Research And Application Of The Global Atmospheric Spectral Model Of Cloud Microphysical Parameterization Scheme

This paper is based on global atmospheric numerical weather prediction system YHGSM for cloud microphysical parameterization scheme research.Parameterization of cloud microphysical process is a very important part in numerical models,it is not only a direct effect of cloud and precipitation process,directly revealing the mechanism of cloud and precipitation formation,having a great impact on the precipitation forecast,and feedbacking to the mode of dynamic change process.First of all,the paper investigates and analyzes the cloud microphysical parameterization scheme,and sorts the development roadmap of cloud microphysical parameterization scheme.In the parameterization scheme of different types,according to the theory of principle and application results of scheme,the paper selects WSM5 parameterization scheme in WRF introduced into the spectral model.This work is in order to develop the spectral model,improve the effect of precipitation forecast in terms of spectral model.The main work and innovation are as follows:(1)This paper compares and analyzes Tiedtke cloud microphysical scheme and WSM5 cloud microphysical scheme: mainly compare and studie the theoretical basis,prediction variables and cloud microphysical processing methods.Finally,the similarities and differences between the two parameterization schemes are summarized.(2)This paper studies the problem of introducing WSM5 scheme into spectral mode: two modes of physical program module,the WSM5 scheme and the YHGSM spectral model dynamic process coupling problem,WSM5 scheme adapting to the business spectrum model YHGSM parallel framework are analyzed,discussed the feasibility of introducing WSM5 scheme into the spectral model.(3)Implementation of WSM5 scheme in spectral model YHGSM: Analysis Tiedtke scheme program and two schemes interface.Solve the initialization of WSM5,the new physical quantity,coordinate inconsistency,different integration steps and the matching of output variables in the spectral model,so as to implement WSM5 program in the spectral model YHGSM.(4)Experiment and statistical test: In order to test the forecasting effect of WSM5 scheme in YHGSM,a experiment and statistical test are adopted to test the prediction result.Taking the global spectral model YHGSM T799 as a platform,a large-scale heavy rainfall process occurred in Southern China area of China in June 22,2017 was selected as an experimental case,and the daily forecast experiment scheme of 10 days is used to test the prediction effect of Tiedtke scheme and WSM5 scheme.The results show that the two parameterization schemes can well predict the distribution and variation of global height field and precipitation.WSM5 compared to the Tiedtke scheme,the 500 hPa height field prediction is closer to the analysis field,in the range of precipitation forecast is closer to the observation field,the false situation precipitation center than the Tiedtke scheme;but the WSM5 scheme in the precipitation forecast than the observation field is not low,such as the Tiedtke program forecast effect.Judging from the traditional scoring test,the WSM5 scheme is better than the Tiedtke scheme for the precipitation or not,and the overall effect of the WSM5 scheme in the 1 day forecast is better than that of the Tiedtke scheme.However,with the increase of precipitation threshold and forecast time,the prediction effect of WSM5 scheme is worse than that of Tiedtke scheme.It is concluded that the WSM5 scheme improves the precipitation forecast and the 24 h forecast,and further optimization is needed for long time forecast and larger rainfall forecast.