HR: 09:00h
AN: GC41B-05    [Abstracts]
TI: Modeling quasi-decadal variability in the QBO and its impact on stratospheric ozone and climate
AU: * McCormack, J P
EM: john.mccormack@nrl.navy.mil
AF: Space Science Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
AB: Simulations of the 11-year solar cycle's effects on stratospheric photochemistry and dynamics are performed with the zonally averaged CHEM2D model. These simulations indicate that the duration of the westerly QBO phase at solar maximum is 3 months shorter than at solar minimum, as a result of solar-induced heating anomalies interacting with the tropical component of the mean meridional circulation. The modeled solar cycle ozone response, determined via multiple linear regression, is compared with observational estimates from the combined Solar Backscattered Ultraviolet (SBUV/2) data set for the period 1979--2003. We find that a model simulation including the effects of this solar-QBO interaction plus an imposed 11-year variation in planetary wave forcing produces a lower stratospheric ozone response that is in good agreement with the SBUV-derived ozone response. Recent observational studies have questioned the connection between solar UV forcing and the quasi- decadal variation in the QBO, particularly after the mid-1990's. We examine other possible mechanisms that may introduce quasi-decadal variability in the QBO, including anomalous wintertime extratropical planetary wave activity and changes in convective latent heating associated with tropical sea-surface temperature fluctuations.
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0341 Middle atmosphere: constituent transport and chemistry (3334)
DE: 1610 Atmosphere (0315, 0325)
DE: 1650 Solar variability (7537)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting