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Impact of heterogeneous ice nuclei on cirrus cloud properties -new model results-
Jun. 22, 2010, 15:00
KIT, Campus Nord, Gebäude 435, Raum 2.05
Clouds are one of the most unknown components in the climate systems. In contrast to liquid clouds the net radiative impact of cirrus clouds in the tropopause region is not well known; both, a net warming and cooling is possible. For the formation of cirrus clouds at cold temperatures (T<235 K) two general mechanisms are present: Homogeneous freezing of aqueous solution droplets and heterogeneous nucleation involving solid aerosols, so-called ice nuclei (IN). Homogeneous nucleation is crucially dependent on the local dynamics and is usually assumed to be the dominant formation mechanism. In former box model studies, the impact of heterogeneous IN was found to be quite small. Recently, the competition of homogeneous and heterogeneous nucleation in different dynamical regimes was investigated using a 2D cloud-resolving cirrus model. In addition to former studies we found that also for high vertical velocities the impact of heterogeneous IN on cirrus cloud properties could be quite strong. Results from dynamically dominated regimes (gravity waves) and convectively dominated regimes (potentially unstable layers) are shown. Finally, the radiative impact of these modified cirrus clouds is investigated.
This event is part of the eventgroup Meteorology Colloquium Karlsruhe
Dr. Peter Spichtinger

ETH Zürich
Institute for Atmospheric and Climate Science (IACETH)
Institut für Meteorologie und Klimaforschung - Atmosphärische Umweltforschung (IMK-IFU)
Karlsruher Institut für Technologie (KIT)
Kreuzeckbahnstraße 19
82467 Garmisch-Partenkirchen
Mail:hape schmidHjs0∂imk kit edu
Scientific Staff
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