Modeling the Influence of Moulin Shape on Subglacial Hydrology

Trunz, Celia; Covington, M. D.; Poinar, Kristin; Andrews, Lauren C.; Mejia, J. Z.; Gulley, Jason

doi:10.1029/2022jf006674

Cited by 3 publications

(9 citation statements)

References 61 publications

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“…The MouSh model is coupled to a single subglacial channel model (Covington et al, 2020;Trunz et al, 2022) that implements the melting and creep closure equations for a subglacial channel from Schoof (2010). The cross-sectional area of the subglacial channel evolves depending on the hydraulic head and controls the retention and evacuation of the water in the moulin.…”

Section: Moulin Shape (Moush) Modelmentioning

confidence: 99%

“…For each of these simulations with idealized parameter values, we calculate the diurnal range of moulin head variability after a period of ∼23 days. This delay allows moulin head to equilibrate in the more extreme scenarios (Trunz et al, 2022).…”

Section: Simulation Categories 165mentioning

confidence: 99%

“…This is due to the constraints of field logistics and the technical finesse required to instrument the complex, imperfectly vertical geometry that characterizes moulins (Covington et al, 2020;Gulley et al, 2009). Models for moulin heads are therefore needed if we are to understand diurnal water pressure variations across larger areas of the Greenland Ice Sheet in order to predict how meltwater infiltration affects ice motion (Trunz et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Alternatively, simpler physically based models have frequently been used to simulate water pressure in subglacial channels (Röthlisberger, 1972), with a subglacial channel that can melt open and creep closed (Spring and Hutter, 1981;Schoof, 2010), and is connected to cavities (Schoof, 2010;Bartholomew et al, 2012) or is not connected to cavities (Covington et al, 2012;Bartholomew et al, 2012;Cowton et al, 2016;Meierbachtol et al, 2013). Some zero and one-dimensional models couple the subglacial channel to englacial storage via a cylindrical or conical moulin whose shape is static in time (Werder et al, 2013;Covington et al, 2012Covington et al, , 2020Cowton et al, 2016;Bartholomew et al, 2012;Trunz et al, 2022), but not all models include such storage (de Fleurian et al, 2016). The size and shape of a moulin within the range of its water level oscillations affect the amplitude and temporal pattern of diurnal water pressure oscillations (Werder et al, 2010;Trunz et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Some zero and one-dimensional models couple the subglacial channel to englacial storage via a cylindrical or conical moulin whose shape is static in time (Werder et al, 2013;Covington et al, 2012Covington et al, , 2020Cowton et al, 2016;Bartholomew et al, 2012;Trunz et al, 2022), but not all models include such storage (de Fleurian et al, 2016). The size and shape of a moulin within the range of its water level oscillations affect the amplitude and temporal pattern of diurnal water pressure oscillations (Werder et al, 2010;Trunz et al, 2022). When these subglacial models are driven by realistic surface meltwater inputs, large englacial or subglacial storage volumes are required in order to produce realistic moulin head outputs (Hoffman et al, 2016;Bartholomew et al, 2012;Covington et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects

Trunz

Poinar²,

Andrews³

et al. 2022

Preprint

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Abstract. In the ablation zone of land-terminating areas of the Greenland Ice Sheet, water pressures at the bed control seasonal and daily ice motion variability. During the melt season, large amounts of surface meltwater access the bed through moulins, which sustain an efficient channelized subglacial system. Water pressure within these subglacial channels can be inferred by measuring the hydraulic head within moulins. However, moulin head data are rare, and subglacial hydrology models that simulate water pressure fluctuations require water storage in moulins or subglacial channels. Neither the volume nor the location of such water storage is currently well constrained. Here, we use the Moulin Shape (MouSh) model, which quantifies time-evolving englacial storage, coupled with a subglacial channel model to simulate head measurements from a moulin in the Pâkitosq region in Greenland. We force the model with surface meltwater input calculated using field-acquired weather data. Our first-order simulations of moulin hydraulic head either over-predict the diurnal range of oscillation of the moulin head or require an unrealistically large moulin size to produce realistic head oscillation ranges. We find that to accurately match field observations of moulin head, additional subglacial water must be added to the system. We hypothesize that this additional `baseflow' represents strong subglacial network connectivity throughout the channelized system and is ultimately sourced from basal melt and non-local surface water inputs upstream.

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Section: Moulin Shape (Moush) Modelmentioning

confidence: 99%

Section: Simulation Categories 165mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects

Trunz

Poinar²,

Andrews³

et al. 2022

Preprint

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Into the ice: Exploration and data capturing in glacial moulins by a tethered robot

Polzin,

Hughes

2024

Journal of Field Robotics

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Glacial moulins (cylindrical meltwater drainage shafts) provide valuable insights into glacier dynamics, but are inaccessible and hazardous environments for humans to study. Exploring them using passive sensor probes has revealed their complex geometry, which has limited further exploration with passive sensor probes. To overcome these challenges, we propose a tethered robot capable of autonomously exploring and capturing data in glacial moulins. Our novel robot is equipped with a tether to support its motion. Combined with novel estimation and control algorithms, the tethered robot is able to safely and efficiently maneuver in confined, chimney‐like structures, such as moulins. Laboratory and field experiments confirm the feasibility of the proposed design, showing successful localization in environments with no access to positional measurements. Field trials on the Mer de Glace glacier demonstrate the robot's capabilities, descending into the largest moulin to depths of 25 m, capturing valuable scientific data. Onboard sensors are used to capture data to reconstruct the moulin's three‐dimensional geometry and two sampling mechanisms are presented and evaluated to extract samples from the icy surface of the moulin. Our results show promising potential for future exploration of moulins, demonstrating the effectiveness of our tethered robot for safely gathering data from these hazardous environments.

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Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects

Trunz,

Poinar,

Andrews

et al. 2023

The Cryosphere

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Abstract. In the ablation zone of land-terminating areas of the Greenland Ice Sheet, water pressures at the bed control seasonal and daily ice motion variability. During the melt season, large amounts of surface meltwater access the bed through moulins, which sustain an efficient channelized subglacial system. Water pressure within these subglacial channels can be inferred by measuring the hydraulic head within moulins. However, moulin head data are rare, and subglacial hydrology models that simulate water pressure fluctuations require water storage in moulins or subglacial channels. Neither the volume nor the location of such water storage is currently well constrained. Here, we use the Moulin Shape (MouSh) model, which quantifies time-evolving englacial storage, coupled with a subglacial channel model to simulate head measurements from a small moulin in Pâkitosq, western Greenland. We force the model with surface meltwater input calculated using field-acquired weather data. Our first-order simulations of moulin hydraulic head either overpredict the diurnal range of oscillation of the moulin head or require an unrealistically large moulin size to reproduce observed head oscillation ranges. We find that to accurately match field observations of moulin head, additional subglacial water must be added to the system. This subglacial baseflow is likely sourced from basal melt and nonlocal surface water inputs upstream. We hypothesize that the additional baseflow represents strong subglacial network connectivity throughout the channelized system and is consistent with our small moulin likely connecting to a higher-order subglacial channel.

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Modeling the Influence of Moulin Shape on Subglacial Hydrology

Abstract: In land-terminating regions of the Greenland Ice Sheet, the response of the subglacial drainage system to meltwater inputs is a primary influence on ice motion (e.g.,

Cited by 3 publications

References 61 publications

Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects

Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects

Into the ice: Exploration and data capturing in glacial moulins by a tethered robot

Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects

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