Abstract
Abstract. Thirteen years of ozone soundings at the Antarctic Belgrano II station (78° S, 34.6° W) have been analysed to establish a climatology of stratospheric ozone and temperature over the area. The station is inside the polar vortex during the period of development of chemical ozone depletion. Weekly periodic profiles provide a suitable database for seasonal characterization of the evolution of stratospheric ozone, especially valuable during wintertime, when satellites and ground-based instruments based on solar radiation are not available. The work is focused on ozone loss rate variability (August–October) and its recovery (November–December) at different layers identified according to the severity of ozone loss. The time window selected for the calculations covers the phase of a quasi-linear ozone reduction, around day 220 (mid-August) to day 273 (end of September). Decrease of the total ozone column over Belgrano during spring is highly dependent on the meteorological conditions. Largest depletions (up to 59%) are reached in coldest years, while warm winters exhibit significantly lower ozone loss (20%). It has been found that about 11% of the total O3 loss, in the layer where maximum depletion occurs, takes place before sunlight has arrived, as a result of transport to Belgrano of air from a somewhat lower latitude, near the edge of the polar vortex, providing evidence of mixing inside the vortex. Spatial homogeneity of the vortex has been examined by comparing Belgrano results with those previously obtained for South Pole station (SPS) for the same altitude range and for 9 yr of overlapping data. Results show more than 25% higher ozone loss rate at SPS than at Belgrano. The behaviour can be explained taking into account (i) the transport to both stations of air from a somewhat lower latitude, near the edge of the polar vortex, where sunlight reappears sooner, resulting in earlier depletion of ozone, and (ii) the accumulated hours of sunlight, which become much greater at the South Pole after the spring equinox. According to the variability of the ozone hole recovery, a clear connection between the timing of the breakup of the vortex and the monthly ozone content was found. Minimum ozone concentration of 57 DU in the 12–24 km layer remained in November, when the vortex is more persistent, while in years when the final stratospheric warming took place "very early", mean integrated ozone rose by up to 160–180 DU.
Highlights
The discovery of the Antarctic ozone hole in the mid-1980s (Farman et al, 1985) intensified interest in stratospheric chemistry for a better understanding of the chemical and dynamical processes involved
Recent studies based on coupled chemistry–climate models have shown that stratospheric ozone affects the whole atmospheric circulation in an unexpected number of ways (Son et al, 2009)
Chemistry– climate models are an excellent tool to investigate how the decreasing in atmospheric halogen compounds loading to natural “background” levels will lead to stratospheric ozone recovery in the near future (Austin et al, 2010)
Summary
The discovery of the Antarctic ozone hole in the mid-1980s (Farman et al, 1985) intensified interest in stratospheric chemistry for a better understanding of the chemical and dynamical processes involved. Parrondo et al.: Antarctic ozone variability inside the polar vortex further. Ozone depletion seems to have contributed to increasing the Southern Annular Mode (SAM) index (Thompson and Solomon, 2002; Arblaster and Meehl, 2006), poleward shifting of the westerly jet in midlatitudes and increasing global tropopause height (Santer et al, 2003) Models predict that these changes will probably reverse due to the ozone recovery (Son et al, 2009). Previous studies of the variability of the ozone loss in the Antarctic region are extended using 13 yr of ozonesonde measurements at Belgrano II, a station located well inside the polar vortex where the ozone hole occurs each year (Parrondo et al, 2007).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
