Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 13869-13890, 2017
https://doi.org/10.5194/acp-17-13869-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Nov 2017
Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990–2013
Camilla Andersson1, Heléne Alpfjord1, Lennart Robertson1, Per Erik Karlsson2, and Magnuz Engardt1 1Swedish Meteorological and Hydrological Institute, 60176 Norrköping, Sweden
2Swedish Environmental Research Institute, P.O. Box 53021, 40014 Gothenburg, Sweden
Abstract. We have constructed two data sets of hourly resolution reanalyzed near-surface ozone (O3) 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 O3 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 O3 concentrations, focusing on the linear trend over the 24-year period. We show that high near-surface O3 concentrations are decreasing and low O3 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 O3 in Sweden are caused by a combination of all three factors, whilst the decrease in the highest O3 concentrations is caused by European O3 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.


Citation: Andersson, C., Alpfjord, H., Robertson, L., Karlsson, P. E., and Engardt, M.: Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990–2013, Atmos. Chem. Phys., 17, 13869-13890, https://doi.org/10.5194/acp-17-13869-2017, 2017.
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We show that high near-surface O3 concentrations in Sweden are decreasing and low O3 concentrations are increasing during 1990–2013. The cause for the change is a combination of change in hemispheric background, meteorology and anthropogenic emissions. We have identified systematic differences in the modelled trend that must be caused by incorrect trends in the utilized emissions or by too high sensitivity in the model. We based the analysis on fused measurements and modelling.
We show that high near-surface O3 concentrations in Sweden are decreasing and low O3...
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