On The Application Of Stochastic Kinetic Energy Backscattering Ensemble Forecast Method Under Different Resolutions

The stochastic kinetic energy backscattering(SKEB)method is an effective method to solve the uncertainty of the interaction between the indistinguishable scales and the distinguishable scales due to a missing dynamic process in the numerical model.The size of the indiscernible scale depends on the resolution of the model.In order to explore the influence of model resolution on this method and its causes,based on WRF model and ERA5 reanalysis data,this paper took a meiyu rainstorm process as an example to analyze the influence of different model resolution on the uncertainty of forecast results.Then,the ensemble forecast experiment based on SKEB method was carried out at different horizontal resolutions,and the forecast effect was compared and analyzed with a variety of test indexes.Finally,the results with different resolutions are analyzed from the distribution and evolution of flow function disturbance,energy disturbance and energy spectrum disturbance.The main conclusions are as follows:(1)The deterministic forecast results are sensitive to the model resolution,and the forecast uncertainty caused by horizontal resolution is greater than that caused by vertical resolution.At convective resolvable scale,the prediction effect of using cumulus parameterization scheme is better than that of using explicit scheme only.(2)Under different resolutions,SKEB ensemble forecast has obvious differences.The high resolution model only has a slightly better effect on precipitation forecast,and its forecast effect on other factors is not better than that of low resolution model’s.In other words,only improving the resolution can not improve the forecast effect comprehensively.(3)Under the two resolutions,the distribution and evolution of flow function perturbations SKEB ensemble prediction are very different.The low-resolution ensemble prediction’s flow function perturbations and internal energy perturbations are larger than those under high resolution,but the kinetic energy perturbations are similar.In the mesoscale spectrum,the increase of kinetic energy spectra of low resolution’s is also larger than that of high resolution’s.