AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
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Distribution, Influential Factors, and Sources of Aerosol Liquid Water during the DISCOVER-AQ 2013 Campaign in Houston, TX
ALEXANDER BUI, Yu Jun Leong, Nancy Sanchez, Henry Wallace, Robert Griffin, Rice University
Abstract Number: 113 Working Group: The Role of Water in Aerosol Chemistry
Abstract Aerosol liquid water content (ALW) affects the size, optical properties, and chemical behavior of aerosols. Specifically, ALW has been shown to play a role in secondary organic aerosol (SOA) formation via the partitioning of gas-phase water-soluble organic compounds to the condensed phase. Here, ALW mass concentrations in Houston during the September 2013 DISCOVER-AQ campaign are calculated using two thermodynamic equilibrium models: (1) the Extended Aerosol Inorganics Model IV (E-AIM) and (2) ISORROPIA1. These models also allow an evaluation of aerosol acidity. In both models, the partitioning of water to the aerosol phase is calculated using ambient temperature, ambient relative humidity, and mass concentrations of inorganic aerosol components (sulfate, nitrate, ammonium, and chloride). Inorganic sub-micron aerosol data were collected using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) deployed on a mobile laboratory.
In this study, the spatial and temporal distributions of ALW in Houston are evaluated, as is the sensitivity of ALW to the relative abundances of sulfate, nitrate, ammonium, and organics. Identification of the dominant aerosol components that drive ALW in Houston is also important for determining potential mechanisms for SOA formation. As such, ALW concentrations are compared to factors derived from a factor analysis applied to the HR-ToF-AMS data. Furthermore, the regions and local anthropogenic sources in Houston that contribute to variability in ALW are characterized.