Evaluation of total ozone recovery inside the Antarctic vortex A. Pazmino1, S. Godin-Beekmann1, A. Hauchecorne1, C. Claud2, F. Lefèvre1, S. Khaykin1, F. Goutail1, J. P. Pommereau1, C. Boonne3, E. Wolfram4, J. Salvador4, E. Quel4 LATMOS, CNRS/UVSQ/UPMC, France, (2) LMD, CNRS/Ecole Polytechnique, France, (3) IPSL, CNRS/UPMC, France, (4) CEILAP-UNIDEF, MINDEF/CONICET, Argentina Contact: andrea.pazmino@latmos.ipsl.fr CONTEXT METHODOLOGY DATA Stabilization of the ozone loss in Antarctica since 2000 Important interannual variability in last decade Significant increase of total ozone linked to Ozone depleted substances decrease (healing) not yet established for October and Sep-Oct-Nov average period (WMO, 2014) Onset of healing process detected by Solomon et al., 2016 using satellites/sondes data in September. Data of particular years 2002 (SSW) and 2015 (influence of stratospheric aerosols from Calbuco volcano) not considered But not significant increase in October when ozone depletion is maximum Trend of total ozone columns (TOC) inside the vortex over 1980-2015 period using multilinear regression model Ozone trend simulated by a piecewise linear trend (PWLT) before and after the break year in 2000 Maximum ozone depletion period considered (Sept. 15 to Oct. 15) Other months also considered (Sept., Oct.) for comparison Proxy of ozone trend for maximum ozone depletion period: linear (1st period 1980-1993), plateau (O3loss saturation 1994-1999) and linear (2nd period 2000-2015) Baroclinicity of the vortex considered. Two classifications of TOC values inside the vortex as a function of Equivalent Latitude (EL) using Nash et al. (1996) criterion Standard: single isentropic level (475K or 550K) New: range of isentropic levels between 400K and 600K with a step of 25K Ozone SAOZ UV-Vis spectrometers Dumont d’Urville (66.7°S, 140°E), 1988-2015 Concordia (75.1°S, 123.3°E), 2007-2015 TOMS/OMI satellite data, 1980-2015 and SBUV in 1995 Vortex position determined using: MIMOSA model (Hauchecorne et al., 2002) forced by ERAinterim data Equivalent Latitude/isentropic level coordinates 1 “Classical” proxies (deLaat et al., 2013) Annual value calculated for the same period as TOC except for HF (Aug-Sept mean) “New” proxy Mean value of maximum PV gradient at 550K to take into account vortex stability - 550K isentropic level representative of the evolution of maximum depletion - Mean value calculated in the studied period - detrending was applied to avoid interferences with final O3 trend MERRA 45-day VT 45°S - 75°S, 70hPa detrended serie COMPARISON OF OZONE DATA SETS Good agreement between SAOZ and TOMS/OMIT for 15 Sept - 15 Oct period et DDU and Concordia QBO at 30 and 10hPa from Berlin University Monthly mean bias (TOMS/OMIT – SAOZ) TRENDS AAO from NCEP/NOAA Sept. Oct 15 Sept – 15 Oct DDU -3.0±3.3% 1.8±5.4% -0.1±2.6% Concordia -3.6±3.7% 1.5±3.5% 0.3±5.1% Influence of vortex barocliniticty not observed (differences in trends between 2 classification criteria not significant at 2) Solar Flux at 10.7 cm wavelength from NRCAN 15 Sept – 15 Oct period TOC evolution from SAOZ and OMIT compared to passive ozone tracer of CTM model REPROBUS (Lèfevre et al., 1994) - Agreement in daily variability between SAOZ and satellite - Similar O3loss (O3 passive tracer – O3 measurements) - Ozone evolution well reproduced by model stratospheric AOD at 550nm from NASA/GISS Dumont d’Urville Concordia 2015 General behavior of interannual variability is well captured Good agreement before and after the “plateau” period (1994-2000) Worse correlation between measurements and model if a “plateau” in not added to the proxy of O3 trend Last 5 years well simulated by the model only if “gradient” proxy is considered Important influence on interannual variability of dynamical proxies In 2015: record of ozone hole size in October Good agreement for stable winters (ex. 2006, largest O3 hole) and perturbed winters (ex. 2002, major SSW) VORTEX BAROCLINICITY Vortex position at different isentropic levels in the maximum O3 depletion altitude range CONCLUSIONS Insignificant impact of vortex baroclinicity in O3loss and O3 trends estimation O3 variability best explained in the maximum O3 depletion period (15Sept-15Oct) by the chosen proxies for 1980-2015 period compared to Sept and Oct Higher contribution to ozone interannual variability of Heat Flux and Gradient (vortex stability) Positive trend observed in September, October and 15 Sept – 15 Oct for 2000-2015 period. Only significant trend at 2 in September. Contribution of proxies to interannual variability Dominant influence of Heat Flux (~27DU) and Gradient (~18DU) AAO, Aerosols and Solar Flux contribution <5DU in absolute value Increase of vortex baroclinicity in October due to higher dynamical activity Impact on TOC? Comparison with other months Interannual O3 variability of 15 Sept - 15 Oct period for different classifications inside the vortex Sept Oct 15 Sept – 15 Oct Trend 1st period (DU/yr) 400-600K 475K -5.7±0.8 -5.3±1.0 -7.1±1.0 -6.8±1.1 -8.2±0.9 -7.7±1.0 plateau No Yes Trend 2000-2015 (DU/yr) 2.5±1.9 2.7±2.2 1.4±1.9 1.7±2.1 1.1±1.6 1.3±1.9 R2 0.91 0.87 0.93 0.95 0.94 STD of residual (DU) 11.2 12.9 9.3 8.3 9.7 Lowest ozone values for 400-600K classification Significant difference at 2 (standard error) between different classifications REFERENCES de Laat et al., Tracing the second stage of ozone recovery in the Antarctic ozone-hole with a “big data” approach to multivariate regressions, Atmos. Chem. Phys., 15, 79–97, 2015, doi:10.5194/acp-15-79-2015. Goutail, et al., Total Ozone depletion in the Arctic during the winters of 1993–94 and 1994–95, J. Atmos. Chem., 32, 1–34, 1999. Hauchecorne et al., Quantification of the transport of chemical constituents from the polar vortex to midlatitudes in the lower stratosphere using the high-resolution advection model MIMOSA and effective diffusivity, J. Geophys. Res., 107, 8289, doi:10.1029/2001JD000491, 2002. Kuttippurath et al., Antarctic ozone loss in 1979–2010: first sign of ozone recovery, Atmos. Chem. Phys., 13, doi: 10.5194/acp-13-1625-2013, 1625-1635, 2013. Lefèvre et al., Chemistry of the 1991–92 stratospheric winter: three dimensional model simulations, J. Geophys. Res., 99, 8183–8195, 1994. Nash et al., An objective determination of the polar vortex using Ertel’s potential vorticity, J. Geophys. Res., 101, 9471–9478, 1996. 28208 Solomon et al., Emergence of healing in the Antarctic ozone layer, Science ,10.1126/science.aae0061, 2016 WMO (World Meteorological Organization), Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project – Report No. 55, 416 pp., Geneva, Switzerland, 2014. … and what about the impact in O3loss ? O3loss=O3passive tracer – O3satellite calculated at different stations (Goutail et al., 1999) More than 90% of interannual variability explained by proxies used in this study Better determination coefficient in the 15S-15O period with lowest residual standard deviation Trend in period 1: best estimation of the trend (-8DU/yr) when O3loss saturation considered. Lowest absolute value in September. Consistent with previous studies (Kuttipurath et al., 2013, deLaat et al., 2015) Trend in period 2: not significant at two standard error except in September (consistent with Solomon et al., 2016) 50% Highest O3loss for 400-600K classification But insignificant difference at 2 with other classifications Weak increase of O3loss in 2014 and 2015 ACKNOWLEDGEMENTS The authors thank SAOZ operators in stations as well as agencies supporting NDACC activities: INSU/CNRS, CNES, IPEV. The authors thank gratefully the French « ESPRI Data Center » (former ETHER) for providing re-analysis data (ERA-Interim) The authors are also thankful to NASA for satellite data (TOMS/OMI and SBUV) This work was supported by the DYNOZPOL/LEFE project.