Based on ClaMS-Ice simulations, it is possible to track the origin of cirrus clouds, their formation mechanisms together with the frequency of occurrence of the respective cloud types. Thus, from CLaMS- Ice simulations, new insights on cirrus clouds microphysical and thus radiative properties are expected. As a first, important step, CLaMS-Ice is evaluated based on in-situ observations from the HALO campaign ML-CIRRUS 2014 in mid-latitude spring (Rolf et al., 2016).
Here, we apply ClaMS-Ice to mid-latitude in comparison to Arctic regions. We analyze in-situ and liquid origin cirrus: overall, in-situ cirrus are more frequent than liquid origin cirrus. However, liquid origin cirrus occur more often at mid-latitudes than in the Arctic, which we attribute to the generally slower updraft velocities in this region. In line with this, in the Arctic thin cirrus are more common.
Analysis of the freezing mechanisms of in-situ and liquid origin cirrus yields that for in-situ cirrus over the complete temperature range, homogeneous freezing occurs most frequently in thick cirrus formed in higher updrafts, while heterogeneous freezing prevails in thin cirrus formed in lower updrafts. For thick as well as thin liquid origin cirrus hetereogeneous freezing is dominating at the higher cirrus temperature range, but at colder temperatures additional homogeneous freezing occurs more often, especially in the Arctic.
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