Nighttime mesospheric ozone enhancements during the 2002 southern hemispheric major stratospheric warming
Artikel i vetenskaplig tidskrift, 2018

Sudden Stratospheric Warmings (SSW) affect the chemistry and dynamics of the middle atmosphere. Major
warmings occur roughly every second winter in the Northern Hemisphere (NH), but has only been observed once
in the Southern Hemisphere (SH), during the Antarctic winter of 2002. Observations by the Global Ozone
Monitoring by Occultation of Stars (GOMOS, an instrument on board Envisat) during this rare event, show a 40%
increase of ozone in the nighttime secondary ozone layer at subpolar latitudes compared to non-SSW years. This
study investigates the cause of the mesospheric nighttime ozone increase, using the National Center for Atmo-
spheric Research (NCAR) Whole Atmosphere Community Climate Model with specified dynamics (SD-WACCM).
The 2002 SH winter was characterized by several reductions of the strength of the polar night jet in the upper
stratosphere before the jet reversed completely, marking the onset of the major SSW. At the time of these wind
reductions, corresponding episodic increases can be seen in the modelled nighttime secondary ozone layer. This
ozone increase is attributed largely to enhanced upwelling and the associated cooling of the altitude region in
conjunction with the wind reversal. This is in correspondence to similar studies of SSW induced ozone en-
hancements in NH. But unlike its NH counterpart, the SH secondary ozone layer appeared to be impacted less by
episodic variations in atomic hydrogen. Seasonally decreasing atomic hydrogen plays however a larger role in SH
compared to NH.

Mesospheric ozone

Sudden stratospheric warming


Christine Smith-Johnsen

Universitetet i Oslo

Yvan Orsolini

Norsk institutt for luftforskning (NILU)

Frode Stordal

Universitetet i Oslo

Varavut Limpasuvan

Coastal Carolina University

Kristell Perot

Chalmers, Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys

Journal of Atmospheric and Solar-Terrestrial Physics

1364-6826 (ISSN)

Vol. 168 100-108


Meteorologi och atmosfärforskning