Clouds affect the Earth climate with an impact that depends on the cloud nature (solid and/or liquid water). Although the Antarctic climate is changing rapidly, cloud observations are sparse over Antarctica due to few ground stations and satellite observations. The Concordia station is located on the eastern Antarctic Plateau (75° S, 123° E; 3233m above mean sea level), one of the driest and coldest places on Earth. We used observations of clouds, temperature, liquid water, and surface irradiance performed at Concordia during four austral summers (December 2018-2021) to analyse the link between liquid water and temperature and its impact on surface irradiance in the presence of supercooled liquid water (liquid water for temperature less than 0 °C) clouds (SLWCs). Our analysis shows that, within SLWCs, temperature logarithmically increases from -36:0 to -16:0 °C when liquid water path increases from 1.0 to 14.0 gm-2. The SLWC radiative forcing is positive and logarithmically increases from 0.0 to 70.0Wm-2 when liquid water path increases from 1.2 to 3.5 gm-2. This is mainly due to the downward longwave component that logarithmically increases from 0 to 90Wm-2 when liquid water path increases from 1.0 to 3.5 gm-2. The attenuation of shortwave incoming irradiance (that can reach more than 100Wm-2) is almost compensated for by the upward shortwave irradiance because of high values of surface albedo. Based on our study, we can extrapolate that, over the Antarctic continent, SLWCs have a maximum radiative forcing that is rather weak over the eastern Antarctic Plateau (0 to 7Wm-2) but 3 to 5 times larger over West Antarctica (0 to 40Wm-2), maximizing in summer and over the Antarctic Peninsula. © 2024 Philippe Ricaud et al.

Export Date: 15 February 2024Correspondence Address: Ricaud, P.; CNRM, France; email: philippe.ricaud@meteo.frFunding details: Centre National d’Etudes Spatiales, CNESFunding details: Institut national des sciences de l'Univers, INSU,CNRSFunding details: Centre National de la Recherche Scientifique, CNRSFunding details: Institut Polaire Français Paul Emile Victor, IPEVFunding text 1: The HAMSTRAD programme 910 was supported by IPEV, the Institut National des Sciences de l'Univers (INSU)/Centre National de la Recherche Scientifique (CNRS), Météo-France, and the Centre National d'Etudes Spatiales (CNES).