Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990–2013

Abstract

Abstract. We have constructed two data sets of hourly resolution reanalyzed near-surface ozone (O 3 ) concentrations for the period 1990-2013 for Sweden. Long-term simulations from a chemistry-transport model (CTM) covering Europe were combined with hourly ozone concentration observations at Swedish and Norwegian background measurement sites using retrospective variational data analysis. The reanalysis data sets show improved performance over the original CTM when compared to independent observations. In one of the reanalyses, we included all available hourly near-surface O 3 observations, whilst in the other we carefully selected time-consistent observations. Based on the second reanalysis we investigated statistical aspects of the distribution of the near-surface O 3 concentrations, focusing on the linear trend over the 24-year period. We show that high nearsurface O 3 concentrations are decreasing and low O 3 concentrations are increasing, which is reflected in observed improvement of many health and vegetation indices (apart from those with a low threshold).Using the CTM we also conducted sensitivity simulations to quantify the causes of the observed change, focusing on three factors: change in hemispheric background concentrations, meteorology and anthropogenic emissions. The rising low concentrations of near-surface O 3 in Sweden are caused by a combination of all three factors, whilst the decrease in the highest O 3 concentrations is caused by European O 3 precursor emissions reductions.While studying the impact of anthropogenic emissions changes, we identified systematic differences in the modeled trend compared to observations that must be caused by incorrect trends in the utilized emissions inventory or by too high sensitivity of our model to emissions changes.

Technical note: Quality assessment of ozone reanalysis products over subarctic Europe for biome modeling and ozone risk mapping

“…Improvements in atmospheric transport as part of the OpenIFS updates may play also a role but cannot be assessed from our analysis. The higher spatial and temporal resolution of CAMSRAQ aside, we can assume the assimilated ground-level ozone data was another driver for the different performance as passive sounders onboard satellites typically resolve [O 3 ] at the surface rather poorly and hence do not constrain the global models well enough (Andersson et al, 2017).…”

“…O 3 as well as its precursors is subject to atmospheric transport causing pollution peaks in the otherwise pristine Arctic and subarctic environments (Stevenson et al, 2005;Young et al, 2013). This long-range transport of pollutants has been identified as one of the main sources of enhanced O 3 concentration ([O 3 ]) in Fennoscandia (Andersson et al, 2017). Peak [O 3 ] in summer is often a combination of stagnant weather situations accompanied by heatwaves and enhanced precursor emissions due to extensive forest fires (e.g.…”

Projections of shipping emissions and the related impact on air pollution and human health in the Nordic region

“…In order to do so, the MATCH 11 km × 11 km gridded data have been aggregated to the d03 grid. The EVA model system has been compared to other similar models (Anenberg et al, 2015;Lehtomäki et al, 2020), is part of the Danish monitoring programme (Ellermann et al, 2020) and has been used routinely in numerous advisory projects for public authorities. In Sect.…”

Decadal Trends of Speciated Non‐methane Hydrocarbons in Taipei

“…The United Nations Economic Commission for Europe (UN ECE) added the Gothenburg Protocol in 1999 and updated it in 2012 which aimed at a cost-effective abatement of acidification, eutrophication, and ground-level ozone (UN ECE, 2016). In accordance with the policy replacement, the current national emission ceilings for SO 2 , NO X , NMHCs, and NH 3 set in 2001 will be renegotiated to meet new reduction objectives for six air pollutants (SO 2 , NO X , NMHCs, NH 3 , PM 2.5 , and CH 4 ) by 2020 and beyond (Bourguignon, 2017), despite significant declines in either anthropogenic VOC emissions and concentrations have been suggested in many European countries in the past decades (Andersson et al, 2017;Derwent et al, 2014;Huang et al, 2017;Hunova & Baumelt, 2018;Sauvage et al, 2009;von Schneidemesser et al, 2010;Waked et al, 2016). In addition, significant decreasing concentrations of individual NMHCs were also observed in the Canadian polar region in early years from 1989 to 1996, which was likely to be a result of reduction in VOC emissions from the Siberia region as a consequence of the major economic changes in the former Soviet Union (Gautrois et al, 2003).…”