Measuring glacier surface roughness using plot-scale, close-range digital photogrammetry. Issue 223 (2014)

• Record Type: Journal Article
• Authors: Irvine-Fynn, Tristram D.L.; Sanz-Ablanedo, Enoc; Rutter, Nick; Smith, Mark W.; Chandler, Jim H.
• Is Part Of: Journal of Glaciology. Volume 60:Issue 223(2014)
• Page Start: 957
• Page End: 969
• Publication Date: 2014
• Subjects: applied glaciology, -- energy balance, -- glaciological instruments and methods, -- snow/ice surface processes, -- surface melt
• DOI: 10.3189/2014JoG14J032
• Languages: English
• ISSNs: 0022-1430

Abstract

Abstract: Glacier roughness at sub-metre scales is an important control on the ice surface energy balance and has implications for scattering energy measured by remote-sensing instruments. Ice surface roughness is dynamic as a consequence of spatial and temporal variation in ablation. To date, studies relying on singular and/or spatially discrete two-dimensional profiles to describe ice surface roughness have failed to resolve common patterns or causes of variation in glacier surface morphology. Here we demonstrate the potential of close-range digital photogrammetry as a rapid and cost-effective method to retrieve three-dimensional data detailing plot-scale supraglacial topography. The photogrammetric approach here employed a calibrated, consumer-grade 5 Mpix digital camera repeatedly imaging a plot-scale (≤25 m 2 ) ice surface area on Midtre Lovénbreen, Svalbard. From stereo-pair images, digital surface models (DSMs) with sub-centimetre horizontal resolution and 3 mm vertical precision were achieved at plot scales ≤4 m 2 . Extraction of roughness metrics including estimates of aerodynamic roughness length ( z 0 ) was readily achievable, and temporal variations in the glacier surface topography were captured. Close-range photogrammetry, with appropriate camera calibration and image acquisition geometry, is shown to be a robust method to record sub-centimetre variations in ablating ice topography. While the DSM plot area may be limited through use of stereo-pair images and issues of obliquity, emerging photogrammetric packages are likely to overcome such limitations.