Analysis of Antarctic Peninsula glacier frontal ablation rates with respect to iceberg melt-inferred variability in ocean conditions

Abstract

Marine-terminating glaciers on the Antarctic Peninsula (AP) have retreated, accelerated and thinned in response to climate change in recent decades. Ocean warming has been implicated as a trigger for these changes in glacier dynamics, yet little data exist near glacier termini to assess the role of ocean warming here. We use remotely-sensed iceberg melt rates seaward of two glaciers on the eastern and six glaciers on the western AP from 2013 to 2019 to explore connections between variations in ocean conditions and glacier frontal ablation. We find iceberg melt rates follow regional ocean temperature variations, with the highest melt rates (mean ≈ 10 cm d−1) at Cadman and Widdowson glaciers in the west and the lowest melt rates (mean ≈ 0.5 cm d−1) at Crane Glacier in the east. Near-coincident glacier frontal ablation rates from 2014 to 2018 vary from ~450 m a−1 at Edgeworth and Blanchard glaciers to ~3000 m a−1 at Seller Glacier, former Wordie Ice Shelf tributary. Variations in iceberg melt rates and glacier frontal ablation rates are significantly positively correlated around the AP (Spearman's ρ = 0.71, p-value = 0.003). We interpret this correlation as support for previous research suggesting submarine melting of glacier termini exerts control on glacier frontal dynamics around the AP.

High-resolution topography of the Antarctic Peninsula combining the TanDEM-X DEM and Reference Elevation Model of Antarctica (REMA) mosaic

“…Antarctic Peninsula (AP) glaciers (north of 70 • S) have the potential to raise the global sea level by 69±5 mm (Huss and Farinotti, 2014). In recent decades they have undergone extensive changes as a consequence of regional climate warming and oceanographic change (Cook et al, 2005(Cook et al, , 2014(Cook et al, , 2016Seehaus et al, 2018;Rott et al, 2018;Rignot et al, 2019;Dryak and Enderlin, 2020). As a complex mountainous coastal glacier system, the mass balance of the individual glaciers is affected by climate and oceanographic forcings and also by the subglacial and surrounding topography (Cook et al, 2012).…”

“…They have been derived from satellite radar altimetry (Helm et al, 2014;Li et al, 2017;Slater et al, 2018), laser altimetry (DiMarzio et al, 2007), a combination of both radar and laser altimetry Griggs and Bamber, 2009), optical photogrammetry (ASTER GDEM Validation Team, 2009Abrams et al, 2020;Howat et al, 2019), the combination of several sources of remote sensing and cartographic data (Liu et al, 2001;Fretwell et al, 2013), and single-pass synthetic aperture radar (SAR) interferometry of the TanDEM-X mission (German Aerospace Center DLR, 2018). In addition, regional DEMs of the marginal areas of the ice sheet have been generated from stereoscopic data (Korona et al, 2009;Fieber et al, 2018). An overview table with the parameters of the AP DEMs can be found in Table S1 of the Supplement.…”

Tracking changes in the area, thickness, and volume of the Thwaites tabular iceberg “B30” using satellite altimetry and imagery

“…The release of relatively cold fresh water facilitates sea ice growth (Bintanja et al, 2015;Merino et al, 2016), immediately lowers the sea surface temperature (Merino et al, 2016), and has been found to even influence ocean water down to 1500 m depth (Helly et al, 2011), as well as lead to upwelling of deep ocean properties (Jenkins, 1999). In terms of nutrients, icebergs have been shown to be the main source of iron in the Southern Ocean (Laufkötter et al, 2018;Raiswell et al, 2016;Wu and Hou, 2017) and therefore foster primary production in the proximity of icebergs (Biddle et al, 2015;Duprat et al, 2016;Helly et al, 2011), which in turn increases the abundance of krill and seabirds (Joiris, 2018;Smith et al, 2007) around icebergs. Furthermore, a range of studies have demonstrated that including more realistic iceberg distributions, trajectories, and volumes in climate models leads to a redistribution of fresh water and heat flux, which agrees better with observations than models that only include small icebergs or that treat iceberg discharge as coastal runoff (Jongma et al, 2009;Martin and Adcroft, 2010;Rackow et al, 2013;Schloesser et al, 2019).…”

Effectively Extracting Iceberg Freeboard Using Bi-Temporal Landsat-8 Panchromatic Image Shadows

“…The full freeboard of an iceberg can be estimated using the Digital Surface Model (DSM) generated using automatic image matching from optical stereo images. For example, Enderlin et al [25] and Dryak et al [26] used the DSM generated using WorldView satellite data to measure the freeboard and then the basal melting of icebergs. Li et al [27] generated a DSM covering an iceberg area in Prydz Bay using Unmanned Aerial Vehicle (UAV) optical images.…”