Application Of Morrison Scheme In GRAPES Model And Simulation Study Of Cloud Radiation Process

In the present study,the Morrison double-moment cloud microphysics scheme including mass and droplet number concentration of water and ice clouds is implemented into the Chinese mesoscale version of the Global/Regional Assimilation and Prediction System(GRAPES?Meso).Sensitivity experiments of different cloud condensation nuclei(CCN)values are conducted to study CCN's impact on cloud microphysical and radiation processes in East China.The Morrison double-moment cloud microphysics scheme is implemented into the GRAPES?Meso model to study stratus system from October 8 to 12 and 23 to 28 2017.The Morrison and WDM6 scheme are used to simulate a systemic cold cloud process which occurred in the region of East China from January 5 to 7 2017 to study and explore the superiority of Morrison scheme and the impact of different physical schemes on cloud microphysical process and cloud radiation process.(1)The model evaluation shows that the simulated cloud liquid water path(CLWP)is consistent with that of the National Center for Environment Prediction(NCEP)reanalysis,and the cloud optical depth(COD)and effective radius of cloud water(Rc)are in agreement with those of the Moderate Resolution Imaging Spectroradiometer(MODIS)datasets both in regional distribution and magnitudes.These comparisons illustrate the effectiveness of the Morrison scheme for the cloud processes in East China.(2)For the study period of 8 to 12 October 2017,the sensitivity experiments show that with CCN increasing from 10 to 3000 cm^-3,the maximum value of daily average Rc decreases by about 63%,which leads to a decrease of cloud-rain conversion rate.Moreover,the maximum value of daily average mixing ratio of cloud water(q_c)increases by 133%,the maximum value of daily average mixing ratio of rain(q_r)decreases by 44%,and the maximum value of daily average CLWP and COD increase by 100%and 150%,respectively.This results in about 65%increasing of the maximum value of daily average Surface cloud downward shortwave radiation forcing(CDSRF)when CCN increases from 10 cm^-3 to 3000 cm^-3.The study result indicates the important impacts of CCN on cloud properties and radiation effects.(3)The result shows that the simulation of Morrison scheme on Rc,effective radius of cloud ice(Ri),CLWP and COD in the cold cloud process is better than that of WDM6 scheme.Shortwave radiation simulated by the Morrison scheme and that of CERES satellite data are more consistent than the WDM6 scheme.That is due to the absence of the cold cloud process in the WDM6 scheme,while the Morrison scheme has detailed cold cloud and warm cloud processes.The two schemes also show significant differences in simulating sea-level temperature and surface heat radiation flux.And this difference is significantly greater on land than on the ocean.