YANG Yong-hong, ZHANG Zhan-yu, RUAN Xin-jian. Temporal and spatial variation law of reference crop evapotranspiration in Tibet[J]. Advances in Water Science, 2009, 20(6): 775-781.
Citation: YANG Yong-hong, ZHANG Zhan-yu, RUAN Xin-jian. Temporal and spatial variation law of reference crop evapotranspiration in Tibet[J]. Advances in Water Science, 2009, 20(6): 775-781.

Temporal and spatial variation law of reference crop evapotranspiration in Tibet

  • Based on the meteorological observation data collected by the 38 weather stations in Tibet for several decades before 2006, the daily values of the reference crop evapotranspiration (ET0) are calculated by FAO-56 standard Penman-Monteith formula, and the daily and monthly change law of ET0 over the seven stations is analyzed. The tendency test is conducted on the data of the monthly and annual ET0 using the Mann-Kendall method. The contour maps of the average annual ET0 in Tibet are obtained using the Golden Software Surfer 8.0. The spatial distribution of the average annual ET0 in Tibet is analyzed with the function of spatial analysis. The results indicate that:the daily ET0 curves of Changdou, Linzhi and Naqu are approximately the same, showing a single peak parabolic shape; and the daily ET0 curves of Lhasa, Rikaze and Zedang are also approximately the same. The curves from June to September quickly take on the downward trend; ET0 of the Shiquanhe presents individual change trend. As for all the observation sites, the maximum monthly ET0 is found in June,and the minimum is in December. In Rikaze, ET0 mainly shows the decreasing trend each month and in wet and dry seasons very significantly, followed by Zedang. While ET0 mainly shows the increasing trend in Linzhi. The Mann-Kendall test also indicates that the decreasing in annual ET0 appears to be the dominate trend in most stations of Tibet. The spatial distribution of average annual ET0 reveals that the ET0 values are higher in the eastern and central-southern regions than those in the west and north as well as in the south-eastern fringe in Tibet.
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