Henry Ice Rise

Henry Ice Rise. It is a substantial, grounded ice feature located within the floating expanse of the Ronne Ice Shelf in West Antarctica. This ice rise plays a critical role in modulating the flow and stability of one of Antarctica's largest ice shelves, acting as a pivotal pinning point. Its study provides essential insights into glaciology, ice-sheet dynamics, and the complex interactions between the Antarctic ice sheet and the Southern Ocean.

Geography and Location

The Henry Ice Rise is situated in the southwestern sector of the Ronne Ice Shelf, near its conjunction with the Antarctic Peninsula and the Foundation Ice Stream. It lies approximately 400 kilometers from the Berkner Island and is positioned within the region historically mapped by the United States Geological Survey and the British Antarctic Survey. The feature is surrounded by the dynamic ice of the Filchner-Ronne Ice Shelf system, with the Rutford Ice Stream and other tributary glaciers influencing its upstream environment. Its location places it within the territorial claim of the British Antarctic Territory, though all such claims are suspended under the Antarctic Treaty System.

Geology and Formation

The ice rise forms where the underlying bedrock topography, likely part of the West Antarctic Rift System, rises sufficiently to contact the base of the ice shelf, causing it to ground. This bedrock high, potentially composed of Precambrian or Paleozoic crystalline rocks similar to those exposed in the Ellsworth Mountains, acts as an anchor. The formation process involves the long-term accumulation and compression of snow into ice, which flows from the interior of the West Antarctic Ice Sheet via outlet glaciers like the Foundation Ice Stream. Over millennia, this grounded ice has developed a distinct ice dome profile, influencing the regional isostatic adjustment and creating a unique subglacial environment.

Glaciological Significance

As a major pinning point, Henry Ice Rise exerts substantial backstress on the Ronne Ice Shelf, critically restraining the seaward flow of ice from the continental interior. Its stability is a key factor in the overall mass balance of the West Antarctic Ice Sheet and its contribution to sea level rise. Scientists from institutions like the National Snow and Ice Data Center and the Alfred Wegener Institute monitor its behavior using satellite data from NASA's ICESat and European Space Agency missions. Changes in its configuration or the onset of ice shelf disintegration events here could accelerate the discharge of ice from upstream basins, such as those drained by the Pine Island Glacier and Thwaites Glacier.

Exploration and Research History

The feature was first identified and broadly mapped during aerial reconnaissance missions conducted by the United States Antarctic Program in the 1960s and 1970s, such as those associated with Operation Deep Freeze. More detailed investigation began with coordinated international efforts like the Filchner-Ronne Ice Shelf Programme and the British Antarctic Survey's long-term geophysical surveys. Key research campaigns, including those led by the Scott Polar Research Institute and the Norwegian Polar Institute, have utilized ice-penetrating radar, seismic sounding, and GPS networks to study its structure. The name "Henry" was formally adopted by the Advisory Committee on Antarctic Names, honoring contributions to polar science.

Interaction with Surrounding Ice

The ice rise creates a complex stress field, diverting and channeling the flow of the surrounding Ronne Ice Shelf. It interacts directly with the inflow from the Foundation Ice Stream and influences the formation of crevasse fields and shear margins in the shelf ice. The downstream side often features a distinct pattern of ice rumples and disturbed flow bands, visible in imagery from satellites like Landsat and Sentinel-1. This interaction affects the location of the grounding line and the formation of polynyas in the adjacent Weddell Sea, which are important for ocean circulation and marine ecosystems studied by expeditions like those of the RV Polarstern.

Category:Ice rises of Antarctica Category:Ronne Ice Shelf Category:Geography of the British Antarctic Territory