|
 October
15 – The National Ice Center reported today that an iceberg
larger than the state
of Delaware has broken or "calved" off the Ronne Ice
Shelf in Antarctica. (image)
The iceberg, named A-38, is 92
x 29.9 miles and covers an area roughly 2750.8 square miles.
It calved off the second largest ice shelf in Antarctica, located
in the southern Weddell Sea.
Mary Keller, a scientist at the National Ice Center in Suitland,
Md., sighted the iceberg using satellite data. The data are from
an instrument on a satellite in the Defense Meteorological Satellite
Program -- the Operational Linescan System, which has a spatial
resolution of .55 km (.34 miles).
Ice shelves are massive, floating
sheets of snow and frozen water that encircle the Antarctic mainland.
Scientists at University College London believe that the calving
of icebergs is an important mechanism in the disintegration of
ice shelves, and a possible indicator of global warming. Scientists
there report that the mechanics of ice shelf fracturing remain
poorly understood. A research group at the college is planning
to study ice core samples from the Ronne Ice Shelf to learn more
about fracture and deformation properties.
The last known iceberg of this magnitude to calve off a Southern
Hemisphere Ice Shelf was B-9 in the Ross Sea in October 1987.
Iceberg names are derived from
the Antarctic quadrant in which they were originally sighted.
The quadrants are divided counter-clockwise in the following
manner:
A = 0 to 90 degrees West longitude (Bellinghausen/Weddell Sea)
B = 90 West to 180 (Amundsen/Eastern Ross Sea)
C = 180 to 90 East (Western ross Sea/Wildesland)
D = 90 East to 0 (Amery/Eastern Weddell Sea)
When an iceberg is first sighted,
the National Ice Center documents its point of origin. The letter
of the quadrant, along with a sequential number is assigned to
the iceberg. For example, A-38 is the 38th iceberg the ice center
has found in the Antarctica in Quadrant A.
The National Ice Center is a
tri-agency operational center represented by the United States
Navy (Department of Defense); the National Oceanic and Atmospheric
Administration Department of Commerce); and the United States
Coast Guard (Department of Transportation). The National Ice
Center's mission is to provide world-wide operational ice analyses
for the armed forces of the United States and allied nations,
U.S. government agencies, and the private sector.
An image of A-38 is on the World
Wide Web at:
http://www.natice.noaa.gov
Click on Icebergs; then click onto Southern Hemisphere Icebergs
The GIF image of A-38 is located above the weekly iceberg update
table. |
