{"dp_type": "Project", "free_text": "Basal Shear Stress"}
[{"awards": "2053169 Kingslake, Jonathan", "bounds_geometry": null, "dataset_titles": null, "datasets": null, "date_created": "Fri, 15 Sep 2023 00:00:00 GMT", "description": "When ice sheets and glaciers lose ice faster than it accumulates from snowfall, they shrink and contribute to sea-level rise. This has consequences for coastal communities around the globe by, for example, increasing the frequency of damaging storm surges. Sea-level rise is already underway and a major challenge for the geoscience community is improving predictions of how this will evolve. The Antarctic Ice Sheet is the largest potential contributor to sea-level rise and its future is highly uncertain. It loses ice through two main mechanisms: the formation of icebergs and melting at the base of floating ice shelves on its periphery. Ice flows under gravity towards the ocean and the rate of ice flow controls how fast ice sheets and glaciers shrink. In Greenland and Antarctica, ice flow is focused into outlet glaciers and ice streams, which flow much faster than surrounding areas. Moreover, parts of the Greenland Ice Sheet speed up and slow down substantially on hourly to seasonal time scales, particularly where meltwater from the surface reaches the base of the ice. Meltwater reaching the base changes ice flow by altering basal water pressure and consequently the friction exerted on the ice by the rock and sediment beneath. This phenomenon has been observed frequently in Greenland but not in Antarctica. Recent satellite observations suggest this phenomenon also occurs on outlet glaciers in the Antarctic Peninsula. Meltwater reaching the base of the Antarctic Ice Sheet is likely to become more common as air temperature and surface melting are predicted to increase around Antarctica this century. This project aims to confirm the recent satellite observations, establish a baseline against which to compare future changes, and improve understanding of the direct influence of meltwater on Antarctic Ice Sheet dynamics. This is a project jointly funded by the National Science Foundation?s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries.\r\n\r\nThis project will include a field campaign on Flask Glacier, an Antarctic Peninsula outlet glacier, and a continent-wide remote sensing survey. These activities will allow the team to test three hypotheses related to the Antarctic Ice Sheet?s dynamic response to surface meltwater: (1) short-term changes in ice velocity indicated by satellite data result from surface meltwater reaching the bed, (2) this is widespread in Antarctica today, and (3) this results in a measurable increase in mean annual ice discharge. The project is a collaboration between US- and UK-based researchers and will be supported logistically by the British Antarctic Survey. The project aims to provide insights into both the drivers and implications of short-term changes in ice flow velocity caused by surface melting. For example, showing conclusively that meltwater directly influences Antarctic ice dynamics would have significant implications for understanding the response of Antarctica to atmospheric warming, as it did in Greenland when the phenomenon was first detected there twenty years ago. This work will also potentially influence other fields, as surface meltwater reaching the bed of the Antarctic Ice Sheet may affect ice rheology, subglacial hydrology, submarine melting, calving, ocean circulation, and ocean biogeochemistry. The project aims to have broader impacts on science and society by supporting early-career scientists, UK-US collaboration, education and outreach, and adoption of open data science approaches within the glaciological community.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "ICE SHEETS; GLACIER MOTION/ICE SHEET MOTION; Antarctic Peninsula; BASAL SHEAR STRESS", "locations": "Antarctic Peninsula", "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Kingslake, Jonathan; Sole, Andrew; Livingstone, Stephen; Winter, Kate; Ely, Jeremy", "platforms": null, "repositories": null, "science_programs": null, "south": null, "title": "NSFGEO-NERC: Investigating the Direct Influence of Meltwater on Antarctic Ice Sheet Dynamics", "uid": "p0010436", "west": null}, {"awards": "2012958 Meyer, Colin", "bounds_geometry": null, "dataset_titles": "Frozen fringe friction ; Ring shear bed deformation measurements ", "datasets": [{"dataset_uid": "601757", "doi": "10.15784/601757", "keywords": "Antarctica", "people": "Zoet, Lucas", "repository": "USAP-DC", "science_program": null, "title": "Ring shear bed deformation measurements ", "url": "https://www.usap-dc.org/view/dataset/601757"}, {"dataset_uid": "601756", "doi": "10.15784/601756", "keywords": "Antarctica", "people": "Zoet, Lucas", "repository": "USAP-DC", "science_program": null, "title": "Frozen fringe friction ", "url": "https://www.usap-dc.org/view/dataset/601756"}], "date_created": "Wed, 13 Sep 2023 00:00:00 GMT", "description": "The fastest-changing regions of the Antarctic and Greenland Ice Sheets that contribute most to sea-level rise are underlain by soft sediments that facilitate glacier motion. Glacier ice can infiltrate several meters into these sediments, depending on the temperature and water pressure at the base of the glacier. To understand how ice infiltration into subglacial sediments affects glacier slip, the team will conduct laboratory experiments under relevant temperature and pressure conditions and compare the results to state-of-the-art mathematical models. Through an undergraduate research exchange between University of Wisconsin-Madison, Dartmouth College, and the College of Menominee Nation, Native American students will work on laboratory experiments in one summer and mathematical theory in the following summer.\u003cbr/\u003e\u003cbr/\u003eIce-sediment interactions are a central component of ice-sheet and landform-development models. Limited process understanding poses a key uncertainty for ice-sheet models that are used to forecast sea-level rise. This uncertainty underscores the importance of developing experimentally validated, theoretically robust descriptions of processes at the ice-sediment interface. To achieve this, the team aims to build on long-established theoretical, experimental, and field investigations that have elucidated the central role of premelting and surface-energy effects in controlling the dynamics of frost heave in soils. Project members will theoretically describe and experimentally test the role of premelting at the basal ice-sediment interface. The experiments are designed to provide quantitative insight into the impact of ice infiltration into sediments on glacier sliding, erosion, and subglacial landform evolution.\u003cbr/\u003e\u003cbr/\u003eThis award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "BASAL SHEAR STRESS; GLACIER MOTION/ICE SHEET MOTION; GLACIERS/ICE SHEETS", "locations": null, "north": null, "nsf_funding_programs": "Arctic Natural Sciences; Antarctic Glaciology", "paleo_time": null, "persons": "Meyer, Colin; Rempel, Alan; Zoet, Lucas", "platforms": null, "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Collaborative Research: Freeze-on of Subglacial Sediments in Experiments and Theory", "uid": "p0010434", "west": null}, {"awards": "1245871 McCarthy, Christine", "bounds_geometry": null, "dataset_titles": "Dataset for Tidal modulation of ice streams: Effect of periodic sliding velocity on ice friction and healing; Rate-state friction parameters for ice-on-rock oscillation experiments; RSFitOSC", "datasets": [{"dataset_uid": "200237", "doi": "", "keywords": null, "people": null, "repository": "GitHub", "science_program": null, "title": "RSFitOSC", "url": "https://github.com/rmskarbek/RSFitOSC"}, {"dataset_uid": "601467", "doi": "10.15784/601467", "keywords": "Antarctica", "people": "Savage, Heather; Skarbek, Rob; McCarthy, Christine M.", "repository": "USAP-DC", "science_program": null, "title": "Rate-state friction parameters for ice-on-rock oscillation experiments", "url": "https://www.usap-dc.org/view/dataset/601467"}, {"dataset_uid": "601497", "doi": "10.15784/601497", "keywords": "Antarctica", "people": "Savage, Heather; McCarthy, Christine M.; Skarbek, Rob", "repository": "USAP-DC", "science_program": null, "title": "Dataset for Tidal modulation of ice streams: Effect of periodic sliding velocity on ice friction and healing", "url": "https://www.usap-dc.org/view/dataset/601497"}], "date_created": "Fri, 04 Jun 2021 00:00:00 GMT", "description": "This award supports a project to conduct laboratory experiments with a new, custom-fabricated cryo-friction apparatus to explore ice deformation oscillatory stresses like those experienced by tidewater glaciers in nature. The experimental design will explore the dynamic frictional properties of periodically loaded ice sliding on rock. Although the frictional strength of ice has been studied in the past these studies have all focused on constant rates of loading and sliding. The results of this work will advance understanding of ice stream dynamics by improving constraints on key material and frictional properties and allowing physics-based predictions of the amplitude and phase of glacier strain due to tidally induced stress variations. The intellectual merit of this work is that it will result in a better understanding of dynamic rheological parameters and will provide better predictive tools for dynamic glacier flow. The proposed experiments will provide dynamic material properties of ice and rock deformation at realistic frequencies experienced by Antarctic glaciers. The PIs will measure the full spectrum of material response from elastic to anelastic to viscous. The study will provide better constraints to improve predictive capability for glacier and ice-stream response to external forcing. The broader impacts of the work include providing estimates of material properties that can be used to broaden our understanding of glacier flow and that will ultimately be used for models of sea level rise and ice sheet stability. The ability to predict sea level in the near future is contingent on understanding of the processes responsible for flow of Antarctic ice streams and glaciers. Modulation of glacier flow by ocean tides represents a natural experiment that can be used to improve knowledge of ice and bed properties, and of the way in which these properties depend on time-varying forcings. Presently, the influence of tidal forcing on glacier movement is poorly understood, and knowledge of ice properties under tidal loading conditions is limited. The study will generate results of interest beyond polar science by examining phenomena that are of interest to seismology, glaciology and general materials science. The project will provide valuable research and laboratory experience for two undergraduate interns and will provide experience for the PI (currently a postdoc) in leading a scientific project. The three PIs are early career scientists. This proposal does not require fieldwork in the Antarctic.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "USAP-DC; USA/NSF; Amd/Us; AMD; Ice Deformation; LABORATORY; BASAL SHEAR STRESS", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "McCarthy, Christine M.; Savage, Heather", "platforms": "OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "GitHub", "repositories": "GitHub; USAP-DC", "science_programs": null, "south": null, "title": "Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers", "uid": "p0010186", "west": null}, {"awards": "1842021 Campbell, Seth", "bounds_geometry": "POLYGON((-168 -82,-162.3 -82,-156.6 -82,-150.9 -82,-145.2 -82,-139.5 -82,-133.8 -82,-128.1 -82,-122.4 -82,-116.7 -82,-111 -82,-111 -82.5,-111 -83,-111 -83.5,-111 -84,-111 -84.5,-111 -85,-111 -85.5,-111 -86,-111 -86.5,-111 -87,-116.7 -87,-122.4 -87,-128.1 -87,-133.8 -87,-139.5 -87,-145.2 -87,-150.9 -87,-156.6 -87,-162.3 -87,-168 -87,-168 -86.5,-168 -86,-168 -85.5,-168 -85,-168 -84.5,-168 -84,-168 -83.5,-168 -83,-168 -82.5,-168 -82))", "dataset_titles": "2017 GPR Observations of the Whillans and Mercer Ice Streams; Whillans and Mercer Shear Margin Ice Flow simulation in ISSM", "datasets": [{"dataset_uid": "601403", "doi": "10.15784/601403", "keywords": "Antarctica; Crevasses; Glaciology; GPR; GPS; Ice Sheet Flow Model; Ice Shelf Dynamics; Snow/ice; Snow/Ice; Whillans Ice Stream", "people": "Kaluzienski, Lynn", "repository": "USAP-DC", "science_program": null, "title": "2017 GPR Observations of the Whillans and Mercer Ice Streams", "url": "https://www.usap-dc.org/view/dataset/601403"}, {"dataset_uid": "601404", "doi": "10.15784/601404", "keywords": "Antarctica; Glaciology; Ice Sheet Flow Model; Ice Shelf Dynamics; Mercer Ice Stream; Model Data; Snow/ice; Snow/Ice; Whillans Ice Stream", "people": "Kaluzienski, Lynn", "repository": "USAP-DC", "science_program": null, "title": "Whillans and Mercer Shear Margin Ice Flow simulation in ISSM", "url": "https://www.usap-dc.org/view/dataset/601404"}], "date_created": "Mon, 14 Dec 2020 00:00:00 GMT", "description": "The Siple Coast in West Antarctica has undergone significant glacier changes over the last millenium. Several ice streams--rapidly moving streams of ice bordered by slow-moving ice--exist in this region that feeds into the Ross Ice Shelf. A long-term slowdown of Whillans Ice Stream appears to be occurring, and this is affecting the zone between the Whillans and Mercer Ice Streams. However, the consistency of this slowdown and resulting changes to the shear margin between the two ice streams are unknown. Shear zone stability represents a potentially critical control on mass balance of ice sheets, especially in regions of fast ice flow where basal shear stress is minimal. This project is therefore focused on understanding the spatial and temporal change of ice flow kinematics, shear margin structure, and shear margin location between Whillans and Mercer Ice Streams. A collateral benefit of and driver for this as a RAPID project is to test a method for assessing where crevassing will develop in this zone of steep velocity gradients. Such a method may benefit not only near-term field-project planning in the 2018-19 field season, but also planning for future fieldwork and traverses.\u003cbr/\u003e\u003cbr/\u003eThe team will use velocity estimates derived from available remote sensing datasets to determine transient velocity patterns and shifts in the shear-zone location over the last 20 years. This velocity time series will be incorporated into a large-scale ice-sheet model to estimate ice-sheet susceptibility to changing boundary conditions over the next century based on likely regional ice-flux scenarios. This approach is an extension of recent work conducted by the team that shows promise for predicting areas of changing high strain rates indicative of an active glacier shear margin. The ultimate objectives are to characterize the flow field of merging ice streams over time and investigate lateral boundary migration. This will provide a better understanding of shear-margin control on ice-shelf and up-glacier stability.\u003cbr/\u003e\u003cbr/\u003eThis award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": -111.0, "geometry": "POINT(-139.5 -84.5)", "instruments": "EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS", "is_usap_dc": true, "keywords": "FIELD SURVEYS; Whillans Ice Stream; USAP-DC; Amd/Us; USA/NSF; GLACIER MOTION/ICE SHEET MOTION; MODELS; AMD", "locations": "Whillans Ice Stream", "north": -82.0, "nsf_funding_programs": "Polar Special Initiatives; Antarctic Glaciology", "paleo_time": null, "persons": "Campbell, Seth; Koons, Peter", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS; OTHER \u003e MODELS \u003e MODELS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -87.0, "title": "RAPID Proposal: Constraining kinematics of the Whillans/Mercer Ice Stream Confluence", "uid": "p0010145", "west": -168.0}, {"awards": "0934534 Sergienko, Olga", "bounds_geometry": "POLYGON((-106 -70,-105.4 -70,-104.8 -70,-104.2 -70,-103.6 -70,-103 -70,-102.4 -70,-101.8 -70,-101.2 -70,-100.6 -70,-100 -70,-100 -70.6,-100 -71.2,-100 -71.8,-100 -72.4,-100 -73,-100 -73.6,-100 -74.2,-100 -74.8,-100 -75.4,-100 -76,-100.6 -76,-101.2 -76,-101.8 -76,-102.4 -76,-103 -76,-103.6 -76,-104.2 -76,-104.8 -76,-105.4 -76,-106 -76,-106 -75.4,-106 -74.8,-106 -74.2,-106 -73.6,-106 -73,-106 -72.4,-106 -71.8,-106 -71.2,-106 -70.6,-106 -70))", "dataset_titles": "Inverted Basal Shear Stress of Antarctic and Greenland Ice Streams and Glaciers", "datasets": [{"dataset_uid": "609626", "doi": "10.7265/N5XS5SBW", "keywords": "Antarctica; Arctic; Bindschadler Ice Stream; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Greenland; Lambert Ice Stream; Macayeal Ice Stream; Pine Island Glacier; Thwaites Glacier", "people": "Sergienko, Olga", "repository": "USAP-DC", "science_program": null, "title": "Inverted Basal Shear Stress of Antarctic and Greenland Ice Streams and Glaciers", "url": "https://www.usap-dc.org/view/dataset/609626"}], "date_created": "Thu, 06 Feb 2014 00:00:00 GMT", "description": "Funds are provided to enable applications of powerful mathematical concepts and computational tools for rigorous sensitivity analysis, pseudo-spectra and generalized stability theory, and advanced state estimation in the context of large-scale ice sheet modeling. At the center of the proposal is the generation and application of adjoint model (ADM) and tangent linear model (TLM) components of the new Community Ice Sheet Model (CISM). The goal will be achieved through rigorous use of automatic differentiation (AD) to ensure synchronicity between the ongoing model development and improvement in terms of better representation of higher-order stress terms (which account for crucial fast flow regimes) of the nonlinear forward model (NLM) code and the derivative codes. The adjoint enables extremely efficient computation of gradients of scalar-valued functions in very high-dimensional control spaces. A hierarchy of applications is envisioned: (1) sensitivity calculations in support of the Intergovernmental Panel on Climate Change (IPCC) in order to determine to which control variables the polar ice sheet volumes are most sensitive; based on adjoint sensitivity maps, to establish quantitative estimates of ice sheet volume changes for relevant forcing scenarios; and to assess how sensitivities change when including higher-order stress terms; (2) coupling of the ADM and TLM to calculate pseudo-spectra or singular vectors (SV?s) of relevant ice sheet norms; SV?s provide perturbation patterns which lead to non-normal growth, optimally amplifying norm kernels over finite times; among the many applications of SV?s are optimal initialization of ensembles to assess uncertainties; SV?s are calculated through matrix-free iterative solution of a generalized eigenvalue problem via Lanczos or Arnoldi implicit restart algorithms; (3) a long-term goal is the development of an ice sheet state estimation system based on the adjoint or Lagrange Multiplier Method (LMM) in order to synthesize, in a formal manner, the increasing number and heterogeneous types of observations with a three-dimensional, state-of-the-art ice sheet model; an important requirement is that the adjoint incorporate new schemes that are being developed for CISM to capture crucial, but as yet unrepresented physical processes.", "east": -100.0, "geometry": "POINT(-103 -73)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PHOTON/OPTICAL DETECTORS \u003e VISUAL OBSERVATIONS", "is_usap_dc": true, "keywords": "Not provided; Inverse Modeling; GROUND-BASED OBSERVATIONS; Basal Shear Stress", "locations": null, "north": -70.0, "nsf_funding_programs": "Arctic Natural Sciences", "paleo_time": null, "persons": "Sergienko, Olga", "platforms": "LAND-BASED PLATFORMS \u003e PERMANENT LAND SITES \u003e GROUND-BASED OBSERVATIONS; Not provided", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -76.0, "title": "COLLABORATIVE RESEARCH: Enabling ice sheet sensitivity and stability analysis with a large-scale higher-order ice sheet model\u0027s adjoint to support sea level change assessment", "uid": "p0000048", "west": -106.0}, {"awards": "0126149 Liu, Hongxing", "bounds_geometry": null, "dataset_titles": "Access to Antarctic coastline coverage and reference documents; Access to Antarctic snow zone coverage and reference documents; Access to boundary file and reference documents; Access to ice velocity data and reference documents; Access to snow melt extent image files and reference documents", "datasets": [{"dataset_uid": "001350", "doi": "", "keywords": null, "people": null, "repository": "PI website", "science_program": null, "title": "Access to boundary file and reference documents", "url": "http://geog.tamu.edu/~liu/research/download.htm"}, {"dataset_uid": "001640", "doi": "", "keywords": null, "people": null, "repository": "PI website", "science_program": null, "title": "Access to snow melt extent image files and reference documents", "url": "http://geog.tamu.edu/~liu/research/download.htm"}, {"dataset_uid": "001779", "doi": "", "keywords": null, "people": null, "repository": "PI website", "science_program": null, "title": "Access to ice velocity data and reference documents", "url": "http://geog.tamu.edu/~liu/research/download.htm"}, {"dataset_uid": "001351", "doi": "", "keywords": null, "people": null, "repository": "PI website", "science_program": null, "title": "Access to Antarctic coastline coverage and reference documents", "url": "http://geog.tamu.edu/~liu/research/download.htm"}, {"dataset_uid": "001352", "doi": "", "keywords": null, "people": null, "repository": "PI website", "science_program": null, "title": "Access to Antarctic snow zone coverage and reference documents", "url": "http://geog.tamu.edu/~liu/research/download.htm"}], "date_created": "Tue, 15 Aug 2006 00:00:00 GMT", "description": "This award supports a project to characterize the morphology, ice motion velocity and mass balance of Lambert Glacier, Antarctica using state-of-the-art remote sensing and GIS techniques. Lambert Glacier is the largest ice stream in the world. Because of its size, it plays a fundamental role in the study of glacial dynamics and mass budget in response to present and future climate changes. Along with the bedrock topography and ice thickness data derived from airborne radio echo soundings and snow accumulation data compiled from ground-based measurements, the dynamic behavior and mass balance of the Lambert glacial basin in a Geographic Information Systems (GIS) environment will be examined. Specific objectives are to: (1) Extract two-dimensional ice velocity field over the entire Lambert glacial basin using speckle matching and differential interferometric SAR (InSAR) techniques, and produce a full coverage of radar coherence map over the drainage basin. With the ice velocity data, calculate the strain rate field from the initiation areas of the ice stream onto the Amery Ice Shelf; (2) Derive high-resolution digital elevation model (DEM) over the Lambert glacial drainage basin using SAR stereo, differential interferometric SAR, and GLAS laser altimetry techniques. Based on the DEM, extract ice divides and ice flow directions, delineate the snow catchment basin, and calculate the balance deformation velocity and the basal shear stress; (3) Interpolate traverse ice thickness data collected by Australian and Russian airborne radio echo sounding surveys into a regular grid, and derive a regular grid of bedrock topography in combination with the DEM; (4) Integrate newly derived ice velocity and ice thickness data as well as snow accumulation rate data compiled from previous ground-based measurements into a geographic information system (GIS), and calculate the mass flux through the ice stream at the grounding lines and net mass balance throughout the drainage basin. With these new measurements and calculations derived from advanced remote sensing techniques, we will be able to improve our understanding of dynamic behavior and current mass balance status of the Lambert glacial basin, gain an insight on the relationship between ice mass change and the variation in regional and global climate at decadal scale, and provide an evaluation on the issue of whether the Lambert glacier basin is subject to surging in the context of future climate change.", "east": null, "geometry": null, "instruments": "EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e SPECTROMETERS/RADIOMETERS \u003e IMAGING SPECTROMETERS/RADIOMETERS \u003e SMMR; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e SPECTROMETERS/RADIOMETERS \u003e IMAGING SPECTROMETERS/RADIOMETERS \u003e SSM/I; EARTH REMOTE SENSING INSTRUMENTS \u003e ACTIVE REMOTE SENSING \u003e IMAGING RADARS \u003e IFSAR; EARTH REMOTE SENSING INSTRUMENTS \u003e ACTIVE REMOTE SENSING \u003e IMAGING RADARS \u003e SAR", "is_usap_dc": false, "keywords": "DEM; Not provided; RADARSAT-1", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Liu, Hongxing; Jezek, Kenneth", "platforms": "Not provided; OTHER \u003e MODELS \u003e DEM; SPACE-BASED PLATFORMS \u003e EARTH OBSERVATION SATELLITES \u003e RADARSAT \u003e RADARSAT-1", "repo": "PI website", "repositories": "PI website", "science_programs": null, "south": null, "title": "High-Resolution Modeling of Surface Topography, Ice Motion, and Mass Balance in the Lambert Glacial Basin using Radar Remote Sensing and GIS Techniques", "uid": "p0000204", "west": null}]
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Project Title/Abstract/Map | NSF Award(s) | Date Created | PIs / Scientists | Dataset Links and Repositories | Abstract | Bounds Geometry | Geometry | Selected | Visible | |||||
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NSFGEO-NERC: Investigating the Direct Influence of Meltwater on Antarctic Ice Sheet Dynamics
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2053169 |
2023-09-15 | Kingslake, Jonathan; Sole, Andrew; Livingstone, Stephen; Winter, Kate; Ely, Jeremy | No dataset link provided | When ice sheets and glaciers lose ice faster than it accumulates from snowfall, they shrink and contribute to sea-level rise. This has consequences for coastal communities around the globe by, for example, increasing the frequency of damaging storm surges. Sea-level rise is already underway and a major challenge for the geoscience community is improving predictions of how this will evolve. The Antarctic Ice Sheet is the largest potential contributor to sea-level rise and its future is highly uncertain. It loses ice through two main mechanisms: the formation of icebergs and melting at the base of floating ice shelves on its periphery. Ice flows under gravity towards the ocean and the rate of ice flow controls how fast ice sheets and glaciers shrink. In Greenland and Antarctica, ice flow is focused into outlet glaciers and ice streams, which flow much faster than surrounding areas. Moreover, parts of the Greenland Ice Sheet speed up and slow down substantially on hourly to seasonal time scales, particularly where meltwater from the surface reaches the base of the ice. Meltwater reaching the base changes ice flow by altering basal water pressure and consequently the friction exerted on the ice by the rock and sediment beneath. This phenomenon has been observed frequently in Greenland but not in Antarctica. Recent satellite observations suggest this phenomenon also occurs on outlet glaciers in the Antarctic Peninsula. Meltwater reaching the base of the Antarctic Ice Sheet is likely to become more common as air temperature and surface melting are predicted to increase around Antarctica this century. This project aims to confirm the recent satellite observations, establish a baseline against which to compare future changes, and improve understanding of the direct influence of meltwater on Antarctic Ice Sheet dynamics. This is a project jointly funded by the National Science Foundation?s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries. This project will include a field campaign on Flask Glacier, an Antarctic Peninsula outlet glacier, and a continent-wide remote sensing survey. These activities will allow the team to test three hypotheses related to the Antarctic Ice Sheet?s dynamic response to surface meltwater: (1) short-term changes in ice velocity indicated by satellite data result from surface meltwater reaching the bed, (2) this is widespread in Antarctica today, and (3) this results in a measurable increase in mean annual ice discharge. The project is a collaboration between US- and UK-based researchers and will be supported logistically by the British Antarctic Survey. The project aims to provide insights into both the drivers and implications of short-term changes in ice flow velocity caused by surface melting. For example, showing conclusively that meltwater directly influences Antarctic ice dynamics would have significant implications for understanding the response of Antarctica to atmospheric warming, as it did in Greenland when the phenomenon was first detected there twenty years ago. This work will also potentially influence other fields, as surface meltwater reaching the bed of the Antarctic Ice Sheet may affect ice rheology, subglacial hydrology, submarine melting, calving, ocean circulation, and ocean biogeochemistry. The project aims to have broader impacts on science and society by supporting early-career scientists, UK-US collaboration, education and outreach, and adoption of open data science approaches within the glaciological community. | None | None | false | false | |||||
Collaborative Research: Freeze-on of Subglacial Sediments in Experiments and Theory
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2012958 |
2023-09-13 | Meyer, Colin; Rempel, Alan; Zoet, Lucas |
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The fastest-changing regions of the Antarctic and Greenland Ice Sheets that contribute most to sea-level rise are underlain by soft sediments that facilitate glacier motion. Glacier ice can infiltrate several meters into these sediments, depending on the temperature and water pressure at the base of the glacier. To understand how ice infiltration into subglacial sediments affects glacier slip, the team will conduct laboratory experiments under relevant temperature and pressure conditions and compare the results to state-of-the-art mathematical models. Through an undergraduate research exchange between University of Wisconsin-Madison, Dartmouth College, and the College of Menominee Nation, Native American students will work on laboratory experiments in one summer and mathematical theory in the following summer.<br/><br/>Ice-sediment interactions are a central component of ice-sheet and landform-development models. Limited process understanding poses a key uncertainty for ice-sheet models that are used to forecast sea-level rise. This uncertainty underscores the importance of developing experimentally validated, theoretically robust descriptions of processes at the ice-sediment interface. To achieve this, the team aims to build on long-established theoretical, experimental, and field investigations that have elucidated the central role of premelting and surface-energy effects in controlling the dynamics of frost heave in soils. Project members will theoretically describe and experimentally test the role of premelting at the basal ice-sediment interface. The experiments are designed to provide quantitative insight into the impact of ice infiltration into sediments on glacier sliding, erosion, and subglacial landform evolution.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. | None | None | false | false | |||||
Laboratory Study of Ice Deformation under Tidal Loading Conditions with Application to Antarctic Glaciers
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1245871 |
2021-06-04 | McCarthy, Christine M.; Savage, Heather | This award supports a project to conduct laboratory experiments with a new, custom-fabricated cryo-friction apparatus to explore ice deformation oscillatory stresses like those experienced by tidewater glaciers in nature. The experimental design will explore the dynamic frictional properties of periodically loaded ice sliding on rock. Although the frictional strength of ice has been studied in the past these studies have all focused on constant rates of loading and sliding. The results of this work will advance understanding of ice stream dynamics by improving constraints on key material and frictional properties and allowing physics-based predictions of the amplitude and phase of glacier strain due to tidally induced stress variations. The intellectual merit of this work is that it will result in a better understanding of dynamic rheological parameters and will provide better predictive tools for dynamic glacier flow. The proposed experiments will provide dynamic material properties of ice and rock deformation at realistic frequencies experienced by Antarctic glaciers. The PIs will measure the full spectrum of material response from elastic to anelastic to viscous. The study will provide better constraints to improve predictive capability for glacier and ice-stream response to external forcing. The broader impacts of the work include providing estimates of material properties that can be used to broaden our understanding of glacier flow and that will ultimately be used for models of sea level rise and ice sheet stability. The ability to predict sea level in the near future is contingent on understanding of the processes responsible for flow of Antarctic ice streams and glaciers. Modulation of glacier flow by ocean tides represents a natural experiment that can be used to improve knowledge of ice and bed properties, and of the way in which these properties depend on time-varying forcings. Presently, the influence of tidal forcing on glacier movement is poorly understood, and knowledge of ice properties under tidal loading conditions is limited. The study will generate results of interest beyond polar science by examining phenomena that are of interest to seismology, glaciology and general materials science. The project will provide valuable research and laboratory experience for two undergraduate interns and will provide experience for the PI (currently a postdoc) in leading a scientific project. The three PIs are early career scientists. This proposal does not require fieldwork in the Antarctic. | None | None | false | false | ||||||
RAPID Proposal: Constraining kinematics of the Whillans/Mercer Ice Stream Confluence
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1842021 |
2020-12-14 | Campbell, Seth; Koons, Peter |
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The Siple Coast in West Antarctica has undergone significant glacier changes over the last millenium. Several ice streams--rapidly moving streams of ice bordered by slow-moving ice--exist in this region that feeds into the Ross Ice Shelf. A long-term slowdown of Whillans Ice Stream appears to be occurring, and this is affecting the zone between the Whillans and Mercer Ice Streams. However, the consistency of this slowdown and resulting changes to the shear margin between the two ice streams are unknown. Shear zone stability represents a potentially critical control on mass balance of ice sheets, especially in regions of fast ice flow where basal shear stress is minimal. This project is therefore focused on understanding the spatial and temporal change of ice flow kinematics, shear margin structure, and shear margin location between Whillans and Mercer Ice Streams. A collateral benefit of and driver for this as a RAPID project is to test a method for assessing where crevassing will develop in this zone of steep velocity gradients. Such a method may benefit not only near-term field-project planning in the 2018-19 field season, but also planning for future fieldwork and traverses.<br/><br/>The team will use velocity estimates derived from available remote sensing datasets to determine transient velocity patterns and shifts in the shear-zone location over the last 20 years. This velocity time series will be incorporated into a large-scale ice-sheet model to estimate ice-sheet susceptibility to changing boundary conditions over the next century based on likely regional ice-flux scenarios. This approach is an extension of recent work conducted by the team that shows promise for predicting areas of changing high strain rates indicative of an active glacier shear margin. The ultimate objectives are to characterize the flow field of merging ice streams over time and investigate lateral boundary migration. This will provide a better understanding of shear-margin control on ice-shelf and up-glacier stability.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. | POLYGON((-168 -82,-162.3 -82,-156.6 -82,-150.9 -82,-145.2 -82,-139.5 -82,-133.8 -82,-128.1 -82,-122.4 -82,-116.7 -82,-111 -82,-111 -82.5,-111 -83,-111 -83.5,-111 -84,-111 -84.5,-111 -85,-111 -85.5,-111 -86,-111 -86.5,-111 -87,-116.7 -87,-122.4 -87,-128.1 -87,-133.8 -87,-139.5 -87,-145.2 -87,-150.9 -87,-156.6 -87,-162.3 -87,-168 -87,-168 -86.5,-168 -86,-168 -85.5,-168 -85,-168 -84.5,-168 -84,-168 -83.5,-168 -83,-168 -82.5,-168 -82)) | POINT(-139.5 -84.5) | false | false | |||||
COLLABORATIVE RESEARCH: Enabling ice sheet sensitivity and stability analysis with a large-scale higher-order ice sheet model's adjoint to support sea level change assessment
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0934534 |
2014-02-06 | Sergienko, Olga |
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Funds are provided to enable applications of powerful mathematical concepts and computational tools for rigorous sensitivity analysis, pseudo-spectra and generalized stability theory, and advanced state estimation in the context of large-scale ice sheet modeling. At the center of the proposal is the generation and application of adjoint model (ADM) and tangent linear model (TLM) components of the new Community Ice Sheet Model (CISM). The goal will be achieved through rigorous use of automatic differentiation (AD) to ensure synchronicity between the ongoing model development and improvement in terms of better representation of higher-order stress terms (which account for crucial fast flow regimes) of the nonlinear forward model (NLM) code and the derivative codes. The adjoint enables extremely efficient computation of gradients of scalar-valued functions in very high-dimensional control spaces. A hierarchy of applications is envisioned: (1) sensitivity calculations in support of the Intergovernmental Panel on Climate Change (IPCC) in order to determine to which control variables the polar ice sheet volumes are most sensitive; based on adjoint sensitivity maps, to establish quantitative estimates of ice sheet volume changes for relevant forcing scenarios; and to assess how sensitivities change when including higher-order stress terms; (2) coupling of the ADM and TLM to calculate pseudo-spectra or singular vectors (SV?s) of relevant ice sheet norms; SV?s provide perturbation patterns which lead to non-normal growth, optimally amplifying norm kernels over finite times; among the many applications of SV?s are optimal initialization of ensembles to assess uncertainties; SV?s are calculated through matrix-free iterative solution of a generalized eigenvalue problem via Lanczos or Arnoldi implicit restart algorithms; (3) a long-term goal is the development of an ice sheet state estimation system based on the adjoint or Lagrange Multiplier Method (LMM) in order to synthesize, in a formal manner, the increasing number and heterogeneous types of observations with a three-dimensional, state-of-the-art ice sheet model; an important requirement is that the adjoint incorporate new schemes that are being developed for CISM to capture crucial, but as yet unrepresented physical processes. | POLYGON((-106 -70,-105.4 -70,-104.8 -70,-104.2 -70,-103.6 -70,-103 -70,-102.4 -70,-101.8 -70,-101.2 -70,-100.6 -70,-100 -70,-100 -70.6,-100 -71.2,-100 -71.8,-100 -72.4,-100 -73,-100 -73.6,-100 -74.2,-100 -74.8,-100 -75.4,-100 -76,-100.6 -76,-101.2 -76,-101.8 -76,-102.4 -76,-103 -76,-103.6 -76,-104.2 -76,-104.8 -76,-105.4 -76,-106 -76,-106 -75.4,-106 -74.8,-106 -74.2,-106 -73.6,-106 -73,-106 -72.4,-106 -71.8,-106 -71.2,-106 -70.6,-106 -70)) | POINT(-103 -73) | false | false | |||||
High-Resolution Modeling of Surface Topography, Ice Motion, and Mass Balance in the Lambert Glacial Basin using Radar Remote Sensing and GIS Techniques
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0126149 |
2006-08-15 | Liu, Hongxing; Jezek, Kenneth | This award supports a project to characterize the morphology, ice motion velocity and mass balance of Lambert Glacier, Antarctica using state-of-the-art remote sensing and GIS techniques. Lambert Glacier is the largest ice stream in the world. Because of its size, it plays a fundamental role in the study of glacial dynamics and mass budget in response to present and future climate changes. Along with the bedrock topography and ice thickness data derived from airborne radio echo soundings and snow accumulation data compiled from ground-based measurements, the dynamic behavior and mass balance of the Lambert glacial basin in a Geographic Information Systems (GIS) environment will be examined. Specific objectives are to: (1) Extract two-dimensional ice velocity field over the entire Lambert glacial basin using speckle matching and differential interferometric SAR (InSAR) techniques, and produce a full coverage of radar coherence map over the drainage basin. With the ice velocity data, calculate the strain rate field from the initiation areas of the ice stream onto the Amery Ice Shelf; (2) Derive high-resolution digital elevation model (DEM) over the Lambert glacial drainage basin using SAR stereo, differential interferometric SAR, and GLAS laser altimetry techniques. Based on the DEM, extract ice divides and ice flow directions, delineate the snow catchment basin, and calculate the balance deformation velocity and the basal shear stress; (3) Interpolate traverse ice thickness data collected by Australian and Russian airborne radio echo sounding surveys into a regular grid, and derive a regular grid of bedrock topography in combination with the DEM; (4) Integrate newly derived ice velocity and ice thickness data as well as snow accumulation rate data compiled from previous ground-based measurements into a geographic information system (GIS), and calculate the mass flux through the ice stream at the grounding lines and net mass balance throughout the drainage basin. With these new measurements and calculations derived from advanced remote sensing techniques, we will be able to improve our understanding of dynamic behavior and current mass balance status of the Lambert glacial basin, gain an insight on the relationship between ice mass change and the variation in regional and global climate at decadal scale, and provide an evaluation on the issue of whether the Lambert glacier basin is subject to surging in the context of future climate change. | None | None | false | false |