Poster presentation “Cloud Supercooled Liquid Water Content In-situ Measurements Near the Antarctic Coast” at the YOPP Final Summit (Montreal, Canada, 29 August – 1 September, 2022)

Authors: Negar Ekrami, Claudio Duran-Alarcon, Penny Rowe and Irina Gorodetskaya

During the YOPP Final summit, a poster on the ACE expedition measurements of clouds supercooled liquid water was presented by Irina Gorodetskaya.

Abstract:

Mixed-phase clouds are very important in Antarctica because of their role in precipitation and radiative forcing, which consequently impact surface energy and mass balance. However, mixed-phase clouds containing supercooled liquid water (SLW) are one of the main sources of bias in the climate models. Therefore, advanced measurements of cloud microphysical properties are crucial to improve our knowledge about their impact on the Antarctic climate system.

In-situ measurements of cloud SLW content were done for the first time in Antarctica during the Antarctic Circumnavigation Expedition (ACE, December 2016- March 2017). During ACE, almost 100 radiosonde launches were conducted, of which 10 were equipped with cloud SLW content sensors manufactured by Anasphere. The ACE measurements showed that geometrically thin SLW layers were detected at heights from just below 1 km up to 5km above sea level. We analyze the vertical distribution of cloud SLW content during precipitation events associated with extra-tropical cyclones and warm/moist intrusions causing mixed-phase cloud formation without precipitation. We found cloud SLW content ranging between 0.05 and 0.3 g/m3, with relative humidity of the cloud liquid layers within the range of 80-100%. Some SLW layers correspond to significant temperature inversions. The shortwave and longwave cloud radiative forcing is estimated based on the SLW and other measured parameters. These high-resolution in-situ measurements of cloud SLW content are used to evaluate ERA5 reanalysis.

Further measurements of mixed-phase clouds using SLW content sensors are planned at the Antarctic Peninsula in summer 2021/2022 and during the winter YOPP-SH targeted observing periods (April-July 2022).