Acta Geographica Sinica ›› 2004, Vol. 59 ›› Issue (1): 49-55.doi: 10.11821/xb200401006

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Validation of the Feasibility of MOD16 Algorithm for Estimating Crop Field Vapor Flux in North China Plain

SUN Zhigang1, WANG Qinxue2, OUYANG Zhu1, WATANABE Masataka2   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. National Institute for Environmental Studies, Tsukuba 305-8506, Japan
  • Received:2003-09-17 Revised:2003-12-25 Online:2004-01-25 Published:2004-01-25
  • Supported by:

    The Asia-Pacific Environmental Innovation Strategy (ASEIS), NIES, Japan

Abstract:

The MODIS product of the land surface vapor flux (MOD16) is not yet released by NASA because some parameters in the algorithm are very unstable in the time and space scales, which are difficult to be or cannot be derived from the remote sensing data. In this study, we validated the original algorithm of MOD16 with the ground measured data from April to May in 2002 (Yucheng Ecological Experimental Station in Shandong, CAS). The result showed that the estimated vapor flux was about 20% more than the observed values. We revised the original model by adjusting the crop physiological temperature parameters and coefficients for calculating the aerodynamic resistance, and the fractional vegetation cover according to the characteristics of winter wheat in Yucheng Station. The slope of the regression line plotted with the result simulated by the revised algorithm and the field measured data was 0.9706, and the correlation coefficient (R2

Key words: MODIS, vapor flux, eddy covariance, resistances, North China Plain