Chinese Journal of Agrometeorology ›› 2017, Vol. 38 ›› Issue (09): 548-557.doi: 10.3969/j.issn.1000-6362.2017.09.002

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Potential Evapotranspiration Changes and its Effects of Meteorological Factors across Sichuan Province

CHEN Dong-dong, WANG Xiao-dong , WANG Sen, LI Xiao-wei   

  1. 1.Institute of Plateau Meteorology, China Meteorological Administration/Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province, Chengdu 610072, China; 2.The Agrometeorological Center of Sichuan Province, Chengdu 610072; 3.Anhui Agrometeorological Center, Hefei 230031; 4.Xinjiang Agrometeorological Bureau, Urumqi 830002; 5.Chongqing University of Education, Chongqing 400065
  • Received:2017-01-19 Online:2017-09-20 Published:2017-09-14

Abstract: Potential evapotranspiration(ET0) is an important metric in measuring drought conditions for an area. Examining ET0 changes is critical for estimating crop water demand, and thus it is crucial for improving water use efficiency in the context of global warming. Based on daily meteorological data of 151 meteorological stations in Sichuan province from 1961 to 2014, the authors calculated ET0 with the Penman-Monteith formula for the three terrain regions of Sichuan: Sichuan basin, Panxi region and Western Sichuan Plateau, and also analyzed relative variation and sensitivity coefficients of the major meteorological factors (i.e., mean air temperature, relative humidity, radiation hours, and mean wind speed), and the spatiotemporal changes in their contribution to ET0 changes. The results showed that ET0 in the Sichuan basin and the Western Sichuan Plateau presented a weak declining trend, as opposed to an increasing trend in Panxi region. In terms of spatial distribution, ET0 was high in the Panxi region and the Western Sichuan Plateau (1000-1350mm·y-1), and it was low in the southwestern Sichuan Plateau (651-900mm·y-1), with a decreasing and then increasing gradient of ET0 from the southwest to northeast. The effect of each meteorological factor on ET0(i.e., contribution of each meteorological factor to ET0 change) was determined by their sensitivity to ET0 and relative variation. ET0 was most sensitive to relative humidity across the three regions, with sensitivity coefficients of -1.13, -1.40, -1.53, respectively. Among all the meteorological factors, the variable with the highest long-term relative variation was mean wind speed in Sichuan basin (-29.7%) and Panxi region (-16.3%), in contrast to mean air temperature in Western Sichuan Plateau (40.4%). Further analyses suggested that the dominant factor determining ET0 for Sichuan basin and Western Sichuan Plateau was mean wind speed, and that for Panxi region was relative humidity.

Key words: Potential evapotranspiration, Meteorological factors, Sensitivity coefficient, Contribution rate