陕北生态治理对当地降水影响的数值模拟

利用中尺度模式MM5V3．5模拟了陕北地区两种植被改进方案对一次降雨过程的敏感性试验，结果表明，陕北植被改善后，能够使区域性降雨的雨带北移，平均降水量增加，降雨时间延长。另外，还分别从环流、大气稳定性、水汽条件、垂直运动等四个方面对上述变化的机理进行了分析，认为植被治理使背景环流的气旋性增强，低层大气不稳定范围向北增强扩展，高空风场辐合汇集的水汽增多，同时垂直上升运动有所增强，导致局地雨带北移、降雨量增加、降雨时间延长。模拟结果同时表明，下垫面生态治理的范围和规模越大，上述影响也越显著。

Numerical Simulation of Influence of Different Vegetation Schemes on Local Precipitation in Northern Shaanxi Region

The mesoscale model(MM5V3.5) is applied to study the sensitivity of local precipitation to two different vegetation development schemes in Northern Shaanxi.It shows that owing to the vegetation improvement,the local rainfall belt shifts northward,the precipitation increases,and the rain period prolongs.Further study for the air circumfluence,the lower-layer stability,the moisture convergence and the vertical motion of atmosphere indicate that all of them make favorable responses to the local rainfall by the vegetation improving.However,it is evident that the larger the spatial scope of the vegetation changing,the more significant its influence on the local rainfall as mentioned above.