Where Does the Irrigation Water Go? An Estimate of the Contribution of Irrigation to Precipitation Using MERRA
Where Does the Irrigation Water Go? An Estimate of the Contribution of Irrigation to Precipitation Using MERRA
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DOI：
10.1175/jhm-d-12-079.1
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发表时间：
2013-01
影响因子：
3.8
通讯作者：
Jiangfeng Wei;P. Dirmeyer;D. Wisser;M. Bosilovich;D. Mocko
中科院分区：
文献类型：
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作者：
Jiangfeng Wei;P. Dirmeyer;D. Wisser;M. Bosilovich;D. Mocko
灌溉是一项重要的人类活动，可能影响局部和区域气候，但目前的气候模式模拟和数据同化系统通常没有明确地包括它。欧洲中期天气预报中心（ECMWF）中期再分析（ERA-Interim）比现代研究与应用回顾性分析（MERRA）显示地表蒸散发（ET）中更多的灌溉信号，因为ERA-Interim根据观测到的地表温度和湿度调整土壤湿度，而MERRA没有明确考虑地表灌溉。但是，与详细考虑农业因素的水文模型的结果相比，两种重新分析的蒸散发在捕捉灌溉影响方面存在很大缺陷。本研究采用反轨迹方法，利用MERRA和基于观测的修正以及水文模型中增加的灌溉引起的ET增加，估算了局地及周边地区灌溉对降水的贡献。结果表明，在亚洲重灌区，灌溉对降水的贡献很大，但在大多数地区，降水的增加远远小于ET的增加，表明灌溉可能导致这些地区的水分亏缺。对于相同的ET增加，在对流更容易触发的湿润地区，降水增加更大，但不同地区的降水增加百分比相似。灌溉影响的模式有很大的区域差异，但对所有研究的区域来说，对降水的贡献百分比最高的是当地土地。
Irrigation is an important human activity that may impact local and regional climate, but current climate model simulations and data assimilation systems generally do not explicitly include it. The European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) shows more irrigation signal in surface evapotranspiration (ET) than the Modern-Era Retrospective Analysis for Research and Applications (MERRA) because ERA-Interim adjusts soil moisture according to the observed surface temperature and humidity while MERRA has no explicit consideration of irrigation at the surface. But, when compared with the results from a hydrological model with detailed considerations of agriculture, the ET from both reanalyses show large deficiencies in capturing the impact of irrigation. Here, a back-trajectory method is used to estimate the contribution of irrigation to precipitation over local and surrounding regions, using MERRA with observation-based corrections and added irrigation-caused ET increase from the hydrological model. Results show substantial contributions of irrigation to precipitation over heavily irrigated regions in Asia, but the precipitation increase is much less than the ET increase over most areas, indicating that irrigation could lead to water deficits over these regions. For the same increase in ET, precipitation increases are larger over wetter areas where convection is more easily triggered, but the percentage increase in precipitation is similar for different areas. There are substantial regional differences in the patterns of irrigation impact, but, for all the studied regions, the highest percentage contribution to precipitation is over local land.