Wednesday, 6 November 2002
Interannual variations in stratospheric tracers
The interannual variations in stratospheric tracers (e.g., CH4 and N2O)
in a chemical transport model driven by winds from a 35-year climate
model simulation are examined. The climate model used was a 2.5x2.0 degree
resolution version of the finite-colume general circulation model (FVGCM),
with 55 levels between the surface and about 80km. The model was run with
no interannual variability in the sea-surface temperatures and sea ice
distributions, specified at the lower boundary, or in the specified zonal-mean
ozone distribution. Despite the absence of variations in these boundary
conditions, there is considerable variabaility in the atmospheric
circulation. Year-to-year and decadal variations in the trace gas
concentrations are examined, as well as the relationship between these
variations and those in the stratospheric circulation (e.g., residual
circulation) and tropospheric wave forcing. The variations in CH4 from
these simulations are also compared with those observed by HALOE.
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