ASR CRM Intercomparison Study on Deep Convective Clouds and Aerosol Impacts

Description

The large spreads in CRM model simulations of deep convection and aerosol effects on deep convective clouds (DCCs) make it difficult to (1) further our understanding of deep convection and (2) define “benchmarks”, limiting their use in parameterization development. Past model intercomparisons used different models with different complexities of dynamic-microphysics interactions, making it hard to isolate the causes of differences between simulations. In this intercomparison study, we employ a much more constrained approach – with the same model and same experiment setups employing a piggybacking approach to isolate contributions from microphysical processes, in order to answer the following questions: • What are the major microphysical processes controlling model differences for warm rain, mixed-phase, and ice phase conditions, especially condensation, deposition and droplet freezing? • How do the conversions of droplets to rain and ice to snow as well as formation of graupel and hail contribute to the model differences, especially for aerosol impacts? • What is the relative importance of latent heating versus hydrometeor loading in terms of the feedback to dynamics? How do the microphysical schemes differ in producing cold pools and aerosol impacts on them? Real-case simulations are conducted for the squall line case on May 20, 2011 from the MC3E field campaign. Results from the piggybacking approach show substantially different responses of the microphysical schemes to the same dynamical fields. We will present in-depth analysis related to the major microphysical processes responsible for the substantial differences. Results on the significance of the feedback to dynamics will be shown as well.