Navigation charts in Antarctica may not be as good as you think. It makes sailing in those regions a little more exciting than you could hope. Here is an example.

The coastline of Rothschild Island just to the west of Alexander Island, Antarctica. The navigation chart says the coastline location could be 5 miles in error
The coastline of Rothschild Island just to the west of Alexander Island, Antarctica. The navigation chart says the coastline location could be 5 miles in error

Five miles wrong... What does that mean?

Here is London with a 5 mile radius circle drawn on it.

London with a 5 mile circle drawn on it
London with a 5 mile circle drawn on it.

If you sailed your ship to a position - say the edge of Rothschild Island, you would not know the exact location of that coast to within the radius of that circle.

Just get your head around that. In this age of satellites, in 2016 we don't know the location of coastline of Antarctica to the same level of accuracy that we already know the topography of Mars, Venus and our Moon.

Why are they so bad?

As usual there are lots of reasons. Most of the coastlines were mapped out by people on sailing ships and huskie drawn sledges decades before the satellites were launched. That means the outlines of the coasts and water depths tend to be excellent. But absolute position - basically the origin of the co-ordinate system - can be out.

The bottom line is if you are trying to calculate position with a sextant and clock, it's hard enough in good conditions (for me!). But in a snowstorm when it has been overcast for several days? The historical navigators are my heroes.

In practice today does this lack of accuracy matter?

Charcot Island. A photograph of a repeater of the navigation display of RRS James Clark Ross in 2008.
Charcot Island. A photograph of a repeater of the navigation display of RRS James Clark Ross in 2008.

That picture of the ship's track tells the story. The ship has skirted the coast of the island, but according to the chart we ended up on land! I have a few examples like this from Antarctica. And even the mighty Google Earth has Charcot Island wrong.

A screengrab of Charcot Island from Google Earth Pro 20 Nov 2016. The island is displaced by ~11 nautical miles.
A screengrab of Charcot Island from Google Earth Pro 20 Nov 2016. The island is displaced by ~11 nautical miles.

Polar ship Captains, officers and crews take ships into areas that are genuinely unexplored. We don't know the coastline or the water depths well.

In fact, in Antarctica all you really can be certain of is you know you are going to be surrounded by icebergs and sea ice.

It's a big responsibility.

The sea Ice is too heavy for the RRS James Clark Ross to make Rothera base right now. You may have thought the sea ice on the satellite images didn't look too bad, but it's all about how thick the sea ice is, and where the open water is.

To quote the radio officer Mike Gloistein:

The sea-ice around the bottom of Adelaide Island has been heavy and whilst (for those of you who look at the satellite pictures) there are some leads and areas of open water,  they are close to land and if we took that route (which also includes shallow water and rocks) and the weather then pushed the ice inland,  the ship could easily become stuck between a rock and a hard place.

And then the ship could get seriously stuck just like I said the John Biscoe did in my previous post. In that case the ship was rescued by Polarstern.

This was the satellite image I posted yesterday:

The MODIS satellite image off Adelaide Island 25 Nov 2016, with the location of the RRS James Clark Ross 0000 28 November 2016.
The MODIS satellite image off Adelaide Island 25 Nov 2016, with the location of the RRS James Clark Ross 0000 28 November 2016.

And this is a navigation chart of that region.

Section of the Navigation Chart around the southern tip of Adelaide Island.
Section of the Navigation Chart around the southern tip of Adelaide Island.

The light blue shading is shallow water and it's not a great place for a ship to go without freedom of navigation. The sea ice takes away that freedom. This is of course a very sensible choice by the ships Master, and exactly the same thing happened to a voyage I was on in 2004.

In another few weeks it will be clear for them.

I don't think this was predictable. You really have to be on the ground to see what the conditions are to make a call on whether it is safe or not. Two months ago on the 6 October I blogged about the sea ice and the potential of this happening, and said:

There are a lot of Antarctic research stations on the west of the Antarctic Peninsula, including Rothera, the largest British Base.  If the winds maintain the westerly direction then I can imagine it could be slow to resupply the base this season. There is time for it to change. According to the published schedule the ship is not due to arrive until 27 November 2016.

A slow resupply is not uncommon and I have been on at least one unsuccessful resupply voyage in my career. I took the picture below on 11 December 2004 under similar conditions.

James Clark Ross making very slow progress in compressed sea ice in Marguerite Bay, the Western Antarctic Peninsula.
James Clark Ross making very slow progress in compressed sea ice in Marguerite Bay, the Western Antarctic Peninsula.

Although it is not predictable, the fantastic British Antarctic Survey Operations will have planned for the consequences.

For a last point on the left of the navigational chart is one of my favourite place names:

Fullastern Rock to the west of Adelaide Island
Fullastern Rock to the west of Adelaide Island

As it says on the UK Antarctic Place Names website:

Fullastern Rock (67° 36′ 58″ S, 69° 25′ 59″ W) is a submerged rock on the west side of Johnston Passage, to the west of Adelaide Island. It was first charted by a Royal Navy Hydrographic Survey Unit from RRS John Biscoe in 1963.  The ship was compelled to go full astern to avoid this hazard  – a story succinctly captured by this evocative name!

 

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RRS James Clark Ross is on route to Rothera, the largest British Antarctic Survey research Station. In the next few hours to get to the base she will have to pass what looks like a continuous sea ice band about 15 km wide, before she enters some looser pack. To get their she will have to do some icebreaking. The band of ice has been stationary for over a week.

If you want to follow the action the ship has a webcam, or you can check the Radio Office Mike Gloistein's update page. The web cam is as I write this but I'm sure it will be switched on soon.

The MODIS satellite image off Adelaide Island 25 Nov 2016, with the location of the RRS James Clark Ross 0000 28 November 2016.
The MODIS satellite image off Adelaide Island 25 Nov 2016, with the location of the RRS James Clark Ross 0000 28 November 2016.

The satellite image is from 25 November 2016, but the sea ice doesn't look like it has changed significantly since then. I chose that date simply because it is relatively cloud free.

The ship has about 130 km to run so could dock later today - but it could be tomorrow given the sea ice.  The path I have shown in red looks quite a long way south of the Island - but close in it gets quite shallow. If your interested in your polar history the ship RRS John Biscoe was actually abandoned in this region for a while before being rescued by the German ship Polarstern.

This is as The Antarctic Report points out, quite early for the ship to reach the base.

The track of the ship is online along with the weather conditions it is experiencing. At at about 0°C it is currently warmer than a lot of the UK.

Dr Helen Jones is the doctor on the James Clark Ross and she is writing a blog Baby it's cold down here.

--UPDATE 1050z --

You can see James Clark Ross is now in the ice and heading for the band of relatively open water at the southern tip of Adelaide Island.

This is an image from the webcam.

I wrote about what a water sky is a while ago.

--UPDATE 0650z 29 November --

It was too early and the RRS James Clark Ross didn't make Rothera.

To quote the radio officer Mike Gloistein:

The sea-ice around the bottom of Adelaide Island has been heavy and whilst (for those of you who look at the satellite pictures) there are some leads and areas of open water,  they are close to land and if we took that route (which also includes shallow water and rocks) and the weather then pushed the ice inland,  the ship could easily become stuck between a rock and a hard place.

And get stuck just like the John Biscoe...

 

The extent and thickness of the Arctic sea ice is decreasing for every month of the year. But looking at straight lines on graphs with a relentless downward trend it’s easy to lose the geographic sense of what is happening.

The red areas in the plot below show where ice was absent on 3 March 2016 compared with the mean 1989-93 at the height of the winter. I chose 1989-93 the comparison period as it is just before the start of the relatively rapid decline in we observe in Arctic sea ice.

The difference between the daily ice extent, in each grid cell and the mean based on historical data for the years 1989-93. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.
The difference between the daily ice extent, in each grid cell and the mean based on historical data for the years 1989-93. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.

As you would expect there is not a lot of blue in the plot, and the ice edge has retreated virtually everywhere. The stand out region is the Northern Barents Sea. On the NSDIC website you can see that the decline of sea ice in the Kara and Barents Seas is part of the long-term trend.

...continue reading

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This is the the full years data to 21 November for the anomalies of the sea ice extent in 2016. See my blog post Antarctic sea ice 2016: Historic lows for full context.

The plot shows the difference between the daily ice extent, in each grid cell, for the year to 21 November 2016, and the mean, for each day, based on historical data for the 5 year period 1989-93.

Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean.

The five year average sea ice extent - the extent for the same day in 2016. Red colours indicate less sea ice than the 5 year mean.
The five year average sea ice extent (1989-93) - the extent for the same day in 2016. Red colours indicate less sea ice than the 5 year mean.

To make the plot for each day of the year and each grid cell I worked out the mean sea ice extent for 5-year period 1989-1993. I then used this calculated mean taken away from the 2016 data for the same day to derive the anomaly maps.

For example if the plot shows very dark blue that means that there is 100% sea ice cover in that grid cell in 2016 and none in the 1989-93 mean.  A dark red means there is no sea ice in 2016 where we would expect 100% sea ice cover.

The original data come from  the DMSP SMMI data set at the NSIDC.

A post describing this data is Antarctic sea ice 2016: Historic lows

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The seasonal cycle of sea ice extent in Antarctica has been fairly stable over the length of the satellite record.  There is a slow growth of sea ice from a minimum of ~3x106 km2 in February to a maximum of ~19 x106km2 in September, before there is a relatively rapid fall in the Antarctic spring.

But this year something different is happening.

Below is Tamino's image for the Southern Hemisphere sea ice extent, the red line is 2016 up to 16 November 2016.

The annotated seasonal extent of sea ice in the Southern hemisphere. From Tamino's post Sea Ice, North and South.
The annotated seasonal extent of sea ice in the Southern hemisphere. From Tamino's post Sea Ice, North and South.

From January up to September the sea ice extent in 2016 follows all previous data.

But what happened in September?

...continue reading

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The summer of 2016 saw the joint second lowest Arctic sea ice extent. But in the middle of October unusual Arctic weather has led to it becoming the lowest extent. At the same time, Antarctic sea ice extent has also reached record lows. Tamino has a simple and clear post about what a surprising thing this is.

The Northern Hemisphere Sea Ice extent from Tamino's blog
The Northern Hemisphere Sea Ice extent from Tamino's blog "Open Mind". The current year 2016 is in Red

 

Why is it so low?

The plot below shows the mean November Arctic sea ice extent, the sea ice extent on 16 November 2016, and the difference between the extents from 1993 to 2016. Regions shaded at the top end of the scale (the red colours) mean there is less ice now compared with in 1993.

The mean Arctic sea ice extent in November 1993, the daily sea ice extent on 16 November 2016, and the difference between them
The mean Arctic sea ice extent in November 1993, the daily sea ice extent on 16 November 2016, and the difference between them.

The stand out region (to me!) is North Russia where the Kara Sea is almost entirely clear, followed by Hudson Bay, Baffin Bay, East Greenland and the edge of the Chuckchi Sea. I was interested in what was going on in the Kara Sea so I made a movie of the sea ice extent from 1 November 2016 to 16 November 2016.

Arctic sea ice 1 to 16 November 2016.
Arctic sea ice 1 to 16 November 2016.

The striking thing in the clip for November 2016 is that the sea ice extent has actually reduced in the Kara Sea!

The sea ice extent in Chuckchi Sea is increasing, but very slowly - and you can see from my previous image that it is very low compared with 1993.

Clearly the Arctic is experiencing strange conditions at the moment. On the climatereanalyzer.org website you can see the 5-day forecast from 17 November 2016 (tomorrow).

The temperature departure from average is off the scale over the Arctic Ocean. It's much colder over Russia.

The 5 day forecast from 17 November 2016 from Climate Reanalyzer.org.
The 5 day forecast from 17 November 2016 from ClimateReanalyzer.org.

These are astonishing observations. When the winds change and the cold air currently over Russia ends up over the ocean I would expect it to freeze up rapidly (once the surface layers have cooled). But starting so late in the year the sea ice could end up thin enough for something impressive in the near future.

I made a gif of the full current Arctic growing season up to 16 November 2016.

I have already written a little about the this years Antarctic sea ice extent in the Antarctic Peninsula sea ice late winter 2016, in The Western Weddell Sea ice factory, in The development of the Amundsen Sea Polynya, in Dotson Getz Polynya ice growth, and in The Prince Gustav Channel is opening.

For interest, I chose November 1993 for comparison for two reasons, first it’s just before the big Arctic sea decline, and secondly I was in the Arctic for 4 months that year doing my PhD research.

Tamino is noting that the global sea ice is "About 6.9 standard deviations below the 1981-2010 mean." . Amazing times.

The Prince Gustav Channel was covered by an ice shelf which collapsed in the 1990's, and for many years it was possible to sail a ship around James Ross Island.

Recently it has been covered with sea ice frozen to the land - we call this fast ice, and it's usually only a few metres thick of frozen sea water - rather than hundreds of metres thick snow derived ice shelf.

Recent images from the TERRA satellite show that this fast sea ice is finally breaking out.

It'll soon be possible to circumnavigate James Ross Island once more.

The Prince Gustav Channel early spring Antarctic summer 2016/7 from MODIS satellite imagery on the TERRA satellite.
The Prince Gustav Channel early spring Antarctic summer 2016/7 from MODIS satellite imagery on the TERRA satellite.

This map shows the location of the channel.

The Antarctic Peninsula showing the location of the Prince Gustav Channel.
The Antarctic Peninsula showing the location of the Prince Gustav Channel.

Now it has started I wonder how long it will take to finally clear. Or more fun, I wonder if tour ships will be able to get around the island?

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My previous posts on Amundsen Sea Polynya and their development showed ~37,600 km2 of open water in front of the ice shelves. It is very early spring in Antarctica at this time of the year and it’s still cold.

That means sea ice can still grow.

This is the Dotson Getz polynya on 9 October 2016. It has a perimeter of ~800 km and an area of ~25,500 km2.

The Dotson Getz polynya on 9 October 2016. Open water is black and streaks of sea ice growth are clear. The location of the Bear Peninsula Automatic Weather Station is marked.
The Dotson Getz polynya on 9 October 2016. Open water is black and streaks of sea ice growth are clear. The location of the Bear Peninsula Automatic Weather Station is marked.

I put together the satellite data from 9-12 October 2016 and it shows extremely rapid sea ice growth.

...continue reading