HR: 17:00h
AN: A54B-05    [Abstracts]
TI: The influence of aerosol composition on cloud drop number concentration
AU: Ervens, B
EM: barbara.ervens@noaa.gov
AF: CIRA/NOAA, 325 Broadway, Boulder, CO 80305 United States
AU: * Feingold, G
EM: graham.feingold@noaa.gov
AF: NOAA/ETL, 325 Broadway, Boulder, CO 80305 United States
AU: Kreidenweis, S M
EM: sonia@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523 United States
AB: The effect of aerosol composition on cloud drop concentration is explored, with a focus on water soluble organic carbon. Studies published to date yield conflicting results regarding the magnitude, and even the sign of the effect, compared to well-characterized inorganics. We present a systematic investigation of the reasons for these discrepancies by examining the ranges of physico-chemical properties of water soluble organics that most influence drop formation. We show that when considered individually, composition parameters such as increased molecular weight and surface tension suppression can lead to significant effects on droplet concentration. When considered together, these effects tend to counteract one another and produce much smaller changes. In addition, an assessment of the published literature suggests that estimates of composition effects on drop concentration based on equilibrium assumptions can be much larger than similar estimates under non-equilibrium conditions.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting