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| DOI：10.13522/j.cnki.ggps.2017.0639 |
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| Spatiotemporal Variation of the Reference Crop Evapotranspiration and the Factors Affecting It in Beijing-Tianjin-Hebei Region |
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MIAO Zhengwei, XU Ligang , ZHANG Wei
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Department of Hydraulic Engineering, Hebei University of Water Resources and Electric Engineering, Cangzhou 061001, China;The Scientific Research Institute of the Water Conservancy of Ningxia, Yinchuan 750021, China
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| Abstract: |
| 【Objective】 The aim of this paper is to analyse the spatiotemporal variation of the reference crop evapotranspiration (ET0) and the factors affecting it in Beijing-Tianjin-Hebei Region. 【Method】 We first calculated ET0 using the Penman-Monteith formula and the daily measured data at 24 meteorological stations from 1961 to 2016 across the region, and then analysed its spatiotemporal variation using the climate tendency rate, Mann-Kendall test and the Morlet wavelet analysis. The factors affecting the variation of ET0 were analysed using the sensitivity coefficients of ET0 to other climatic factors. 【Result】 The annual and seasonal ET0 across the regions has been in decline over the past 55 years; spatially, ET0 decreases with increasing altitude. There were abrupt changes in annual and autumn ET0 in 1975 and 2009. The annual and seasonal ET0 had periodic cycles of 7, 11, 16, 19 and 19 years. Sensitivity analysis revealed that annual ET0 was most sensitive to relative humidity. Seasonally, relative humidity was most sensitive to ET0 in spring, autumn and winter, whilst the highest temperature was most sensitive in summer for ET0. 【Conclusion】 In spring, autumn, winter, as well as annual average, the temporal changes in ET0 are primarily caused by decrease in wind speed, while in summer it is due to the decrease in sunshine duration. |
| Key words: Beijing-Tianjin-Hebei; Penman-Monteith equation; sensitivity analysis; reference crop evapotranspiration |
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