The main objectives of "Aerosol and Climate" are: i) To assess the
direct and indirect climate effect of aerosols and quantify and
reduce several of the associated main uncertainties using climate
models. ii) To evaluate the impact of different emissions, via aerosol
formation, on the global environment and climate. Progress will be
achieved following an innovative approach to represent the optical,
chemical and hygroscopic properties of the multi-component mixed
aerosol considering all major aerosol components in a size-dependent
aerosol dynamic model embedded within a global 3-dimensional
atmospheric general circulation model (ECHAM5). The parameterisations
of i) the formation of particulate nitrate and secondary carbonaceous
aerosol, ii) the wet and dry removal of aerosols, iii) aerosol
processing in clouds, iv) the optical and hygroscopic properties of
aerosol will be specifically improved on the basis of detailed process
models and constrained by selected in-situ measurements. The over-all
uncertainty of the aerosol-forcing calculations will be evaluated
utilising ground based sun-photometer measurements and satellite data.
A new strategy for optimal use of satellite data will be developed
considering sampling issues and aerosol optical properties. The work
will be performed in close cooperation with seven European groups
within the framework of an EC funded project and one Canadian group.