A23a is a large tabular iceberg which calved from the Filchner–Ronne Ice Shelf in 1986. It was stuck on the sea bed for many years but then started moving in 2020. Its area is about 3,900 square kilometres (1,500 sq mi), which made it one of the largest icebergs in the world until it was temporarily surpassed in size by A76.[2][3]
In November 2023, A23a was tracked moving past the northern tip of the Antarctic Peninsula and heading towards the Southern Ocean.[4] On 1 December 2023, the iceberg was intercepted by the polar research ship RRS Sir David Attenborough, off the tip of the Antarctic Peninsula.[5] At 10 knots, it took the ship several hours to sail along two sides of the iceberg.[5] A23a is expected to release a significant quantity of mineral dust as it melts, so the ship took water samples around its perimeter.[5]
On 14 January 2024, dramatic archways caused by wave action on A23a were documented by a drone operated by Eyos Expeditions videographer Richard Sidey and expedition leader Ian Strachan. Their footage was published widely by the BBC and CNN.[6] In early April 2024, the iceberg entered the Antarctic Circumpolar Current, but stays in place as it was trapped in a Taylor column, as confirmed in August 2024, over the Pirie Bank seamount, turning counterclockwise by around 15 degrees every day, near the South Orkney Islands. [7][8] This counterclockwise rotation is occurring about 375 miles from the Antarctic Peninsula.[9]
The base Druzhnaya I, which was originally established on the Filchner–Ronne Ice Shelf, was situated on the iceberg when it calved.[2] Subsequently, a rescue mission was started in 1987 and ultimately moved/renamed the base to Druzhnaya III.[10]
References
edit- ^ "Antarctic Iceberg Sails Away". NASA Earth Observatory. 28 November 2023.
- ^ a b Amos, Jonathan (24 November 2023). "A23a: World's biggest iceberg on the move after 30 years". BBC News.
- ^ "Largest iceberg (current)". GuinnessWorldRecords.com. 28 October 2022.
- ^ Smith, Stephen (24 November 2023). "World's largest iceberg – 3 times the size of New York City – "on the move" for the first time in 37 years". CBS News. Retrieved 25 November 2023.
- ^ a b c Amos, Jonathan (4 December 2023). "Attenborough ship encounters mammoth iceberg". BBC News.
- ^ Amos, Jonathan (16 January 2024). "A23a: Spectacular arches, caves as monster iceberg decays". BBC News. Retrieved 22 January 2024.
- ^ Tumin, Remy (7 August 2024). "After Breaking Free, World's Largest Iceberg Is Stuck Spinning in Circles". The New York Times. Archived from the original on 7 August 2024. Retrieved 10 August 2024.
- ^ Amos, Jonathan; Rivault, Erwan (4 August 2024). "World's biggest iceberg spins in ocean trap". BBC News. Archived from the original on 4 August 2024.
- ^ https://www.npr.org/2024/08/10/nx-s1-5069771/iceberg-a23a-spinning-ocean-vortex-trapped-taylor-columnhttps://www.npr.org/2024/08/10/nx-s1-5069771/iceberg-a23a-spinning-ocean-vortex-trapped-taylor-column
- ^ Shabad, Theodore (22 February 1987). "Russians Recover Lost Ice Station". The New York Times. Archived from the original on 9 March 2014. Retrieved 4 August 2024.
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