We Blogged It!
Lat 74° 24S Long 112°22W
Dotson Ice Shelf Team
The Dotson Ice Shelf is 48 km (30 mi) wide and is located between the Martin and Bear Peninsulas on the coast of Marie Byrd Land. An ice shelf is a thick platform of ice that forms where a glacier or ice sheet flow into the ocean. Gravity drives the ice onto the ocean surface. With the stress of shearing, “calving” occurs and creates icebergs. It is estimated that only 1/9 of the floating ice is above the ocean surface!
The Dotson reaches about 45 m above the water and about 300m below. The largest ice shelf in Antarctica is the Ross Ice Shelf- about the size of France!
The NBP recently completed a transect as close to the Dotson as they could safely go- about .2nm. Sharon Stammerjohn set up a camera on the radar image so that they could see exactly how far away they were the entire time. Chief Tish said, “That number is needed to use the multibeam sensor data and calibrate an ice-shelf thickness. That bright green vertical strip (on the image) is the ice shelf. The ship is in the center of the circle.”
If you look at the Multi Beam bathymetry map image, the black show the old location of the ice shelf. The ships track is in yellow along the coast of the current ice shelf. The number on the upper corner is the depth at the time the picture was taken. The deepest part during the transect was 1200m.
So, why is this called the Iron Curtain? The trace metal team is looking at the Dotson as a source of iron to the polynya!
Question of the Day
- What are Polynyas and why are they important to study?
Polynyas, are recurring areas of seasonally open water surrounded by ice.
Energy and material transfer between the atmosphere, polar surface ocean, and the deep sea in polynas provide polar ecosystems with just the right ingredients needed for high productivity and intense biogeochemical recycling.
Polynyas may be the key to understanding the future of Polar Regions since their extent is expected to increase with anthropogenic warming.