Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009
Atmospheric Chemistry and Physics
European Geosciences Union
This is the final version of the article. Available from the European Geosciences Union via the DOI in this record.
Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry–climate models. Here we compare the HadGEM3-UKCA (Hadley Centre Global Environment Model-United Kingdom Chemistry and Aerosols) coupled chemistry–climate model for the period 1960–2009 against extensive ground-based observations of sulfate aerosol mass (1978–2009), total suspended particle matter (SPM, 1978– 1998), PM10 (1997–2009), aerosol optical depth (AOD, 2000–2009), aerosol size distributions (2008–2009) and surface solar radiation (SSR, 1960–2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = −0.4), SPM (NMBF = −0.9), PM10 (NMBF = −0.2), aerosol number concentrations (N30 NMBF = −0.85; N50 NMBF = −0.65; and N100 NMBF = −0.96) and AOD (NMBF = −0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of −68 % (−78 %), SPM of −42 % (−20 %), PM10 of −9 % (−8 %) and AOD of −11 % (−14 %). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5 %) during 1990–2009 (“brightening”) is better reproduced by the model when aerosol radiative effects (ARE) are included (3 %), compared to simulations where ARE are excluded (0.2 %). The simulated topof-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by > 3.0 W m−2 during the period 1970–2009 in response to changes in anthropogenic emissions and aerosol concentrations.
Steven Turnock would like to acknowledge the funding for his PhD studentship from the Natural Environment Research Council (NERC) and Met Office. For making their data available to be used in this study we would like to acknowledge the EMEP, GEBA and AERONET measurement networks along with any data managers involved in data collection. We would also like to acknowledge Ari Asmi for providing the aerosol size distribution data from the EUSAAR and GUAN networks and Carly Reddington for pre-processing this data set for use in the model evaluation. Anthropogenic and biomass-burning emissions from the MACCity data set were retrieved from the ECCAD emissions server. This work was also made possible by participation in the EU Framework 7 PEGASOS project (no. 265148). We acknowledge use of the MONSooN system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. Matthew Woodhouse would like to thank the Royal Society for support via the International Exchange Scheme. Arturo Sanchez-Lorenzo was supported by a postdoctoral fellowship JCI-2012-12508 and projects CGL2014-55976-R, CGL2014-52135-C3-1-R financed by the Spanish Ministry of Economy and Competitiveness.
Atmospheric Chemistry and Physics, Vol. 15, pp. 9477 - 9500