Latest Altimetry-Based Sea Ice Freeboard and Volume Inter-Annual Variability in the Antarctic over 2003–2020

The relatively stable conditions of the sea ice cover in Antarctic, observed for almost 40 years, seem to be changing recently. Therefore, it is essential provide thickness (SIT) and volume (SIV) estimates order anticipate potential multi-scale changes Antarctic ice. For that purpose, main objectives this work are: (1) assess a new freeboard, altimetry dataset over 2003–2020 (2) identify first impacts recent conditions. To produce these series, we use neuronal network calibrate Envisat radar freeboards onto CryoSat-2 (CS2). This method addresses surface roughness on Low Resolution Mode (LRM) measurements. During 2011 common flight period, found mean deviation between by about 0.5 cm. Using Advanced Microwave Scanning Radiometer (AMSR) dual-frequency Altimetric Snow Depth (ASD) data, our solutions are compared with Upward looking sonar (ULS) draft some in-situ measurement SIMBA campaign, total 6 Operation Ice Bridge (OIB) missions ICESat-2 freeboards. Over 2003–2020, global freeboard decreased −14% per decade SIT SIV −10% (considering snow depth climatology). marked slight increase through 2015, which directly followed strong decrease 2016. Thereafter, generally remained low even continued regions such as Weddell sea. Considering 2013–2020 ASD data available, −40% decade. −60% After 2016, values contrast extent has rather increased again, reaching near-average winter 2020. regional analysis underlines thinning (from 2016) occurs all except Amundsen-Bellingshausen sector. Meanwhile, reversal trends from may signature significant ongoing