Influence of the Antarctic ozone hole on the polar mesopause region as simulated by the Canadian Middle Atmosphere Model
Artikel i vetenskaplig tidskrift, 2012

It is well established that variations in polar stratospheric winds can affect mesospheric temperatures through changes in the filtering of gravity wave fluxes, which drive a residual circulation in the mesosphere. The Canadian Middle Atmosphere Model (CMAM) is used to examine this vertical coupling mechanism in the context of the mesospheric response to the Antarctic ozone hole. It is found that the response differs significantly between late spring and early summer, because of a changing balance between the competing effects of parametrised gravity wave drag (GWD) and changes in resolved wave drag local to the mesosphere. In late spring, the strengthened stratospheric westerlies arising from the ozone hole lead to reduced eastward GWD in the mesosphere and a warming of the polar mesosphere, just as in the well known mesospheric response to sudden stratospheric warmings, but with an opposite sign. In early summer, with easterly flow prevailing over most of the polar stratosphere, the strengthened easterly wind shear within the mesosphere arising from the westward GWD anomaly induces a positive resolved wave drag anomaly through baroclinic instability. The polar cooling induced by this process completely dominates the upper mesospheric response to the ozone hole in early summer. Consequences for the past and future evolution of noctilucent clouds are discussed.

NLCs

Ozone hole

Vertical coupling

Mesopause region

Författare

Stefan Lossow

Chalmers, Rymd- och geovetenskap, Global miljömätteknik och modellering

C. McLandress

University of Toronto

A. I. Jonsson

University of Toronto

T. G. Shepherd

University of Toronto

Journal of Atmospheric and Solar-Terrestrial Physics

1364-6826 (ISSN)

Vol. 74 111-123

Ämneskategorier

Meteorologi och atmosfärforskning

DOI

10.1016/j.jastp.2011.10.010