Toward an Operational Scheme for Deriving High-Spatial-Resolution Temperature and Emissivity Based on FengYun-3D MERSI-II Thermal Infrared Data

Land surface temperature (LST) is a pivotal parameter in many study areas. At present, numerous algorithms are available to retrieve accurate LST from different satellite thermal infrared (TIR) observations. However, rare studies focus on simultaneous LST and land surface emissivity (LSE) retrieval from the TIR measurements of MERSI-II onboard Chinese FengYun-3D satellite designed with a spatiotemporal resolution of 250 meters and five days, that just bridges the Terra/Aqua-MODIS and Landsat-TIRS observations. Although simultaneous LST and LSE retrieval could be achieved by the existing temperature-emissivity separation (TES) method, only two of the three MERSI-II TIR channels are with the spatial resolution of 250 meters leading to the difficulty of directly applying the traditional TES method. Inspired by the TES method and the theory of temperature-independent spectral indices (TISI), this study proposed a new scheme for deriving the 250-meters LST and LSE simultaneously from the MERSI-II TIR data. T-based validations using the ground measurements indicated that the LST retrieval accuracy was about 3.19 K and 2.51 K in the daytime and nighttime, respectively. Cross-validations taking MODIS LST product as the references showed that errors in the retrieved LST was <2.1 K in the daytime while <1.4 K during the nighttime. Overall, results showed that the proposed method can be used to retrieve global LST and LSE from the MERSI-II data, which can facilitate their applications in relevant fields.