一次梅雨锋暴雨过程中陆面影响的数值模拟研究

目的]数值模拟一次梅雨锋暴雨过程中的陆面影响。方法]用耦合了NOAH陆面模块的中尺度大气非静力模式GRAPES-Meso,模拟了2005年7月6～8日江淮流域一次梅雨锋暴雨过程,通过有无陆面过程的敏感性试验,研究了陆面过程对梅雨锋暴雨的影响。结果]耦合NOAH陆面过程后,GRAPES-Meso能模拟出梅雨锋降水和大气低层西南急流的日变化特征。陆面过程对降水启动、强度和分布的模拟都有改进,其中,对降水启动模拟的改进尤为明显,较好地改善了模式的spin-up问题。不考虑陆气交换,则模式的降水启动非常慢,模拟的降水强度演变与实况差异很大,且不能模拟出降水和西南急流的日变化特征。结论]陆面过程对此次江淮梅雨过程有重要影响。

Study on Numerical Simulation of the Impact of the Land-Surface Process in a Meiyu Front Rainstorm

Objective] The research aimed to carry out numerical simulation on impact of land-surface process in a Meiyu front rainstorm.Method] Based on the meso-scale atmospheric non-hydrostatic model GRAPES-Meso which coupled with NOAH land-surface module,a Meiyu front rainstorm in Jiang-Huai basin during 6-8 July,2005 was simulated.Via sensitivity tests with and without land-surface process,the impact of land-surface process on Meiyu front rainstorm was studied.Result] GRAPES-Meso which coupled with NOAH land-surface process could simulate the daily variation characteristics of Meiyu front precipitation and atmospheric low-level southwest jet.The land-surface process could improve the simulations of precipitation initiation,intensity and distribution.The improvement of precipitation initiation simulation was especially obvious,which solved the spin-up problem of model to some extent.When the land-atmosphere interaction wasn’t considered,the precipitation initiation of model was very slow.The intensity evolution of simulated precipitation was different from actual situation.Moreover,it couldn’t simulate daily variation characteristics of precipitation and southwest jet.Conclusion] The land-surface process had important impact on Jiang-Huai Meiyu process.