Icebergs A-68A and A-68B Calve from Iceberg A-68 in the Larsen-C Ice Shelf

By Evelyn V. Bowens
U.S. National Ice Center
July 17, 2017

Suitland, MD — The U.S. National Ice Center (USNIC) confirmed that iceberg A-68 has broken into two smaller icebergs. A-68 calved off of the Larsen-C Ice Shelf on July 13th and has remained within a few miles of the ice shelf on the east side of the Antarctic Peninsula. The larger iceberg, A-68A, measures 82 nautical miles on its longest axis, 25 nautical miles on its widest axis and is located at 67° 56' South and 60° 55' West. The smaller iceberg, A-68B, measures 6.5 nautical miles by 3 nautical miles and is located at 67° 15' South and 60° 49' West.

A-68A and A-68B were confirmed by USNIC Ice Analysts using longwave infrared imagery (shown below) from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the NOAA/NASA Suomi National Polar-orbiting Partnership (NPP) satellite. These icebergs are expected to drift east-northeast along the Antarctic Peninsula in the Weddell Gyre over the next several months. Additional fracturing is likely before smaller bergs may drift far enough north to enter the Antarctic Circumpolar Current.

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 = 0-90W (Bellingshausen/Weddell Sea)
B = 90W-180 (Amundsen/Eastern Ross Sea)
C = 180-90E (Western Ross Sea/Wilkesland)
D = 90E-0 (Amery/Eastern Weddell Sea)

When first sighted, an iceberg’s point of origin is documented by the USNIC. The letter of the quadrant, along with a sequential number, is assigned to the iceberg. For example, C-19 is sequentially the 19th iceberg tracked by the USNIC in Antarctica between 180-90E (Quadrant C). Icebergs with letter suffixes have calved from already named icebergs, where the letters are added in sequential order. For example, C-19D, is the 4th iceberg to calve off the original C-19 iceberg.

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 Homeland Security). The National Ice Center mission is to provide the highest quality strategic and tactical ice services tailored to meet the operational requirements of U.S. national interests and to provide specialized meteorological and oceanographic services to United States government agencies.

Satellite image of Iceberg A-68AB
Figure 1: VIIRS IR image of A68A and A68B dated July 17th, 2017

For more information, please contact:
National Ice Center
Command Duty Officer
Voice: (301) 943-6977
Twitter: @usnatice
Facebook: @usnatice

The U.S. National Ice Center is a tri-agency center operated by the Navy, NOAA, and Coast Guard and provides global to tactical scale ice and snow products, ice forecasting, and related environmental intelligence services for the United States government.

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