Supercooled Liquid Water Clouds

During the international YOPP campaign (2018-2019), remote-sensed observations of Supercooled Liquid Water (SLW, the water staying in liquid phase below 0°C) clouds at Dome C have shown that ~50% of the days in summer time exhibited SLW clouds for at least one hour. The lack of simulated SLW in meteorological forecasts or reanalyses impacted the net surface radiation that was, in some cases, 50 W m-2 higher in the observations than in the calculations. Therefore, accurately modelling the presence of SLW clouds appears crucial to correctly simulate the surface energy budget over the Antarctic Plateau. The main objective of the Supercooled Liquid Water Cloud (SLW-CLOUD) programme 1247 is to measure in-situ SLW clouds over Dome C, to get the vertical and horizontal distributions of these clouds, and a time distribution of their appearance over the summertime period in order to check their impacts on the net surface radiation. These observations will be performed during two different campaigns. The first campaign will be held in summer 2021-2022 using in-situ SLW sondes mounted on meteorological balloons and coupled to conventional radiosondes. During the second campaign in summer 2022-2023, similar observations will be conducted on balloons, and completed with SLW sondes aboard a light remotely-piloted aircraft system (RPAS). These unique in-situ SLW observations will be compared and analysed with 1) remote-sensed SLW measurements performed at the station (microwave radiometer HAMSTRAD and depolarization backscattering LIDAR) together with surface radiation from the Baseline Surface Radiation Network (BSRN) and 2) modelled results: meteorological reanalyses (ERA5 and ARPEGE), and PolarWRF.