Mixed-phase clouds are clouds that
occur at temperatures between 0 and -40ºC. They consist of cloud
droplets and ice crystals.
Aerosols such as mineral dust particles play an important role
in the formation process of these clouds. They are on one hand
crucial for the initialization
of freezing via heterogeneous nucleation in mixed-phase clouds,
aerosols act as ice nuclei (IN) and reduce the activation energy
the phase change.
However, the interactions of aerosols
mixed-phase clouds are not very well understood yet, especially in
the Arctic, where mixed-phase clouds are the dominant cloud type.
Many models have difficulties to accurately estimate mixed-phase
clouds in the Arctic. This might be a result of the simplified
parameterization of the freezing process and the aerosol
processing, which may lead to a poor
representation of mixed-phase clouds. As the composition of clouds
has an impact on the microphysical processes within the cloud,
precipitation and the climate this issue has to be solved to
The freezing mechanisms and
aerosol-cloud interactions in mixed-phase clouds are
with the global climate model ECHAM HAM. For that purpose a new
parameterization of freezing processes in mixed-phase clouds
implemented into ECHAM HAM, which is based on the Classical
Nucleation Theory. This new parameterization scheme makes it
to incorporate different lab measurements.
The impact of different freezing parameterization schemes and inclusion of aersol processing on the representation of mixed-phase clouds will then be investigated focusing on the Arctic.
Diese Website wird in älteren Versionen von Netscape ohne graphische Elemente dargestellt. Die Funktionalität der Website ist aber trotzdem gewährleistet. Wenn Sie diese Website regelmässig benutzen, empfehlen wir Ihnen, auf Ihrem Computer einen aktuellen Browser zu installieren. Weitere Informationen finden Sie auf
The content in this site is accessible to any browser or Internet device, however, some graphics will display correctly only in the newer versions of Netscape. To get the most out of our site we suggest you upgrade to a newer browser.