Dynamical quantifications of ozone minihole formation in both hemispheres

Abstract

[1] Transient and localized severe total ozone reduction events, ozone miniholes, have been sometimes observed in both hemispheres. Dynamical contributions to the minihole formation are estimated for 22 events and the mean features are explored in each hemisphere. For the estimation, global distributions of ozone mixing ratio are reconstructed dynamically by using three kinds of satellite ozone data and isentropic distributions of potential vorticity. As a result, most of the total ozone reductions are explained by dynamical processes in both hemispheres. On miniholes in the Northern Hemisphere, about a half of the dynamical reduction of column ozone in the upper troposphere and the stratosphere is due to isentropic transport of ozone-poor air which is poleward around the tropopause and equatorward in the middle stratosphere. The remaining half is explained by loss of air masses in isentropic layers, which is caused by vertical uplift of isentropes in the lower and middle stratosphere. The same type of miniholes is also found in the Southern Hemisphere. The other type in the Southern Hemisphere is caused by displacement or stretching of the Antarctic ozone hole toward midlatitudes, where the total ozone is reduced by the equatorward transport of ozone depleted polar air throughout the stratosphere, while the local uplift of isentropes due to the associated advection of cold temperature also contributes to reduce total ozone.

The spring 2011 final stratospheric warming above Eureka: anomalous dynamics and chemistry

“…This is consistent with the formation of an ozone mini-hole, which can lead to large decreases in the ozone column over a short time period (e.g. Peters et al, 1995;James, 1998;Hood et al, 2001;Iwao and Hirooka, 2006). Ozone mini-holes are caused by dynamical processes (e.g., Hood et al, 2001), usually resulting from a combination of the transport of lower-latitude ozone-poor air masses and a rise in the tropopause, as shown on 22 May 2011 above Eureka.…”

Analysis of a low ozone episode over Extremadura (Spain) in January 2006 and its influence on UV radiation

“…This type of episodes are usually named ozone mini-holes (Newman et al, 1988) and they can be explained by different dynamic processes such as the displacement of the polar vortex (James et al, 2000), influence of planetary waves (Schoeberl et al, 1983), advection from the tropics of air patches with low total ozone content (Allart et al, 2000) or isentropic vertical uplift air-mass in the lower and middle stratosphere (Iwao et al, 2006). The ultraviolet (UV) radiation is strongly influenced by ozone due to absorption at wavelengths below 320 nm.…”

Ozone mini‐holes over Valencia (Spain) and their influence on the UV erythemal radiation

“…Thus, the total ozone amount serves as a tracer for the meteorological processes on a grand scale in the high stratosphere. Iwao and Hirooka (2006) studied the dynamic contribution to mini-hole formation by analysing 22 events. To do this, they reconstructed dynamically the global distribution of the ozone mixing ratio using three kinds of satellite data and the isentropic distribution of potential vorticity.…”