Automated detection and analysis of surface calving waves with a terrestrial radar interferometer at the front of Eqip Sermia, Greenland

Guillaume Jouvet,Andreas Vieli,Andrea Walter,Martin P Lüthi,Adrien Wehrlé

doi:10.5194/tc-15-5659-2021

Abstract

Abstract. Glacier calving is a key dynamical process of the Greenland Ice Sheet and a major driver of its increasing mass loss. Calving waves, generated by the sudden detachment of ice from the glacier terminus, can reach tens of meters in height and provide very valuable insights into quantifying calving activity. In this study, we present a new method for the detection of source location, timing, and magnitude of calving waves using a terrestrial radar interferometer. This method was applied to 11 500 1 min interval acquisitions from Eqip Sermia, West Greenland, in July 2018. Over 7 d, more than 2000 calving waves were detected, including waves generated by submarine calving, which are difficult to observe with other methods. Quantitative assessment with a wave power index (WPI) yields a higher wave activity (+49 %) and higher temporally cumulated WPI (+34 %) in deep water than under shallow conditions. Subglacial meltwater plumes, occurring 2.3 times more often in the deep sector, increase WPI and the number of waves by a factor of 1.8 and 1.3, respectively, in the deep and shallow sector. We therefore explain the higher calving activity in the deep sector by a combination of more frequent meltwater plumes and more efficient calving enhancement linked with better connections to warm deep ocean water.

Highlights

Many outlet glaciers of the Greenland Ice Sheet have undergone rapid retreat, thinning, and flow acceleration within the past 2 decades (e.g., Moon et al, 2012; Enderlin et al, 2014; King et al, 2020) and have become important contributors to the observed increasing mass loss rates of the Greenland Ice Sheet (Shepherd et al, 2012; IPCC, 2013; Shepherd et al, 2020)
We presented a novel method (TeRACWA) for the detection and the quantitative assessment of calving activity by analysis of calving waves recorded with a terrestrial radar interferometer (TRI)
We developed a novel automated method named TeRACWA (Terrestrial Radar Assessment of Calving Wave Activity) for the detection and the quantification of ocean waves generated by glacier calving

Summary

Introduction

Many outlet glaciers of the Greenland Ice Sheet have undergone rapid retreat, thinning, and flow acceleration within the past 2 decades (e.g., Moon et al, 2012; Enderlin et al, 2014; King et al, 2020) and have become important contributors to the observed increasing mass loss rates of the Greenland Ice Sheet (Shepherd et al, 2012; IPCC, 2013; Shepherd et al, 2020). A sudden fracture phenomenon that releases large quantities of ice to the proglacial fjord during short-lived events, has been identified as an important factor in the dynamics of tidewater glaciers (e.g., Joughin et al, 2004; Luckman et al, 2006; Nettles et al, 2008; Amundson et al, 2008) This process has been studied using various methods including seismic source inversion (Walter et al, 2012; Sergeant et al, 2019), detailed numerical modeling (e.g., Benn et al, 2017; Mercenier et al, 2020), underwater acoustics (Glowacki and Deane, 2020), and radar interferometry (e.g., Lüthi and Vieli, 2016; Xie et al, 2019; Cassotto et al, 2019; Walter et al, 2020; Cook et al, 2021; Kane et al, 2020). These methods are complemented with high-rate time-lapse photography (e.g., Dietrich et al, 2007; Amundson et al, 2008; Lüthi et al, 2009; Minowa et al, 2018)

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Discussion

Conclusion