Supercooled liquid water and mixed-phase in Antarctic clouds

• Main Authors: Listowski, Constantino, Delanoë, Julien, Kirchgaessner, Amélie, Lachlan-Cope, Tom, King, John
• Other Authors: SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), British Antarctic Survey (BAS), Natural Environment Research Council (NERC)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; The Antarctic; East Antarctica; West Antarctica; South Pole; Antarc*; Antarctica; Sea ice; South pole
• Online Access: https://insu.hal.science/insu-04451738

International audience Surface radiation biases of several tens of watt per square meters are derived in global climate models and high-resolution atmospheric models in the Antarctic. This points to major problems in the simulation of the cloud phase, and more particularly of the supercooled liquid water. In this remote region satellite observations appear as a crucial complement. Radar-lidar DARDAR satellite products were developed in order to take advantage of both radar (CloudSat/CPR) and lidar (CALIPSO/CALIOP) measurements which are used seamlessly to retrieve cloud properties at a horizontal resolution of 1.7x1.4 km and a vertical resolution of 60 m. We will present results of the analysis of Antarctic cloud thermodynamic phase using the most recent DARDAR products v2 over the period 2007-2010 between 60°S and 82°S. We investigate the seasonal and monthly evolutions of the thermodynamic phases' occurrences Antarctic-wide and over specific regions. The cloud fraction (occurrence frequency) is divided into the supercooled liquid water-containing cloud fraction and the all-ice cloud fraction (where no liquid is present in the considered atmospheric column). The low-level (< 3km above the surface) supercooled liquid water fraction varies according to temperature and sea ice fraction seasonality, and it is the largest over water. We demonstrate the agreement of our satellite observations of supercooled liquid on the outskirts of the Antarctic Plateau with published ground-based lidar observations made at South Pole in 2009. We show that, in East Antarctica, the supercooled liquid fraction decreases sharply polewards and that it is twice to three times higher in West Antarctica. The geographical distribution of all-ice clouds is shaped by the interaction of the main low-pressure systems surrounding the continent and the orography, with little links with sea ice fraction throughout the year. We demonstrate the largest impact of sea ice on the liquid-bearing cloud fraction (mostly mixed-phase clouds) in autumn ...