Application of Morrison Cloud Microphysics Scheme in GRAPES_Meso Model and the Sensitivity Study on CCN’s Impacts on Cloud Radiation

Yishe Shi,Hong Wang,Meng Zhang,Zhaodong Liu,Yue Peng,Jing Han,Wenjie Zhang,Xinyong Shen,Xiao Zhang

doi:10.3390/atmos12040489

Abstract

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 the impacts of CCN on cloud microphysical processes and radiation processes in East China. 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. For the study period of 8 to 12 October 2017, the sensitivity experiments show that with initial CCN number concentration (CCN0) 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 (qc) increases by 133%, the maximum value of daily average mixing ratio of rain (qr) 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 cloud downward shortwave radiative forcing (CDSRF) when CCN0 increases from 10 cm−3 to 3000 cm−3. The study indicates the important impacts of CCN on cloud properties and radiation effects.

Highlights

Introduction conditions of the Creative CommonsClouds are an essential component for the earth’s water cycle, and intensely influence energy exchange between earth and atmosphere [1,2]
All of CORRs have exceeded 0.05 significance level. These results show that the simulations when the initial cloud condensation nuclei (CCN) is set as 250 cm−3 agree with the observed data and are more accurate than those when setting CCN as 100 cm−3 or 300 cm−3
To illustrate the possible impacts of CCN0 on clouds physical, microphysics, and optical features, the radiation processes, temporal and spatial changing of mass mixing of cloud hydrometeors, radius of cloud water (Rc), radius of cloud ice (Ri), cloud optical depth (COD) of water cloud (CODC), and ice cloud (CODI) corresponding to different CCN0 values in Morrison scheme, and the possible relationships between the changes of above factors are compared and discussed in detail

Summary

Introduction

Introduction conditions of the Creative CommonsClouds are an essential component for the earth’s water cycle, and intensely influence energy exchange between earth and atmosphere [1,2]. Bin schemes explicitly calculate the evolution of the particle size distribution and divide a hydrometeor size distribution into several size bins, based on the microphysical properties of hydrometeors and aerosol such as phase state, particle size, shape, density, which is widely used to study the liquid and ice-phase cloud microphysical processes [9,10]. Double-moment schemes simulate both mass mixing ratio and number concentration of hydrometeors [14]. Ferrier proposed a double-moment ice-phase volumetric water microphysics scheme to simulate the distribution of condensate in convective precipitation and layered cloud precipitation under different large-scale environmental conditions [17]. A relatively complete double-moment microphysics scheme was proposed to study cumulonimbus related issues, which can numerically calculate the number concentration of cloud (nc ), raindrops (nr ), ice (ni ), snow (ns ), and graupel (ng ) droplets [18]. Double-moment schemes incorporate the number concentration of hydrometeors and increase the degrees of freedom of the particle size distribution, and the number and quality of hydrometeor particles in the physical mechanism are more coordinated, which is incorporated in climate or weather models and widely used in weather and climate simulations [19,20,21]

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Results

Conclusion