Spatio-Temporal Distribution of Supra-Glacial Ponds and Ice Cliffs on Verde Glacier, Chile

Thomas Loriaux,Lucas Ruiz

doi:10.3389/feart.2021.681071

Abstract

Known for their important role in locally enhancing surface melt, supraglacial ponds and ice cliffs are common features on debris-covered glaciers. We use high resolution satellite imagery to describe pond-cliff systems and surface velocity on Verde debris-covered glacier, Monte Tronador, and Southern Chile. Ponds and ice cliffs represent up to 0.4 and 2.7% of the glacier debris-covered area, respectively. Through the analyzed period and the available data, we found a seasonality in the number of detected ponds, with larger number of ponds at the beginning of the ablation season and less at the end of it. Using feature tracking, we determined glacier surface velocity, finding values up to 55 m/yr on the upper part of the debris-covered area, and decreasing almost to stagnation in the terminus. We found that larger ponds develop in glacier zones of low velocity, while zones of high velocity only contain smaller features. Meanwhile, ice cliffs appeared to be less controlled by surface velocity and gradient. Persistent ice cliffs were detected between 2009 and 2019 and backwasting up to 24 m/yr was measured, highlighting significant local glacier wastage.

Highlights

Interest has been recently growing about debris-covered glaciers (DCGs) in mountain areas worldwide (e.g., Fyffe et al, 2012; Janke et al, 2015; Bhushan et al, 2018; Miles et al, 2019)
Supraglacial ponds are common features on DCGs, where they have been observed for decades (Iwata et al, 1980; Kirkbride, 1993)
Supraglacial ponds and ice cliffs are observed across the whole elevation range, their distribution is uneven over the tongue (Figure 3)

Summary

Introduction

Interest has been recently growing about debris-covered glaciers (DCGs) in mountain areas worldwide (e.g., Fyffe et al, 2012; Janke et al, 2015; Bhushan et al, 2018; Miles et al, 2019). Studies about supraglacial ponds on DCGs are mostly centered in High Mountain Asia (e.g., Sakai and Fujita, 2010; Miles et al, 2018; Watson et al, 2018a; Chand and Watanabe, 2019), where they can locally represent significant portion of the DCGs. Seasonal and interannual variations in ponds count and area have been observed (Steiner et al, 2019), as well as rapid filling and draining (Miles et al, 2017b), associated with englacial hydrological networks (Miles et al, 2017a; Miles et al, 2019; Watson et al, 2018b). Exposed ice cliffs often appear at the ponds margins and can help identify the emplacement of drained features (Miles et al, 2017a)

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