Acta Geographica Sinica ›› 2011, Vol. 66 ›› Issue (7): 917-927.doi: 10.11821/xb201107005

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MODIS-based Air Temperature Estimation in the Hengduan Mountains and Its Spatio-temporal Analysis

YAO Yonghui, ZHANG Baiping, HAN Fang   

  1. State Key Laboratory of Resource and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • Received:2011-04-15 Revised:2011-05-19 Online:2011-07-20 Published:2011-07-20
  • Supported by:

    National Natural Science Foundation of China, No.41030528; No.41001278

Abstract: Climatic conditions are difficult to obtain in high mountain areas due to few meteorological stations and, if any, their poorly representative locations in valleys. Fortunately, remote sensing data can be used to estimate near-surface air temperature (Ta) and other climatic conditions. This paper makes use of recorded meteorological data and MODIS data on land surface temperature (Ts) to estimate monthly mean air temperatures in the Hengduan Mountains. A total of 64 weather stations and 84 MODIS images for seven years (2001 to 2007) are used for analysis. Regression analysis and spatio-temporal analysis of monthly mean Ts vs. monthly mean Ta are carried out, showing that recorded Ta is closely related to MODIS Ts in the study region (mean R2 = 0.72) and the mean standard error of 2.07 oC. The regression analysis of monthly mean Ts vs. Ta for every month of all the stations shows that monthly mean Ts can be used to accurately estimate monthly mean Ta (R2 ranging from 0.63 to 0.90 and standard error between 2.22 oC and 3.05 oC). Thirdly, the retrieved monthly mean Ta for the whole study region varies between -2.25 oC (in January, the coldest month) and 15.64 oC (in July, the warmest month), and for the warm (growing) season (May-September), it is from 10.44 oC to 15.64 oC. Finally, the elevation of isotherms is greater in the central mountain ranges than that in the outer margins; the 0 oC isotherm occurs at elevations of about 4700±500 m in October, and it drops to 3500±500 m in January, and ascends back to 4700±500 m in May next year, which means that monthly mean Ta in the areas below 5200 m is above 0 oC for 6 to 12 months. This clearly indicates that MODIS data could be used to have an accurate estimation of air temperature in mountain regions.

Key words: land surface temperature, MODIS, air temperature estimation, spatial-temporal analysis, the Hengduan Mountains