Formation of pedestalled, relict lakes on the McMurdo Ice Shelf, Antarctica


Type
Article
Change log
Authors
Macdonald, GJ 
Banwell, AF 
Willis, IANC 
Mayer, DP 
Goodsell, B 
Abstract

jats:titleABSTRACT</jats:title>jats:pSurface debris covers much of the western portion of the McMurdo Ice Shelf and has a strong influence on the local surface albedo and energy balance. Differential ablation between debris-covered and debris-free areas creates an unusual heterogeneous surface of topographically low, high-ablation, and topographically raised (‘pedestalled’), low-ablation areas. Analysis of Landsat and MODIS satellite imagery from 1999 to 2018, alongside field observations from the 2016/2017 austral summer, shows that pedestalled relict lakes (‘pedestals’) form when an active surface meltwater lake that develops in the summer, freezes-over in winter, resulting in the lake-bottom debris being masked by a high-albedo, superimposed, ice surface. If this ice surface fails to melt during a subsequent melt season, it experiences reduced surface ablation relative to the surrounding debris-covered areas of the ice shelf. We propose that this differential ablation, and resultant hydrostatic and flexural readjustments of the ice shelf, causes the former supraglacial lake surface to become increasingly pedestalled above the lower topography of the surrounding ice shelf. Consequently, meltwater streams cannot flow onto these pedestalled features, and instead divert around them. We suggest that the development of pedestals has a significant influence on the surface-energy balance, hydrology and flexure of the ice shelf.</jats:p>

Description
Keywords
Glacier hydrology, Ice shelves, Supraglacial debris
Journal Title
Journal of Glaciology
Conference Name
Journal ISSN
0022-1430
1727-5652
Volume Title
65
Publisher
Cambridge University Press (CUP)
Sponsorship
Leverhulme Trust (ECF-2014-412)
Isaac Newton Trust (1408(g))
Ian