Abstract
The properties of Southern Ocean (SO) liquid phase non precipitating
clouds (hereafter clouds) are examined using shipborne data collected
during the Measurements of Aerosols, Radiation and Clouds over the
Southern Ocean (MARCUS) and the Clouds Aerosols Precipitation Radiation
and atmospheric Composition Over the SoutheRN ocean (CAPRICORN) I and II
campaigns that took place in the Southern Ocean south of Australia
during 2016 and late 2017 into early 2018. The cloud properties are
derived using W-band radar, lidar, and microwave radiances using an
optimal estimation algorithm. The SO clouds tended to have larger liquid
water paths (LWP, 115 ±117 g m-2), smaller effective radii (, 8.7 ±3um),
and higher number concentrations (, 90 ±107 cm), than typical values of
eastern ocean basin stratocumulus. The clouds demonstrated a tendency
for the LWP to increase with presumably due to precipitation suppression
up to of approximately 100 cm when mean LWP decreased with increasing .
Due to higher optical depth, cloud albedos were less susceptible to
changes in compared to subtropical stratocumulus. The high latitude
clouds observed along and near the Antarctic coast presented a
distinctly bimodal character. One mode had the properties of marine
clouds further north. The other mode occurred in an aerosol environment
characterized by high cloud condensation nuclei concentrations and
elevated sulfate aerosol without any obvious continental aerosol markers
that had much higher , smaller and overall higher LWP suggesting
distinct sensitivity of the clouds to seasonal biogenic aerosol
production in the high latitude regions.