Assessing the impact of interannual variability of precipitation and potential evaporation on evapotranspiration |
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| Institution: | 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China;2. College of Water Resources and Hydrology, Hohai University, Nanjing 210098, China;3. CSIRO Mathematics, Informatics and Statistics, Private Bag 5, Wembley, WA 6913, Australia;4. Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, NV 89154, USA;5. CSIRO Mathematics, Informatics and Statistics, GPO Box 664, Canberra, ACT 2601, Australia;1. Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, PR China;2. Huanjiang Observation and Research Station for Karst Ecosystem, Chinese Academy of Sciences, Huanjiang 547100, PR China;3. Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA;1. College of Water Resources and Architecture Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China;2. Institute of Water Saving Agriculture in Arid Areas of China, Northwest Agriculture and Forestry University, Yangling, Shaanxi 712100, China;3. Key Lab of Agricultural Water and Soil Engineering of Education Ministry, Northwest Agriculture and Forestry University, Yangling 712100, PR China;4. NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia;5. Climate Change Research Centre and ARC Centre of Excellence for Climate Extremes, University of New South Wales, Sydney, NSW 2052, Australia;1. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;2. Joint Center for Global Change Studies, Beijing 100875, China;3. College of Tourism and Environment, Shaanxi Normal University, Xi''an 710062, China;4. College of Urban and Environmental Sciences, Northwest University, Xi''an 710027, China |
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| Abstract: | The impact of interannual variability of precipitation and potential evaporation on the long-term mean annual evapotranspiration as well as on the interannual variability of evapotranspiration is studied using a stochastic soil moisture model within the Budyko framework. Results indicate that given the same long-term mean annual precipitation and potential evaporation, including interannual variability of precipitation and potential evaporation reduces the long-term mean annual evapotranspiration. This reduction effect is mostly prominent when the dryness index (i.e., the ratio of potential evaporation to precipitation) is within the range from 0.5 to 2. The maximum reductions in the evaporation ratio (i.e., the ratio of evapotranspiration to precipitation) can reach 8–10% for a range of coefficient of variation (CV) values for precipitation and potential evaporation. The relations between the maximum reductions and the CV values of precipitation and potential evaporation follow power laws. Hence the larger the interannual variability of precipitation and potential evaporation becomes, the larger the reductions in the evaporation ratio will be. The inclusion of interannual variability of precipitation and potential evaporation also increases the interannual variability of evapotranspiration. It is found that the interannual variability of daily rainfall depth and that of the frequency of daily rainfall events have quantitatively different impacts on the interannual variability of evapotranspiration; and they also interact differently with the interannual variability of potential evaporation. The results presented in this study demonstrate the importance of understanding the role of interannual variability of precipitation and potential evaporation in land surface hydrology under a warming climate. |
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| Keywords: | Budyko Evapotranspiration Precipitation Potential evaporation Interannual variability Stochastic soil moisture model |
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