Analysis of the Antarctic Ozone Hole in November

Abstract

The factors responsible for the size of Antarctic ozone hole in November are analyzed. Comparing two samples of anomalously large and small November ozone hole with respect to 1980–2017 climatology in November, the results show that the anomalously large ozone hole in austral late winter is not a precondition for the anomalously large ozone hole in November. The size of Antarctic ozone hole in November is mainly influenced by dynamical processes from the end of October to mid-November. During large November ozone hole events, weaker dynamical ozone transport appears from the end of October to mid-November, which is closely related to planetary wave divergence in the stratosphere between 60°S and 90°S. Further analyses indicate that the wave divergence is partially attributed to less upward propagation of planetary waves from the troposphere, which is associated with weak baroclinic disturbances at the end of October. Subsequently, zonal wind speed in the upper stratosphere intensifies, and the distance between critical layer (U=0) and wave reflecting surfaces becomes larger. As a result, more planetary waves are reflected and then wave divergence enhances. The processes responsible for the anomalously small Antarctic ozone holes in November are almost opposite to those for the anomalously large Antarctic ozone holes.

Influence of Asian Topography on the Arctic Stratospheric Ozone

“…To explore the changes in zonal-mean ozone concentration, the following equation will be examined in the log-pressure coordinates (Liu et al, 2020;Monier & Weare, 2011;Z. Wang et al, 2021): where,…”

“…According to the transformed Eulerian mean (TEM) momentum equations (Andrews et al, 1987) ) can be derived (Equations 6 and 7), which is advantageous for quantitatively determining the specific impact of different forcing terms on residual mean velocities (Song & Chun, 2016;Z. Wang et al, 2021)…”

“…ERA5 is a comprehensive and dependable dataset that combines model data with worldwide observations, resulting in a high‐quality and globally complete dataset. Particularly, it incorporates 19 diverse sources of ozone observation from different periods, hence it has superior performance to other existing reanalysis datasets including predecessor ERA‐Interim (Ramon et al., 2019; S. Wang et al., 2021).…”

“…To explore the changes in zonal‐mean ozone concentration, the following equation will be examined in the log‐pressure coordinates (Liu et al., 2020; Monier & Weare, 2011; Z. Wang et al., 2021): $$$\frac{\partial \overline{\chi }}{\partial t}=-\frac{{\overline{v}}^{\ast }}{a}\frac{\partial \overline{\chi }}{\partial \varphi }-{\overline{w}}^{\ast }\frac{\partial \overline{\chi }}{\partial z}-\frac{1}{{\rho }_{0}}\nabla \cdot \overrightarrow{M}+\overline{S}$$$ where, $$${\overline{v}}^{\ast }=\overline{v}-\frac{1}{{\rho }_{0}}\frac{\partial }{\partial z}\left({\rho }_{0}\frac{\overline{{v}^{\prime }{\theta }^{\prime }}}{{\overline{\theta }}_{z}}\right)$$$ $$${\overline{w}}^{\ast }=\overline{w}+\frac{1}{a\,\mathrm{cos}\,\varphi }\frac{\partial }{\partial \varphi }\left(\mathrm{cos}\,\varphi \frac{\overline{{v}^{\prime }{\theta }^{\prime }}}{{\overline{\theta }}_{z}}\right)$$$ …”

“…According to the transformed Eulerian mean (TEM) momentum equations (Andrews et al., 1987), another description of residual mean circulation ($${\overline{v}}^{\ast }$$, $${\overline{w}}^{\ast }$$) can be derived (Equations and ), which is advantageous for quantitatively determining the specific impact of different forcing terms on residual mean velocities (Song & Chun, 2016; Z. Wang et al., 2021). $$${\overline{v}}^{\ast }=-\frac{1}{{\rho }_{0}\,\mathrm{cos}\,\varphi }\frac{\partial }{\partial z}\left\{-\mathrm{cos}\,\varphi \int \nolimits_{z}^{\infty }{\rho }_{0}\left[\frac{\frac{1}{{\rho }_{0}a\,\mathrm{cos}\,\varphi }\nabla \cdot \overrightarrow{F}-\frac{\partial \overline{u}}{\partial t}+\overline{\text{GWD}}+\overline{X}}{f-\frac{1}{a\,\mathrm{cos}\,\varphi }\frac{\partial }{\partial \varphi }\left(\overline{u}\mathrm{cos}\,\varphi \right)}\right]d{z}^{\prime }\right\}$$$ …”