CR
Cryospheric Sciences

Ice shelf

Image of the Week: Under the Sea

Image of the Week: Under the Sea

Always wondered how it looks like under the sea ice?
Getting an answer is simpler than you might think: Just go out to the front of McMurdo ice shelf in Antarctica and drill a tube into the sea ice. Then let people climb down and take pictures of the ice from below.
More information:
– Photo taken by Marcus Arnold, Gateway Antarctica, University of Canterbury during his November 2015, Antarctic Expedition.
– More photos of their expedition on https://instagram.com/the_ross_ice_shelf_programme/

Image of the Week: Antarctic ice-shelf thickness

Image of the Week: Antarctic ice-shelf thickness

Thickness of floating ice shelves in Antarctica. Ice thickness is greatest close to the grounding line where it can reach 1000 meters or more (red). Away from the grounding line, the ice rapidly thins to reach a few hundreds of meters at the calving front. Ice thickness varies greatly from one ice shelf to another. Within ice shelves, “streams of ice” can be spotted originating from individual tributary glaciers and ice streams.

This dataset was used to compute calving fluxes and basal melt rates of Antarctic ice shelves (see Depoorter et al, 2013). This ice thickness map was derived from altimetry data (ERS and ICESat) acquired between 1994 and 2009 and corrected for elevation changes during this period.

Follow this link to download the georeferenced map and see Depoorter et al (2013)‘s paper for more information.

Image of the week : formation of an ice rise

Image of the week : formation of an ice rise

Deglaciation and formation of an ice rise with the ice-sheet model BISICLES.  The simulation starts with an ice sheet in steady state that overrides a topographic high in the bed, close to the calving front. The sea level is then forced to rise steadily with 1 cm per year during 15 thousand years, and the simulation goes on until the ice sheet reaches steady state.
The animation below shows that the formation of an ice rise delays the grounding line retreat.

For more information see Favier and Pattyn (2015)‘s recent paper.

movieicerise

The  movie shows the ice sheet retreat and the ice rise formation and evolution in between the two steady states. The movie starts after 5 thousands years of sea level rise. The ice upper surface is colored as a function of the velocity magnitude. The ice lower surface is colored either in light gray for floating ice or dark gray for grounded ice. Credit: L. Favier.