Arid Zone Research ›› 2021, Vol. 38 ›› Issue (6): 1637-1649.doi: 10.13866/j.azr.2021.06.15

• Weather and Climate • Previous Articles     Next Articles

Downscaling land surface temperature through AMSR-2 passive microwave observations by Catboost semiempirical algorithms

LI Yongkang1,2(),WANG Xinjun1(),MA Yanfei3,HU Guifeng1,GUI Haiyue1,ZHANG Guanhong1   

  1. 1. College of Grassland and Environment Sciences of Xinjiang Agricultural University, Xinjiang Key Laboratory of Soil and Plant Ecological Processes, Urumqi 830052, Xinjiang, China
    2. Key Laboratory of Digital Earth Science,Aerospace Information Research Institute, Chinese Academy of Sciences,Beijing 100094, China
    3. Department of Geography of Handan University, Handan 056005, Hebei, China
  • Received:2020-12-10 Revised:2021-05-05 Online:2021-11-15 Published:2021-11-29
  • Contact: Xinjun WANG E-mail:yongkang_xau@163.com;wxj8112@163.com

Abstract:

This study aimed to fill in the missing pixels of MYD11A1 in the Gurbantunggut Desert and provide a theoretical basis for obtaining all-weather and multilayer soil temperatures during daytime and nighttime. We explored the feasibility of the CatBoost algorithm for the spatial downscaling of passive microwave surface temperature by using the four-channel passive microwave brightness temperature and MODIS vegetation index of the 2019 AMSR-2. Results show that (1) the spatial differentiation between feature vectors and surface temperature is evident during daytime and nighttime in the Gurbantunggut Desert. It indicates high desert correlation, low oasis correlation, and strong daytime differentiation. The salt mine coverage reduces the correlation between passive microwave brightness temperature and surface temperature. (2) The mapping relation between the passive microwave brightness temperature and surface temperature from the four-channel CatBoost model is robust. The accuracy of the downscaled results is high, with daytime-nighttime R2 of 0.977 and 0.980, RMSE of 3.69 and 2.38 K, and MAE of 2.71 K and 1.70 K, respectively. (3) Single-channel correlation and importance analysis results are different, suggesting that feature correlation results cannot be directly used as a basis for selecting surface temperature features with the CatBoost passive microwave inversion of LST. (4) Downscaling LST is significantly and positively correlated with the soil temperature in six layers from the Fukang site. The correlation coefficient decreases, and RMSE increases as depth increases.

Key words: land surface temperature, AMSR-2, Catboost, downscale, Gurbantunggut Desert