Correlation Between Droplet Spectral Dispersion And Cloud Droplet Number Concentration In Warm Cloud Over North China And Its Influence On Mixed Cloud Precipitation

Based on the observations of warm clouds over North China by aircraft,the correlation between the dispersion of warm clouds(?)and cloud droplet concentration(N_c)is obtained and the main causes of the correlation are analyzed.On this basis,the influence of the correlation on the automatic conversion rate of cloud and rain is considered by using WRF-Morrison.Furthermore,the effects of?-N_c correlation properties on mixed cloud precipitation in highly polluted areas of North China were simulated.The results show that the vertical velocity,temperature inversion region and coiling are all important factors affecting?-N_c.When the updraft or downdraft increases or weakens with the height,?and N_c increase with the height,showing a positive correlation with each other.The updraft promotes collision and increases,which results in the decrease of N_c with height,while the downdraft velocity increases with height,which results in the accumulation of water vapor in the lower air mass and promotes the activation of aerosol,which has a negative correlation with?.When the inversion region is thick in the cloud,the?decreases with height,and the?-N_c is positively correlated,while when the inversion region is thin,the?-N_c is negatively correlated.The upper part of the inversion region is not saturated,and the cloud droplets evaporate.The?and N_c decrease with the height,respectively.The?-N_c presents a positive correlation.The strong entanglement near the top of the cloud reduced the number of cloud droplets,and?-N_c showed a positive correlation.In the simulation of WRF-Morrison microphysics scheme,we found that the?-N_cnegative correlation can enhance the melting process of graupel and the formation of raindrops to enhance precipitation.In order to meet the characteristics of highly polluted areas in North China,increasing the concentration of CCN can reduce the mass concentration of cloud drops,increase the mass concentration of graupel and rain drops,enhance the ice phase process and increase precipitation,which is more in line with the actual situation.The addition of cloud and rain automatic conversion rate strengthens the release of latent heat to lift the updraft and greatly influences the ice phase process,so as to enhance the formation of graupel and thus improve the precipitation intensity.Weak negative correlation,the precipitation mature stage of snow melting process is stronger,enhance the precipitation.