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Update on the motion of Antarctic Iceberg A23a

By Scott Bachmeier •

Sequence of daily NOAA-20 VIIRS Visible (0.64 µm) images, from 01 November 2023 to 19 February 2024 (courtesy Yinghui Liu, NOAA/CIMSS) [click to play animated GIF | MP4]

A sequence of daily NOAA-20 VIIRS Visible (0.64 µm) images from 01 November 2023 to 19 February 2024 (above) showed Iceberg A23a as it migrated northward away from the Antarctic Peninsula to east of the South Shetland Islands (days when dense cloud cover obscured A23a were omitted). Near the end of this time period, the iceberg — whose motion was driven by a combination of winds and ocean currents — performed a complete rotation, and reversed its path to begin drifting back toward the South Shetland Islands.

Daily NOAA-20 VIIRS Natural Color RGB images (excluding cloudy days) from 27 December 2023 to 15 February 2024 (below) also displayed the rotation of A23a, along with the change in direction of its drift within the Southern Ocean.

NOAA-20 VIIRS Natural Color RGB images, from 27 December 2023 to 15 February 2024 (courtesy Rich Dworak, CIMSS) [click to play MP4 animation]

A toggle between Suomi-NPP VIIRS False Color RGB imagery and the Sea Ice Temperature product as viewed using RealEarth (below) showed A23a as it was located just east of Elephant Island and Clarence Island on 15 February. Sea Ice Temperature values were near or just below freezing.

Suomi-NPP VIIRS False Color RGB image and Sea Ice Temperature product on 15 February [click to enlarge]

GOES-16 (GOES-East) True Color RGB images (source) on minimally-cloudy days from 03 February to 19 February (above) also displayed the motion of A23a as it reversed course and drifted southwestward, back toward the South Shetland Islands (while performing part of its rotation).

GOES-16 True Color RGB images, on minimally-cloudy days from 03 February to 19 February [click to play MP4 animation]

Categories: Antarctic, Cryosphere, GOES-16, NOAA-20, RealEarth, Red-Green-Blue (RGB) images, Suomi NPP, VIIRS