AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Dimethyl Sulfide Control of the Clean Summertime Arctic Aerosol and Cloud
RICHARD LEAITCH, Sangeeta Sharma, Lin Huang, Desiree Toom-Sauntry, Alina Chivulescu, Annie-Marie Macdonald, Knut von Salzen, Jeffrey Pierce, Allan Bertram, Jason Schroder, Nicole Shantz, Rachel Chang, Ann-Lise Norman, Environment Canada
Abstract Number: 619 Working Group: Remote and Regional Atmospheric Aerosols
Abstract One year of observations from Alert, Nunavut shows that new particle formation is common during clean periods of the summertime Arctic, associated with low condensation sinks and the presence of methane sulfonic acid. The clean aerosol time periods, defined using the distribution of refractory black carbon number concentrations, increase in frequency from June through August as the anthropogenic influence dwindles. During the clean periods, the number concentrations of particles that can act as cloud condensation nuclei increase from June through August suggesting that dimethyl sulfide, and possibly other oceanic organic precursors, exert significant control on the Arctic summertime submicron aerosol, a proposition supported by simulations from the GEOS-Chem-TOMAS global chemical transport model with particle microphysics. The cloud condensation nucleus concentrations increase for the clean periods across the summer is estimated to be able to increase cloud droplet number concentrations by 23-44 cm-3, comparable to the mean increase in droplet number concentrations needed to yield the current global cloud albedo forcing from industrial aerosols. These results suggest that dimethyl sulfide contributes significantly to modification of the Arctic summer shortwave cloud albedo.