Verification and Assessment of"23·7"Severe Rainstorm Numerical Prediction in North China
During the severe rainstorm in North China from 31 July to 1 August in 2023,CMA-GFS,CMA-EPS,EC-EPS,EC-HR,NCEP-GFS,CMA-TYM,CMA-MESO,and CMA-BJ are tested and evaluated using synoptic verification,threat score(TS),and MODE(method for object-based diagnostic evaluatin).The persistence and intensity of long-term heavy rainfall,as well as the area and intensity of short-term heavy rainfall,are tested and analyzed for their effectiveness over time.Results indicate that the cumula-tive precipitation predicted by EC-EPS may exceed 100 mm for 14 days in advance,but there is no predic-tion ability for extreme heavy precipitation above 600 mm.EC-HR forecast for the location of precipitati-on is generally accurate up to 8 days in advance.In the short term,the daily precipitation intensity forecast by CMA-BJ closely matches the actual situation,indicating its significance in predicting precipitation ex-tremes.The average and maximum precipitation values of CMA-GFS,EC-HR,and NCEP-GFS in the are-as with concentrated heavy precipitation are lower than actual values.CMA-GFS doesn't perform very well while EC-HR is closer to the actual situation.CMA-GFS,EC-HR,and NCEP-GFS models all pro-vide inadequate forecasts for the persistence of heavy rainfall.However,EC-HR has a relative advantage in predicting persistent precipitation 8 days in advance.TS of CMA-BJ is highest for precipitation fore-casts above 50 mm and 100 mm.EC-HR and CMA-TYM precipitation forecasts above 50 mm are relative-ly stable.From the daily MODE results of the precipitation concentration period from 29 July to 31 July,it is evident that EC-HR exhibits a northward predictive characteristic,while the prediction of CMA-BJ is slightly southward.The forecasting ability of CMA-GFS is insufficient,and forecasts from NCEP-GFS and CMA-MESO are not stable.The high-pressure system in North China has a significant impact on the precipitation.EC-HR model forecasts the formation and reinforcement of a 500 hPa high-pressure system 3 to 4 days earlier than CMA-GFS and NCEP-GFS models.It also surpasses both in predicting the precise location and strength of intense precipitation.Additionally,EC-HR model predicts the emergence of a 925 hPa low-pressure trough and a low-level jet 7 days in advance.However,it underestimates the intensi-ty of the trough and jet system,with the actual location being to the west to north.CMA-GFS and NCEP-GFS underestimate the impact of the Taihang Mountains on easterly winds,leading to significantly lower precipitation forecasts.The analysis of the deviation in the 36 h precipitation forecast for 30 July also shows that EC-HR has weak predictions for low-level wind fields,trough positions,and convective precip-itation,resulting in a weak intensity of heavy precipitation and a west-north precipitation area.
North China severe rainstormnumerical modelsynoptic verificationverificationTSMODE
NETL
NSTL
万方数据
