Iceberg D-36B Has Calved from Iceberg D-36A

By LT Jacquelyn Putnam, NOAA
NIC.PAO@noaa.gov
U.S. National Ice Center
April 18, 2025

SUITLAND, MD — The U.S. National Ice Center (USNIC) has confirmed that iceberg D-36B calved from D-36A in the southern Amery Sea. As of April 15, D-36A was centered at 66° 18' South and 86° 33' East and measured 6 nautical miles on its longest axis and 5 nautical miles on its widest axis. D-36B was centered at 66° 15' South and 86° 44' West and measured 9 nautical miles on its longest axis and 2 nautical miles on its widest axis. D-36A first calved from the West Ice Shelf in 2024.

The new iceberg was first spotted and confirmed by USNIC Analyst, Isabelle Marcus, using the RADARSAT-2 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.