Classification of cloud microphysical properties as a function of sea
ice concentration conditions during MOSAiC
Abstract
As part of the (AC)3 Arctic Amplification project, we are studying the
influence of specific sea ice conditions like the presence of leads or
polynyas on micro- and macrophysical cloud properties such as cloud
fraction, altitude, thickness, thermodynamic phase, and their coupling
state with respect to the underlying surface during the MOSAiC
expedition’s legs 1 to 3. Micro- and macrophysical properties of
surface-coupled clouds are analyzed as a function of sea ice
concentration (SIC) in the vicinity of the ground-based atmospheric
remote-sensing observations onboard the RV Polarstern. Only situations
are analyzed where wind favored the transportation of air from location
where open sea ice is detected. Cloud microphysical properties are
obtained from the CloudNet cloud target classification algorithm which
uses the atmospheric remote-sensing instrumentation suite on board of RV
Polarstern provided by the US Atmospheric Radiation Measurement (ARM)
mobile facility, the TROPOS ship-borne Atmosphere observation suite
(OCEANET) and liquid water path retrievals by the University of Cologne.
Primarily, the classical Matlab-based CloudNet classifications retrieved
by TROPOS are used. Furthermore, the recently released ARM
“evaluation” Active Remote Sensing Clouds (ARSCL) data product for the
KA-band cloud radar is also evaluated by the new Python CloudNet version
developed at the Finish Meteorological Institute. Discrepancies between
those two CloudNet versions will be evaluated and reported as feedback
for the ARM evaluation data set. High resolution (1-km) merged
AMSR2-MODIS satellite retrievals of Sea Ice Concentration by the
University of Bremen are used as information for sea ice monitoring. The
present contribution only exploits SIC data, however future studies will
focus on MOSAiC specific products for the classification of leads.
Statistics for the cloud properties as a function of SIC will be
presented as first approach to investigate the influence of sea ice
conditions to central Arctic clouds.