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Volume 18, issue 13 | Copyright
Atmos. Chem. Phys., 18, 9741-9765, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 11 Jul 2018

Research article | 11 Jul 2018

Solar “brightening” impact on summer surface ozone between 1990 and 2010 in Europe – a model sensitivity study of the influence of the aerosol–radiation interactions

Emmanouil Oikonomakis1, Sebnem Aksoyoglu1, Martin Wild2, Giancarlo Ciarelli3, Urs Baltensperger1, and André Stephan Henry Prévôt1 Emmanouil Oikonomakis et al.
  • 1Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
  • 2Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
  • 3Laboratoire Inter-Universitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot, Institut Pierre Simon Laplace, Créteil, France

Abstract. Surface solar radiation (SSR) observations have indicated an increasing trend in Europe since the mid-1980s, referred to as solar brightening. In this study, we used the regional air quality model, CAMx (Comprehensive Air Quality Model with Extensions) to simulate and quantify, with various sensitivity runs (where the year 2010 served as the base case), the effects of increased radiation between 1990 and 2010 on photolysis rates (with the PHOT1, PHOT2 and PHOT3 scenarios, which represented the radiation in 1990) and biogenic volatile organic compound (BVOC) emissions (with the BIO scenario, which represented the biogenic emissions in 1990), and their consequent impacts on summer surface ozone concentrations over Europe between 1990 and 2010. The PHOT1 and PHOT2 scenarios examined the effect of doubling and tripling the anthropogenic PM2.5 concentrations, respectively, while the PHOT3 investigated the impact of an increase in just the sulfate concentrations by a factor of 3.4 (as in 1990), applied only to the calculation of photolysis rates. In the BIO scenario, we reduced the 2010 SSR by 3% (keeping plant cover and temperature the same), recalculated the biogenic emissions and repeated the base case simulations with the new biogenic emissions. The impact on photolysis rates for all three scenarios was an increase (in 2010 compared to 1990) of 3–6% which resulted in daytime (10:00–18:00 Local Mean Time – LMT) mean surface ozone differences of 0.2–0.7ppb (0.5–1.5%), with the largest hourly difference rising as high as 4–8ppb (10–16%). The effect of changes in BVOC emissions on daytime mean surface ozone was much smaller (up to 0.08ppb,  ∼ 0.2%), as isoprene and terpene (monoterpene and sesquiterpene) emissions increased only by 2.5–3 and 0.7%, respectively. Overall, the impact of the SSR changes on surface ozone was greater via the effects on photolysis rates compared to the effects on BVOC emissions, and the sensitivity test of their combined impact (the combination of PHOT3 and BIO is denoted as the COMBO scenario) showed nearly additive effects. In addition, all the sensitivity runs were repeated on a second base case with increased NOx emissions to account for any potential underestimation of modeled ozone production; the results did not change significantly in magnitude, but the spatial coverage of the effects was profoundly extended. Finally, the role of the aerosol–radiation interaction (ARI) changes in the European summer surface ozone trends was suggested to be more important when comparing to the order of magnitude of the ozone trends instead of the total ozone concentrations, indicating a potential partial damping of the effects of ozone precursor emissions' reduction.

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We report a model sensitivity study on the impact of aerosol–radiation interaction (ARI) changes in Europe between 1990 and 2010 on summer surface ozone via effects on photolysis rates and biogenic emissions. The overall impact of ARI changes on ozone was relatively small when compared to the total ozone concentrations, but it was more important when compared to the order of magnitude of ozone trends, indicating a potential partial damping of the effects of ozone precursor emissions' reduction.
We report a model sensitivity study on the impact of aerosol–radiation interaction (ARI)...