AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
The Impact of Source-Oriented Aerosols on Fog Formation and Energy Budget in the California Central Valley
HSIANG-HE LEE, Shu-Hua Chen, Michael Kleeman, Steven DeNero, David Joe, Hongliang Zhang, UC Davis
Abstract Number: 376 Working Group: Aerosols, Clouds, and Climate
Abstract Tule fog events are common in California’s heavily polluted San Joaquin Valley (SJV) during the winter season, where they provide an aqueous volume for secondary reactions. The aerosol number concentration, size, and composition can alter fog formation and the radiation budget. Direct emissions of anthropogenic particles serve as the majority of the cloud condensation nuclei (CCN) during fog events in the SJV, but most current models that predict interactions between aerosols and fogs/clouds make simplified assumptions about the mixing state of anthropogenic particles.
The primary goal of this research is to implement a source-oriented CCN module in the Weather Research and Forecasting model (WRF-Chem) to investigate the effects of aerosols from various sources on fog formations and their optical properties. This work builds on a recent project to implement a source-oriented framework for particulate matter operations within WRF-Chem (SO-WRF-CHEM6D) at UC Davis. Particle radius, number concentration, and chemical composition are calculated explicitly for each particle source and size bin. The new source-oriented CCN module in SO-WRF-CHEM6D is combined with the two-moment Purdue Lin microphysics scheme including cloud feedbacks on aerosol distribution and number concentration.
Four numerical experiments will be conducted for two fog events (February 21, 2007 and January 17, 2011) to understand the influence of aerosol particles serving as CCN in clean and polluted environments on the fog formation and radiation budget. Aerosol direct and indirect effects will be studied in these numerical experiments. Comparison among these experiments will help us understand the impact of source-oriented aerosol-cloud-radiation effects on the energy and moisture budget, boundary layer instability, fog lifetime, fog thickness, etc.