Icebergs | Mallemaroking

Mark Brandon • October 15, 2024

I love looking at satellite images of the Antarctic and picking out the icebergs. In the last few years we have had great stories about the giant icebergs A68 in 2020, A76 in 2022 and most recently A23a currently in the Southern Scotia Sea.

At the moment there are two of very large icebergs at the southern end of Antarctic Sound. Here is a map to orientate yourself and show where they are.

A basemap with a MODIS image from 7 October 2024. The yellow box is the location of Antarctic Sound and is expanded on below.

There is a lot in the image above. As well as the Antarctic Peninsula there are clouds, sea ice, and icebergs. Zooming into Antarctic Sound shows the giant icebergs more clearly.

A MODIS satellite image of Antarctic Sound taken on 7 October 2024. Two large icebergs are at the southern end of the Sound. These are A80A and A76C.

And in the radar sensor on Sentinel-1 the icebergs leap out because that sensor “sees” through the clouds.

A Sentinel-1 SAR image from 8 October 2024. Land is coloured blue, the giant icebergs are solid grey, and sea ice and smaller icebergs make up the grey shades colouring the rest of the image.

A80A is 10×9 nautical miles and it calved from the Larsen D Ice Shelf in November 2022. A76C is currently 16×7 nautical miles and was part of iceberg A76 that calved from the Ronne Ice Shelf in May 2021. These are pretty decent sized icebergs: A80A looks to be pinned against Rosamel Island and Andersson Island at the southern end of Antarctic Sound, and A76C grounded against A80A.

Personally I would be surprised if they broke out before the start of the Antarctic season proper, so they could cause some complexities in navigating into the Weddell Sea through Antarctic Sound.

Finally we can’t forget the current monster of them all: A23A at 40×32 nautical miles, and it has been spinning above Pirie Bank north of the South Orkney’s since April 2024. I described it as “the iceberg that just refuses to die” when I spoke to the BBC, and it has been spinning for seven months in pretty much the same location. When it finally breaks free, it’ll head up towards South Georgia and it’s inevitable demise rapid demise.

A MODIS satellite image from 13 October 2024 showing iceberg A23A just north of the South Orkney Islands.

It’s amazing to think that A23A has been in existence since 1986 when it fractured from the Filchner-Ronne Ice Shelf.

The summary? It looks like if you’re going South this season you could see some very big icebergs, and navigation could be complicated in the North West Weddell Sea.

Posted in Science, Uncategorized. Tags: Antarctic Peninsula, Antarctic Sound, antarctica, iceberg, Icebergs on October 15, 2024 by Mark Brandon. Mark Brandon • March 25, 2015

Mark Brandon, The Open University

You never forget the first time you see an iceberg. The horizon of a ship at sea is a two dimensional space and to see a three dimensional piece of ice appear in the ocean is quite something. But, in truth, the first iceberg you see is likely to be small. Most icebergs that make it far enough north from Antarctica to where they are danger to shipping are sometimes many years old and at the end of their lives. They are small fragments of what once left the continent.

Once in a while, however, a monster breaks free from the edge of Antarctica and drifts away. Tens of kilometres long these bergs can tower perhaps 100 metres above the sea and reach several hundred more below the surface. These are called tabular icebergs – and while it is rare for humans to see something on such a scale they are part of the normal cycle of glacial ice in Antarctica.

A tabular iceberg gets stuck in thin, seasonal sea ice.
Mark Brandon, CC BY-NC-SA

Everyone knows Antarctica is an ice-covered continent, but the ice is not static. To a scientist it is a dynamic environment – it’s just a question of the timescale you are looking at. Snow falls on the continent and over time it has built up layers of ice which flow in glaciers towards the coast.

…continue reading →

Posted in Science. Tags: antarctica, Conversation, Icebergs, Mertz Glacier, polynya, sea ice on March 25, 2015 by Mark Brandon. Mark Brandon • October 29, 2014

Everyone likes a wandering albatross (Diomedea exulans), but to see them swoop around icebergs is a special experience. At South Georgia you can watch this sort of thing for hours.

A wandering albatross in front of Icebergs off the coast of South Georgia.

You can download the full resolution image at my flickr page.

But Ruth Mottram reminded me of Coleridge and The Rime of the Ancient Mariner.

In that poem they did not feel the same way about the albatross. This is memorably captured by the wonderful art of Gustave Doré.

The Albatross by Gustave Doré

I like albatross.

Posted in History. Tags: albatross, antarctica, Diomedea exulans, Icebergs, South Georgia on October 29, 2014 by Mark Brandon.