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Estimation of Reference Crop Evapotranspiration in Northwest China
Earth Sciences
Volume 9, Issue 3, June 2020, Pages: 89-99
Received: Feb. 29, 2020; Accepted: Mar. 17, 2020; Published: May 14, 2020
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Biao Wang, Key Laboratory for Mesoscale Serve Weather of Ministry of Education, Nanjing University, Nanjing, China
Xinmin Zeng, College of Oceanography, Hohai University, Nanjing, China
Gang Huang, State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Chinese Academy of Sciences, Beijing, China
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Based on the daily meteorological data from 1956 to 2011 in Northwest (NW) China and the Penman-Monteith (PM) equation, the regional reference crop evapotranspiration (ET0) is estimated. The ET0 variations in time series and spatial distributions are analyzed. The trend analysis, Mann-Kendall (M-K) test, wavelet analysis, stepwise regression and EOF analysis methods are used to investigate the spatiotemporal variability of ET0 and its contributing climatic factors, the mutation of ET0, the period of ET0, and the main influencing meteorological factors, respectively. Major conclusions are obtained as follows: (1) In the past 56 years, the trend of average annual ET0 time series in the NW China is significantly reduced, the differences exists in different seasons, i.e., the trends of ET0 in spring (-0.26mm/a), summer (-0.72mm/a) and autumn (-0.31mm/a) are decreased, respectively, the ET0 in winter is slowly increased (0.02mm/a). (2) The region which ET0 decreased most is located at the field from Kumul to Hotan (from northeast to southwest). ET0 has a sharply decrease around the 1980s, with a multiple-time scale nesting complex structure in the period. The first, second and third EOF models account 36.84%, 13.87% and 9.04% for the explained variance, respectively. The summer EOF model is the main contributor to the annual first model. (3) The upward trend of mean surface air temperature (T) and the decreased trend of sunshine duration (SD), relative humidity (RH) and wind speed at 2 m high (U2) induce ET0 to decline. The variability of annual ET0 rate is most influenced by the variations of U2, followed by SD, RH and T, which is influenced by various climatic variables. The investigation of spatiotemporal variability of ET0 and its contributor meteorological factors may help us better understand how ET0 responds to regional climate change.
Climate Change, Penman-Monteith (PM) Model, Reference Crop Evapotranspiration (ET0), Northwest China, EOF Analysis
To cite this article
Biao Wang, Xinmin Zeng, Gang Huang, Estimation of Reference Crop Evapotranspiration in Northwest China, Earth Sciences. Special Issue: Recent Advances in Hydrological Cycle Process: Evaporation and Precipitation. Vol. 9, No. 3, 2020, pp. 89-99. doi: 10.11648/
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This article is an open access article distributed under the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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