Surface meltwater drainage and ponding on Amery Ice Shelf, East Antarctica, 1973–2019

Julian J Spergel,Timothy Creyts,Helen A Fricker,Jonathan Kingslake,Melchior Van Wessem

doi:10.1017/jog.2021.46

Julian J Spergel, Timothy Creyts + Show 3 more

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https://doi.org/10.1017/jog.2021.46

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Abstract

AbstractSurface melting on Amery Ice Shelf (AIS), East Antarctica, produces an extensive supraglacial drainage system consisting of hundreds of lakes connected by surface channels. This drainage system forms most summers on the southern portion of AIS, transporting meltwater large distances northward, toward the ice front and terminating in lakes. Here we use satellite imagery, Landsat (1, 4 and 8), MODIS multispectral and Sentinel-1 synthetic aperture radar to examine the seasonal and interannual evolution of the drainage system over nearly five decades (1972–2019). We estimate seasonal meltwater input to one lake by integrating output from the regional climate model [Regional Atmospheric Climate Model (RACMO 2.3p2)] over its catchment defined using the Reference Elevation Model of Antarctica. We find only weak positive relationships between modeled seasonal meltwater input and lake area and between meltwater input and lake volume. Consecutive years of extensive melting lead to year-on-year expansion of the drainage system, potentially through a link between melt production, refreezing in firn and the maximum extent of the lakes at the downstream termini of drainage. These mechanisms are important when evaluating the potential of drainage systems to grow in response to increased melting, delivering meltwater to areas of ice shelves vulnerable to hydrofracture.

Highlights

Surface meltwater drainage systems have been regularly observed in summer on the Antarctic ice shelves since the exploration of these regions began (Mellor and McKinnon, 1960; Bell and others, 2017)
We have examined the spatial and temporal patterns of surface meltwater drainage on Amery Ice Shelf (AIS), East Antarctica from 1973 to 2019 using Landsat (1 and 4–8), MODIS and WorldView optical imagery and Sentinel-1 synthetic aperture radar (SAR) imagery
We have shown that AIS’s surface drainage networks are topographically controlled and exhibit significant interannual variability in maximum downstream drainage extent, lake size, areal coverage and meltwater volume

Summary

Introduction

Surface meltwater drainage systems have been regularly observed in summer on the Antarctic ice shelves since the exploration of these regions began (Mellor and McKinnon, 1960; Bell and others, 2017). Meltwater can flow into and enlarge these fractures, a process referred to as hydrofracturing (Weertman, 1973; Rack and Rott, 2004; van der Veen, 2007; MacAyeal and others, 2015; Banwell and others, 2019; Robel and Banwell, 2019; Lai and others, 2020). These processes have been linked to increased meltwater production that caused the collapse of several Antarctic Peninsula ice shelves (Scambos and others, 2004; Banwell and others, 2013). As surface drainage systems relocate water long distances across ice shelves, it is important to identify the controls on their multi-year growth under warming conditions

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