Modeling in Glaciology

19 April 2021
5 December 2023

Table of Contents

Open Access

Reduced Ice Loss From Greenland Under Stratospheric Aerosol Injection

Key Points

  • Stratospheric aerosol injection at the rate of 5 Tg/yr (G4) lowers Greenland mass loss relative to RCP4.5 by 31%–38% by 2090

  • Across four Earth System Model and two ice dynamic models (G4–RCP4.5) differences are 34%–40% in surface mass balance and 16%–34% in ice discharge

  • Dynamic mass loss by calving from glaciers is the largest uncertainty between ice dynamics models

Marginal Detachment Zones: The Fracture Factories of Ice Shelves?

Key Points

  • Many calving events originate as near-margin rifts where ice shelves flow beyond lateral obstructions or boundaries

  • Physical detachment from lateral obstructions is a major source of near-margin tension and fracture

  • Within shelf-marginal detachment zones, thinning/changes to fracture patterns may presage ice shelf destabilization

Open Access

Modeling Potential Glacial Lake Outburst Flood Process Chains and Effects From Artificial Lake-Level Lowering at Gepang Gath Lake, Indian Himalaya

Key Points

  • Sissu is potentially exposed to high-intensity glacial lake outburst flood hazard under all current scenarios and the moderate and large magnitude future scenarios

  • Lake lowering by 10 m reduces the high-intensity zone by 54% and 63% for the current and future scenarios respectively

  • Lake lowering by 30 m leads to a reduction in the affected area of 78% and 93% in current and future scenarios, respectively

Open Access

Modeling the Greenland Ice Sheet's Committed Contribution to Sea Level During the 21st Century

Key Points

  • Glacier terminus position change has a lasting impact on velocity and mass loss of Greenland

  • Greenland's committed sea level response by 2100 is comparable to that due to RCP2.6 forcings

  • Satellite observations can constrain uncertainty in probabilistic ice sheet model projections

Open Access

Hydraulic Conditions for Stick-Slip Tremor Beneath an Alpine Glacier

Key Points

  • Seismogenic stick-slip tremor occurs at the confluence of two subglacial channels during diurnal high-melt periods on an Alpine glacier

  • During tremor, the seismic moment released by stick-slip sliding is ∼10 times higher than outside of tremor periods

  • An extended spring-loaded slider-block model describes tremor activity with asperity loading from viscous creep and cavity formation

Uncovering Basal Friction in Northwest Greenland Using an Ice Flow Model and Observations of the Past Decade

Key Points

  • Observed evolution of glaciers in northwest Greenland is best reproduced under semi-plastic beds with changes in effective pressure

  • The analysis at glacier scale suggests heterogeneous bed conditions in northwest Greenland, not detected from a regional analysis

  • The future sea-level contribution of northwest Greenland varies by 118% under different representations of friction

Open Access

A Consistent Framework for Coupling Basal Friction With Subglacial Hydrology on Hard-Bedded Glaciers

Key Points

  • We introduce a consistent framework to describe the effect of cavitation on both friction and hydraulic transmissivity

  • This approach reduces the number of parameters of the coupled hydro-mechanical problem and shows better performance in explaining our data

  • We find that seasonal sliding variations are well captured assuming cavities in equilibrium with their average discharge

Free Access

A Weak Precipitation Sensitivity of Glacier Runoff

Key Points

  • Glacier runoff is relatively insensitive to the interannual variability of precipitation

  • The above property is independent of the climate setting of the glacier

  • A temperature-sensitive glacier runoff and a precipitation-sensitive off-glacier runoff determine the climate response of catchment runoff

Open Access

Modeling the Deformation Regime of Thwaites Glacier, West Antarctica, Using a Simple Flow Relation for Ice Anisotropy (ESTAR)

Key Points

  • Flow relations that account for tertiary creep and anisotropy change the simulated contributions of deformation and sliding to overall flow

  • Ice in tertiary creep is softer leading to increased simulated vertical shear deformation where bed parallel shear stresses dominate

  • How flow relations account for anisotropy influences the simulated contributions of longitudinal and transverse stresses in momentum balance

Open Access

Seasonal Tidewater Glacier Terminus Oscillations Bias Multi-Decadal Projections of Ice Mass Change

Key Points

  • Seasonal terminus oscillations induce a systematic bias in multi-decadal mass loss of retreating glaciers

  • Sign of mass loss bias depends on bed slope and magnitude of oscillations in ice front position

  • Mass loss bias is more sensitive to bed slope at the terminus than to sliding law

Open Access

On the Limitations of Using Polarimetric Radar Sounding to Infer the Crystal Orientation Fabric of Ice Masses

Key Points

  • Radar returns over glacier ice are, for normal incidence, insensitive to whether or not a vertical principal fabric direction exists

  • The harmonic mode responsible for a nonvertical principal fabric direction might be determined from oblique radar sounding

  • Assuming a vertical principal fabric direction when there is none can substantially affect inferred directional viscosities of glacier ice

Open Access

Modeling the Dynamics of Supraglacial Rivers and Distributed Meltwater Flow With the Subaerial Drainage System (SaDS) Model

Key Points

  • SaDS dynamically models supraglacial water flow in a distributed sheet and in supraglacial channels

  • Modeled moulin inputs show complex and heterogeneous seasonal dynamics

  • Predicted supraglacial lake and river locations agree with mapping on the Greenland Ice Sheet

Free Access

Mapping the Sensitivity of the Amundsen Sea Embayment to Changes in External Forcings Using Automatic Differentiation

Key Points

  • Future ice discharge is sensitive to basal conditions within 60 km of the grounding zone

  • Pine Island Glacier's projected mass balance is most sensitive to the strength of its shear margins

  • The integrity of Thwaites' ice shelf connecting to the Eastern Ice Rise is critical

Open Access

Fine Structure of Microseismic Glacial Stick-Slip

Key Points

  • We study frictional processes at the bed of a glacier by drilling through 200 m ice and reaching an active stick-slip asperity

  • Seismicity that is not measurable from the ice surface clusters at distinct asperities located within a confined bed region

  • Asperities host characteristic multi-asperity ruptures, similar to the Parkfield section of the San Andreas Fault

Free Access

Drivers of Change of Thwaites Glacier, West Antarctica, Between 1995 and 2015

Key Points

  • The reduction in basal traction due to grounding line retreat plays a critical role on Thwaites's dynamics in agreement with previous studies

  • Ocean-induced melt leads to a sustained acceleration and grounding line retreat consistent with observations and earlier work

  • Improved forecasts of Thwaites demand reliable melt estimates coupled to models that accurately reproduce the response to downstream changes

Open Access

Grounding-Zone Flow Variability of Priestley Glacier, Antarctica, in a Diurnal Tidal Regime

Key Points

  • Terrestrial radar interferometry and GNSS identify dynamic changes at Priestley Glacier, Antarctica, forced by diurnal ocean tides

  • Horizontal displacements vary semi-diurnally, are strongest in the shelf and decay near-linearly >10 km upstream of the grounding line

  • Grounding line migration is small and flexural softening in ice-shelf shear margins can explain the semi-diurnal ice flow component

Open Access

Quantifying Relative Contributions of Light-Absorbing Particles From Domestic and Foreign Sources on Snow Melt at Sapporo, Japan During the 2011–2012 Winter

Key Points

  • A model chain of a detailed aerosol chemical transport model and a multilayered physical snowpack model is evaluated at Sapporo, Japan

  • The model reproduces the measured seasonal evolution of the mass concentrations of light-absorbing particles in the surface snowpack

  • Light-absorbing particles from domestic and foreign sources could shorten the snow cover duration by a maximum of 5 and 10 days, respectively

Free Access

Surface Expression and Apparent Timing of Subglacial Lake Oscillations Controlled by Viscous Ice Flow

Key Points

  • Altimetry-derived estimates of subglacial lake size and volume change can deviate considerably from their true values due to ice flow

  • Viscous relaxation of topography can force the apparent highstand and lowstand times to precede the true times by months to years

  • Changes in subglacial lake volume are not always observable due to relaxation of the ice-sheet surface and altimetry resolution limitations

Open Access

The Role of Differential Ablation and Dynamic Detachment in Driving Accelerating Mass Loss From a Debris-Covered Himalayan Glacier

Key Points

  • Debris-covered glaciers are losing mass at a similar rate to clean-ice glaciers in High Mountain Asia

  • Parameterizing differential ablation in an ice-flow model increases net mass loss from Khumbu Glacier by 29%–47%

  • Dynamic detachment of the upper active glacier from the stagnant debris-covered tongue after 1900 CE could have accelerated recent mass loss

Open Access

Evaluating the Forecast Impact of Assimilating ATOVS Radiance With the Regional System of Multigrid NLS-4DVar Data Assimilation for Numerical Weather Prediction (SNAP)

Key Points

  • The multigrid NLS-4DVar method is used to assimilate satellite radiance

  • Assimilating Advanced TIROS Operational Vertical Sounder (ATOVS) data with regional SNAP improves precipitation forecast

  • The regional SNAP performs better than Gridpoint Statistical Interpolation (GSI) for u/v wind and temperature variables