湄公河流域农业干旱主要影响因素分析和预估

以湄公河流域作为模拟试验区域,采用区域气候模式RegCM3为模拟工具,单向嵌套全球海气耦合模式ECHAM5/MPI-OM当代(1980-2009年)和SRES A1B情景下未来(2010-2039年)的输出结果,以根系层土壤含水量为代表性指标,对试验区月尺度农业干旱进行了预估。基于地表能量平衡,系统分析了降水、蒸发、地表温度等农业干旱主要影响因素与区域气候模式模拟的大气环流、地表感热通量、地表潜热通量、地表净通量之间的联系和变化规律,从气陆间能量和水汽通量平衡角度,对农业干旱发生机理进行了初步识别。预估结果表明:未来春末(6月)和秋末(10月)湄公河流域温度增加、土壤含水量减少较为明显;同时,在这个时段试验区蒸发旺盛和降水减少的趋势,有可能导致湄公河流域局部地区农业干旱的发生。

Influencing factors analysis and prediction of agricultural drought in Mekong River Basin

Taking the Mekong River Basin as a study area, agricultural drought in monthly scale was predict based on the typical index of soil moisture of root layer by regional climate model(RegCM3) forced by the output of ECHAM5/MPI-OM global atmosphere-ocean coupled model in current(1980-2009) and future(2010-2039) under SRES A1B scenario in this paper. Based on the theory of surface energy balance, the relationship and changing regularity was analyzed between the main influencing factors of agricultural drought (such as precipitation, evaporation, surface temperature) and atmosphere circulation, energy fluxes (such as sensible flux, latent heat flux, surface net flux) simulated by RegCM3. From the aspects of surface energy and moisture flux balance, the mechanism of agriculture drought in the Mekong River Basin was preliminarily identified. The results show that the trend of the precipitation decrease, surface temperature increase, evaporation increase, and soil moisture decrease of experimental zone in late spring (June) and autumn (October) may cause the agricultural drought occurrence in local region of Mekong River basin in future.