Role of external factors in the evolution of the ozone layer and stratospheric circulation in 21st century

Abstract

The chemistry-climate model (CCM) SOCOL has been used to evaluate the contributions of the main anthropogenic factors to the simulated changes of ozone and stratospheric dynamics during the 21st century. As the main anthropogenic factors we consider the atmospheric concentration of the greenhouse gases (GHG), ozone depleting substances (ODS) and sea surface temperature and sea ice (SST/SI). The latter is considered here as an independent factor because the majority of the CCMs prescribe its evolution. We have performed three sets of "time slice" numerical experiments for the years 2000, 2050, and 2100 taking into account all factors separately and all together. The total column ozone increase during the first half of the 21st century is caused by the ODS, especially in the middle and high latitudes of both hemispheres. In the tropics and the extra tropical region of the Northern Hemisphere (NH) the SST/SI forcing plays a very important role in the evolution of atmospheric ozone during the second half of the 21st century. The GHG affect the temperature and ozone mainly in the upper stratosphere and in the lower stratosphere of the high latitudes of the Southern Hemisphere (SH). In the lower tropical stratosphere of the NH, the long-term changes of the temperature, zonal wind and the meridional circulation are controlled mainly by the SST/SI. The strong contribution of the SST/SI to the ozone and circulation changes in the future implies that some differences between the results by different CCMs could be caused by the applied SST/SI rather than by the CCM's deficiencies. We suggest taking this issue into account for the planning of the future model evaluation campaigns

Total ozone trends from 1979 to 2016 derived from five merged observational datasets – the emergence into ozone recovery

“…Continued ozone observations and monitoring are needed to consolidate the evidence of ozone recovery and also further improve our understanding of the complex ozoneclimate feedback (in combination with chemistry-climate modeling) that will have a significant impact on future evolution of ozone (Fleming et al, 2011;Zubov et al, 2013;Pawson et al, 2014).…”

An upper-branch Brewer–Dobson circulation index for attribution of stratospheric variability and improved ozone and temperature trend analysis

“…Wave forcing depends on the mean state of the flow, and vice versa (Charney and Drazin, 1961;Holton and Mass, 1976); changes in either affect ozone transport by a change in the speed of the BDC that leads to adiabatic heating, or cooling, and directly affects chemistry through temperature-dependent reaction rates (Chen et al, 2003;García-Herrera et al, 2006;Shepherd et al, 2007;Lima et al, 2012). As such, ozone and temperature have an inverse relationship in the equatorial stratosphere above 10 hPa, which in turn has a dependence on dynamics (Fusco and Salby, 1999;Mäder et al, 2007;Stolarski et al, 2012), although this is not always the case in the lower stratosphere (Zubov et al, 2013). Ultimately, then, dynamical perturbations at mid-to-high latitudes can directly influence the variability of ozone and temperature (Sridharan et al, 2012;Nath and Sridharan, 2015).…”

Implications of potential future grand solar minimum for ozone layer and climate

“…Because of this effect, future tropical ozone levels even show further decline at the end of 21 st century compared to near present values. The slowing of photochemical ozone loss reactions caused by the cooling in the stratosphere (Barnett et al, 1975;Jonsson et al, 2004) contributes to a smaller degree to the overall TOC evolution (Zubov et al, 2013). Li et al (2009) showed that the BDC acceleration plays a crucial role in future ozone recovery and spatial distribution.…”

“…The tropospheric warming reaches a maximum of around 3 K in the tropical upper troposphere. Zubov et al (2013) showed that tropospheric warming is mainly caused by the surface warming due to increase of down-welling infrared radiation by GHG, enhanced by latent heat release in the middle troposphere. The temperature decrease in the stratosphere and mesosphere results from increased cooling rates of GHGs.…”