Formation of 2-Methyltetrol and 2-Methylglyceric Acid in the Northern Hemisphere from Marine Isoprene Emission

JIE ZHANG, Minsu Choi, Junyi Liu, Xiang Ding, Mei Zheng, Qi Ying, Texas A&M University

     Abstract Number: 375
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
Field measurements have shown that isoprene emitted from ocean surfaces are significant. However, their contributes to secondary organic aerosol (SOA) formation in the polluted and remote marine troposphere have not been accurately quantified. In this study, we used a modified hemi-spheric community multiscale air quality model (hemisphere CMAQ) to study the formation of 2-methyltetrols (2-MT) and 2-methylglyceric acid (2-MG) due to isoprene emissions originated from chlorophyll-a and marine and sea surface microlayer in the northern hemisphere. The modified hemi-sphere CMAQ model considers the formation of 2-MT and 2-MG from the acid-driven reactive surface uptake of isoprene epoxide (IEPOX), methacrylic acid epoxide (MAE), and hydroxymethyl-methyl-α-lactone (HMML). In addition, it considers the photochemical decay of 2-MT and 2-MG in gas and aerosol aqueous phase, and the gas-aqueous-organic phase partitioning. The emissions of isoprene and other biogenic VOCs from on-land sources are also considered in the model using the estimations from the Model of Emissions of Gases and Aerosols from Nature (MEGAN), and anthropogenic emissions are based on the EDGAR emission inventory. Our simulations will reveal the concentrations of the marine-originated isoprene tracers and total SOA in various parts of the marine boundary layer in the northern hemisphere and their contributions to total SOA loading.