 |
| Titel |
The impact of polar stratospheric ozone loss on Southern Hemisphere stratospheric circulation and climate |
| VerfasserIn |
J. Keeble, P. Braesicke, N. L. Abraham, H. K. Roscoe, J. A. Pyle |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 24 ; Nr. 14, no. 24 (2014-12-22), S.13705-13717 |
| Datensatznummer |
250119261
|
| Publikation (Nr.) |
 copernicus.org/acp-14-13705-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| The impact of polar stratospheric ozone loss resulting from chlorine
activation on polar stratospheric clouds is examined using a pair of model
integrations run with the fully coupled chemistry climate model UM-UKCA.
Suppressing chlorine activation through heterogeneous reactions is found to
produce modelled ozone differences consistent with observed ozone
differences between the present and pre-ozone hole period. Statistically
significant high-latitude Southern Hemisphere (SH) ozone loss begins in
August and peaks in October–November, with > 75% of ozone
destroyed at 50 hPa. Associated with this ozone destruction is a
> 12 K decrease of the lower polar stratospheric temperatures and
an increase of > 6 K in the upper stratosphere. The heating
components of this temperature change are diagnosed and it is found that the
temperature dipole is the result of decreased short-wave heating in the lower
stratosphere and increased dynamical heating in the upper stratosphere. The
cooling of the polar lower stratosphere leads, through thermal wind balance,
to an acceleration of the polar vortex and delays its breakdown by
~ 2 weeks. A link between lower stratospheric zonal wind
speed, the vertical component of the Eliassen–Palm (EP) flux, Fz and the residual mean
vertical circulation, w*, is identified. In November and
December, increased westerly winds and a delay in the breakup of the polar
vortex lead to increases in Fz, indicating increased wave activity
entering the stratosphere and propagating to higher altitudes. The resulting
increase in wave breaking, diagnosed by decreases to the EP flux divergence,
drives enhanced downwelling over the polar cap. Many of the stratospheric
signals modelled in this study propagate down to the troposphere, and lead
to significant surface changes in December. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|