Aerosol-cloud interactions during DYCOMS-II

Markus Petters, PhD candidate

University of Wyoming

Aerosols are liquid and solid materials which are suspended in the atmosphere. A subset of the aerosol are the cloud condensation nuclei (CCN). CCN facilitate the formation of clouds, wherefore changes in the CCN lead to changes in the microstructure of clouds. It has been suggested that cooling effects by aerosols may be tantamount to warming caused by greenhouse  gases. For this reason, studying the origin and composition of the aerosol is critical when quantitative assertions about the effects of aerosol on clouds are to be made.

This work presents the current theory about the origin and dynamics of aerosols in the remote cloud-topped marine boundary layer. The theory is tested with data obtained from a recent field campaign over the Pacific Ocean (DYCOMS-II). Furthermore, climate feedback loops, such as the Dimethyl-Sulfide (DMS) --- Aerosol --- Climate hypothesis are explored in some detail. The results show that DMS may play an important role in replenishing CCN under conditions which formerly were believed to lead to dissipation of the cloud layer. If this is true, marine stratocumulus clouds may be more stable than previously suggested.