Data Stories for IPY
Are We Witnessing the Initial Stages of a Collapse
of the West Antarctic Ice Sheet?
Following is an example of a Data Story which provides
background information about the "who, what, where,
when, how, and why" of a research effort, providing
context for non-technical users as to how relevant data are
collected and analyzed.
3) What Each Will Do
Robert Bindschadler will provide the overall direction and coordination of the separate components, lead the recon field work, be responsible for the GPS data reduction and will conduct the remote sensing analysis to produce the maps of ice shelf elevation and ice thickness. An early planner of IPY, he will work extensively with education and outreach teams.
Sridhar Anandakrishnan will design the seismic survey, analyze the data and produce a map of sub shelf cavity geometry. He will also collect organize and lead the collection of radar and gravity measurements during the seismic survey and will assist BAS in the inversion of airborne gravity data collected in 2005-06.
Alberto Behar will be responsible for the design, construction, and field operation of the video camera system.
David Holland will lead the ocean modeling effort and interact with collaborator Tony Payne to integrate the ocean model with the ice model and help define the measurement requirements
Martin Truffer will lead the hot water drilling including the deployment of ice sensors for internal ice properties and help interpret the ice velocity and strain rate measurements in terms of glacier response to external forces, such as tides, sea ice, and water properties.
Miles McPhee will analyze the sub-shelf profiler data to deduce exchange rates of mass, heat and salinity.
Tim Stanton will be responsible for design, construction, calibrating and field testing the profiler systems, as well as the data processing, archiving, analysis and integration into coupled ice/ocean models of the ice cavity structure and turbulent flux data sets.
Disrupted flow of the floating ice shelf caused where the edge of the shelf turns a sharp corner around an obstacle. Open tears are created and filled by calved ice blocks into the opening. Other crevasses are appear farther from the opening indicating large stresses farther back from the calving front.
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4) What-focus of the research
Our goal is to understand the interaction of the ocean and ice (heat, mass and salt fluxes) at the sub-ice-shelf interface and to incorporate this knowledge into a coupled model that includes dynamics of the ocean and of the ice along with their interaction. The primary objectives to achieve this goal are listed below with the lead scientist responsible for this aspect of the research.
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5) Methods to be used
- Analyze satellite imagery and satellite altimetry to define the shape (surface elevation and thickness) of the ice shelf (Bindschadler)
- Use seismic soundings to define the shape of the ocean cavity beneath the ice shelf (Anandakrishnan)
- Access the cavity by drilling through the ice shelf (Truffer)
- Lower a waterproof videocamera into the sub-shelf cavity to visually explore the ocean cavity, sea floor and ice-shelf underside (Behar)
- Develop and deploy remotely-controlled instrumentation to measure the temporal and spatial variations of water properties and of the mass exchange with the ice shelf
- Apply our understanding of the physical interactions between water and ice to define the nature of heat, mass and salt exchange between the ocean and the ice (McPhee)
- Incorporate the interactive processes into a coupled ocean-ice dynamics model
The entire 25km x 45km floating ice shelf experiences complex stresses that create a variety of crevasse patterns. View is toward the sea.
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6) Where
74.1 degrees south latitude and 105.1 degrees west longitude.
Pine Island Glacier (PIG) ice shelf is the floating extension of the Pine Island Glacier, one of the two largest outlet glaciers (Thwaites Glacier is the other) draining the West Antarctic ice sheet into the Amundsen Sea. Together, these two glaciers drain roughly one-third of the West Antarctic ice sheet, a volume of ice equivalent to raising global sea level one meter. The ice shelf is approximately 40 km long and 20 km wide.
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Dr. David Holland looking at imagery of the field area as he flies to the ice shelf area.
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7) Global connections
Ice sheets matter because they can change sea level---fast. When ice sheets grow, ocean level sinks. This usually happens very slowly because ice sheet growth is limited by the amount of snow that falls. When ice sheets shrink, sea level rises and records of past sea level show this happens generally faster and sometimes much faster than ice sheet growth, with periods of very rapid sea level rise indicating very rapid loss of ice.
8) When
We have organized our field activities into two seasons of intensive work preceded by an initial reconnaissance trip and a final visit to remove as much equipment as possible.
Top-of-the-mast view of the 3-person field camp occupied adjacent to the ice shelf. Feathery snow crystals have formed on the wind vane. Snow wall protects one tent from high winds.
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Read about the 2007-08 field season at Discover Earth Blog:
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- 2009-10
- The field work begins by setting up a helicopter support camp next to
the ice shelf, transferring the scientific field party to the ice shelf and
drilling the first hole through the ice shelf. The initial hole will be
used for exploration of the ocean.
- 2010-11
- The drilling team returns to drill three additional holes for new ocean
profiling instruments Additional video exploration may occur depending on
results from the previous season. The AWS and the GPSs will be serviced,
data downloaded, and readied again for the following winter. On-site work
is estimated to require five weeks.
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Setting up web-camera perched above solar panel.
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9) How
This is a complex and challenging project. Many parts of the work are at the cutting edge of science, technology or logistic capabilities. Each of these problems must be successfully overcome for complete success. The sequence of separate project elements is:
Click an element to view details and images.
10) Why
The type of ice sheet believed most susceptible to rapid ice loss is a "marine-based" ice sheet, that is, one that rests on a bed below sea level. West Antarctica is the last of this type of ice sheet on earth and has been in the science spotlight for the past 20 years. Sure enough, satellite observations have shown a portion of the West Antarctic ice sheet is acting up. It's the portion that flows into the Amundsen Sea, one sector of the Southern Ocean that surrounds Antarctica. This ice is thinning, the flow rate is increasing and the junction between the grounded ice and floating ice is retreating inland. The thickness and speed changes are most dramatic at the near the grounding line and decrease inland. This signals scientists that the trigger for these changes is at or near the grounding line.
A favored theory to explain these changes is that the ice shelf provides resistance against the seaward flow of the grounded ice sheet and as the size (thickness in this case) decreases, so does the resistance and the ice sheet can flow seaward faster. Warm water is believed to be the cause of the thinning ice shelf.
Our project is aimed at testing this hypothesis. We are motivated by the urgent need to predict future ice sheet behavior so that future rates of sea level change can be anticipated. Progress toward this goal is impossible without the quantitative understanding of the processes controlling the exchange of mass, heat and salt beneath the Amundsen Sea ice shelves and the incorporation of that knowledge into prognostic coupled models of ocean and ice dynamics.
