扩展水凝物控制变量的雷达资料同化对台风“天鸽”数值模拟的影响

利用WRF(Weather Research and Forecast)模式及WRFDA(WRF model data assimilation system)系统，针对2017年台风“天鸽”个例通过同化雷达径向速度(Vr)和反射率因子(RF)，研究水凝物控制变量的雷达资料同化对台风分析预报的影响。研究表明：雷达径向速度的直接同化有效地改进了模式初始场中台风涡旋区的中小尺度信息，分析场中产生了气旋性的风场增量，对模式背景场中的台风有显著增强作用。通过在传统控制变量中扩展针对水凝物的控制变量可有效地同化雷达反射率因子资料，对初始场的水物质进行调整，并对随后确定性预报的台风路径和强度都有一定的正效果。此外，相比没有水凝物控制变量的雷达同化试验，加入了水凝物控制变量的雷达资料同化试验降水预报效果更好。这为将我国近海的地基多普勒天气雷达用于台风初始化分析和预报提供了一定的技术支撑和保障。

INFLUENCE OF RADAR DATA ASSIMILATION WITH EXTENDED HYDROMETEOR CONTROL VARIABLES ON NUMERICAL SIMULATION OF TYPHOON HATO

In the present study, the impact of radar radial velocity and reflectivity assimilation using hydrometeor control variables on the analyses and forecast of Typhoon Hato was investigated using the Weather Research and Forecast model and its data assimilation system. It was found that the direct assimilation of radar radial velocity effectively improved the small-and-meso scale data in the typhoon vortex area and generated a cyclonic wind field increment in the analysis field, which significantly enhanced the typhoon in the background field of the model. With the introduction of the control variables of hydrometeors to the traditional control variables, the radar reflectivity factor data can be effectively assimilated, the hydrometeors in the initial field can be adjusted, and it had a positive effect on the subsequent deterministic forecast of the track and intensity of the typhoon. In addition, compared with the radar assimilation trial without hydrometeor control variables, the trial with hydrometeor control variables can produce a better precipitation forecast. These results could help ensure full use of the ground-based Doppler weather radar in offshore China.