AeroCom (initiatve)

    to improve complex component aerosol modules in global model
    involvement via project co-coordination and via data-preparation

MACC (EU-project)
    to make chemical weather forecast operational in the ECMWF environment
    involvement via evaluation of forecast skill for aerosol optical properties

ACTRIS (EU-project)
    to integrate ground obs. of aerosol, clouds and trace-gases in Europe
    involvement via regular active and passive remote sensing at Hamburg

Aerosol-CCI (ESA climate-initiative)
    to produce useful ESA satellite aerosol products for climate modeling
    involvement via user requirements and product evaluation

GEWEX assessements (international collaboration)
    involvement as team member for radiation, aerosol and clouds assessments