Investigation of Multiple Aerosol-Cloud Equilbrium Regimes During VOCALS

“The goal of the project is to gain a more detailed understanding of the physiochemical processes driving the maritime boundary layer through a multi-scale study, grounded in the observations from VOCALS focusing on the impact of varying emissions on the cloud properties to determine specifically if a threshold exists whereby the maritime boundary layer clouds exist in either the open or closed cells of convection observed in the marine boundary layer state as a preferred regime. This is critical given the difficulty current climate models have reproducing marine boundary layer cloud properties. The chemistry version of the Weather Research and Forecasting model (WRF-Chem) will be run at mesoscale, cloud-system resolving and cloud resolving scales using the full aerosol-cloud interaction modules developed by Battelle�??Pacific Northwest Division scientists to allow detailed process studies including the direct, semi-direct, and indirect aerosol-cloud effects coupled with fully interactive aerosols. Each of the model configurations will be run using a wide range of anthropogenic emission scenarios based on those observed during the VOCALS campaign. The result will enable us to understand the cloud properties as a function of anthropogenic emissions with an emphasis on how the different physiochemical processes in the system change for different cloud states as well as for different model scales for the SEP region. Example targeted variables that will be examined are: cloud albedo, cloud optical depth, cloud droplet number and diameter, cloud fraction, and radar reflectivity.”