally achieved good accuracy. The three-channel method performs well in grasslands and barren lands during the daytime, with a Root Mean Square Error (RMSE) ranging from 4 to 5 K. At night, it excels in grasslands, croplands, and barren lands, with an RMSE from 2 to 3 K. The PWV-CLW method demonstrates superior accuracy for forests and croplands during the daytime, with RMSE values from 3.6 to 5.3 K, respectively. At night, this method excels in accuracy for forests, with an RMSE of 2.9 K. Additionally, a fusion method was proposed to improve the overall accuracy of LST estimation across different land cover types. The RMSE values for ascending and descending overpasses are 4.22 K and 2.76 K, with biases of -0.29 K and -0.6 K, respectively. This approach effectively mitigates spatial heterogeneity and atmospheric effects, enabling all-weather LST retrieval and showcasing the potential of CRE FY-3D/MWRI data for LST monitoring.