English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. The long-term evolution of total ozone column inside the Antarctic polarvortex is investigated over the 1980–2017 period. Trend analyses areperformed using a multilinear regression (MLR) model based on various proxiesfor the evaluation of ozone interannual variability (heat flux,quasi-biennial oscillation, solar flux, Antarctic oscillation and aerosols).Annual total ozone column measurements corresponding to the mean monthly values inside thevortex in September and during the period of maximum ozone depletion from15 September to 15 October are used. Total ozone columns fromthe Multi-Sensor Reanalysis version 2 (MSR-2) dataset and from a combined record basedon TOMS and OMI satellite datasets with gaps filled by MSR-2 (1993–1995)are considered in the study. Ozone trends are computed by a piece-wisetrend (PWT) proxy that includes two linear functions before and after theturnaround year in 2001 and a parabolic function to account for thesaturation of the polar ozone destruction. In order to evaluate average totalozone within the vortex, two classification methods are used, based on thepotential vorticity gradient as a function of equivalent latitude. The firststandard one considers this gradient at a single isentropic level (475 or550 K), while the second one uses a range of isentropic levels between 400and 600 K. The regression model includes a new proxy (GRAD) linked to thegradient of potential vorticity as a function of equivalent latitude andrepresenting the stability of the vortex during the studied month. Thedetermination coefficient ( R2 ) between observations and modelled valuesincreases by ∼  0.05 when this proxy is included in the MLRmodel. Highest R2 (0.92–0.95) and minimum residuals are obtained for thesecond classification method for both datasets and months. Trends in September over the 2001–2017 period are statisticallysignificant at 2 σ level with values ranging between 1.84  ±  1.03and 2.83  ±  1.48 DU yr −1 depending on the methods and consideredproxies. This result confirms the recent studies of Antarctic ozone healingduring that month. Trends from 2001 are 2 to 3 times smaller than before theturnaround year, as expected from the response to the slowly ozone-depletingsubstances decrease in polar regions. For the first time, significant trends are found for the period of maximumozone depletion. Estimated trends from 2001 for the 15 September–15 October period over2001–2017 vary from 1.21  ±  0.83 to 1.96 DU  ±  0.99 yr −1 andare significant at 2 σ level. MLR analysis is also applied to the ozone mass deficit (OMD) metric for bothperiods, considering a threshold at 220 DU and total ozone columns south of60 ∘  S. Significant trend values are observed for all cases andperiods. A decrease of OMD of 0.86  ±  0.36 and 0.65  ±  0.33 Mt yr −1 since 2001 is observed in September and 15 September–15 October,respectively. Ozone recovery is also confirmed by a steady decrease of the relative areaof total ozone values lower than 175 DU within the vortex in the15 September–15 October period since 2010 and a delay in the occurrence of ozone levelsbelow 125 DU since 2005.

Multiple symptoms of total ozone recovery inside the Antarctic vortex during austral spring