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    • Keywords


      Terrestrial evapotranspiration; evaporative wet index; inner Mongolia autonomous region; surface drought.

    • Abstract


      Evapotranspiration (ET) plays an important role in exchange of water budget and carbon cycles over the Inner Mongolia autonomous region of China (IMARC). However, the spatial and decadal variations in terrestrial ET and drought over the IMARC in the past was calculated by only using sparse meteorological point-based data which remain quite uncertain. In this study, by combining satellite and meteorology datasets, a satellite-based semi-empirical Penman ET (SEMI-PM) algorithm is used to estimate regional ET and evaporative wet index (EWI) calculated by the ratio of ET and potential ET (PET) over the IMARC. Validation result shows that the square of the correlation coefficients (R2) for the four sites varies from 0.45 to 0.84 and the root-mean-square error (RMSE) is 0.78 mm. We found that the ET has decreased on an average of 4.8 mm per decade (p=0.10) over the entire IMARC during 1982–2009 and the EWI has decreased on an average of 1.1% per decade (p=0.08) during the study period. Importantly, the patterns of monthly EWI anomalies have a good spatial and temporal correlation with the Palmer Drought Severity Index (PDSI) anomalies from 1982 to 2009, indicating EWI can be used to monitor regional surface drought with high spatial resolution. In high-latitude ecosystems of northeast region of the IMARC, both air temperature (Ta) and incident solar radiation (Rs) are the most important parameters in determining ET. However, in semiarid and arid areas of the central and southwest regions of the IMARC, both relative humidity (RH) and normalized difference vegetation index (NDVI) are the most important factors controlling annual variation of ET.

    • Author Affiliations


      Zhaolu Zhang1 Hui Kang2 Yunjun Yao3 Ayad M Fadhil4 Yuhu Zhang5 Kun Jia3

      1. School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255000, Shandong, China.
      2. China Mobile Group Beijing Co., Ltd., Beijing 100027, China.
      3. State Key Laboratory of Remote Sensing Science, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China.
      4. Earth Sciences Department, Faculty of Science, University of Kufa, Najaf 34003, Iraq.
      5. College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China.
    • Dates

  • Journal of Earth System Science | News

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      Posted on July 25, 2019

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