红外高光谱IASI卫星资料同化对一次大风过程的影响研究

Impact of Assimilating IASI Infrared Radiances on the Numerical Results of a Strong Wind Case

以2019年4月24日发生在辽宁省的一次大风天气过程为例,选取GFS(全球预报系统)0.25°×0.25°再分析资料,基于WRF模式三维变分同化技术,分别进行IASI资料同化试验和未同化任何资料的控制试验(CTNL),通过对比两组试验结果分析IASI资料同化对改进数值模式初始场的影响及其后续预报的机制。结果表明:经过IASI资料同化的模拟结果质量有很大改善,分析场与背景场相比更接近观测场;经过云检测之后不同通道使用的观测数目不同,资料同化对模拟的改善效果在通道0~800最佳;IASI资料同化对地表10 m风场的预报技巧有显著的改进作用,相比控制试验可以更精准地预报大风天气的区域和强度;IASI同化试验的预报质量高于控制试验且随时间比较稳定。

A strong wind event which occurred in Liaoning province on April 24 th,2019 is selected as a study case for the numerical simulation and data assimilation. The simulation applies the GFS(Global Forecast System)0.25°× 0.25°reanalysis data,based on the WRF(Weather Research and Forecasting).The impact of IASI data assimilation on improving the initial field and the mechanism of subsequent prediction are investigated by conducting two experiments,which based on the three-dimensional variational assimilation method,a IASI data assimilation experiment and a control experiment(CTNL)without any data assimilation processing were conducted. The results show that,the quality of the simulation results after IASI data assimilation has been greatly improved. The analysis field fits better with the observation field than the background field. For the cloud detection procedure,the number of observations is dependent on the weighting peak of the channels. The improvement of the data assimilation on the simulation is significant in channels 0-800;the forecasting skills of the 10-meter wind field on the surface are obviously enhanced by the IASI data assimilation. Compared with the control experiment,it can more accurately predict the location and the intensity of windy fields;the forecast quality of the IASI assimilation experiment is higher than that of the control experiment and is relatively stable with the forecast leading time.