There has been significant stratospheric ozone depletion since the late 1970s due to ozone-depleting substances (ODSs). With the implementation of the Montreal Protocol and its amendments and adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. In this study, we examine the implications of stratospheric ozone recovery for the tropospheric che...

EXECUTIVE SUMMARY 85 1.1 Introduction 87 1.1.1 Purpose and scope of this chapter 87 1.1.2 Ozone in the atmosphere and its role in climate 87 1.1.3 Chapter outline 93 1.2 Observed changes in the stratosphere 93 1.2.1 Observed changes in stratospheric ozone 93 1.2.2 Observed changes in ODSs 96 1.2.3 Observed changes in stratospheric aerosols, water vapour, methane and nitrous oxide 96 1.2.4 Obser...

The vertical profile of global-mean stratospheric temperature changes has traditionally represented an important diagnostic for the attribution of the cooling effects of stratospheric ozone depletion and CO2 increases. However, CO2-induced cooling alters ozone abundance by perturbing ozone chemistry, thereby coupling the stratospheric ozone and temperature responses to changes in CO2 and ozoned...

Thedownward transport of stratospheric ozone is an important natural source of tropospheric ozone, particularly in the upper troposphere, where changes in ozone have their largest radiative e ect1. Stratospheric circulation is projected to intensify over the coming century, which could lead to an increase in the flux of ozone from the stratosphere to the troposphere2–4. However, large uncertain...

Due to larger multiple scattering effects in the troposphere compared to that in the stratosphere, the optical path of tropospheric ozone is markedly enhanced (as compared with that of stratospheric ozone) in the Huggins bands from 310 to 345 nm. Model study of the direct and diffuse solar fluxes on the ground shows differences between tropospheric and stratospheric ozone. The characteristic si...

Skin cancer mortality resulting from stratospheric ozone depletion has been widely studied. Similarly, there is a deep body of literature on surface ozone and its health impacts, with modeling and observational studies demonstrating that surface ozone concentrations can be increased when stratospheric air mixes to the Earth’s surface. We offer the first quantitative estimate of the trade-off be...

Free-running and nudged versions of a Met Office chemistry–climate model are evaluated and used to investigate the impact of dynamics versus transport and chemistry within the model on the simulated evolution of stratospheric ozone. Metrics of the dynamical processes relevant for simulating stratospheric ozone are calculated, and the free-running model is found to outperform the previous model ...

The substantial springtime loss in ozone amount in the lower Antarctic polar stratosphere has prompted extensive studies of ozone depletion over the last two decades (World Meteorological Organization (WMO) 1992, 1995, 1999). Due to the important role ozone plays in absorbing harmful ultraviolet radiation, the ozone decline in mid-latitudes and dramatic ozone depletion over Antarctica may have ...

We quantify the sources contributing to background surface ozone concentrations in the US Intermountain West by using the GEOS-Chem chemical transport model with 1/2× 2/3 horizontal resolution to interpret the Clean Air Status and Trends Network (CASTNet) ozone monitoring data for 2006–2008. We isolate contributions from lightning, wildfires, the stratosphere, and California pollution. Lightnin...

We use a chemistry-climate model and new estimates of smoke produced by fires in contemporary cities to calculate the impact on stratospheric ozone of a regional nuclear war between developing nuclear states involving 100 Hiroshima-size bombs exploded in cities in the northern subtropics. We find column ozone losses in excess of 20% globally, 25-45% at midlatitudes, and 50-70% at northern high ...