A place where icebergs are going to die
A place where icebergs are going to die
Today's story is the answer to the Puzzle of October 2018.
This could be a scene from a spooky movie. But the reality is just as morbid for this iceberg in the form of a coffin. After 18 years at sea, the B-15T has entered a region where the Antarctic icebergs are going to die.
On September 23, 2018, when an astronaut on the International Space Station took this picture, the B-15T iceberg had already left the Southern Ocean. It was discovered in the South Atlantic between the islands South Georgia and South Sandwich. The second image shows a broad view, acquired on the same day by the moderate resolution imager spectroradiometer (MODIS) on NASA's Terra satellite. It is known that icebergs like this melt rapidly as they move northward into warmer waters.
The B-15T trip to this iceberg graveyard has been long. Your father berg (B-15) first separated of the Ross Ice Shelf in March 2000. It fractured over time into smaller bergs, many of which continued to mount the Antarctic coastal stream (on the left) around Antarctica.
By the end of 2017, the turn of the Weddell Sea had redirected the B-15T from its almost circumnavigation and had sent the iceberg northward. This third image was acquired in October 2017 by MODIS on NASA's Aqua satellite. It shows the iceberg when it was near Elephant Island, an icy rock located a few hundred kilometers north-northeast of the tip of the Antarctic Peninsula.
the Antarctic circumpolar current, which is channeled through the Drake Passage, then directed the iceberg eastward and its current location. Water at this latitude, approximately 54 degrees to the south, is generally warmer than the Southern Ocean and deadly to icebergs. NASA / UMBC glaciologist Chris Shuman noted that the winter in the southern hemisphere was ending when the astronaut detected the iceberg, so the return of the abundant sunlight could warm the water around him even more. The lack of sea ice in the vicinity of B-15T implies that the water was above the freezing point.
The spooky form of the B-15T was acquired long before he moved to this cemetery of icebergs. For more than a decade, the B-15 had numerous collisions: it crashed into the Ross ice shelf where it originated, hit the bedrock along the coast and ran into other tabular icebergs. Such collisions can be strong enough to abruptly fracture crystalline ice and produce linear edges, similar to the rectangular iceberg that debuted this month near the Larsen C ice shelf and the A-68 iceberg. That iceberg is visible in the photograph below, acquired on October 16 during a Operation IceBridge flight of science.
"This fracture is similar to" breaking "a mineral crystal with a strong hammer blow," Shuman said. Of course, the edges are not always so linear. Other bergs have edges that are curved. Some become jagged when the pull of gravity or the cutting action of the waves causes the ice to splinter irregularly.
"The shape of the coffin is an accident of time and space, given the approximately 18.5-year trip of the B-15T," Shuman said. "We can only guess the forces that have acted on this remnant of B-15 on the long road around Antarctica."
Astronaut photograph ISS056-E-195042 was acquired on September 23, 2018, with a Nikon D5 digital camera with an 800-millimeter lens and is provided by the Earth Observation Facility of the ISS crew and the Earth Science and Remote Sensing Unit, Center Space Johnson The image was taken by a member of the Expedition 56 crew. The image has been trimmed and enhanced to improve contrast, and the lens artifacts have been removed. the International space station program supports the laboratory as part of the National Laboratory of the ISS to help astronauts take photographs of the Earth that will be of great value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be seen at NASA / JSC Gateway to the astronaut photography of the earth. Images from the NASA Earth Observatory by Lauren Dauphin and Jeff Schmaltz, using MODIS data from NASA EOSDIS / LANCE and GIBS / Worldview. Airborne photography by NASA / Jeremy Harbeck. Story of Kathryn Hansen.
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