Antarctic ozone loss in 1979-2010: first sign of ozone recovery.

A long-term ozone loss time series is necessary to understand the evolution of ozone in Antarctica. Therefore, we construct the time series using ground-based, satellite and bias-corrected multi-sensor reanalysis (MSR) data sets for the period 1989-2010. The trends in ozone over 1979-2010 are also estimated to further elucidate its evolution in the wake of decreasing halogen levels in the stratosphere. Our analysis with ground-based observations shows that the average ozone loss in the Antarctic is about -33 to -50% (-90 to -155DU (Dobson Unit)) in 1989-1992, and then stayed at around -48% (-160 DU). The ozone loss in the warmer winters (e.g. 2002 and 2004) is lower (-37 to -46 %), and in the very cold winters (e.g. 2003 and 2006) it is higher (-52 to -55 %). These loss estimates are in good agreement with those estimated from satellite observations, where the differences are less than ±3 %. The ozone trends based on the equivalent effective Antarctic stratospheric chlorine (EEASC) and piecewise linear trend (PWLT) functions for the vortex averaged ground-based, Total Ozone Mapping Spectrometer/Ozone Monitoring Instrument (TOMS/OMI), and MSR data averaged over September-November exhibit about -4.6 DU yr^-1 over 1979-1999, corroborating the role of halogens in the ozone decrease during the period. The ozone trends computed for the 2000-2010 period are about +1 DU yr^-1 for EEASC and +2.6 DU yr^-1 for the PWLT functions. The larger positive PWLT trends for the 2000- 2010 period indicate the influence of dynamics and other basis functions on the increase of ozone. The trends in both periods are significant at 95% confidence intervals for all analyses. Therefore, our study suggests that Antarctic ozone shows a significant positive trend toward its recovery, and hence, leaves a clear signature of the successful implementation of the Montreal Protocol. [ABSTRACT FROM AUTHOR]