HR: 1330h
AN: A52C-0800    [PDF]
TI: Comparison of Measured and Modeled Ozone Profiles Above McMurdo Station, Antarctica, During August-October, 1992-2000
AU: * Mercer, J L
EM: mercer@uwyo.edu
AF: Department of Atmospheric Science, The University of Wyoming, PO Box 3038, Laramie, WY 82071 United States
AU: Deshler, T
EM: deshler@uwyo.edu
AF: Department of Atmospheric Science, The University of Wyoming, PO Box 3038, Laramie, WY 82071 United States
AU: Chipperfield, M P
EM: martyn@env.leeds.ac.uk
AF: School of the Environment, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT United Kingdom
AU: Santee, M L
EM: mls@praxis.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mailstop 183-701 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AB: Measurements are needed to understand the present state of the atmosphere while models are required to test our quantitative understanding of complex processes and for future predictions. These models must be validated and tested by detailed comparison with observations. Here, we compare more than 9 years of balloon-borne ozonesonde profile observations at $78\deg$S with calculations from the SLIMCAT 3-dimensional chemical transport model (CTM). The CTM is forced by ECMWF meteorological analyses and has a detailed stratospheric chemistry scheme. Here the model is run on 18 isentropic levels with a horizontal resolution of $7.5\deg$. While SLIMCAT performs well in reproducing total column ozone values as well as the general trends of spring-season ozone depletion in both the Northern and Southern hemispheres, a detailed comparison with austral polar measurements has not been completed. Here, at the vertical resolution of SLIMCAT, we compare modeled and measured ozone mixing ratios (OMR) between 12 and 30km (potential temperatures of $\sim$330-1000K) over McMurdo Station, Antarctica from 1992 to 2000 in the period of late August to late October. A one-to-one comparison of OMR at the SLIMCAT levels covered by the measurements gives a linear relationship where SLIMCAT OMR = 0.82(Measured OMR)+ 0.54 with R$^{2}$ = 0.83. A slope $<$1 and positive y-intercept correspond to an overestimation of OMR by SLIMCAT, especially in the region of most active ozone destruction ($\sim$12-20km). The overestimation by SLIMCAT is more evident after mid-September of each year during the period of high ozone depletion. The percent differences between the model and measurements through the austral spring seasons range from -50 to 450% in the active region, and are between -50 and 50% above this region ($\sim$20-30km). Some of this discrepancy is related to the extent of ClO activation in SLIMCAT. Preliminary analyses suggest that SLIMCAT is underestimating ClO and thereby overestimating ozone at the altitudes of greatest ozone loss.
DE: 0340 Middle atmosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting