用二步变分法反演的单多普勒雷达风场研究中尺度暴雨

Meso-scale rainstorm analysis by retrieved wind field from single Doppler radar using twi-adjoint method

采用二步变分法反演多普勒雷达风场来研究中尺度暴雨过程。首先采用多元最优插值方法将常规探空资料插值生成初始风场,在此基础上在不考虑背景场约束以及三维风场平滑量约束的条件下极小化目标函数,反演出的三维风场作为最终反演所需的背景场,然后再进行反演得到最终的三维风场。将最终反演结果与WRF模式模拟的结果进行对比检验,两者的一致表明此方法具有一定的可用性,并用得出的结果分析了2005年6月发生在江苏中部的一次中尺度暴雨过程,初步揭示了强降水中心形成的原因,印证了采用二步变分法反演多普勒雷达风场可以揭示出中小尺度降水的特征。

Twi-adjoint method has been used to retrieve wind field from single Doppler radar, then meso-scale rain storm depending on it was analyzed. First, we created initial wind field from routine sonde data using multivariate optimum interpolation, then on the basis of it, we make the aim-function infinitesimal without the background field restriction and the smoothness of three-dimensonal wind field restriction. Doing it again and adding the two disregarded restriction condition and adopting the retrieved three-dimensonal wind field as background field, we can get the three-dimensonal wind field finally. And then, we analyzed a meso-seale rain storm in the middle of Jiangsu province in June, 2005 by making use of the outcome. It can elementarily show us the reason why the strong rainfall center existed. At last, comparing the retrieved results to the outcomes of WRF model, it is found that they were almost the same. So, it can be explained that the twi-adjoint method could show the characters of meso-scale rainfall relatively clearly.