A high-resolution bedrock map for the Antarctic Peninsula

Abstract. Assessing and projecting the dynamic response of glaciers on the Antarctic Peninsula to changed atmospheric and oceanic forcing requires high-resolution ice thickness data as an essential geometric constraint for ice flow models. Here, we derive a complete bedrock data set for the Antarctic Peninsula north of 70° S on a 100 m grid. We calculate distributed ice thickness based on surface topography and simple ice dynamic modelling. Our approach is constrained with all available thickness measurements from Operation IceBridge and gridded ice flow speeds for the entire study region. The new data set resolves the rugged subglacial topography in great detail, indicates deeply incised troughs, and shows that 34% of the ice volume is grounded below sea level. The Antarctic Peninsula has the potential to raise global sea level by 71 ± 5 mm. In comparison to Bedmap2, covering all Antarctica on a 1 km grid, a significantly higher mean ice thickness (+48%) is found.

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Large-Scale Numerical Modelling of the Antarctic Ice Sheet

Annals of Glaciology ◽

10.1017/s0260305500002500 ◽

1982 ◽

Vol 3 ◽

pp. 42-49 ◽

Cited By ~ 54

Author(s):

W.F. Budd ◽

I.N. Smith

Keyword(s):

Sea Level ◽

Large Scale ◽

Accumulation Rate ◽

Ice Sheet ◽

Ice Thickness ◽

Ice Flow ◽

Antarctic Ice Sheet ◽

Flow Parameters ◽

The Antarctic ◽

Thinning Rate

A large-scale dynamic numerical model of the Antarctic ice sheet has been developed to study its present state of ice flow and mass balance as well as its response to long-term changes of climate or sea-level.The flow of ice over a two-dimensional grid is determined from the ice thickness, the basal shear stress, the bedrock depth, and ice flow parameters derived from velocities of existing ice sheets. The change in ice thickness with time is governed by the continuity equation involving the ice flux divergence and the ice accumulation or ablation. At the ice sheet seaward boundary, a floating criterion and floating ice thinning rate apply. Bedrock depression with a time-delayed response dependent on the history of the ice load is also included.A 61 × 61 point grid with 100 km spacing has been used to represent the ice-sheet surface, bedrock, and accumulation rate. The model has been used to simul a te the growth of the present ice sheet and i ts reaction to changes of sea-level, bedrock depression, accumulation rate, ice flow parameters, and the iceshelf thinning rate.Preliminary results suggest that the present ice sheet is not in equilibrium but rather is still adjusting to changes of these parameters.

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A complete glacier inventory of the Antarctic Peninsula based on Landsat 7 images from 2000 to 2002 and other preexisting data sets

Earth System Science Data ◽

10.5194/essd-9-115-2017 ◽

2017 ◽

Vol 9 (1) ◽

pp. 115-131 ◽

Cited By ~ 6

Author(s):

Jacqueline Huber ◽

Alison J. Cook ◽

Frank Paul ◽

Michael Zemp

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Antarctic Peninsula ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Data Sets ◽

Rock Outcrops ◽

Data Set ◽

Glacier Inventory ◽

The Antarctic

Abstract. The glaciers on the Antarctic Peninsula (AP) potentially make a large contribution to sea level rise. However, this contribution has been difficult to estimate since no complete glacier inventory (outlines, attributes, separation from the ice sheet) is available. This work fills the gap and presents a new glacier inventory of the AP north of 70° S, based on digitally combining preexisting data sets with geographic information system (GIS) techniques. Rock outcrops have been removed from the glacier basin outlines of Cook et al. (2014) by intersection with the latest layer of the Antarctic Digital Database (Burton-Johnson et al., 2016). Glacier-specific topographic parameters (e.g., mean elevation, slope and aspect) as well as hypsometry have been calculated from the DEM of Cook et al. (2012). We also assigned connectivity levels to all glaciers following the concept by Rastner et al. (2012). Moreover, the bedrock data set of Huss and Farinotti (2014) enabled us to add ice thickness and volume for each glacier. The new inventory is available from the Global Land Ice Measurements from Space (GLIMS) database (doi:10.7265/N5V98602) and consists of 1589 glaciers covering an area of 95 273 km2, slightly more than the 89 720 km2 covered by glaciers surrounding the Greenland Ice Sheet. Hence, compared to the preexisting data set of Cook et al. (2014), this data set covers a smaller area and one glacier less due to the intersection with the rock outcrop data set. The total estimated ice volume is 34 590 km3, of which one-third is below sea level. The hypsometric curve has a bimodal shape due to the unique topography of the AP, which consists mainly of ice caps with outlet glaciers. Most of the glacierized area is located at 200–500 m a.s.l., with a secondary maximum at 1500–1900 m. Approximately 63 % of the area is drained by marine-terminating glaciers, and ice-shelf tributary glaciers cover 35 % of the area. This combination indicates a high sensitivity of the glaciers to climate change for several reasons: (1) only slightly rising equilibrium-line altitudes would expose huge additional areas to ablation, (2) rising ocean temperatures increase melting of marine terminating glaciers, and (3) ice shelves have a buttressing effect on their feeding glaciers and their collapse would alter glacier dynamics and strongly enhance ice loss (Rott et al., 2011). The new inventory should facilitate modeling of the related effects using approaches tailored to glaciers for a more accurate determination of their future evolution and contribution to sea level rise.

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Large-Scale Numerical Modelling of the Antarctic Ice Sheet

Annals of Glaciology ◽

10.3189/s0260305500002500 ◽

1982 ◽

Vol 3 ◽

pp. 42-49 ◽

Cited By ~ 4

Author(s):

W.F. Budd ◽

I.N. Smith

Keyword(s):

Sea Level ◽

Large Scale ◽

Accumulation Rate ◽

Ice Sheet ◽

Ice Thickness ◽

Ice Flow ◽

Antarctic Ice Sheet ◽

Flow Parameters ◽

The Antarctic ◽

Thinning Rate

A large-scale dynamic numerical model of the Antarctic ice sheet has been developed to study its present state of ice flow and mass balance as well as its response to long-term changes of climate or sea-level.The flow of ice over a two-dimensional grid is determined from the ice thickness, the basal shear stress, the bedrock depth, and ice flow parameters derived from velocities of existing ice sheets. The change in ice thickness with time is governed by the continuity equation involving the ice flux divergence and the ice accumulation or ablation. At the ice sheet seaward boundary, a floating criterion and floating ice thinning rate apply. Bedrock depression with a time-delayed response dependent on the history of the ice load is also included.A 61 × 61 point grid with 100 km spacing has been used to represent the ice-sheet surface, bedrock, and accumulation rate. The model has been used to simul a te the growth of the present ice sheet and i ts reaction to changes of sea-level, bedrock depression, accumulation rate, ice flow parameters, and the iceshelf thinning rate.Preliminary results suggest that the present ice sheet is not in equilibrium but rather is still adjusting to changes of these parameters.

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Recent ice-surface-elevation changes of Fleming Glacier in response to the removal of the Wordie Ice Shelf, Antarctic Peninsula

Annals of Glaciology ◽

10.3189/172756410791392727 ◽

2010 ◽

Vol 51 (55) ◽

pp. 97-102 ◽

Cited By ~ 15

Author(s):

J. Wendt ◽

A. Rivera ◽

A. Wendt ◽

F. Bown ◽

R. Zamora ◽

...

Keyword(s):

Antarctic Peninsula ◽

Regional Climate ◽

Airborne Lidar ◽

Similar Data ◽

Ice Shelf ◽

International Polar Year ◽

Ice Flow ◽

Ice Shelves ◽

Elevation Changes ◽

The Antarctic

AbstractRegional climate warming has caused several ice shelves on the Antarctic Peninsula to retreat and ultimately collapse during recent decades. Glaciers flowing into these retreating ice shelves have responded with accelerating ice flow and thinning. The Wordie Ice Shelf on the west coast of the Antarctic Peninsula was reported to have undergone a major areal reduction before 1989. Since then, this ice shelf has continued to retreat and now very little floating ice remains. Little information is currently available regarding the dynamic response of the glaciers feeding the Wordie Ice Shelf, but we describe a Chilean International Polar Year project, initiated in 2007, targeted at studying the glacier dynamics in this area and their relationship to local meteorological conditions. Various data were collected during field campaigns to Fleming Glacier in the austral summers of 2007/08 and 2008/09. In situ measurements of ice-flow velocity first made in 1974 were repeated and these confirm satellite-based assessments that velocity on the glacier has increased by 40–50% since 1974. Airborne lidar data collected in December 2008 can be compared with similar data collected in 2004 in collaboration with NASA and the Chilean Navy. This comparison indicates continued thinning of the glacier, with increasing rates of thinning downstream, with a mean of 4.1 ± 0.2 m a−1 at the grounding line of the glacier. These comparisons give little indication that the glacier is achieving a new equilibrium.

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A global high-resolution data set of ice sheet topography, cavity geometry and ocean bathymetry

10.5194/essd-2016-3 ◽

2016 ◽

Cited By ~ 4

Author(s):

Janin Schaffer ◽

Ralph Timmermann ◽

Jan Erik Arndt ◽

Steen Savstrup Kristensen ◽

Christoph Mayer ◽

...

Keyword(s):

High Resolution ◽

Continental Shelf ◽

Ice Sheet ◽

The Arctic ◽

Global Ocean ◽

Data Set ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

Surface Topographies ◽

The Antarctic

Abstract. The ocean plays an important role in modulating the mass balance of the polar ice sheets by interacting with the ice shelves in Antarctica and with the marine-terminating outlet glaciers in Greenland. Given that the flux of warm water onto the continental shelf and into the sub-ice cavities is steered by complex bathymetry, a detailed topography data set is an essential ingredient for models that address ice-ocean interaction. We followed the spirit of the global RTopo-1 data set and compiled consistent maps of global ocean bathymetry, upper and lower ice surface topographies and global surface height on a spherical grid with now 30-arc seconds resolution. We used the General Bathymetric Chart of the Oceans (GEBCO_2014) as the backbone and added the International Bathymetric Chart of the Arctic Ocean version 3 (IBCAOv3) and the International Bathymetric Chart of the Southern Ocean (IBCSO) version 1. While RTopo-1 primarily aimed at a good and consistent representation of the Antarctic ice sheet, ice shelves and sub-ice cavities, RTopo-2 now also contains ice topographies of the Greenland ice sheet and outlet glaciers. In particular, we aimed at a good representation of the fjord and shelf bathymetry surrounding the Greenland continent. We corrected data from earlier gridded products in the areas of Petermann Glacier, Hagen Bræ and Sermilik Fjord assuming that sub-ice and fjord bathymetries roughly follow plausible Last Glacial Maximum ice flow patterns. For the continental shelf off northeast Greenland and the floating ice tongue of Nioghalvfjerdsfjorden Glacier at about 79° N, we incorporated a high-resolution digital bathymetry model considering original multibeam survey data for the region. Radar data for surface topographies of the floating ice tongues of Nioghalvfjerdsfjorden Glacier and Zachariæ Isstrøm have been obtained from the data centers of Technical University of Denmark (DTU), Operation Icebridge (NASA/NSF) and Alfred Wegener Institute (AWI). For the Antarctic ice sheet/ice shelves, RTopo-2 largely relies on the Bedmap-2 product but applies corrections for the geometry of Getz, Abbot and Fimbul ice shelf cavities. The data set is available in full and in regional subsets in NetCDF format from the PANGAEA database at https://doi.pangaea.de/10.1594/PANGAEA.856844.

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Characterizing Arctic sea ice topography using high-resolution IceBridge data

The Cryosphere ◽

10.5194/tc-10-1161-2016 ◽

2016 ◽

Vol 10 (3) ◽

pp. 1161-1179 ◽

Cited By ~ 15

Author(s):

Alek A. Petty ◽

Michel C. Tsamados ◽

Nathan T. Kurtz ◽

Sinead L. Farrell ◽

Thomas Newman ◽

...

Keyword(s):

High Resolution ◽

Sea Ice ◽

Arctic Sea Ice ◽

Surface Feature ◽

Ice Thickness ◽

First Year ◽

Data Set ◽

Surface Features ◽

Developed Surface ◽

Arctic Sea

Abstract. We present an analysis of Arctic sea ice topography using high-resolution, three-dimensional surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009 to 2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes. The results demonstrate that Arctic sea ice topography exhibits significant spatial variability, mainly driven by the increased surface feature height and volume (per unit area) of the multi-year ice that dominates the Central Arctic region. The multi-year ice topography exhibits greater interannual variability compared to the first-year ice regimes, which dominates the total ice topography variability across both regions. The ice topography also shows a clear coastal dependency, with the feature height and volume increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. A strong correlation between ice topography and ice thickness (from the IceBridge sea ice product) is found, using a square-root relationship. The results allude to the importance of ice deformation variability in the total sea ice mass balance, and provide crucial information regarding the tail of the ice thickness distribution across the western Arctic. Future research priorities associated with this new data set are presented and discussed, especially in relation to calculations of atmospheric form drag.

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Major increases projected in extreme surface melt events in Antarctica, even under a moderate emission scenario

10.5194/egusphere-egu2020-21267 ◽

2020 ◽

Author(s):

Sarah Feron ◽

Raul Cordero

Keyword(s):

Sea Level ◽

Antarctic Peninsula ◽

Climate Models ◽

Emission Scenario ◽

Global Climate ◽

Global Climate Models ◽

Reference Period ◽

West Antarctica ◽

Surface Melt ◽

The Antarctic

Surface Melt (SM) is one of the factors that contribute to sea level rise; surface&#160;meltwater draining through the ice and beneath&#160;Antarctic&#160;glaciers may cause acceleration in their flow towards the sea. Changes in the frequency of relatively warm days (including heatwaves) can substantially alter the SM variability, thus leading to extreme melting events.&#160;By using simulations from 13 Global Climate Models (GCMs) and according to a moderate representative concentration pathways (RCP4.5), here we show that the frequency of extreme SM events (SM90; according to the 90th percentile over the reference period 1961-1990) may significantly increase in coastal areas of West Antarctica; in particular in the Antarctic Peninsula. By the end of the century SM90 estimates are expected to increase from currently 0.10 kg/m2/day to about 0.45 kg/m2/day in the Antarctic Peninsula. Increments in SM90 estimates are not just driven by changes in the average SM, but also by the variability in SM. The latter is expected to increase by around 50% in the Antarctic Peninsula.

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An evaluation of the surface climatology over the Totten region (Antarctica) using COSMO-CLM2

10.5194/egusphere-egu2020-5211 ◽

2020 ◽

Author(s):

Samuel Helsen ◽

Sam Vanden Broucke ◽

Alexandra Gossart ◽

Niels Souverijns ◽

Nicole van Lipzig

Keyword(s):

High Resolution ◽

Sea Level Rise ◽

Sea Level ◽

Climate Models ◽

Climate Model ◽

Ice Sheet ◽

Ocean Model ◽

Precipitation Pattern ◽

Outlet Glacier ◽

The Antarctic

The Totten glacier is a highly dynamic outlet glacier, situated in E-Antarctica, that contains a potential sea level rise of about 3.5 meters. During recent years, this area has been influenced by sub-shelf intrusion of warm ocean currents, contributing to higher basal melt rates. Moreover, most of the ice over this area is grounded below sea level, which makes the ice shelf potentially vulnerable to the marine ice sheet instability mechanism. It is expected that, as a result of climate change, the latter mechanisms may contribute to significant ice losses in this region within the next decades, thereby contributing to future sea level rise. Up to now, most studies have been focusing on sub-shelf melt rates and the influence of the ocean, with much less attention for atmospheric processes (often ignored), which also play a key-role in determining the climatic conditions over this region. For example: surface melt is important because it contributes to hydrofracturing, a process that may lead to ice cliff instabilities. Also precipitation is an important atmospheric process, since it determines the input of mass to the ice sheet and contributes directly to the surface mass balance. In order to perform detailed studies on these processes, we need a well-evaluated climate model that represents all these processes well. Recently, the COSMO-CLM2 (CCLM2) model was adapted to the climatological conditions over Antarctica. The model was evaluated by comparing a 30 year Antarctic-wide hindcast run (1986-2016) at 25 km resolution with meteorological observational products (Souverijns et al., 2019). It was shown that the model performance is comparable to other state-of-the-art regional climate models over the Antarctic region. We now applied the CCLM2 model in a regional configuration over the Totten glacier area (E-Antarctica) at 5 km resolution and evaluated its performance over this region by comparing it to climatological observations from different stations. We show that the performance for temperature in the high resolution run is comparable to the performance of the Antarctic-wide run. Precipitation is, however, overestimated in the high-resolution run, especially over dome structures (Law-Dome). Therefore, we applied an orographic smoothening, which clearly improves the precipitation pattern with respect to observations. Wind speed is overestimated in some places, which is solved by increasing the surface roughness. This research frames in the context of the PARAMOUR project. Within PARAMOUR, CCLM2 is currently being coupled to an ocean model (NEMO) and an ice sheet model (f.ETISh/BISICLES) in order to understand decadal predictability over this region.

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