Assessing the changes in hydrological budget including anthropogenic effect estimated by the reanalyses and rain-gauge based precipitation data over Asia

利用再分析资料，可以明确25-50年来大气水文收支的变化，并可以确定农业用水增加引起的蒸散量增加。利用APHRODITE项目（Yatagai et al.，2009年），其中使用了通过全球电信系统（GTS）网络提供的4倍以上的雨量计数据，并考虑了地形降水。在再分析中，我们使用了欧洲中期天气预报中心（ECMWF）编制的ERA 40数据和日本气象厅编制的JRA 25数据。结果表明，在中国、中亚、土耳其和印度等荒漠化严重的半干旱地区，蒸散量（Et）的增加被认为是水汽辐合与降水之间的残差。对于其中一些地区，这些来自再分析和降水的事实与当地报告的农业用水（使用河水、地下水、大坝水进行灌溉）增加是一致的。

With the benefit of the reanalysis datasets, the 25-50 years change in atmospheric hydrological budget should be clarified, and increase in evapotranspiration (Et) caused by the increase in agricultural water use may be identified. Analyses have been done on the interannual change of hydrological budget over Asia, by using meteorological reanalyses data and a rain-gauge based grid precipitation dataset developed by the APHRODITE project (Yatagai et al., 2009), in which more than 4 times rain-gauge data available through the global telecommunication system (GTS) network is used and orographic precipitation is taken into account. As for the reanalysis, we used ERA40 data compiled by the European Centre for Medium Range Weather Forecast (ECMWF) and JRA25 compiled by Japan Meteological Agency. As a result, increase in evapotranspiration (Et) estimated as a residual between moisture convergence and precipitation is found at the semi-arid regions of China, Central Asia, Turkey and India etc, where the progress of desertification is reported. For some of these regions, these facts derived from the reanalysis and precipitation are consistent with the local reports that agricultural water use (irrigation by using river water, ground water, dam water) has been increased.