Abstract:

Based on the advanced microwave sounding unit (AMSU-A), AMSU-Band high resolution infrared sounder (HIRS) data from advanced television and infrared observational satellite (ATOVS), conventional station data, TRMM 3B42 data and NCEP reanalysis data, the experiments of assimilating different types data on simulation of a snowfall process occurring in Northern China from 2 to 5 March 2007 were carried out  by using Weather Research and Forecasting (WRF) model and its 3DVAR assimilation system, the effect of assimilation to three types of ATOVS data on simulation of the snowstorm process was discussed. The results showed that compared to the positive effect of conventional data assimilation on simulated intensity and center position of precipitation, the improvements of assimilating AMSU-A or AMSU-B data on precipitation were less, while that of assimilating HIRS data was very significant. The simulation of assimilating AMSU-A and AMSU-B data had a fewer improvement on rainfall, while the assimilation of AMSU-B, HIRS data and conventional observation data to WRF model could effectively adjust the distribution of wind field and moisture field, so as to significantly generate the moisture convergence in precipitation center and adjacent areas over the lower level of troposphere, which was very beneficial to improve the precipitation simulation.

Key words: snowstorm, variation assimilation, ATOVS data, numerical simulation

摘要：

针对2007年3月2~5日发生在华北地区的一次降雪过程，采用WRF及其3DVAR同化系统，基于ATOVS卫星的红外和微波3类资料以及常规台站资料和TRMM降水资料进行不同循环同化模拟试验，探讨同化ATOVS资料后WRF模式对此次暴雪过程的模拟效果。结果表明：相对于同化常规资料对此次降水强度和中心位置模拟的正效应，AMSU-A、AMSU-B对降水的模拟改进较小，而HIRS对降水的模拟改进最为显著。同时同化AMSU-B、HIRS和常规资料的组合试验对此次降水模拟的效果改进最大，它有效地调整了风场和湿度场的分布，使得在降水中心及邻近地区对流层低层出现明显的水汽辐合区，显著地增强了降水的模拟效果。

关键词: 暴雪, 变分同化, ATOVS资料, 数值模拟