Icebergs D-33A and D-33B Have Calved from Borchgrevink Ice Shelf

By LT Jacquelyn Putnam, NOAA
NIC.PAO@noaa.gov
U.S. National Ice Center
August 31, 2023

SUITLAND, MD — The U.S. National Ice Center (USNIC) has confirmed that icebergs D-33A and D-33B (Figure 1, below) calved from Borchgrevink Ice Shelf in the southern Weddell Sea. As of September 01, D-33A was centered at 69°47' South and 19°14' West and measured 34 nautical miles on its longest axis and 10 nautical miles on its widest axis. D-33B was centered at 69°54' South and 20°31' West and measured 21 nautical miles on its longest axis and 12 nautical miles on its widest axis.

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 Sentinel-1A 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 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 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.

Iceberg positions are analyzed weekly and are available on the USNIC webpage at: https://usicecenter.gov/Products/AntarcIcebergs

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:
National Ice Center
Command Duty Officer
Voice: (301) 943-6977
E-mail: nic.cdo@noaa.gov
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.