城区下垫面特征对成都地区一次暴雨过程影响的数值模拟

Numerical Simulation of City Underlying Surface Effect on a Rainstorm Process in Chengdu

利用NCEP/NCAR再分析资料对成都地区的一次区域性暴雨过程进行了诊断分析,并利用WRF模式对暴雨过程中城市下垫面的可能影响进行了敏感性试验。结果表明,WRF模式能较好地模拟出这次暴雨过程。改变城区下垫面特征后,与控制试验相比,敏感性试验的暴雨落区变化较小,强降雨中心面积有所增加,对四川盆地东部丘陵山区的温度增加影响较大。这可能与下垫面特征改变后,使地面的感热通量增加,加大了城区气层的不稳定度有关。

Using NCEP/NCAR global reanalysis grid data,a regional heavy rain process in Chengdu city have been analyzed.The numerical experiment by WRF and the sensitivity experiment changed the underlying surface feature in Chengdu were conducted to reproduce the regional heavy rainstorm process.The result shows that,using the latest data of underlying surface feature,there are a little varieties in the rainfall and area between the two simulations,the temperature in Sichuan basin obviously increase.The possiblly reasons for those are： The reduced surface albedo causes the increasing sensible heat flux from the surface and changing the instability of the boundary layer in the city after changed the underlying surface feature in the city.