区域干旱的数值模拟试验

针对土壤干旱,利用大气和土壤耦合模式对干旱过程进行数值模拟研究。在数值模拟方法上,引入美国国家大气研究中心和宾西法尼亚大学联合开发的第四代中尺度区域数预报模式MM4作为与土壤耦合的大气运动模式;将区域中尺度大气运动模式MM4与土壤水传导模式耦合,通过对土壤湿度的连续计算来试验模拟出干旱过程的几个阶段的状态。在大气与土壤耦合的过程中,主要考虑了4个的方面作用:分别是地表水蒸发、蒸腾作用、地表水渗透和地面风场。在进行区域干旱过程模拟试验中,以土壤湿度作为干旱划分指标,针对壤土选取长江中下游地区,1999年8月1日至30日的地面、高空资料进行连续计算。试验分三个阶段:第一阶段为长江中下游地区土壤供水量满足农作物需水量阶段;第二阶段为根系层土壤供水量小于农作物生长需水量阶段;第三阶段为长江中下游地区农作物干旱阶段。在对模拟试验的结果进行了分析后,得到了一些干旱形成过程的初步结论。

Numerical simulation experiment on regional drought

To research the drought of soil,the numerical simulation of the drought process was researched with atmosphere and soil coupling model.This paper introduced the fourth-generation mesoscale modeling forecasting system model(MM4) created by NCAR and Penn State University as the atmospheric movement model to couple with soil.The main goal is to couple the regional mesoscale atmospheric movement model(MM4) and conduction mode of soil water by the continuous calculation of soil humidity and the several stages of numerical simulation on drought development process was tested.In the process of coupling the atmosphere and soil,four major effects were considered: the evaporation of surface water,the effect of transpiration,the surface wind and the infiltration of ground water.The upper air and ground data of the middle and lower reaches in the Yangtze River from July 1 to 30,1995 were selected to calculate continuously.The test was divided into three stages: in the first one,the supply of water in the middle and lower reaches of the Yangtze River can meet water demand of crops;in the second one,the water supply of the crops roots soil can't demand the crops growth;in the third one,the crops in the middle and lower reaches of the Yangtze River are in drought.After the analysis of simulation test,some results are discussed in the paper.