A Predicting Method of the Strong Cooling Process during Winter with Numerical Model Prediction and its Operational Application

Abstract

At first this paper quantitatively evaluated the low-frequency wave performance of NCEP-CF Sv2 model over the eight key areas on 700 hPa from January to March and from October to December of 2017， and then made operationally the fifteen extended-range operational predictions of strong cooling process for January to April of 2018 and for November to January 2019 with the 1~30 days prediction given by CFSv2 model as well as the low-frequency wave conceptual predicting model.The results show that the phase and evolution trend of the low-frequency wave in the key area predicted by CFSv2 model are highly consistent with the reality， with the correlation coefficients of 0.839 of the predicted low-frequency waves with the observed for the extended-range （11~30 days）， the accuracy of low frequency wave trend by the model over 3~6 pentad up to percent of 83.3 on average， and the percentage of 100-percent accuracy of the trend even up to 45.8.The average accuracy， Cs and Zs scores of 15 strong cooling process operational predicting are 61.2%， 0.149 and 0.158 respectively， and at the same time the occurrence of the two strongest cooling processes at the beginning and the end of 2018 were accurately given with the lead-time of 18 and 16 days in turn， which are significantly higher than those of the operation predicting for the same period of 2015 to 2017 without CFSv2 results.

Keywords

• extended-range strong cooling process
• low-frequency wave
• numerical model