Ground surface temperature regimes are controlled by the topography and snow cover in the ice-free areas of Maritime Antarctica

Abstract

Ground Surface Temperature (GST) is especially relevant in permafrost regions, such as the ice-free areas of the Antarctic Peninsula, to the understanding of environmental changes, where a long-term warming trend has been detected since 1950. To better understand GST regimes and the topoclimatic controlling factors, 20 iButtons were installed at sites according to elevation, exposure, curvature, and proximity to permanent snow, recording temperatures at 3-hour intervals from March 2019 to February 2020. Multiple Factorial Analysis (MFA) was used to evaluate the influence of these factors on GST parameters and to group the sensors based on their similarities. An analysis of daily temperatures was conducted to classify types of daily ground temperature regimes for use in a spatial model, developed using Discriminant Analysis (DA). As was predicted elevation was identified as the main controlling factor, with a negative correlation to the Mean Annual Ground Surface Temperature, ranging from 0.6 degrees C at 16 m a.s.l. to - 2 degrees C at 254 m a.s.l., and a positive correlation with Freezing Degree Days, ranging from 438 (at 16 m a.s.l.) to 1042 (at 254 m a.s.l.). Snow cover duration is the second control factor highlighted, determining the duration of the freezing season, which was prolonged where snow cover persisted longer, resulting in a more pronounced insulating effect. The diversity of conditions was reinforced with the identification of seven types of daily GST regimes (three frozen, two unfrozen, and two with freeze - thaw), leading to the categorization of four annual distribution types. These were spatialized for Barton Peninsula using the DA model (90 % accuracy). The spatialization revealed a long frost season in proximity to snow patches, moderate frost season in areas above 160 m a.s.l., a short frost season with slow warming in areas ranging from 90 to 160 m a.s. l., and a short frost season with rapid warming in areas below 90 m a.s.l.