Effective approaches to extending medium-term forecasting of persistent severe precipitation in regional models

摘要

A set of methods designed to improve (i.e.extend) the medium-term forecasting of persistent severe rainfall (PSR) events in China using the regional Weather Research and Forecasting model are summarized.Simulations show that achieving a more efficient use of large-scale atmospheric variations of the global model and retaining small-scale features in the regional model are critical for better forecasting PSR events.For precipitation,the larger the magnitude and longer the lead time,the more significant the improvement-especially for the methods of spectral nudging and updated initial conditions.In terms of large-scale circulation,the anomaly correlation coefficient can be distinctly improved for 1-5-day lead times by adopting the spectral nudging technique,whereas lateral boundary filtering results in marked improvement for 7-11-day lead times.%延伸持续性强降水的模式动力预报能力对防灾减灾具有重要意义.本文总结概述了区域模式对中国南方持续性强降水的一系列动力延伸中期预报新技术方法,研究表明有效利用全球模式的大尺度预报场和区域模式的中小尺度信息对提高持续性强降水的预报至尖重要.对于降水场,预报时间越长,降水量级越大,新方案的改进效果越明显,特别是使用谱逼近和更新初值方案.对于大尺度环流场,谱逼近方案对提前1-5天预报的距平相关系数有明显的改进,侧边界滤波方案对提前7-11天的预报有改进效果.