[{"awards": "1643455 Enderlin, Ellyn; 1933764 Enderlin, Ellyn", "bounds_geometry": "POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))", "dataset_titles": "Crane Glacier centerline observations and modeling results ; Remotely-sensed iceberg geometries and meltwater fluxes", "datasets": [{"dataset_uid": "601679", "doi": "10.15784/601679", "keywords": "Antarctica; Elevation; Glaciology; Iceberg; Meltwater; Submarine Melt", "people": "Dickson, Adam; Enderlin, Ellyn; Miller, Emily; Dryak, Mariama; Oliver, Caitlin; Aberle, Rainey", "repository": "USAP-DC", "science_program": null, "title": "Remotely-sensed iceberg geometries and meltwater fluxes", "url": "https://www.usap-dc.org/view/dataset/601679"}, {"dataset_uid": "601617", "doi": "10.15784/601617", "keywords": "Antarctica; Antarctic Peninsula; Crane Glacier; Glacier Dynamics; Glacier Mass Discharge; Glaciers/ice Sheet; Glaciers/Ice Sheet; Glaciology; Modeling; Model Output", "people": "Marshall, Hans-Peter; Aberle, Rainey; Enderlin, Ellyn; Kopera, Michal; Meehan, Tate", "repository": "USAP-DC", "science_program": null, "title": "Crane Glacier centerline observations and modeling results ", "url": "https://www.usap-dc.org/view/dataset/601617"}], "date_created": "Mon, 28 Jun 2021 00:00:00 GMT", "description": "Enderlin/1643455 This award supports a project that will use a novel remote sensing method, which was initially developed to investigate melting of icebergs around Greenland, to examine spatial and temporal variations in ocean forcing around the Antarctic ice sheet periphery. Nearly three-quarters of the Antarctic ice sheet is fringed by regions of floating glacier ice called ice shelves. These ice shelves play an important role in modulating the flow of ice from the ice sheet interior towards the coast, similar to how dams regulate the downstream flow of water from reservoirs. Therefore, a reduction in ice shelf size due to changing air and ocean temperatures can have serious implications for the flux of glacier ice reaching the Antarctic coast, and thus, sea level change. Observations of recent ocean warming in the Amundsen Sea, thinning of the ice shelves, and increased ice flux from the West Antarctic ice sheet interior suggests that ice shelf destabilization triggered by ocean warming may already be underway in some regions. Although detailed observations are available in the Amundsen Sea region, our understanding of spatial and temporal variations in ocean conditions and their influence on ice shelf stability is limited by the scarceness of observations spanning the ice sheet periphery. The project will yield insights into variability in the submarine melting of ice shelves and will help advance the career of a female early-career scientist in a male-dominated field. The project will use repeat, very high-resolution (~0.5 m pixel width and length) satellite images acquired by the WorldView satellites, to estimate rates of iceberg melting in key coastal regions around Antarctica. The satellite images will be used to construct maps of iceberg surface elevation, which will be differenced in time to derive time series of iceberg volume change and area-averaged melt rates. Where ocean data are available, the melt rates will be compared to these data to assess whether variations in ocean temperature can explain observed iceberg melt variability. Large spatial gradients in melt rates will be compared to estimates of iceberg drift rates, which will be inferred from the repeat satellite images as well as numerically modeled drift rates produced by (unfunded) collaborators, to quantify the effects of water shear on iceberg melt rates. Spatial and temporal patterns in iceberg melting will also be compared to independently derived ice shelf thickness datasets. Overall, the analysis should yield insights into the effects of changes in ocean forcing on the submarine melting of Antarctic ice shelves and icebergs. The project does not require field work in Antarctica.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": null, "is_usap_dc": true, "keywords": "Amery Ice Shelf; FIELD SURVEYS; Totten Glacier; GLACIER MASS BALANCE/ICE SHEET MASS BALANCE; USAP-DC; Antarctic Peninsula; ICEBERGS; Mertz Glacier; OCEAN TEMPERATURE; USA/NSF; Amd/Us; Amundsen Sea; Ronne Ice Shelf; Filchner Ice Shelf; AMD", "locations": "Antarctic Peninsula; Totten Glacier; Ronne Ice Shelf; Filchner Ice Shelf; Amery Ice Shelf; Mertz Glacier; Amundsen Sea", "north": -60.0, "nsf_funding_programs": "Antarctic Glaciology; Antarctic Glaciology", "paleo_time": null, "persons": "Enderlin, Ellyn", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD SURVEYS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Antarctic Submarine Melt Variability from Remote Sensing of Icebergs", "uid": "p0010210", "west": -180.0}, {"awards": "0229292 Cressie, Noel", "bounds_geometry": null, "dataset_titles": null, "datasets": null, "date_created": "Wed, 28 Feb 2007 00:00:00 GMT", "description": "Ice streams are believed to play a major role in determining the response of their parent ice sheet to climate change, and in determining global sea level by serving as regulators on the fresh water stored in the ice sheets. Ice streams are characterized by rapid, laterally confined flow which makes them uniquely identifiable within the body of the more slowly and more homogeneously flowing ice sheet. But while these characteristics enable the identification of ice streams, the processes which control ice-stream motion and evolution, and differences among ice streams in the polar regions, are only partially understood. Understanding the relative importance of lateral and basal drags, as well as the role of gradients in longitudinal stress, is essential for developing models for future evolution of the polar ice\u003cbr/\u003esheets. In this project, physical statistical models will be used to explore the processes that control ice-stream flow, and to compare these processes between seemingly different ice-stream systems. In particular, Whillans Ice Stream draining into the Ross Ice Shelf, will be compared with Recovery and RAMP glaciers draining into the Ronne-Filchner Ice Shelf, and the Northeast Ice Stream in Greenland. Geophysical models lie at the core of the approach, but are embellished by modeling various components of variability statistically. One important component comes from the uncertainty in observations on basal elevation, surface elevation, and surface velocity. In this project new observational data collected using remote-sensing techniques will be used. The various components, some of which are spatial, are combined hierarchically using Bayesian statistical methodology. All these components will be combined mathematically into a physical statistical model that yields the posterior distribution for basal, longitudinal, and lateral stress fields, and velocity fields, conditional on the data. Inference based on this distribution will be carried out via Markov chain Monte Carlo techniques, to obtain estimates of these unknown fields along with uncertainty measures associated with them.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": false, "keywords": "Surface Elevation; Stress Field; Basal Elevation; DHC-6", "locations": null, "north": null, "nsf_funding_programs": "Antarctic Glaciology", "paleo_time": null, "persons": "Cressie, Noel; Jezek, Kenneth; Berliner, L.", "platforms": "AIR-BASED PLATFORMS \u003e PROPELLER \u003e DHC-6", "repositories": null, "science_programs": null, "south": null, "title": "Dynamics of Ice Streams: A Physical Statistical Approach", "uid": "p0000711", "west": null}]

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Antarctic Submarine Melt Variability from Remote Sensing of Icebergs

1643455
1933764

2021-06-28

Enderlin, Ellyn

Remotely-sensed iceberg geometries and meltwater fluxes	USAP-DC
Crane Glacier centerline observations and modeling results	USAP-DC

Enderlin/1643455 This award supports a project that will use a novel remote sensing method, which was initially developed to investigate melting of icebergs around Greenland, to examine spatial and temporal variations in ocean forcing around the Antarctic ice sheet periphery. Nearly three-quarters of the Antarctic ice sheet is fringed by regions of floating glacier ice called ice shelves. These ice shelves play an important role in modulating the flow of ice from the ice sheet interior towards the coast, similar to how dams regulate the downstream flow of water from reservoirs. Therefore, a reduction in ice shelf size due to changing air and ocean temperatures can have serious implications for the flux of glacier ice reaching the Antarctic coast, and thus, sea level change. Observations of recent ocean warming in the Amundsen Sea, thinning of the ice shelves, and increased ice flux from the West Antarctic ice sheet interior suggests that ice shelf destabilization triggered by ocean warming may already be underway in some regions. Although detailed observations are available in the Amundsen Sea region, our understanding of spatial and temporal variations in ocean conditions and their influence on ice shelf stability is limited by the scarceness of observations spanning the ice sheet periphery. The project will yield insights into variability in the submarine melting of ice shelves and will help advance the career of a female early-career scientist in a male-dominated field. The project will use repeat, very high-resolution (~0.5 m pixel width and length) satellite images acquired by the WorldView satellites, to estimate rates of iceberg melting in key coastal regions around Antarctica. The satellite images will be used to construct maps of iceberg surface elevation, which will be differenced in time to derive time series of iceberg volume change and area-averaged melt rates. Where ocean data are available, the melt rates will be compared to these data to assess whether variations in ocean temperature can explain observed iceberg melt variability. Large spatial gradients in melt rates will be compared to estimates of iceberg drift rates, which will be inferred from the repeat satellite images as well as numerically modeled drift rates produced by (unfunded) collaborators, to quantify the effects of water shear on iceberg melt rates. Spatial and temporal patterns in iceberg melting will also be compared to independently derived ice shelf thickness datasets. Overall, the analysis should yield insights into the effects of changes in ocean forcing on the submarine melting of Antarctic ice shelves and icebergs. The project does not require field work in Antarctica.

Dynamics of Ice Streams: A Physical Statistical Approach

0229292

2007-02-28

Cressie, Noel; Jezek, Kenneth; Berliner, L.

No dataset link provided

Ice streams are believed to play a major role in determining the response of their parent ice sheet to climate change, and in determining global sea level by serving as regulators on the fresh water stored in the ice sheets. Ice streams are characterized by rapid, laterally confined flow which makes them uniquely identifiable within the body of the more slowly and more homogeneously flowing ice sheet. But while these characteristics enable the identification of ice streams, the processes which control ice-stream motion and evolution, and differences among ice streams in the polar regions, are only partially understood. Understanding the relative importance of lateral and basal drags, as well as the role of gradients in longitudinal stress, is essential for developing models for future evolution of the polar ice<br/>sheets. In this project, physical statistical models will be used to explore the processes that control ice-stream flow, and to compare these processes between seemingly different ice-stream systems. In particular, Whillans Ice Stream draining into the Ross Ice Shelf, will be compared with Recovery and RAMP glaciers draining into the Ronne-Filchner Ice Shelf, and the Northeast Ice Stream in Greenland. Geophysical models lie at the core of the approach, but are embellished by modeling various components of variability statistically. One important component comes from the uncertainty in observations on basal elevation, surface elevation, and surface velocity. In this project new observational data collected using remote-sensing techniques will be used. The various components, some of which are spatial, are combined hierarchically using Bayesian statistical methodology. All these components will be combined mathematically into a physical statistical model that yields the posterior distribution for basal, longitudinal, and lateral stress fields, and velocity fields, conditional on the data. Inference based on this distribution will be carried out via Markov chain Monte Carlo techniques, to obtain estimates of these unknown fields along with uncertainty measures associated with them.

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