HR: 14:40h
AN: A22E-04    [PDF]
TI: Aerosol Mixing State Inferred From Highly Time Resolved Composition Measurements And an Aerosol Thermodynamic Model: Case Studies From ACE-Asia And TRACE-P
AU: * Song, C H
EM: cs222@prism.gatech.edu
AF: Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332 United States
AB: In this study highly time-resolved bulk aerosol composition data recorded from airborne measurements during TRACE-P P3B Flight \#10 and ACE-ASIA C130 Flight \#6 are used to investigate the extent of fine particle mixing among various inorganic aerosol particle constituents. First, a biomass-burning plume, roughly 3-4 day old, superimposed on a background aerosol recorded in the Philippine Sea during the NASA TRACE-P experiment is investigated. Focusing on the fine particle NO3-, SO42-, K+, and NH4+ system, the observed correlations suggest the existence of a fine mode K+-NO3- aerosol. Because K+-NO3- is thermodynamically less favored than 2K+-SO42- in a mixture of NO3-, SO42-, K+, and NH4+, the correlations suggest that aerosols could be composed of biomass burning particles (KNO3) mixed externally with the background (NH4)2SO4 aerosols. A ``closed-mode'' thermodynamic aerosol simulation predicts a degree of external mixing of 60 to 100 % is necessary to achieve the observed ionic associations. The same methodology is applied to a dust aerosol plume mixed with polluted urban and sea-salt aerosols recorded in the marine boundary layer of the Yellow Sea during the ACE-ASIA mission. The aerosol simulation carried out assuming various degrees of external mixing between dust and urban particles indicates the observed 2NH4+-SO42- association only exists when most of fine-mode dust particles exist externally. In this case, the degree of external mixing is estimated to be between 72 % and 100 %.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 4801 Aerosols (0305)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting