Introduction of operational convection permitting ensemble prediction system of North China

Abstract: With the development of technology, major operational centers and scientific research institutions have carried out research and development of convection permitting ensemble prediction technology and systems. In order to meet the needs of accurate forecasting in the capital, the Convection permitting ensemble prediction system of North China CMA-BJ-EN v1.0 developed by the Institute of Urban Meteorology was officially put into operation in January 2023. This paper introduces the research and development background and key technologies of the system in detail. The results show that the CMA-BJ-EN v1.0 system has a resolution of 3km convective resolution scale, covering 21 members, and can provide hourly probability prediction results of 48h forecast effectiveness in North China; The system is coupled with advanced technologies such as initial conditon perturbation of ensemble data assimilation, stochastic physical process tendency(SPPT) model perturbation, and has complete pre-processing, initial condition perturbation, model perturbation, and post-processing configuration, which can provide a series of probability prediction products; The qualitative and quantitative evaluation of CMA-BJ-EN v1.0 system and its comparison with NCEP global ensemble forecast system show that the system can effectively grasp several major weather processes in North China, and can obtain local refined probability forecast results relative to global ensemble; The statistical results also show that compared with the NCEP GEFS global ensemble forecast, the CMA-BJ-EN v1.0 forecast system can effectively reduce the RMSE of 2m temperature and 10m wind speed, and can effectively improve the probability forecast score of precipitation forecast. The operation of the system can provide users with effective refined probability forecast reference.

Keywords: convection permitting, ensemble prediction system, initial condition perturbation, model perturbation