On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes – Part 2: The effects of the El Niño/Southern Oscillation, volcanic eruptions and contributions of atmospheric dynamics and chemistry to long-term total ozone changes

Abstract

We present the first spatial analysis of "fingerprints" of the El Niño/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichón and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs, respectively) and mean values of total ozone for the northern and southern mid-latitudes (defined as the region between 30° and 60° north and south, respectively). Significant influence on ozone extremes was found for the warm ENSO phase in both hemispheres during spring, especially towards low latitudes, indicating the enhanced ozone transport from the tropics to the extra-tropics. Further, the results confirm findings of recent work on the connection between the ENSO phase and the strength and extent of the southern ozone "collar". For the volcanic eruptions the analysis confirms findings of earlier studies for the northern mid-latitudes and gives new insights for the Southern Hemisphere. The results provide evidence that the negative effect of the eruption of El Chichón might be partly compensated by a strong warm ENSO phase in 1982–83 at southern mid-latitudes. The strong west-east gradient in the coefficient estimates for the Mt. Pinatubo eruption and the analysis of the relationship between the AAO and ENSO phase, the extent and the position of the southern ozone "collar" and the polar vortex structure provide clear evidence for a dynamical "masking" of the volcanic signal at southern mid-latitudes. The paper also analyses the contribution of atmospheric dynamics and chemistry to long-term total ozone changes. Here, quite heterogeneous results have been found on spatial scales. In general the results show that EESC and the 11-yr solar cycle can be identified as major contributors to long-term ozone changes. However, a strong contribution of dynamical features (El Niño/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Antarctic Oscillation (AAO), Quasi-Biennial Oscillation (QBO)) to ozone variability and trends is found at a regional level. For the QBO (at 30 and 50 hPa), strong influence on total ozone variability and trends is found over large parts of the northern and southern mid-latitudes, especially towards equatorial latitudes. Strong influence of ENSO is found over the Northern and Southern Pacific, Central Europe and central southern mid-latitudes. For the NAO, strong influence on column ozone is found over Labrador/Greenland, the Eastern United States, the Euro-Atlantic Sector and Central Europe. For the NAO's southern counterpart, the AAO, strong influence on ozone variability and long-term changes is found at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and central southern mid-latitudes

Spatio-temporal variations of nitric acid total columns from 9 years of IASI measurements – a driver study

“…Its signature is nonetheless visible and significant in the eastern Pacific, where it contributes to up to 30% of the HNO 3 variability, and in the mid-latitudes of the Northern Hemisphere. The east-west gradient is in good agreement with chemical and dynamical effects of El Niño on O 3 , and with previous studies that showed the same patterns for the influence of the MEI on O 3 (Hood et al, 2010;Rieder et al, 2013;Wespes et al, 2017).…”

“…The impact of these oscillations on O 3 distributions has been demonstrated in several studies (e.g. Rieder et al, 2013;Wespes et al, 2016). We may expect a similar influence on the HNO 3 distributions, particularly because, even though they are tropospheric features, their phase and intensity affect the atmospheric circulation, and in particular the Brewer-Dobson Circulation, up to the stratosphere (Miller et al, 2006;Chehade et al, 2014).…”

“…Sioris et al, 2014;de Laat et al, 2015). They also often include climate-related proxies for specific dynamical patterns such as El Niño-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) or the Antarctic Oscillation (AAO) Rieder et al, 2013). In various multivariate regression studies, an iterative selection procedure is used to isolate the relevant variables for the concerned species (Steinbrecht, 2004;Mäder et al, 2007;Knibbe et al, 2014;Wespes et al, 2016Wespes et al, , 2017.…”

On the capabilities and limitations of GCCM simulations of summertime regional air quality: A diagnostic analysis of ozone and temperature simulations in the US using CESM CAM-Chem

“…Several recent studies (Frossard et al, 2013;Rieder et al, 2013aRieder et al, , 2013b have utilized extreme value theory (EVT) to characterize DM8H O 3 distributions since they are generally positively skewed (i.e. have long right-hand tails) and since state and federal agencies are particularly concerned with characterizing and controlling high ozone exceedances.…”

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

“…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).…”