Impact of biogenic very short-lived bromine on the Antarctic ozone hole during the 21st century

Rafael P Fernandez,Simone Tilmes,Jean-Francois Lamarque,Douglas E Kinnison,Alfonso Saiz-Lopez

doi:10.5194/acp-17-1673-2017

Rafael P Fernandez, Simone Tilmes + Show 3 more

Open Access

https://doi.org/10.5194/acp-17-1673-2017

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Abstract

Abstract. Active bromine released from the photochemical decomposition of biogenic very short-lived bromocarbons (VSLBr) enhances stratospheric ozone depletion. Based on a dual set of 1960–2100 coupled chemistry–climate simulations (i.e. with and without VSLBr), we show that the maximum Antarctic ozone hole depletion increases by up to 14 % when natural VSLBr are considered, which is in better agreement with ozone observations. The impact of the additional 5 pptv VSLBr on Antarctic ozone is most evident in the periphery of the ozone hole, producing an expansion of the ozone hole area of ∼ 5 million km2, which is equivalent in magnitude to the recently estimated Antarctic ozone healing due to the implementation of the Montreal Protocol. We find that the inclusion of VSLBr in CAM-Chem (Community Atmosphere Model with Chemistry, version 4.0) does not introduce a significant delay of the modelled ozone return date to 1980 October levels, but instead affects the depth and duration of the simulated ozone hole. Our analysis further shows that total bromine-catalysed ozone destruction in the lower stratosphere surpasses that of chlorine by the year 2070 and indicates that natural VSLBr chemistry would dominate Antarctic ozone seasonality before the end of the 21st century. This work suggests a large influence of biogenic bromine on the future Antarctic ozone layer.

Highlights

The detection of the springtime Antarctic ozone hole (Farman et al, 1985) has been one of the great geophysical discoveries of the 20th century
The increase in sea surface temperature (SST) and atmospheric temperature projected for the 21st century is expected to produce a strengthening of the convective transport within the tropics (Hossaini et al, 2012; Braesicke et al, 2013; Leedham et al, 2013), which could enhance the stratospheric injection of very short-lived bromocarbons (VSLBr)
We have shown that biogenic VSLBr have a profound impact on the depth, size and vertical distribution of the springtime Antarctic ozone hole

Summary

Introduction

The detection of the springtime Antarctic ozone hole (Farman et al, 1985) has been one of the great geophysical discoveries of the 20th century. The consequent turnover on the anthropogenic emissions of long-lived chlorine (LLCl) and bromine (LLBr) sources (WMO, 2014) has controlled the evolution of the strong springtime ozone depletion within the Antarctic vortex, and the first signs of recovery of the ozone hole became evident at the beginning of the 21st century (WMO, 2014; Chipperfield et al, 2015; Solomon et al, 2016). The multi-model CCMVal-2 ozone assessment (Eyring et al, 2010a) determined that the Antarctic ozone return date to 1980 values is expected to occur around the years 2045–2060, while the impact of halogenated ozone depleting substances (ODSs, such as LLCl and LLBr) on stratospheric ozone photochemistry will persist until the end of the 21st century.

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