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Land surface temperature (LST) is a key parameter in land surface system. The National Aeronautics and Space Administration (NASA) recently released new Moderate Resolution Imaging Spectroradiometer (MODIS) LST products (MOD21 and MYD21). Here, we conducted a detailed comparison between the MYD11 and MYD21 LST data in mainland China. The LSTs of MYD21 were approximately 1°C higher than those of MYD11 averaged for mainland China, as MYD21 corrected the cold bias of MYD11. The proportions of the valid value of MYD21 were generally lower than those of MYD11 because the cloud removal method of MYD21 was stricter than that of MYD11. Furthermore, the outliers were less significant in MYD11 than in MYD21 because the outliers in MYD11 were removed using temporal constraints on LST. The outliers in MYD21A2 resulted in a difference of greater than 3°C in average seasonal surface urban heat island intensity (SUHII) between MYD11A2 and MYD21A2. Finally, using MYD11 may underestimate the slope of long-term trends of SUHII. MYD21 LST data may have some uncertainties in urban areas. This study provided a reference for users for selecting LST products and for data producers to further improve MODIS LST products.
Yao et al. (Mon,) studied this question.