Time-lapse photogrammetry reveals hydrological controls of fine scale High-Arctic glacier surface roughness evolution

Irvine-Fynn, Tristram D.L., Holt, Tom O, James, Timothy D, Smith, Mark W, Rutter, Nick, Porter, Philip R. and Hodson, Andrew J (2022) Time-lapse photogrammetry reveals hydrological controls of fine scale High-Arctic glacier surface roughness evolution. Earth Surface Processes and Landforms, 47 (6). pp. 1635-1652. ISSN 0197-9337

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Official URL: https://doi.org/10.1002/esp.5339

Abstract

In a warming Arctic, as glacier snowlines rise, short- to medium-term increases in seasonal bare-ice extent are forecast for the next few decades. These changes will enhance the importance of turbulent energy fluxes for surface ablation and glacier mass balance. Turbulent energy exchanges at the ice surface are conditioned by its topography, or roughness, which has been hypothesized to be controlled by supraglacial hydrology at the glacier scale. However, current understanding of the dynamics in surface topography, and the role of drainage development, remains incomplete, particularly for the transition between seasonal snow cover and well-developed, weathered bare-ice. Using time-lapse photogrammetry, we report a daily timeseries of fine (millimetre)-scale supraglacial topography at a 2 m2 plot on the Lower Foxfonna glacier, Svalbard, over two 9-day periods in 2011. We show traditional kernel-based morphometric descriptions of roughness were ineffective in describing temporal change, but indicated fine-scale albedo feedbacks at depths of ~60 mm contributed to conditioning surface topography. We found profile-based and two-dimensional estimates of roughness revealed temporal change, and the aerodynamic roughness parameter, z0, showed a 22–32% decrease from ~1 mm following the exposure of bare-ice, and a subsequent 72–77% increase. Using geostatistical techniques, we identified ‘hole effect’ properties in the surface elevation semivariograms, and demonstrated that hydrological drivers control the plot-scale topography: degradation of superimposed ice reduces roughness while the inception of braided rills initiates a subsequent development and amplification of topography. Our study presents an analytical framework for future studies that interrogate the coupling between ice surface roughness and hydro-meteorological variables and seek to improve parameterizations of topographically evolving bare-ice areas.

Item Type: Article
Additional Information: Funding information: Research funded by Royal Geographical Society, Leverhulme Trust (RF‐2018‐584/4).
Uncontrolled Keywords: Glacier surface, roughness, photogrammetry, hydrology, semivariance
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: John Coen
Date Deposited: 01 Feb 2022 11:13
Last Modified: 24 May 2022 15:00
URI: http://nrl.northumbria.ac.uk/id/eprint/48316

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