The Multiple Faces of Antarctic Ice
The IceBridge mission has been having trouble getting flights up recently, which we have been assured is par for the course in this kind of work, but still it is frustrating! Here we are down in Punta Arenas waiting…waiting…waiting. We have faced a series of weather related stoppages and then the normal issues with equipment repairs causing this season to unfold with agonizing slowness. We were, of course, spoiled by all our successes of the prior campaigns, when flights seemed to lift off with uncanny regularity!
However, last week there was a period where the weather and airplane were in synch and we got three flying days in a row, one to the South Pole with my colleague onboard, and two that I was on along the Western edge of the Antarctic Peninsula. The targets of my two flights were the ice shelves, where the ice flows off the Antarctic continent and ends floating in the sea. (see image)
I was eager to be involved in these two flights along the Antarctic Peninsula as they were to survey the Getz and the Dotson ice shelves which involves flying over the Amundsen Sea and past Thwaites Glacier. These floating ice shelves appear in a line, Thwaites, then Dotson, and then Getz (moving from the direction of tip of the peninsula downward). I have been working on data that were collected last year from the Thwaites area so it was good to at least be flying in the ‘neighborhood’. The Dotson flight was particularly useful for me, since the grid flown over it can be connected in to the Thwaites grid, extending my survey area and our understanding of that area.
I hadn’t been on a science flight before, so everything was new to me. There is a network on the plane so we can all sit with our laptops and follow our position on the map, see where we are going, how high and fast we are flying, and other information. There are additional cameras looking forwards and downwards, so we have a wide field of view in addition to looking out the window (which we did plenty of!) (see image)!
The different kinds of ice we flew over captured my interest…from icebergs in the open water, to big plates of sea ice, the expanse of flat, floating ice shelves and the crevassed glaciers. Each has a function in the polar region and studying the movements, expanse, depth of each can tell us a different piece of information about our changing polar region. There was a lot of variation in what was all essentially ice. For this flight, however, the targets was ice shelves, where the ice is floating on the sea. Collecting gravity data, which is Lamont’s role in this project, is important on these surveys because while the other instruments can measure the top (laser), bottom and internal surfaces of the ice (radar), they don’t “see” all the way down to the sea floor. The gravity measurement is controlled by the bathymetry of the sea floor, as well as by changes in geology, so we can use it to model the sea floor. Knowing what is under the shelves, how the ice is “hinged” to the continent, and how the ocean water beneath is coming into contact with the ice flowing off the continent is important to understanding how that ice might melt or move in the future.
On the trip home, I sat in the jump seat in the cockpit, a real treat! We flew back in to Punta Arenas over vegetated valleys, the landscape still marvelous but very different from how we had spent the day (see image).