Global tropospheric ozone variations from 2003 to 2011 as seen by SCIAMACHY

Abstract

Abstract. An analysis of the tropospheric ozone (O 3 ) columns (TOCs) derived from SCIAMACHY limb-nadirmatching (LNM) observations during the period 2003-2011, focusing on global variations in TOC, is described. The changes are derived using a multivariate linear regression model. TOC shows changes of −0.2±0.4, 0.3±0.4, 0.1±0.5 and 0.1 ± 0.2 % yr −1 , which are not statistically significant at the 2σ level in the latitude bands 30-50 • N, 20 • S-0, 0-20 • N and 50-30 • S, respectively. Tropospheric O 3 shows statistically significant increases over some regions of South Asia (1-3 % yr −1 ), the South American continent (up to 2 % yr −1 ), Alaska (up to 2 % yr −1 ) and around Congo in Africa (up to 2 % yr −1 ). Significant increase in TOC is determined off the continents including Australia (up to 2 % yr −1 ), Eurasia (1-3 % yr −1 ) and South America (up to 3 % yr −1 ). Significant decrease in TOC (up to −3 % yr −1 ) is observed over some regions of the continents of North America, Europe and South America. Over the oceanic regions including the Pacific, North Atlantic and Indian oceans, significant decreases in TOC (−1 to −3 % yr −1 ) were observed. In addition, the response of the El Niño-Southern Oscillation (ENSO) and quasi-biennial oscillation (QBO) to changes in TOC for the period 2003-2011 was investigated. The result shows extensive regions, mostly in the tropics and Northern Hemisphere extratropics, of significant ENSO responses to changes in TOC and a significant QBO response to TOC changes over some regions.

O3 variability in the troposphere as observed by IASI over 2008–2016: Contribution of atmospheric chemistry and dynamics

“…[] and Langford [], which found correlations between free tropospheric ozone and El Niño following a several month (from 2 to 6 months) lag in lidar data from a site in Colorado, as originating from enhanced STE induced by ENSO. Despite the fact that ENSO‐related tropospheric O 3 responses over tropical and extratropical regions have been reported in recent studies [e.g., Oman et al ., ; Lin et al ., ; Neu et al ., ; Ziemke et al ., ; Ebojie et al ., ; Olsen et al ., ], it is the first time that such a timing of the O 3 response is identified from satellite measurements, which constitutes an important finding of this study. Note, finally, that longer time lags for ENSO have been also tested in this study but without significant improvement on the fitting residuals.…”

“…The ENSO influence on tropospheric O 3 in the extratropics may reflect the O 3 response associated with specific tropospheric and stratospheric pathways which are connected with the ENSO changes in the tropics, which alter the tropospheric circulation and which impact on the O 3 levels over the middle and high latitudes [e.g., Langford , ; Zeng and Pyle , ; Koumoutsaris et al ., ; Oman et al ., ; Lin et al ., ; Neu et al ., ; Ebojie et al ., ]. Butler et al .…”

“…Such methods aim to gain a better understanding of the chemical and dynamical mechanisms behind the interannual variability and, therefore, to allow accurate examination of the trends observed in tropospheric column ozone. To the best of our knowledge, regression methods have only been applied on regional and global observations of tropospheric O 3 in a few recent studies [ Oman et al ., ; Heue et al ., ; Ebojie et al ., ; Olsen et al ., ], which underlines the lack of comprehensive and continuous global observations over a long period in the troposphere.…”

Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

“…A deeper investigation is needed to understand the contributions of tropospheric column ozone and stratospheric column ozone to total column ozone, especially considering uncertainties carefully, but this is beyond the scope of this work. We note that studies using various data sources show less significant regional increases (and some decreases), with global estimates ranging from 0.2 to 0.7 % per year (∼ 0.6-2 DU per decade) (Cooper et al, 2014;Ebojie et al, 2016;Heue et al, 2016), though these estimates considered different time periods. This suggests a large range of uncertainty, but even the lower end of the estimated increases in tropospheric column ozone are in line with the missing part of the total column ozone change, after considering stratospheric column ozone that we estimate here.…”

The ENSO and QBO Impact on Ozone Variability and Stratosphere‐Troposphere Exchange Relative to the Subtropical Jets

“…In the midlatitudes, tropospheric ozone sensitivity to ENSO has also been identified, albeit with a weaker sensitivity compared to the tropics. Ebojie et al () showed a response in midlatitude TCO observations from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography, particularly in the NH where the sensitivity is statistically significant in regions as far poleward as 60°N. Likewise, a midlatitude response is evident in IASI TCO observations, as well (Wespes et al, ).…”