Influence of Ecosystem Processes on Aerosol Organic Hygroscopicity

MARIA FLORES, Celia Faiola, University of California, Irvine

     Abstract Number: 523
     Working Group: Aerosol-Ecosystem Interactions

Abstract
Secondary organic aerosol influences the transfer of radiation by scattering and absorbing light and acting as cloud condensation nuclei (CCN). The particular composition of aerosols influences how likely they are to take up water and act as CCN, a property that is often described with aerosol hygroscopicity. Many ecosystem processes, such as spring bud bursts and fall leaf senescence, can alter biogenic emissions and thereby alter overall aerosol hygroscopicity, but can also alter the hygroscopicity of the organic component in the condensed phase (k_org). Since climate change is altering many ecosystem processes, including seasonal phenology, it is important to have a better understanding of how these processes alter aerosol hygroscopicity to allow us to better predict aerosol climate effects.

This project leverages field data collected at DOE ARM sites. The field sites used for this study include the South Great Plains site in Oklahoma, and the SMEAR II station in Hyytiäläˌ Finland. First, the particle hygroscopicity, k_CCN was calculated by determining the maximum activated fraction as a function of particle size at different supersaturations. Secondly, the k_org was calculated by using ARM field campaign data derived from CCN hygroscopicity and particle composition. Finally, the k_org was compared between both sites to investigate the effects of plant emission types, seasonality, and other ecosystem properties and processes on aerosol hygroscopicity. A synthesis of that analysis will be presented.