acquired July 14, 2013
download large image (469 KB, JPEG, 1374x1592)
acquired July 14, 2013
download GeoTIFF file (735 KB, TIFF)
The longest and fastest moving glacier in West Antarctica calved a new iceberg in July 2013. The Advanced Spaceborne Thermal Emission and Reflection Radiometer
(ASTER) instrument—built by Japan’s Ministry of Economy, Trade, and
Industry for NASA’s Terra satellite—acquired this image of two widening
cracks along an edge of the Pine Island Glacier
(PIG) in Antarctica. To the west of the cracks—in the image, north is
to the upper right—a new 720-square-kilometer (280-square-mile) ice
island was formed.
The false-color image above was composed from thermal infrared
wavelengths of light because natural-color imagery is not possible
during the lightless nights of Antarctic winter. Lighter shades of white
and gray are cooler, while darker areas are warmer and typically reveal
the cracks and exposed water. The large scene (downloadable beneath the
image above) shows the cracking patterns across a broader scale along
the coast.
The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, or DLR) captured a synthetic aperture radar image
of the same cracks and ice island on July 8, 2013. German researchers
have been examining Pine Island Glacier regularly for years with the TerraSAR-X satellite, which can see the ice through darkness and clouds.
The rift that led to this new ice island was discovered in October 2011 during an instrumented airplane flight in NASA’s annual Operation IceBridge
campaign. At the time, the crack was about 24 kilometers (15 miles)
long and 50 meters (160 feet) wide. For two years, researchers examined
satellite and airborne imagery, as well as data from ice-based
instruments, to see when the rift would fully open. In May 2012, they
observed the opening of a second crack. And just before the calving this
summer, the original rift was roughly 28 kilometers (17 miles) long and
540 meters (1,770 feet) wide.
The ice island is adjacent to some open water in Pine Island Bay and
the Amundsen Sea, but it did not appear to move much in the week between
the TerraSAR-X and ASTER images. It is unclear whether it will take
days, months, or years before the huge iceberg moves out to the sea.
Rock and other glacial ice along the horizontal edges could create
friction and slow its movement. Winds and sea ice also could press it
against the coast.
“It is interesting that the iceberg has not drifted farther from the
ice shelf now that it is no longer connected. Being July, there probably
is sea ice that is helping to hold the iceberg near shore,” said Robert
Bindschadler, an emeritus NASA scientist who has studied Pine Island
Glacier for more than a decade. “We were on the ice shelf last December
and January, and we left GPS receivers to record ice flow. We will be
analyzing those data to see if the ice shelf flow reacted when the
iceberg detached.”
Further Reading
- German Aerospace Center (2013, July 9) Longest glacier in Antarctica has ‘calved’ Accessed July 22, 2013.
- NASA (2013, July 11) Antarctic Glacier Calves Iceberg One-Fourth Size of Rhode Island. Accessed July 22, 2013.
- NASA Earth Observatory Natural Hazards Gallery: Crack in the Pine Island Glacier.
- NASA Earth Observatory (2011, December) Notes from the Field: Pine Island Glacier 2011.
NASA Earth Observatory image by Jesse Allen and Robert Simmon, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Mike Carlowicz, based on information from George Hale, NASA GSFC, and Elisabeth Mittelbach, German Aerospace Center.
- Instrument:
- Terra - ASTER
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Mis blogs son una casa abierta a todas las culturas, religiones y países. Se un seguidor si quieres, con esta acción usted está construyendo una nueva cultura de la tolerancia, la mente y el corazón abiertos para la paz, el amor y el respeto humano.
Mis blogs son una casa abierta a todas las culturas, religiones y países. Se un seguidor si quieres, con esta acción usted está construyendo una nueva cultura de la tolerancia, la mente y el corazón abiertos para la paz, el amor y el respeto humano.
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