单多普勒雷达径向风同化的改进

Improvement of radial wind data assimilation of single Doppler radar

基于现有的单多普勒雷达径向速度资料直接同化和间接同化方法,提出了一种改进同化方法,通过引入反演方程组作为观测算子,将分析单元内径向风的空间变化信息作为同化变量。同时,根据模式的分辨率和精度要求调整分析单元大小,从而能够有效地弥补数据稀释化所带来的高分辨率数据遗失问题。相对于直接同化只同化雷达观测径向风,改进方法不仅包含径向风信息,而且包含径向风的空间变化信息;相对于传统的间接同化,改进方法不直接使用强约束求解析风场,避免了将反演风场完全等同于"观测风场",能够较大程度地克服反演误差对同化效果的影响。通过理想实验和观测系统模拟试验表明:改进方法对于传统的直接同化和间接同化具有一定的兼容性,应用灵活,具有积极的改进意义。

Based on the direct and indirect assimilation methods of single Doppler radar radial velocity,an improved method was proposed.In the improved method,the Doppler radar wind retrieval equations were used as observation operators,the spatial variation information of the radial velocity in a given analysis unit was regarded as variables,meanwhile,the size of analysis unit size was adjusted according to the resolution and precision requirement of the model,which which makes up for the data thinning problem.Compared with the direct assimilation method,the improved method introduced not only the radial velocity information,but its spatial variation information.Compared with the indirect methed,the improved one avoided the weakness induced by retrieval wind calculated from analytical solution with strong constraint so as to reduce the impact of retrieval error effectively.The ideal experiment and OSSE （Observer System Simulations experiments） show that the improved method has better performance in being compatible for direct and indirect assimilation methods.