Total ozone and Umkehr observations at Hoher Sonnblick 1994–2011: Climatology and extreme events

Abstract

Umkehr and total ozone measurements have been carried out at Hoher Sonnblick (47.05°N, 12.95°E; 3106 m above sea level) since 1994 with the Brewer MkIV #093 spectrophotometer. These measurements are used to investigate trends in total and vertically resolved ozone in the period 1994–2011 and for establishing an Umkehr climatology. A method to estimate daily thresholds for extreme events in total ozone (TO3) based on skewed log‐Weibull distributions is presented and applied to the record. An analysis of the such defined extreme events reveals a significant decline in the number of low events, whereas the high events increased by about the same amount. However, no significant trend is observed in the magnitude of extreme events. Solar activity and equivalent effective stratospheric chlorine show weak to no correlation with vertically resolved ozone, presumably due to the record's limited extent, while tropopause pressure and quasi‐biennial oscillation show a significant influence. Trend analysis of total and vertically resolved ozone indicates a significant increase in TO3 of 2.0% per decade since 1994, whereas no recovery is observed in the upper stratosphere. While ozone concentrations continue to decrease or stagnate in the upper stratosphere, the loss is overcompensated by large gains in the lowest layers during winter, leading to a significant overall increase in TO3. During events with extremely low TO3, the largest deficiencies are found in the bottommost layers with a marked seasonal component. The topmost layers mainly contribute to TO3 reductions during late winter and fall.

Uv Extreme Events in Northeast of Brazil

“…However no significant trend is observed in the magnitude of extreme events. These measurements were used to investigate vertically trends in total ozone in the period 1994-2011 and for establishing an climatology [18].…”

Influence of low ozone episodes on erythemal UV-B radiation in Austria

“…Previous studies used (1) fixed thresholds (e.g., Bojkov and Balis 2001;Brönnimann and Hood 2003), (2) time-varying thresholds based on the deviation from monthly means (e.g., Anton et al 2008;Koch et al 2005;Krzyscin 2002), or (3) the application of extreme value theory (e.g., Fitzka et al 2014;Rieder et al 2010aRieder et al , b, 2011Petropavlovskikh et al 2015) to determine low ozone episodes. Furthermore, only few studies focused on changes in the UV field during low ozone episodes and the general connection between low ozone episodes and UV extremes (e.g., Anton et al 2008;Fragkos et al 2016;Martinez-Lozano et al 2011;Rieder et al 2010c).…”

“…Several studies investigated the evolution of low ozone episodes at mid-latitudes (Anton et al 2008;Bojkov and Balis 2001;Brönnimann and Hood 2003;Fitzka et al 2014;Frossard et al 2013;Hood et al 2001;Iwao and Hirooka 2006;James 1998;Koch et al 2005;Krzyscin 2002;Newman et al 1988;Petzoldt 1999;Rieder et al 2010aRieder et al , b, 2011Rieder et al , 2013. The definitions for low ozone episodes, often referred to as ozone miniholes, vary among studies, and to date, only few studies have analyzed changes in the UV field during low ozone episodes and the general connection between low ozone episodes and UV levels (e.g., Anton et al 2008;Bartlett and Webb 2000;Fragkos et al 2016;MartinezLozano et al 2011;McKenzie et al 1991;Rieder et al 2010c).…”

The influence of the North Atlantic Oscillation and El Niño–Southern Oscillation on mean and extreme values of column ozone over the United States

“…Analyses of interannual and long-term variability in total column ozone on regional (e.g., Mäder et al, 2007;Rieder et al, 2010aRieder et al, , b, 2011Fitzka et al, 2014) and global (e.g., Frossard et al, 2013;Rieder et al, 2013) scales have been presented in a number of recent studies. There is now a broad consensus that long-term negative ozone trends are domi-I.…”

“…In addition, recent work analyzing the tails of the ozone distribution (i.e., the extremes) in relation to the bulk properties (i.e., the mean) has shown that analysis of the tails allows for a more systematic attribution of ozone changes to dynamical features than mean value analysis can achieve (e.g., Rieder et al, 2010aRieder et al, , b, 2011Rieder et al, , 2013Frossard et al, 2013). These studies also showed that even moderate NAO and ENSO events can have significant effects on the midlatitude ozone field.…”