On 26th September 2016 the MODIS sensor on The TERRA satellite captured this beautiful image of South Georgia, with Iceberg A66 drifting past.

Iceberg A66 passing South Georgia captured in a MODIS image on the 26 September 2016.
Iceberg A66 passing South Georgia captured in a MODIS image on the 26 September 2016. The image is available on a KML file on the MODIS Websites.

The iceberg A66 is about 15 km at it's widest point in this image.

We can do a bit simple maths. Estimate the iceberg has a 200 m thickness and it is triangular in shape with a base of ~4 km.

the volume =  0.5 x 15 km x 4 km x 0.2 km = 6 km3.

So the relatively small A66 contains of 6000 gigtons of water. It's a lot. But it's not a lot.

Icebergs get their reference number depending on where they originate from. This one has an identifier "A" which means it came from the sector 0° to 90°W - that's the Bellingshausen and Weddell Sea region. You can track icebergs like this both visually - like in in the image above - or using something called a Scatterometer. A scatterometer can measure the winds over the ocean, and because the winds change over the ice one can track the icebergs. Prof David Long at Brigham Young University provides an excellent database of Antarctic iceberg data based on that idea (this is their research paper on how they do that).

If we look at the location data from the ASCAT sensor you can see that A66 is at the tip of the Antarctic Peninsula - but this data is only from this year. I will have to dig a little deeper. A job for later.

The track of Iceberg A66 from the BYU database
The track of Iceberg A66 from the BYU database

Once the icebergs reach the edge of the Weddell Sea they get to South Georgia very quickly. I did write about that in a paper in the OU database Physical oceanography in the Scotia Sea during the CCAMLR 2000 survey, austral summer 2000.

And some of these icebergs (although not A66) ground at South Georgia and ultimately can affect the ecosystem. Jon Amos wrote about some work I did at a San Francisco conference  in 2010 about that - it's still available on the BBC website: Giant icebergs head to watery end at island graveyard.

Giant icebergs head to watery end at island graveyard
Giant icebergs head to watery end at island graveyard. By Jon Amos

Overall A66 is nothing special, this is not an unusual observation.

It is a beautiful image though.

The low sea ice extent I noticed in my previous blog post about Antarctic Sound has extended southwards along the east side of the Antarctic Peninsula.

The sea ice extent along the Antarctic Peninsula 24 September 2016
The sea ice extent along the Antarctic Peninsula 24 September 2016. Data from DMSP SSMIS

The open water that shows up as black in the image above extends to at least as far south as the Antarctic Circle (66° 33′S). Open water along this part of the Antarctic Peninsula is unusual at any time of the year let alone the height of winter. The image below is from the National Snow and Ice Data Centre. It shows  sea ice extent >15% with an outline of the typical extent for that day based on a 30-year (1981-2010) median (orange line).

NSIDC Antarctic sea ice extent 24 September 2016 with the median extent (1981-2010) for this day.
NSIDC Antarctic sea ice extent 24 September 2016 with the median extent (1981-2010) for this day.

You can see how unusual this observation is, and I wrote a general post Antarctic Sea Ice Extent a while ago.

The open water is also very clear in the MODIS imagery as the black wedge between the Antarctic Peninsula, and the sea ice of the Weddell Sea.

The MODIS imagery for the Antarctic Peninsula 25 September 2016.
The MODIS imagery for the Antarctic Peninsula 25 September 2016.

In my previous post I pointed at weather systems as likely being responsible. Now to me it looks like a large system is pushing the whole Weddell Sea sea ice to the east and away from Antarctic Peninsula.

There is always some open water in the pack ice at any time of the year, but it's clear that their is a pathway south right now. I imagine it will close soon and wouldn't be keen to be on a ship in that open water heading south.

What is interesting is the heat transfer from the ocean to the atmosphere that far south at this time of the year will be huge. This is what I wrote about that heat loss for the Arctic.

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Just noticed this on the MODIS  sensor on the TERRA satellite image from 10 September 2016.  (Tile Antarctica_rc05c01 if you are interested in that sort of thing)

Antarctic Sound on the tip of the Antarctic Peninsula 10 Sept 2016
Antarctic Sound on the tip of the Antarctic Peninsula 10 Sept 2016

The Antarctic sea ice ice extent map for 10 September 2016 shows an interesting and large low concentration right at the tip of the Antarctic Peninsula

The sea ice extent around Antarctic 10 September 2016. Yellow box is roughly where the MODIS image is, and Antarctic Sound is labelled. Data from DMSP SMMI
The sea ice extent around Antarctic 10 September 2016. Yellow box is roughly where the MODIS image is, and Antarctic Sound is labelled. Data from DMSP SMMI

So why the missing sea ice at the top of the Peninsula?  It could be a storm, or could be heat from the ocean keeping the area ice free. I'll have a look at the data when I've time, but for now I would bet on the ocean.

Interestingly historically it has been a bit of a tough place. Otto Nordenskjöld navigated the sound in December 1902 on the Swedish Antarctic Expedition before their ship, the Antarctic was crushed and lost. They were stranded for two years...

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This just on twitter from the UK Ministry of Defence about the recent magnificent voyage of HMS Protector.

The Tweet posted by MOD on 18th Jan 2016
The Tweet posted by MOD on 18th Jan 2016

On the web page in the link it says

By visiting this region Protector achieved a latitude of 77 Degrees 56 Minutes South – the very edge of the vast Ross Ice Shelf, named for James Clark Ross who led the exploration of the area.

No official British ship has been this far south since 1936 and it is believed not since James Clark Ross’s own expedition in 1842.

I don't think this is true. The British Antarctic Survey Ship RRS Bransfield reached likely a little further south. According to this note from the Second Officer Chris Elliot which is published on the website The LOFTSMAN which is about the shipyards of Leith.

Furthest South of the RRS Bransield was 77 56' 44''
Furthest South of the RRS Bransield was 77 56' 44''

RRS Bransfield reached 77°56' 44"S.

So 44 seconds further south than HMS Protector.

Which is what? 1.3 km?

I know it's not much further south and Protector likely matched it (they don't give their decimal). I just wanted to make the point that it is close. Very close.

The second officer in the note - Chris Elliot went on to become the Captain of the RRS John Biscoe, and then he was a member of the team that built the RRS James Clark Ross for many years, before becoming one of the Captains of that great ship.

UPDATE See comment below by Radio Officer of the RRS James Clark Ross Mike Gloistein.

Yet more beautiful MODIS imagery showing some wonderful patterns in a plankton bloom in the Barents Sea.

Plankton patterns in the Barents Sea
Plankton patterns in the Barents Sea

The screen grab is from the 250m resolution imagery, and the whole arctic panel shows just where the bloom is located.

The Arctic on 29 July 2015 in MODIS imagery
The Arctic on 29 July 2015 in MODIS imagery

This particular region seems to show plankton blooms regularly in the MODIS imagery and the Wikipedia page has a similar (but not as nice) image dated summer 2009.

 

 

There is a lot happening at the edge of the Greenland Ice Sheet as summer progresses, and the MODIS sensor on the TERRA and AQUA satellites is a wonderful way to observe it.

I noticed the other day (8 July 2015) this beautiful image of fast ice breaking out of a Fjord on the east coast at 76N

Fast ice breaking out of an East Greenland fjord
Fast ice breaking out of an East Greenland fjord

The full image can get down to 250 m per pixel and it is amazing stuff. The image below (from Google Earth) shows the location.

Location of the enlargment
Location of the enlargement

And now in the 9 July MODIS image you can see very many large pools of water on the edge of the Greenland Ice sheet. Again, remember each pixel of this image is 250 m across - they look small but that are large pools.

...continue reading

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The MODIS sensor satellite imagery is showing a beautiful and evolving large plankton bloom in the Chukchi Sea at the moment.

Plankton bloom in the Chukchi Sea, as seen in the MODIS sensor on 23 June 2015.
Plankton bloom in the Chukchi Sea, as seen in the MODIS sensor on 23 June 2015. Alaska is on the LEFT and Russia the RIGHT. The image is looking SOUTH.

The plankton are the lighter green bands I've labelled and the full image is available at an astonishing 250m resolution.

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I was enjoying my polar books the other night and came across a quote attributed to everyone's  favourite humanitarian polar explorer and scientist, Fridtjof Nansen.

Fridtjof Nansen
Fridtjof Nansen, 1915, from the George Grantham Bain Collection

If I were not a Norwegian, I would be an Englishman rather than belong to any other nation

Nansen is quoted in Fridtjof Nansen, his life and explorations, by James Arthur Bain, 1897.

Fridtjof Nansen quoted by James Bain, 1897. Page 45

Fridtjof Nansen quoted by James Bain, 1897. Page 45

It's hard not to be in awe of Nansen.

...continue reading

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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.

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Last week I enjoyed an Inaugural lecture by Professor Martin Siegert of Imperial College. Inaugural Lectures are a big deal:

Imperial's Inaugural Lecture series provides a platform to showcase and celebrate the College's new professors. The inaugural lecture provides official recognition and celebration of the academic’s promotion to professor. A number of guests are invited to attend and students, other staff, and the general public may also attend the lecture. Inaugural lectures are preceded by tea and cakes for invited guests and often followed by a drinks reception, buffet or dinner again for invited guests.

Tea and cakes... I love being English.

Martin spoke brilliantly on how Antarctica is changing to an audience of about 150 people. For a crash course in "where we are now" I would say it is a must watch.

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