A Comparison of Parameterizations of Secondary Organic Aerosol Production: Global Budget and Spatiotemporal Variability

Tuesday, 16 December 2014
Junfeng Liu1, Zhuo Chen1, Larry Wayne Horowitz2, Ann Marie G Carlton3, Songmiao Fan2, Yanli Cheng4, Barbara Ervens5, Tzung-May Fu6, Cenlin He7 and Shu Tao1, (1)Peking University, College of Urban and Environmental Sciences, Beijing, China, (2)Princeton Univ-NOAA GFDL, Princeton, NJ, United States, (3)Rutgers University New Brunswick, Department of Environmental Sciences, New Brunswick, NJ, United States, (4)CAMS Chinese Academy of Meteorological Sciences, Beijing, China, (5)CIRES, University of Colorado, Boulder, CO, United States, (6)Peking University, Beijing, China, (7)University of California Los Angeles, Los Angeles, CA, United States
Secondary organic aerosols (SOA) have a profound influence on air quality and climate, but large uncertainties exist in modeling SOA on the global scale. In this study, five SOA parameterization schemes, including a two-product model (TPM), volatility basis-set (VBS) and three cloud SOA schemes (Ervens et al. (2008, 2014), Fu et al. (2008) , and He et al. (2013)), are implemented into the global chemical transport model (MOZART-4). For each scheme, model simulations are conducted with identical boundary and initial conditions. The VBS scheme produces the highest global annual SOA production (close to 35 Tg·y-1), followed by three cloud schemes (26-30 Tg·y-1) and TPM (23 Tg·y-1). Though sharing a similar partitioning theory to the TPM scheme, the VBS approach simulates the chemical aging of multiple generations of VOCs oxidation products, resulting in a much larger SOA source, particularly from aromatic species, over Europe, the Middle East and Eastern America. The formation of SOA in VBS, which represents the net partitioning of semi-volatile organic compounds from vapor to condensed phase, is highly sensitivity to the aging and wet removal processes of vapor-phase organic compounds. The production of SOA from cloud processes (SOAcld) is constrained by the coincidence of liquid cloud water and water-soluble organic compounds. Therefore, all cloud schemes resolve a fairly similar spatial pattern over the tropical and the mid-latitude continents. The spatiotemporal diversity among SOA parameterizations is largely driven by differences in precursor inputs. Therefore, a deeper understanding of the evolution, wet removal, and phase partitioning of semi-volatile organic compounds, particularly above remote land and oceanic areas, is critical to better constrain the global-scale distribution and related climate forcing of secondary organic aerosols.