闪电资料在中尺度WRF模式中同化方法的研究

A STUDY ON THE ASSIMILATION METHOD OF LIGHTNING DATA WITH MESOSCALE MODEL WRF

利用强对流天气中雷电活动与对流性降水之间的统计关系,将闪电资料反演成降水资料,通过四维变分同化方法,将地闪资料同化入中尺度WRF模式中,并对四川地区一次强降水天气过程进行模拟。结果显示,经过同化的初始场能有效改善初始时刻强对流系统雨带结构,使得模式的初始场较好反应出大气的真实状态,并对暴雨的预报有正面影响。而在其短时模拟效果中,闪电资料的同化更好地模拟出川东北地区的降水过程,雨区的中心位置和强度都得到明显改善,改善了WRF模式在四川地区对强对流天气的模拟能力。

In this paper, we transform lighting data into precipitation data by the statistical relationship between lighting activity and convective precipitation during severe convection weather. By assimilating cloud-to-ground lightning flashes with a four-dimensional variational assimilation method, we simulated one of the severe convections that occurred in Sichuan province by WRF. The result shows that after assimilation the initial field can effectively improve the rainband structure of the severe convective system at the initial time, so that the model can better simulate the true state of the atmosphere and has positive impacts on the forecast of convective system rains. In the 0 ~ 6 h simulation test, by assimilating lightning flashes we can better simulate the precipitation process, especially the storm center and its intensity, in northeast Sichuan province.