Evolution of the eastward shift in the quasi-stationary minimum of the Antarctic total ozone column

Abstract

Abstract. The quasi-stationary pattern of the Antarctic total ozone has changed during the last 4 decades, showing an eastward shift in the zonal ozone minimum. In this work, the association between the longitudinal shift of the zonal ozone minimum and changes in meteorological fields in austral spring (September-November) for 1979-2014 is analyzed using ERA-Interim and NCEP-NCAR reanalyses. Regressive, correlative and anomaly composite analyses are applied to reanalysis data. Patterns of the Southern Annular Mode and quasi-stationary zonal waves 1 and 3 in the meteorological fields show relationships with interannual variability in the longitude of the zonal ozone minimum. On decadal timescales, consistent longitudinal shifts of the zonal ozone minimum and zonal wave 3 pattern in the middle-troposphere temperature at the southern midlatitudes are shown. Attribution runs of the chemistry-climate version of the Australian Community Climate and Earth System Simulator (ACCESS-CCM) model suggest that long-term shifts of the zonal ozone minimum are separately contributed by changes in ozone-depleting substances and greenhouse gases. As is known, Antarctic ozone depletion in spring is strongly projected on the Southern Annular Mode in summer and impacts summertime surface climate across the Southern Hemisphere. The results of this study suggest that changes in zonal ozone asymmetry accompanying ozone depletion could be associated with regional climate changes in the Southern Hemisphere in spring.

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

“…However, it is notable that the centre longitude for successively smaller ellipses is located successively further to the east. This result is similar to previous work by Grytsai et al (2007), who show that the longitude of the ozone minimum is located further east at more poleward latitudes. This shows that the centre longitude displays a similar tendency if the size of the ellipse is increased either by choosing a larger TCO value for the edge contour or by increased depletion of ozone.…”

“…The results presented here support those of Grytsai et al (2017) in that changes in the concentration of ODSs, more so than changes in GHG concentrations, are linked to the shifting zonally asymmetric ozone distribution. However, the approach taken here -the use of elliptical diagnostics -makes the comparison of the particulars of the results somewhat unclear.…”

“…However, the approach taken here -the use of elliptical diagnostics -makes the comparison of the particulars of the results somewhat unclear. This study shows that the ellipse centre longitude moves west and the eccentricity decreases over the 1960-1999 time span, while Grytsai et al (2005Grytsai et al ( , 2007 show that the extra-tropical ozone minima move eastward and the maxima remain stationary. The fact that the centre longitude moves in the opposite direction to the extra-tropical ozone minima perhaps indicates that it is the rotation of the ellipse that is a more descriptive measure of the ozone distribution at mid-latitudes.…”

“…Using observations from the Total Ozone Mapping Spectrometer (TOMS), Grytsai et al (2005) find that over the period 1979-2003 the position of the ozone minimum at 65 • S drifts eastward at a rate of 23.6 ± 7.2 • per decade, with the position of the maximum remaining constant. Grytsai et al (2007) extended this study showing eastward trends in the ozone minimum for all latitudes between 50 and 80 • S. The cause of this trend (and its reversal over the subsequent decade) is investigated by Grytsai et al (2017) by comparing chemistry-climate model simulations in which the concentration of ozone-depleting substances (ODSs) are fixed or to simulations in which they varied. They show the position of ozone minima to differ latitudinally between the different simulations, which suggests that the shifts in the zonal distribution of ozone is due to changes in the concentration of ODSs.…”

Hemispheric asymmetry in stratospheric NO<sub>2</sub> trends

“…The drifting of the APV during the spring has been studied over the past decade (Hassler et al, 2011;Grytsai et al, 2017) using both observations and models. The results show longitudinal displacements of the APV across the years.…”