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. We retrieved lower stratospheric vertical profiles of O3 , HNO3 ,and HCl from solar spectra taken with a ground-based Fourier transforminfrared spectrometer (FTIR) installed at Syowa Station, Antarctica(69.0 ∘  S, 39.6 ∘  E), from March to December 2007 andSeptember to November 2011. This was the first continuous measurement ofchlorine species throughout the ozone hole period from the ground inAntarctica. We analyzed temporal variation of these species combined withClO, HCl, and HNO3 data taken with the Aura MLS (Microwave LimbSounder) satellite sensor and ClONO2 data taken with the Envisat MIPAS(the Michelson Interferometer for Passive Atmospheric Sounding) satellitesensor at 18 and 22 km over Syowa Station. An HCl and ClONO2 decreaseoccurred from the end of May at both 18 and 22 km, and eventually, in early winter, both HCl and ClONO2 were almost depleted. When the sun returnedto Antarctica in spring, enhancement of ClO and gradual O3 destructionwere observed. During the ClO-enhanced period, a negative correlation betweenClO and ClONO2 was observed in the time series of the data at SyowaStation. This negative correlation was associated with the relative distancebetween Syowa Station and the edge of the polar vortex. We used MIROC3.2chemistry–climate model (CCM) results to investigate the behavior of wholechlorine and related species inside the polar vortex and the boundary regionin more detail. From CCM model results, the rapid conversion of chlorinereservoir species (HCl and ClONO2 ) into Cl2 , gradual conversion of Cl2 into Cl2O2 , increase in HOCl in the winter period, increase in ClO when sunlight became available, and conversion of ClO into HCl were successfully reproduced. The HCl decrease in the winter polar vortex corecontinued to occur due to both transport of ClONO2 from the subpolarregion to higher latitudes, providing a flux of ClONO2 from more sunlitlatitudes into the polar vortex, and the heterogeneous reaction of HCl withHOCl. The temporal variation of chlorine species over Syowa Station was affectedby both heterogeneous chemistries related to polar stratospheric cloud (PSC)occurrence inside the polar vortex and transport of a NOx -rich air massfrom the polar vortex boundary region, which can produce additional ClONO2 by reaction of ClO with NO2 . The deactivation pathways fromactive chlorine into reservoir species (HCl and/or ClONO2 ) wereconfirmed to be highly dependent on the availability of ambient O3 . At18 km, where most ozone was depleted, most ClO was converted to HCl. At 22 kmwhere some O3 was available, an additional increase in ClONO2 fromthe prewinter value occurred, similar to the Arctic.

Chlorine partitioning near the polar vortex edge observed with ground-based FTIR and satellites at Syowa Station, Antarctica, in 2007 and 2011