Decrease in tropospheric O3 levels of the Northern Hemisphere

Wespes et al. (2018) present the global fingerprints of recent changes in the tropospheric O3 levels measured by IASI over 2008 – 2017. Using appropriate multivariate regression methods, we discriminate significant anthropogenic trends from various modes of natural variability captured by IASI. A band-like pattern of significant negative trends of ~|0.5| DU/yr on average is detected during summer in the mid-high latitudes of the North Hemisphere. The influence of continental pollution on that latitudinal band is supported by the analysis of the IASI O3-CO relationship.

Seasonal distributions of the adjusted trends in DU yr−1 from the multi-linear regression models. The grey areas and crosses refer to the non-significant grid cells in the 95 % confidence limits (2σ level). Wespes et al. (2018)

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