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Science

Scientists Observe Birth of an Iceberg

In the midst of its third field campaign in Antarctica, NASA’s Operation IceBridge mission has provided the first ever detailed airborne measurements of the process of a massive iceberg calving from its parent glacier.

Pine Island Glacier has not calved such a significant iceberg since 2001, and many scientists had suspected that it was now time for another such event to take place. But until the large crack running across the glacier was found on October 14, no one had been able to pinpoint any specific evidence that suggested the glacier would soon calve.

Only in hindsight, knowing that a crack did indeed exist, were scientists able to find the signs of the crack in early October.

“We are actually now witnessing how it happens and it’s very exciting for us,” said IceBridge project scientist Michael Studinger, Goddard Space Flight Center, Greenbelt, Md. “It’s part of a natural process but it’s pretty exciting to be here and actually observe it while it happens. To my knowledge, no one has flown a lidar instrument over an actively developing rift such as this.”

In their press release which provided us with these amazing images, NASA explained wonderfully the scientific inevitability of a glacier the size of Pine Island Glacier calving such a massive iceberg;

“Gravity pulls the ice in the glacier westward along Antarctica’s Hudson Mountains toward the Amundsen Sea. A floating tongue of ice reaches out 30 miles into the Amundsen beyond the grounding line, the below-sea-level point where the ice shelf locks onto the continental bedrock. As ice pushes toward the sea from the interior, inevitably the ice shelf will crack and send a large iceberg free.”

The flight was conducted in a very rare 30 minute divergence from the primary Operation IceBridge mission.

The primary goal of Operation IceBridge is to put the same data recording instruments over the exact same flight lines and satellite tracks, year after year, in an effort to gather “meaningful and accurate data of how ice sheets and glaciers are changing over time.”

On board the DC-8, the Airborne Topographic Mapper measured the dimensions of the rift;

  • At its widest, the rift is 820 feet apart (250 meters)
  • On average, it is about 260 feet across
  • The deepest point from the ice shelf surface ranged from 165 to 195 feet (50 to 60 meters)
  • When the iceberg finally breaks free of its parent glacier, it will cover approximately 340 square miles (880 square kilometers) of surface area.
  • It will also be approximately 1,640 feet (500 meters) feet thick, with only about 160 feet of that floating above water and the rest submerged.
  • “The pilots did a really nice job of keeping the aircraft and our ATM scan swath pretty much centered over the rift as you flew from one end to the other,” said Jim Yungel, who leads the ATM team out of NASA’s Wallops Island Flight Facility in Virginia. “It was a real challenge to be told…we’re going to attempt to fly along it and let’s see if your lidar systems can map that crack and can map the bottom of the crack.

    “And it was a lot of fun on a personal level to see if something that you built over the years can actually do a job like that. So, yeah, I enjoyed it. I really enjoyed seeing the results being produced.”

    Source: NASA




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