Simulation of marine stratocumulus clouds using two different Large Eddy Simulation models

Marine stratocumulus clouds exert strong cooling effect on the earth climate system because of low cloud top and significant cloud liquid water path. Marine stratocumulus clouds also have wide areal coverage with a great persistency, thus they impact on global climate change significantly. However, these clouds are found to be hard to simulate realistically. Large Eddy Simulation (LES) models are known to be a better tool to simulate stratocumulus since it solves large eddies directly that dominate the flow field in these clouds and parameterizes only small eddies, although it needs more computational time and resources than the other models that do not resolve large eddies. In this study, we compare two different LES models; Weather Research and Forecast (WRF) LES and the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) LES. These two models have different dynamical framework and microphysical options. WRF provides a number of microphysics schemes, but they are all bulk schemes. On the other hand, CIMMS LES offers both bulk and explicit microphysics schemes. We will show their differences by simulating the same cases and comparing their results. Four different thermodynamic sounding, two observed and the other two modified from the observed, will be used for the simulation. This research will help us distinguish their different performances and use each model properly for a given circumstance.