基于WRFDA-Chem三维变分同化系统的中国PM2.5和PM10资料同化试验北大核心CSCD

将大气化学三维变分同化系统WRFDA_Chem引入睿图—化学环境气象数值预报系统(RMAPS-Chem),利用2016年11月地面观测细颗粒物(PM2.5)和颗粒物(PM10)逐小时质量浓度资料进行同化预报试验:6 h循环同化结果表明,WRFDA-Chem对初始场PM2.5和PM10的模拟偏差和相关性有显著改善,均方根误差(RMSE)减小40%左右,相关性提高0.27~0.37;同化对预报改进能持续24 h以上,PM2.5(PM10)浓度预报RMSE降低25%(10%),相关性提升14%(25%);加密同化频次(逐小时循环同化)进一步改进预报效果。未来需要进一步开展同化数据质量控制方案研究以优化业务预报效果,并在深入理解模式不确定性和偏差来源的情况下,进一步开展模式和同化系统的协同发展。

PM2.5 and PM10 Data Assimilation Experiments in China Based on the WRFDA-Chem Three-Dimensional Variational (3DVAR) System

The WRFDA-Chem system with the atmospheric chemistry three-dimensional variational (3DVAR) algorithm was developed and applied in the Rapid Refresh Multi-scale Analysis and Prediction System-Chem (RMAPS-Chem), and experiments were conducted with and without the assimilation of the hourly surface PM2.5 and PM10 mass concentration in November 2016 to analyze the impacts of data assimilation on forecasting. The 6-h cycle assimilation results demonstrate that the assimilation of the surface PM2.5 and PM10 observations significantly improved the model performance of PM2.5 and PM10 initial fields with an increase in the correlation by 0.27–0.37 and a reduction in the root mean square error (RMSE) of about 40%. The improvement of the PM2.5 and PM10 forecasts was acquired for over 24 h with the initial analyzed field; the RMSE of the 24-h forecast PM2.5 (PM10) was reduced by 25% (10%), and the correlation of PM2.5 (PM10) increased by 14% (25%), respectively. The increase in the data assimilation (DA) cycling frequency (from 6-h to hourly DA cycle) could further improve the PM2.5 and PM10 forecast. In future operational applications, additional experiments on the data quality control/filtering in the system should be considered to obtain an optimized assimilation performance. Since the biases reflected the combining results of model uncertainties from various aspects, better understanding and diagnosis of model uncertainties should be aimed to promote the synergistic development of the model and the data assimilation system in the future.