HR: 09:00h
AN: A31D-04    [Abstracts]
TI: Microphysical Modeling and POAM III Observations of Aerosol Extinction in the 1998-2003 Antarctic Stratosphere
AU: * Benson, C M
EM: benson@wvms.nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375 United States
AU: Drdla, K
EM: katja@katja.arc.nasa.gov
AF: NASA Ames Research Center, Moffett Field, Mountain View, CA 94035 United States
AU: Nedoluha, G E
EM: nedoluha@nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375 United States
AU: Shettle, E P
EM: shettle@wvms.nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375 United States
AU: Alfred, J
EM: alfred@cpi.com
AF: Computational Physics, Inc., 8001 Braddock Rd. Ste. 210, Springfield, VA 22151 United States
AU: Hoppel, K W
EM: hoppel@wvms.nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375 United States
AB: The Integrated Microphysics and Chemistry on Trajectories (IMPACT) model is used to study Polar stratospheric cloud formation and evolution in the Southern Polar vortex during the 1998-2003 winters. The model is applied to individual air parcels which are advected through the vortex on UKMO wind and temperature fields. The parcel temperature and pressure histories are used by IMPACT to calculate the formation and sedimentation of ice, NAT, SAT, and STS aerosols. Model results are validated by the Polar Ozone and Aerosol Measurement (POAM) III solar occultation instrument. Comparisons of POAM data to the model results help to constrain the microphysical parameters influencing aerosol formation and growth. Measurements of the water vapor mixing ratio are of limited use in clarifying the model microphysics; however, POAM measurements of aerosol extinction prove to be valuable in differentiating model runs. Specifically, the relationship of aerosol extinction to temperature arises from the different temperatures at which the various particle types form and grow. Comparisons of IMPACT calculations of this relationship to POAM measurements constrain the initial fraction of nuclei available for heterogeneous NAT freezing to 0.02% of all aerosols. Constraints are also placed on the ice accommodation coefficient and the NAT-ice lattice compatibility factor. However, these two parameters have similar effects on the extinction-temperature relationship, and thus a range of values are permissible for each.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0319 Cloud optics
DE: 0320 Cloud physics and chemistry
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005