Abstract
The effect of stratospheric ozone depletion is simulated in GFDL AM4
model with three ozone schemes: prescribing monthly zonal mean ozone
concentration, full interactive stratospheric chemistry, and a
simplified linear ozone chemistry scheme but with full dynamical
interactions. While similar amounts of ozone loss are simulated by the
three schemes, the two interactive ozone schemes produce significantly
stronger stratospheric cooling than the prescribed one. We find that
this temperature difference is driven by the dynamical responses to
ozone depletion. In particular, the existence of ozone hole leads to
strong ozone eddies that are in-phase with the temperature eddies. The
coherence between ozone and temperature anomalies leads to a weaker
radiative damping as ozone absorbs shortwave radiation that compensates
for the longwave cooling. As a result, less wave dissipates at the lower
stratosphere, leading to a weaker descending and dynamical heating over
the polar lower stratosphere, and hence a stronger net cooling there.
The covariance between ozone and temperature is largely suppressed when
ozone is prescribed as monthly zonal mean time series, as is the
reduction in the radiative damping following ozone depletion. With much
lower computational cost, the simplified ozone scheme is capable of
producing similar magnitude of ozone loss and the consequent dynamical
responses to those simulated by the full chemistry.