By LT Jacquelyn Putnam, NOAA
April 29, 2023
Suitland, MD — The U.S. National Ice Center (USNIC) has confirmed that iceberg A-76D (figure 1, below) calved from iceberg A-76A in the northern Weddell Sea. As of April 28, A-76 was centered at 56°46' South and 42°10' West and measured 19 nautical miles on its longest axis and 5 nautical miles on its widest axis. A-76 first calved from the Ronne Ice Shelf in May 2021. A-76 calved into A-76A, A-76B and A-76C later that month.
The new iceberg was first spotted by Dr Jan Lieser of Australia’s Bureau of Meteorology and confirmed by USNIC Analyst Britney Fajardo using the MODIS image below.
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.
USNIC is a multi-agency center—subordinate to Naval Meteorology and Oceanography Command—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.
Naval Meteorology and Oceanography Command directs and oversees more than 2,500 globally-distributed military and civilian personnel who collect, process and exploit environmental information to assist Fleet and Joint Commanders in all warfare areas to make better decisions faster than the adversary.
For more information, please contact:
U.S. National Ice Center
Command Duty Officer
Voice: (301) 943-6977
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.