ICE Bridge measures springtime Arctic ice melt streaming into ocean
Posted by Jim Cochran
The ICE Bridge mission is designed to build a continuous seasonal measure of ice cover in the polar-regions over the next 5 years. Why 5 years? Beginning in 2003 NASA measured ice cover in the polar-regions through satellite imagery using ICESat. Early in 2010 ICESat captured its last image, and there will be no replacement ready until late 2015, 5 years from now. But the polar-regions are experiencing rapid change and 5 years is a long time to wait without data. Continuous collection of data is needed for us to understand what is happening both on and below the ice, so for the next 5 years the ICE Bridge mission will be aircraft based, flying in the Arctic in the spring and in the Antarctic in the late fall.
The ICE Bridge campaign began in Antarctica in Fall 2009 measuring changes along the West Antarctic peninsula. Now we are shifting north for a springtime look at the Arctic region. Greenland alone is estimated to be sending over 200 gigatons/year (200 cubic kms) of ice streaming into the world’s oceans. Lamont-Doherty Earth Observatory is involved in this mission operating the gravimeter.
We will be running this mission from two locations and using two aircraft platforms. The early part of the mission will be flown from the large DC-8 out of Thule high on the northwestern tip of Greenland. Most of the early flights from Thule will look at sea ice extent and thickness, or surface measures of ice using high altitude LVIS (a laser swath-mapping instrument) flights, although a few flights over the northern glaciers will use the DC-8.
Our home for the next few weeks is Thule, Greenland. Situated next to the sea, Thule is 750 miles north of the Arctic Circle on a bay off of northern Baffin Bay, which separates Greenland from Canada. Located in a glacial valley between two long ridge, the Great Land Glacier which carved the valley, is now located about ten miles inland. Once a busy Strategic Air Command Base in the 1950s with 5,000-10,000 Air Force personnel, today Thule is a town of about 500 people, split between Air Force personnel and Greenlander and Danish contractors who provide most of the maintenance and service functions. The Air Force people are involved with the ballistic missile early warning system and satellite tracking and control. There are actually very few resident airplanes. Most of the buildings date from the 1950s era and are long, low sheet metal structures like the attached image, although greatly updated on the interior. A former hanger now serves as the Sports and Fitness Center. Looking at these 60 year old buildings I wonder what ice cover changes these buildings have seen in their tenure, and what changes they might see in the next 60 years.
Jim Cochran is a geophysicts at Columbia University’s Lamont-Doherty Earth Observatory in the Marine Geology and Geophysics division. Jim has worked extensively on processes under the Earth oceans including several projects in the Arctic Ocean including the Gakkel Ridge, a mid-ocean ridge spreading center in the central Arctic, and the adjacent Amerasian Basin. Jim brings extensive gravity expertise to this project.
Featured image: E&S Headquarters building with U.S., Danish and Greenland flags.jpg An example of the 1950’s structure of the Thule base.