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Working Group: The Chemistry, Clouds, Aerosols and Radiation (CCAR)


Mariano Mertens (DLR)


Bodo Ahrens (Univ. Frankfurt), Ulrich Blahak (DWD Offenbach),  Ernesto Caetano (Univ. Mexico), Emanuel Christner (KIT Karlsruhe), Andreas Dobler (FU Berlin), Christiane Hofmann (Univ. Bonn), Patrick Jöckel (DLR), Astrid Kerkweg (Univ. Bonn), Mariano Mertens (DLR), Anna-Leah Nickl (DLR),  Daniel Rieger (DWD Offenbach), Gerd Schädler (KIT Karlsruhe), Bernhard Vogel (KIT Karlsruhe)


Clouds play a major role in the climate system, due to their interactions with infrared and solar radiation their impact of the dynamics of the system and also their role for precipitation. In the context of climate change they play a key role as feedback in the system.

The formation of clouds is influenced by the aerosol load of the atmosphere and their composition, which is determined by the chemistry of the atmosphere, showing the strong link between, the chemistry, aerosols, clouds and radiation that represent the core of this working group. This coupling introduces a further uncertainty in the climate projections, related to the anthropogenic emissions of aerosols, creating a link between climate change and air pollution. These considerations led the IPCC to list the microphysics of clouds as one of the key-uncertainties in the synthesis report of the 4th Assessment report published in 2007.

Due to the large spectrum of scales involved in the formation of clouds, their representation in models, with large-scale grid-boxesis a real challenge. The approach of regional modeling with their higher resolution, permits an explicit representation of finer structures (down to a few kilometers), but also permits the use of certain approaches (e.g. two-moment scheme from Seifert and Beheng, 2006), that are difficult to implement in models with coarser resolution.

The aim of the CCAR working group is to coordinate the efforts done with CCLM and COSMO-ART on these topics as well as to promote interactions between the different work topics and point to gaps that need to be investigated. This will be done in order to gain further insight into the fundamental representation of clouds in climate models, but also to improve the reliability of climate projections done with the model.

Main research axes of the CCAR working group

WG Meetings

CLM WG Spring Meeting 2010

CLM Community Assembly 2010 Berlin

CLM WG Spring Meeting 2011

CLM Assembly Lueneburg 2016

CLM Assembly Graz 2017

CLM Assembly Karlsruhe 2018