AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Partitioning of Inorganic Gases to Atmospheric Ice: Effects on CMAQ Predictions of Nitrogen and Sulfur Compounds
Brian Marmo, ANNMARIE CARLTON, Rutgers University
Abstract Number: 419 Working Group: Aerosol Chemistry
Abstract This work describes the first implementation of gas-to-ice partitioning of three inorganic gases (HNO3, SO2 and H2O2), along with subsequent chemical reactions and changes in gas phase and particle mass concentrations in the Community Multiscale Air Quality (CMAQ) chemical transport model. Adsorbed HNO3 was assumed to condense and partition to the aerosol phase. Adsorbed SO2 and H2O2 reacted to form sulfate on the ice surface. Four different simulations were performed with CMAQv4.7.1 for August 12th-25th of 2005: 1) base case simulation without the addition of lightning-generated NOx, 2) a simulation with the addition of lightning-generated NOx, 3) 100% partitioning case and 4) 25% partitioning case. Simulations 3) and 4) provide an upper and lower bound for the partitioning of adsorbed HNO3 to remain in the aerosol phase. Considerable decreases, greater than 25% in gas phase HNO3, were noted in the 100% partitioning case for 200-600 mb, with the largest changes at 300 mb and 400 mb. Potential effects induced on other gases in the nitrogen budget (NOx and HONO) and oxidant cycling of atmosphere (O3) due to gas-to-ice partitioning of HNO3 were considered. Decreases in NOx and HONO gas mixing ratios were found to be as high 20%, but were generally less than 10%. Changes in O3 concentration were less than 1%. Increases in nitrate aerosol mass concentration were as high as 0.15 µg/m3 for the upper levels of the atmosphere. No changes in H2O2, SO2, or sulfate aerosol concentrations were observed.