Active layer and permafrost thermal regime in a patterned ground soil in Maritime Antarctica, and relationship with climate variability models

Abstract

Permafrost and active layer studies are important to understand and predict regional climate changes. The objectives of this work were: i) to characterize the soil thermal regime (active layer thickness and permafrost formation) and its interannual variability and ii) to evaluate the influence of different climate variability modes to the observed soil thermal regime in a patterned ground soil in Maritime Antarctica. The study was carried out at Keller Peninsula, King George Island, Maritime Antarctica. Six soil temperatures probes were installed at different depths (10, 30 and 80cm) in the polygon center (Tc) and border (Tb) of a patterned ground soil. We applied cross-correlation analysis and standardized series were related to the Antarctic Oscillation Index (AAO). The estimated active layer thickness was approximately 0.75cm in the polygon border and 0.64cm in the center, indicating the presence of permafrost (within 80cm). Results indicate that summer and winter temperatures are becoming colder and warmer, respectively. Considering similar active layer thickness, the polygon border presented greater thawing days, resulting in greater vulnerability to warming, cooling faster than the center, due to its lower volumetric heat capacity (Cs). Cross-correlation analysis indicated statistically significant delay of 1day (at 10cm depth) in the polygon center, and 5days (at 80cm depth) for the thermal response between atmosphere and soil. Air temperature showed a delay of 5months with the climate variability models. The influence of southern winds from high latitudes, in the south facing slopes, favored freeze in the upper soil layers, and also contributed to keep permafrost closer to the surface. The observed cooling trend is linked to the regional climate variability modes influenced by atmospheric circulation, although longer monitoring period is required to reach a more precise scenario.

Thermal variations of the active layer in Fildes Peninsula, King George Island, Maritime Antarctica

“…In Keller Peninsula (90 m a.s.l.) the ALT varied between -64 cm and -75 cm (Chaves et al 2017), therefore having ALT similar to the maximum value measured in this study. In Deception Island (130 m a.s.l.…”

Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017

“…Ozone depletion has influenced recent temperatures across Antarctica and been implicated in changes in precipitation patterns across the Southern Hemisphere and into Asia [154][155][156][157][158][159][160] (Fig. 6; see also section 1.3).…”

Area and borders of Antarctic and permafrost—A review and synthesis

“…38 Another interesting direction of research is observing the nature and changes of morphological processes, rock weathering, and soil formation in the so-called paraglacial environment, in which permafrost and its evolution play an essential role. Permafrost is here an important regulator of processes in the transformation of glacial to nonglacial environments, with a time scale of 10 1 -10 4 years (e.g., 10,22,[39][40][41][42][43] ). Recent studies on the role of snow cover also allow us to observe the conditions of transition from a subaerial to a subnival regime, 44 which can be treated as "an analogue for the transition from a periglacial to a subglacial environment in longer periods of cooling in the paleoenvironmental record."…”