GPS可降水量与掩星折射率资料同化对暴雨模拟的影响

The Effect of Precipitable Water Vapor and Radio Occultation Refractivity Assimilation on Heavy Rainfall Simulation

利用WRF-3DVAR系统同化GPS地基可降水量资料和空基掩星探测资料,对2011年6月14日我国夏季江淮流域暴雨天气过程进行数值模拟试验,对比分析可降水量和掩星折射率资料在暴雨天气数值模拟中的影响。结果表明:可降水量和掩星探测对底层水汽都有明显改善,可降水量对水汽的改善更为显著,比掩星同化平均高一个量级,改进了暴雨的强度和暴雨的影响范围;掩星折射率资料的同化通过改善强对流区域的风场和温度场,从而改进暴雨的降水落区;GPS可降水量和折射率资料的同时同化,一定程度上弥补了可降水量探测站点分布的不足和掩星折射率资料稀疏,对暴雨的强度、范围和落区预报都有很好的提高,两者可以很好地相互补充。

The WRF -3 DVAR system is used to assimilate GPS radio occultation and GPS precipitable water,in order to simulate the heavy rain weather process on June 14th,2011. The results show that： both precipitable water and radio occulta- tion refractivity data in numerical simulation can significantly improve the low levels＇ water condition of the analysis field. Pre- cipitable water vapor has more impact than radio occultation refractivity, in improving the rainstorm intensity and influence scope. The assimilation of radio occultation refractivity data can expand the storm rainfall area by modifying the wind fields and potential temperature fields. GPS radio occultation refractivity assimilation can supply the precipitable water vapor detection site distribution. Combination of GPS precipitable water and radio occultation assimilation can greatly improve the forecast of rain- belt distribution, intensity, scope and falling area. Both of them can be well complement for each other.