Cloud Precipitation Forecast Using Different Initial Values And Parameterization Schemes In WRF Model

Based on inversion data of China’s FY meteorological satellites and TRMM(Tropical Rainfall Measuring)satellites’ TMI(TRMM Microwave Imager)detection,the WRF(Weather Research and Forecasting)model is employed to quantitatively evaluate the results of 19 individual batch simulations with six different microphysical parameterization schemes,from the perspective of the macroscopic and microscopic characteristics of the cloud system and the precipitation field.On the basis of quantitative verification,the ensemble forecasting experiments are carried out by the ensemble mean(EMN),the bias-removed ensemble mean(BREM),the multi-model Super-ensemble(SUP),and the applications of multi-physical ETKF’s(Ensemble Transform Kalman Filter)initial disturbance method in the macroscopic and microscopic characteristics of the cloud system and the precipitation field are explored.First of all,from the aspect of the macro characteristics of the cloud system,it is found that when the calculation threshold of cloud top height and cloud top temperature is selected as 2×10-4kg/kg,the simulated value is more accurate,but there is a problem that the simulation of the range of the cloud system is relatively small.Evaluation of the results of six different microphysical parameterization schemes found that each scheme can roughly simulate the direction and distribution of the cloud system,but the specific results are different.The prediction performance of the CAM5.1 scheme is better than that of other schemes,in particular,the prediction of cloud top height in Jiangsu,Zhejiang and Anhui is more accurate;The Morrison 2-mom scheme is second only to CAM5.1 scheme.The three ensemble methods can improve the forecasting skills of cloud top height and cloud top temperature to a certain extent,and the improvement effect is more obvious with the lengthen of lead time.The multi-physical ETKF can effectively improve the problem of small scope of the cloud system.It is superior to the only multi-physical ensemble.Secondly,from the perspective of the simulation of hydro meteors in the cloud,it is found that different parameterization schemes have different sensitivities to different hydrometeors particles.The CAM5.1 scheme has good simulation effect when the rainwater content is large,but the error is large when the rainwater content is small.The forecast results for ice water ofLin scheme are closer to the actual situation.The NSSL 2-mom scheme is obviously inferior to other schemes for the prediction of cloud water.And the forecast results of the six parameterization schemes for ice water are basically better than those for cloud water.On this basis,the ensemble forecasting experiment is carried out and it is found that the BREM shows a significant improvement in the omitting of cloud water in the range of 0.01-0.05 kg/m2.Multi-physics ETKF combines the advantages of each scheme,improves forecasting skills,and is superior to only multi-physics.Finally,in terms of precipitation forecasts,the prediction advantage of the CAM5.1 scheme is not obvious when the forecasting time is short,but the error of the CAM5.1 scheme is obviously smaller than other schemes with the lead time lengthens,and it’s better for the simulation of small rainfall levels.The three ensemble methods have certain improvement effects on precipitation forecast,and the SUP is better than the other two methods.The multi-physical ETKF is also suitable for precipitation forecasting,and the improvement effect is better than only multi-physics.In addition,a comparative study of cumulus convective parameterization scheme is introduced to simulate 12 strong convective weather in Hubei.The results show that the microphysical parameterization scheme CAM5.1 is still excellent,and the heavy rainfall forecast is also sensitive to the cumulus convection parameterization scheme.