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Centre for Atmospheric Science

Reconciliation of measured aerosol properties.

The potential of aerosol particles to take on water and form cloud droplets plays a critical role in determining the global climate. Linking aerosol size, composition, “mixing state” (the way that particle components are mixed), “hygroscopicity” (the sub-saturated water uptake behaviour) and “cloud activation potential” (their ability to form cloud droplets) is vital in understanding and modelling their affects. By making measurements of these aerosol properties and comparing these with model predictions using a variety of tools including ADDEM, ZSR (Stokes and Robinson, 1966) and κ-Köhler theory (Petters and Kreidenweis, 2007), our understanding of both the measurement techniques and underlying aerosol properties is tested. Select these links for details of the measurement techniques, ZSR and κ-Köhler modelling approaches. Extension of these “closure” studies to predict optical properties using Mie theory allows further insight into the absorption and scattering of light by atmospheric aerosol and hence their influence on direct radiative forcing. The reconciliation of aerosol property measurements using the above techniques has been carried out within the NERC-funded Tropospheric Organic CHemistry (TORCH) project, the EU FP6 funded ACCENT Access to Infrastructures chamber experiments at the Paul Scherrer Institute in Switzerland, the EU FP6 funded Marine Aerosol Production (MAP) project and will be continued within the NERC UK SOLAS funded ACMME project, the NERC COPS and OP3 consortium projects and within the NERC APPRAISE ICE consortium project. CAS personnel developing and using these tools include Ben Corris, Nick Good, Martin Irwin and Gordon McFiggans.