The Spatio-Temporal Variability of Frost Blisters in a Perennial Frozen Lake along the Antarctic Coast as Indicator of the Groundwater Supply

Abstract

Remote sensing, and unmanned aerial vehicles (UAVs) in particular, can be a valid tool for assessing the dynamics of cryotic features as frost blisters and to monitor the surface changes and the sublimation rates on perennially frozen lakes that host important ecosystems. In this paper, through the use of these remote sensing techniques, we aim to understand the type of groundwater supply of an Antarctic perennial frozen lake that encompasses two frost blisters (M1 and M2) through the temporal analysis of the features’ elevation changes (frost blisters and lake ice level). The frozen lake is located at Boulder Clay (northern Victoria Land, Antarctica). We relied on several photogrammetric models, past satellite images and ground pictures to conduct differencing of digital elevation models, areal variations and pixel counting. In addition, in situ measurements of the ice sublimation or snow accumulation were carried out. The two frost blisters showed different elevation trends with M1 higher in the past (1996–2004) than recently (2014–2019), while M2 showed an opposite trend, similarly to the ice level. Indeed, the linear regression between M2 elevation changes and the ice level variation was statistically significant, as well as with the annual thawing degree days, while M1 did not show significant results. From these results we can infer that the groundwater supply of M1 can be related to a sublake open talik (hydraulic system) as confirmed also by pressurized brines found below M1, during a drilling in summer 2019. For M2 the groundwater flow is still not completely clear although the hydrostatic system seems the easiest explanation as well as for the uplift of the lake ice.

Foehn Winds at Pine Island Glacier and their role in Ice Changes

“…The surface sublimation rate (Fig. 4c) is considerable, with the values at PIG comparable to the maximum rates at a site in northern Victoria Land during November 2018 (Ponti et al, 2021), four times larger than that estimated just off East Antarctica in late winter 2007 (Toyota et al, 2011), but smaller than those at individual events at the Princess Elizabeth base in East Antarctica (Gorodetskaya et al, 2015). The magnitude of the surface sublimation rate during Foehn events is roughly an order of magnitude smaller than that due to melting resulting from ice dynamics at the Ronne Ice Shelf in the Weddell Sea (Holland et al, 2007), Totten Ice Shelf in East Antarctica (Rintoul et al, 2016), and at PIG and Thwaites Glacier in West Antarctica (Feldmann et al, 2019).…”

UAVs for Science in Antarctica

“…The detailed mapping of geomorphological slope processes related to snow patches after UAV surveys and field observations in James Ross Island, East Antarctic Peninsula, are detailed by K ňažková et al (2021) [59], allowing this team to discuss the role of snow related processes as landscape-shaping factors. Another type of landforms, whose full details are only observable at the scale of UAV datasets, are permafrost mounds and in particular frost blisters, whose multitemporal size variations were quantified by Ponti et al (2021) [60] for assessing the sublimation rates on perennially frozen lakes and water supply mechanisms.…”