Investigation and Validation of the Chinese Fengyun-4A Land Surface Temperature Products in the Heihe River Basin.

Land Surface Temperature (LST) is a key factor in the land surface energy budget. The accuracy of the LST is affected by topographical fluctuations, observation time, and other factors. Thus, it is necessary to validate the retrieved LST products. In this study, the Fengyun-4A (FY-4A) LST was evaluated against the in-situ LST, which is collected from four ground sites in the Heihe River basin from August 1st, 2019 to December 31st, 2019. The results show that the root-mean-square error(RMSE) varies from 2.39 K to 4.07 K. Therefore, it is considered that FY-4A LST has good correlations with the in-situ LST. However, the FY-4A LST product has large systematic errors over some sites, e.g Jingyangling. The main reason is that the longwave radiometer has a scale mismatch between the pixels of FY-4A, and the scale mismatch can affect the representatives of measurements at pixel scales.