Articles | Volume 17, issue 22
Research article
27 Nov 2017
Research article |  | 27 Nov 2017

The evolution of zonally asymmetric austral ozone in a chemistry–climate model

Fraser Dennison, Adrian McDonald, and Olaf Morgenstern

Abstract. Asymmetry in the Southern Hemisphere stratospheric ozone hole is important due to both direct radiative heating and its effect on dynamics. It is also a strong indicator of the underlying quality of the stratospheric dynamics of a climate model. We investigate the simulation of the zonal asymmetry in ozone in the NIWA-UKCA atmosphere–ocean chemistry–climate model using elliptical diagnostics, a methodology used for the first time in this subject area. During spring, the region most depleted in ozone is displaced from the pole toward South America based on ERA-Interim and the model output. The model correctly simulates the direction of this displacement but significantly underestimates its magnitude. The model shows that as ozone becomes increasingly depleted over the late 20th century this asymmetry in the ozone distribution moves west, before moving east as polar ozone recovers over the course of the 21st century. Comparison with model runs in which ozone-depleting substances are held fixed at pre-ozone-hole levels shows that this shift is primarily a function of the magnitude of ozone depletion, although increases in greenhouse gases also have some effect.

Short summary
The Antarctic ozone is not centred directly over the pole. In this research we examine how the position and shape of the ozone hole changes using a chemistry–climate model. As ozone becomes increasingly depleted during the late 20th century the centre of the ozone hole moves toward the west and becomes more circular. As the ozone hole recovers over the course of the 21st century the ozone hole moves back towards the east.
Final-revised paper