Abstract
Abstract. Analyses of stratospheric ozone data determined from Dobson–Umkehr measurements since 1977 at the Syowa (69.0° S, 39.6° E), Antarctica, station show a significant decrease in ozone at altitudes higher than that of the 4 hPa pressure level during the 1980s and 1990s. Ozone values over Syowa have remained low since 2001. The time series of upper stratospheric ozone from the homogenized NOAA SBUV (Solar Backscatter Ultraviolet Instrument)(/2) 8.6 overpass data (±4°, 24 h) are in qualitative agreement with those from the Syowa station data. Ozone recovery during the austral spring over the Syowa station appears to be slower than predicted by the equivalent effective stratospheric chlorine (EESC) curve. The long-term changes in the station's equivalent latitude (indicative of vortex size/position in winter and spring) are derived from MERRA (Modern Era Retrospective-analysis for Research and Applications) reanalyses at ~ 2 and ~ 50 hPa. These data are used to attribute some of the upper and middle stratospheric ozone changes to the changes in vortex position relative to the station's location. In addition, high correlation of the Southern Hemisphere annular mode (SAM) with polar upper stratospheric ozone during years of maximum solar activity points toward a strong relationship between the strength of the Brewer–Dobson circulation and the polar stratospheric ozone recovery. In the lower stratosphere, ozone recovery attributable to CFCs (chlorofluorocarbons) is still not definitive, whereas the recovery of the upper stratosphere is slower than predicted. Further research indicates that dynamical and other chemical changes in the atmosphere are delaying detection of recovery over this station.
Highlights
The history of depletion of stratospheric ozone over Antarctica in the austral spring is well known and well documented from the time of its discovery (Farman et al, 1985)
Our research is based on Umkehr observations from Dobson ozone spectrophotometers that are of the high quality required for detection of significant ozone change www.atmos-chem-phys.net/14/3945/2014/
The long-term variability and trend observed in Umkehr ozone profile data is in good agreement with that seen in the SBUV V8.6 merged ozone data set
Summary
The history of depletion of stratospheric ozone over Antarctica in the austral spring is well known and well documented from the time of its discovery (Farman et al, 1985). We investigate the information in the data from the Syowa ground-based station (69.0 S, 39.6 E), which has been collecting ozone profiles from Dobson–Umkehr measurements since 1977 (Miyagawa et al, 2009a), for longterm changes in the upper and middle stratospheric ozone. 3. In this paper we concentrate on analysis of the long-term changes in the upper, middle and lower stratospheric ozone concentrations in Antarctica. The high interannual variability in the Antarctic region and the changes in the atmosphere from other factors since 1977 must be well quantified to be able to detect the signal in the middle- and low-stratospheric ozone due to ODS. This paper assesses long-term trends in ozone profile measurements at the Syowa station during the austral spring and summer season.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
