Anatomy of a glacial meltwater discharge event in an Antarctic cove

Abstract

Glacial meltwater discharge from Antarctica is a key influence on the marine environment, impacting ocean circulation, sea level and productivity of the pelagic and benthic ecosystems. The responses elicited depend strongly on the characteristics of the meltwater releases, including timing, spatial structure and geochemical composition. Here we use isotopic tracers to reveal the time-varying pattern of meltwater during a discharge event from the Fourcade Glacier into Potter Cove, northern Antarctic Peninsula. The discharge is strongly dependent on local air temperature, and accumulates into an extremely thin, buoyant layer at the surface. This layer showed evidence of elevated turbidity, and responded rapidly to changes in atmospherically driven circulation to generate a strongly pulsed outflow from the cove to the broader ocean. These characteristics contrast with those further south along the Peninsula, where strong glacial frontal ablation is driven oceanographically by intrusions of warm deep waters from offshore. The Fourcade Glacier switched very recently to being land-terminating; if retreat rates elsewhere along the Peninsula remain high and glacier termini progress strongly landward, the structure and impact of the freshwater discharges are likely to increasingly resemble the patterns elucidated here.This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

Meltwater sediment transport as the dominating process in mid-latitude trough mouth fan formation

“…Meltwater can transport large quantities of lithogenic particles derived from glacial erosion 58 , and large turbidity currents are documented to have lost their freshwater after distances of up to 300 km 59 . An increased meltwater input from the Norwegian Channel Ice Stream could activate sediment-downslope transport in turbidity currents, and thereby explaining the long runout distances.…”

“…Eight glacial sub-units are colored in yellow to red, and are indicated by arrows. The top reflections of the sub-units can have a negative-amplitude reflection(54,(56)(57)(58), or a positive amplitude reflection(52, 53, and 55). Deep, V-shaped depressions are recognized both at the top of the sub-units and along reflections within the subunits.…”

Investigation of Sediment-Rich Glacial Meltwater Plumes Using a High-Resolution Multispectral Sensor Mounted on an Unmanned Aerial Vehicle

“…The analysis of turbidity or similar measures for the identification of glacial discharges was previously described in studies in both the Arctic and Antarctic regions [19,64,65]. However, combining it with remote sensing methods is less common in the Antarctic [66].…”

“…To achieve these goals, during the 2019 austral summer in the Admiralty Bay in West Antarctica, recurrent plumes in front of four glaciers, which differ in shape, dynamics, and geological location, were investigated, and their plume waters were examined. A large glacial sediment discharge has an impact on the salinity and temperature of seawater [4], biodiversity, the productivity as well aswell-being of marine flora and fauna, and, dependent on the latter, land animals and birds [19][20][21][22][23][24][25]. Consequently, changes in polar ecosystems require monitoring.…”

The marine system of the West Antarctic Peninsula: status and strategy for progress

“…Meredith et al [19] use a novel high-resolution approach to existing isotopic methods to characterize and trace episodic meltwater release off King George Island (Isla 25 Mayo), northern WAP near Carlini Station, and elucidate the structure of a specific glacial discharge event in unprecedented detail. Strong dependence on atmospheric variability is found, with influences from both air temperature (via the amount of glacial melt discharge) and winds (which impact the retention and fate of freshwater in the ocean).…”