Further Development of an Algorithm to Determine Cirrus Cloud Dynamics

Abstract:

Cirrus clouds have an important impact on the radiation balance of the Earth due to their interaction with
solar and terrestrial radiation. They are also important in terms of climate feedbacks. To predict how climate
change influences their radiative forcing is a difficult task, since not all processes concerning cirrus are fully
understood yet. Especially cloud scale dynamics are an active field of research. To improve models, in situ
measurements and cirrus cloud statistics are essential. Using long term measurements from ground-based,
profiling Doppler cloud radars is one way to gather cirrus dynamic-statistics. Building on the work of
Kalesse and Kollias (2013), a cloud radar based algorithm to decompose the mean Doppler velocity into
reflectivity-weighted particle terminal fall velocity and the vertical air motion is further developed and applied
to several years of cloud radar measurements from the Leipzig Aerosol and Cloud Remote Observations
System (LACROS) stationed in Leipzig, Germany and Limassol, Cyprus for six and two years, respectively.
The resulting climatologies of cirrus clouds over Leipzig and Limassol are presented and compared to each
other. The possibility of using the algorithm within the European remote-sensing network Cloudnet is
explored.

Kalesse, Heike, and Kollias, Pavlos. 2013. “Climatology of High Cloud Dynamics Using Profiling ARM
Doppler Radar Observations.” J. Climate 26 (17): 6340–59. https://doi.org/10.1175/jcli-d-12-00695.1.