AeroCom (initiatve)

    to improve complex component aerosol modules in global model
    involvement via project co-coordination and via data-preparation
    http://dataipsl.ipsl.jussieu.fr/AEROCOM/

MACC (EU-project)
    to make chemical weather forecast operational in the ECMWF environment
    involvement via evaluation of forecast skill for aerosol optical properties
    http://www.gmes-atmosphere.eu/news/new_aerosol

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
    http://www.eusaar.net/actris.cfm

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