业务模式晴雨预报能力分析及其改进方法研究

Analysis of the capability of operational model clear-rain forecast and research on its improvement method

以欧洲中心全球预报模式和中国华南区域中尺度模式(GZ 3 km)为例分析了2019年中国南方逐日晴雨预报的情况,并讨论模式晴雨预报的性能。借助TS检验评估方法,在与简单外推预报等的比较中,发现模式雨量预报特点及模式晴雨预报的统计规律,如两个模式同时预报晴天,或者模式预报有雨且降水量大于某阈值等情况,其预报准确率非常高;而对于两个模式预报不一致,或模式预报有雨且雨量较小等情况,则存在较大不确定性。基于上述研究,提出利用模式预报改进观测外推和利用观测与模式的频率匹配改进模式预报等方法。

Based on the European Center for Medium-range Weather forecast(ECMWF)model and the Regional Mesoscale Model for South China(GZ 3 km),clear or rain daily forecast in South China in 2019 was analyzed,the performance of the model prediction was discussed.With the use of TS evaluation method,the characteristics of the model rainfall forecast and the statistical law of the model rain or clear forecast are found in comparison with simple extrapolation forecast.For instance,the case that two models forecast clear simultaneously,or model predict rainy and the predicted precipitation exceed a certain threshold can reach very high accuracy.However,there are some uncertainties when the two models do not agree,or when the model predict rain with small rainfall.Based on the above research,the method of using improved model-based observation extrapolation and using frequency matching between observation and model to improve model prediction is proposed.