浙江省冬季降水相态预报指数研究

Index Research on Winter Precipitation Phase Forecasting in Zhejiang Province

摘要: 为了探明不同微物理过程对浙江省冬季降水相态预报的影响，利用中尺度模式WRF (V3.9)，采用NCEP/NCAR 1˚ × 1˚再分析资料和GFS 0.5˚ × 0.5˚资料，选取Purdue Lin方案、WSM 6类方案和新Thompson方案等3种不同微物理过程方案，在对2000~2017年浙江省冬季存在降水相变的10次降水过程进行敏感性试验的基础上，再选取2018年1月浙江省2次降雪过程进行SRF指数阈值检验和预报性能评估，得到不同方案的预报差异和SRF指数的阈值。结果表明：新Thompson微物理方案的指示作用相对较优；当SRF指数阈值设定为90%，能较准确预报出降水过程中雨区、雪区和雨雪混合区的分布以及降水相态随时间的演变。同时SRF指数预报时效较长，不同起报时次对降水相态判别结果影响不大。

Abstract: In order to ascertain the impact of different microphysical processes of WRF model on precipitation phase forecasting in Zhejiang, 10 precipitation processes with precipitation phase change in Zhejiang Province from 2000 to 2017 are simulated based on WRF V3.9, NCEP/NCAR 1˚ × 1˚ reanalysis data and GFS 0.5˚ × 0.5˚ data by three microphysical schemes, i.e. a Purdue Lin scheme, a WSM6 scheme and a new Thompson scheme. Then two snowfall processes in Zhejiang Province in January 2018 were selected to carry out threshold test of SRF index and forecast performance evaluation, and the forecast differences of different schemes and the threshold value of SRF index were obtained. The result shows that the prediction effect of the new Thompson scheme is optimal. It can accurately predict the distribution of rain, snow and sleet area during precipitation and the evolution of precipitation process with time when the SRF index threshold is set to 90%. And the SRF index has a long time-effectiveness because the different starting times have little influence on the result of precipitation phase discrimination.