Summary of the CARBOSOL project: Present and retrospective state of organic versus inorganic aerosol over Europe

[1] Aerosol is an important source of uncertainty concerning the role of the atmosphere in climate forcing. In particular, major gaps exist with respect to its carbonaceous fraction in terms of composition, source apportionment (natural versus anthropogenic), change over the past, and radiative impact. The CARBOSOL project contributes to reduce these uncertainties. CARBOSOL combines a 2-year study of present-day carbonaceous aerosol in air and precipitation in western/central Europe with the trends of climatically relevant species in Alpine ice cores. Comparisons between observed atmospheric distributions (present and proxy of past) and transport/chemistry model simulations allow to test the accuracy of present and past anthropogenic emission inventories and enable for the first time a comparison of the model results for individual components (primary, secondary, fossil fuel, and biogenic) against data derived from measurements. The net radiative effect of the aerosol load and composition (inorganic/organic) in Europe is evaluated using radiative/chemistry/transport models. This summary paper gives an overview of the CARBOSOL goals, and reports on the key findings as a guide to the results detailed in the papers that follow.