Cruise summary

Now that the research voyage is nearing its end, what has been achieved by the team of 24 scientists and engineers? We’re delighted by the quantity and quality of the observations and data sets that we’ve been able to obtain. We’ve been helped by the unusually small amounts of sea ice in Pine Island Bay & this meant that we could get to areas that are very rarely accessible. There are many aspects of the data that will take many months of careful study to understand the processes fully, and other chemical measurements that we can’t even start to analyse until we get the samples transported home to our laboratories. However here are some of the highlights so far:

  • We’ve mapped the temperature, salinity, current velocity and amount of oxygen in the water, at 105 places all over the eastern Amundsen Sea from the edge of the glaciers to where the continental shelf ends and the sea bed slopes steeply down to the ocean abyss. We’ve been exploring some places where no-one has ever measured what the ocean is like. It is very exciting to be able to map the paths of a current for the first time.
  • Some of the observations were repeats of temperature and salinity measurements made by other oceanographers in 1994, 2003, 2007 or 2009. Compared with 2009, our measurements in 2014 show that the deep layer of warm salty water is thinner and so the water reaching the ice shelf is colder than in 2009.
  • 14 seals are now sporting the latest in stylish headgear. They have obligingly spread out all over the eastern Amundsen Sea. One surprise is that they seem to be targeting the fronts of the various ice shelves for their foraging. We don’t yet know why that might be!
  • We’ve sent an autonomous submarine into the cavity beneath the ice shelf, measuring the properties of the water and the currents. It ventured bravely all the way to the grounding line, where the ice meets the solid earth continent of Antarctica, well below sea level. The sub discovered some fascinating waves in the sea bed, that might be caused by the ice shelf moving up and down in previous years or centuries.
  • The water that enters into the cavity beneath Pine Island Glacier is relatively warm and salty (ok, by “warm” we mean about zero Celsius!). This warm water melts the ice shelf and the resulting meltwater is mixed in. This water eventually exits higher up than it entered, because it has now got some fresh (not salty) water mixed in. We’ve studied the area where this meltwater mixture comes out. We’re looking forward to the results of the various chemical tracer measurements in this meltwater.
  • A big surprise has been the large amount of mixing happening in the meltwater just after it comes out from under the ice shelf. We’ve measured this for the first time and are coming up with theories for what is causing this turbulence.
  • We’ve recovered 63 instruments (of which 62 worked!) that have been moored to the sea bed in 7 places for the last 2 years, measuring temperature, salinity and current velocity all the time. 2012 was a very different year from 2013 with very different temperatures.

We’re looking forward to exploring why this is. We’re now steaming back to Rothera, one of the British Antarctic bases on the Antarctic Peninsula. We should arrive on Saturday, when we’ll be transferred to a small plane to fly back to Punta Arenas, almost exactly 6 weeks since we left!

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Pancakes all around!

We have been surrounded by pancakes for the past few days now – but of the ice variety rather than the culinary! Pancake ice is just one stage of many in the route that sea ice takes to form the more solid looking, snow topped ice floes that we’re more used to associating with sea ice. The weather has been so cold here recently that we’ve been able to see nearly all of the first stages of sea ice formation, as well as lots of older sea ice from last winter!

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Pancakes of ice!

The freezing point of seawater is cooler than that of freshwater – due to its salt content – at approximately -1.9C. As the seawater cools to the freezing point, ice crystals begin to form, and when a significant amount of these are present they are known as frazil ice. This type of initial sea ice is very difficult to see, as it hasn’t yet formed a larger scale structure.

As more and more groups of frazil ice join together, they form the next stage of sea ice formation; grease ice. This is so named due to the appearance it gives the sea surface when it forms – it looks like streaks of grease across the surface! This layer is only a couple of centimetres thick, and as it thickens it will become nilas ice, which can be up to 10 cm thick. This is still quite a delicate layer of ice, and can be easily broken through by the ship.

Since nilas ice is still quite thin, it can be affected by wind and waves. As these processes affect the ice, the separate nilas ‘floes’ will begin to collide with each other, rumpling the outer edges on impact. This results in the type of ice that we have seen the most recently; pancake ice! It is very distinctive through its flat inner area, with a raised rim – a bit like a pancake or a deep pan pizza.

Over time, the thickness of these pancake ice floes will increase, and they’ll begin to join together to form this year’s sea ice. The sea ice is still considered ‘new ice’ until it’s about 30 cm thick, and only becomes ‘first year ice’ when it is between 30 – 120 cm. Any ice that survives next summer to continue to grow during the next winter becomes ‘old ice’ – eventually becoming ‘multiyear ice’ once it has weathered several summers.

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A lead in thick sea ice

For sea ice to form, salt cannot be present and so large amounts of salt are removed from the seawater whilst it is freezing. The seawater contains on average 3.4% salt, yet first year sea ice will only have 0.6% salt (all this salt gets forced into the surrounding seawater with important consequences for ocean circulation). By the time the sea ice becomes multiyear ice it will only have 0.1-0.2% salt content and will begin to take on a blueish hue – this is a much more solid type of ice and wouldn’t be ideal for the ship to break through!

Luckily, we’ve been able to get everywhere that we’ve needed to go to so far; the thickest ice we’ve had to break through was thick first year sea ice (formed over the winter). Hopefully this good fortune will continue for our final few CTD stations and last mooring on the eastern shelf edge of the Amundsen Sea! 

Seal tagging part 2

Written by Mike Fedak.

After a long stretch of physical oceanographic work, on February 23rd, we got a suitable time window to once again try to catch seals and attach CTD-SRDLs. Our original plan was to tag roughly 8 elephant seals and 8 Weddell seals, but until the last few days we had only applied tags to 7 elephant seals. The ship has been totally occupied with physical oceanographic work. After completing work at the Thwaites Glacier front and recovering Autosub, we decided to once again try catching at the Edwards Islands.

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Crew and Scientists aboard the JCR watch as the team on the ice tag seals

Unlike last time, this proved difficult. On the morning we were to set out in the rubber boats, it was cold (about -9 C) and the wind was strong, but the forecast was for improving conditions. This proved optimistic, to say the least, and by the time we were all on the water in the boats, the wind began to increase. But, having invested the time and energy of the crew and ourselves in getting that far, we headed into the wind for the islands, about 1 mile off. There was a steep and nasty chop. Imagine getting bounced around on some theme park ride while someone throws buckets of ice water (and I do mean buckets!) hard, into your face. It was a difficult situation to enjoy. But there was a brief highpoint as a passing leopard seal took an interest in the two boats and began swimming after us, surfing on the waves and pushing the first third of itself out of the water to have a good look at what it must have figured was an unusual potential foraging opportunity. But it soon gave up and we were left trying to avoid the worst of the spray. Each boat held four of us and the 3 passengers in each could at least get low down in the boat and turn our backs to the spray. No such luck for the driver who just has to take it full in the face.

We got into the lee of the islands where we had hoped for some protection from the worst of the wind. But the islands are low and almost seem to be streamlined with respect to the wind blowing off the ice fields of the continent. That is why they are relatively snow free. And the wind was rising rather than dropping, with gusts reaching 40 knots (force 8 gale). So we decided to give up and head back to the ship to see if conditions improved later. The ride back, going with the wind was relatively relaxing, although even waiting to get on board while the first boat was hoisted up to the deck was pretty miserable.

Conditions did not improve all day so the following morning we set off West across the Pine Island Bay over to the north of the Thwaites Glacier front where there was a large band of sea ice stretching northwest, which we hoped would provide good opportunities for catching Weddell seals. The weather improved, the wind dropped, the sun came out as the ship pushed into dense pack ice. We roamed the bridge, scanning with binoculars to locate the “right kind of seal”. Both Weddell and Crabeater seals are numerous in the pack ice. We were only interested in Weddell seals because of their benthic diving habit and their tendency to remain fairly local, as in other areas they have previously been tagged. Crabeaters were numerous but we also saw a few Weddells. We located one on a suitable floe and approached it with the ship.

From a seal’s perspective, a bright red, 7000 tonne ship pushing flows into one another pulling up next to yours with all the sound and vibration can’t be a very ordinary occurrence. I suspect that, were I that seal, I would be tempted to get in the water pretty sharpish. Yet, while showing signs of some concern and moving slowly away across the flow, the first seal we approached remained on the flow even after we were lowered onto the ice via the ship’s “Wor Geordie” (a netted platform that is lowered by the ship’s crane over the side). This may be because the seals have no land-based predators; the two main predators, leopard seals and killer whales take seals in the water. So if the seals feel threatened, they hesitate before entering the water.

Whatever the reason, three of us were easily able to surround the seal, keeping it on the flow. Then we darted it with the anesthetic and waited for it to become relaxed enough to glue the tag onto fur on its neck, just behind the head. We did not even have to clean and dry the fur. Unlike with the elephant seals who were lying on a filthy beach, the Weddell seal’s fur was clean and dry. The biggest problem was keeping the tag and epoxy warm enough so the glue would set properly. The entire process took just over 30 min. We waited until the seal was clearly alert enough to be left and then were winched aboard to look for another candidate.

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A freshly tagged Weddell Seal.

By this time it was late afternoon and, moving off through very heavy pack, we soon saw an area with lots of hauled out seals, basking in what passes for warm sunshine down here (about -6 with light winds). We were able to tag 2 more seals before the Captain called time, and we went in for a late dinner, feeling that all captures would be this easy. This is not how it turned out.

We were up at local dawn the next morning, but the seals that had been present the previous evening were no longer on the ice. Indeed no seals were visible. And the weather had worsened. The wind was up to 35 knots and the temperature had dropped to -11C. The ship set off through the dense pack and we went back to searching the ice for seals.

In late morning, we located a seal and landed on the flow. We darted it easily enough but the air was bitterly cold and the wind was driving snow along the flow. We used a sledge to form a wind break to work behind and to protect us from the drifting snow. Everything seems more difficult in a strong wind. Our hands would go numb in moments after exposure, and thick gloves are not an option for the work of attaching the tags. The low temperatures slowed down the setting of the epoxy and it seemed a very long time before we were able to leave the seal and head off to the ship to search again.

Later in the day we spotted two more seals on a very large flow, the size of several football pitches. The captain drove the ship into the flow some distance from the seals. Once stopped, it looked like the ship was sitting in the middle of a broad snow covered field. Conditions were still the same and these animals had moved 100m or so away from the ship and were moving well away from the edge. Once lowered down we had a 100m sprint to the seals. Running full tilt through knee deep snow in full survival gear is hard work. Blowing hard, three of us managed to catch up with one of the seals while two others circled round the other and herded it slowly towards where we had settled to work on the first one. If anything, the wind was stronger and the air colder so, while the seals seemed un-phased by conditions, we found it difficult. But we managed to attach the two tags and get back to the ship. Several other candidate seals were in sight but given the time the crew spent out in the wind providing safety cover while we worked, the captain decided we should call it a day.

The following day, conditions were better and we had time to catch two more seals. One of these was still moulting so we could not tag it but we did catch and tag the second. That brings the number of tags we have applied to 14. We hope to get the chance to catch two more Weddell seals before we have to head back to Rothera to start our flights home.

The tagged animals have spread out in and around the Pine Island and Thwaites glacier area (see map), just as we had hoped. They have been diving to the sea bed in up to 1000 m of water sending back hundreds of CTD profiles. Whenever the animals surface to breathe, the locations, CTD profiles and diving behavior information is relayed via the Argos satellite to a database back in St Andrews where it is decoded, archived and available to the project online. We hope that the seals will continue to provide this data through the coming winter when we would otherwise have little information coming in. Of course the seals might have other ideas of where to spend the winter but we are betting they will continue to use the area of interest. Certainly, just now, the seals are diving and feeding where we hoped they would. We will keep our fingers crossed that they keep up the good work. One way or another, we will gain valuable info on the movements and foraging behaviour of these species, here at the limits of their range.


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Map of seal tracks using tags deployed during this mission. Note that the ice distribution is from Google Earth and out of date!

Working in an extreme environment

Whilst we’ve been out of main internet contact, we have still been receiving daily news reports of what’s going on back at home – and the weather in the UK has been consistently making headline news.

Although we don’t have constant rainfall (as Antarctica is the driest continent on Earth), we have had our fair share of tough conditions to work in! Over the past 10 days, we’ve worked in temperatures down to -15 degrees C, with wind strengths of up to 45 knots (about 52 mph) – that’s approximately -35 degrees C once you take the wind chill into consideration!! As I write this, the outside temperature (at 3.30am local time) is -10 degrees C, with a wind speed of 7 knots – which feels relatively warm compared with previous days!

When we work on deck we have lots of layers to put on to try to stay warm, but for longer jobs the scientists and crew rotate every 30 minutes so no one gets too cold – their time off is spent in front of the heaters to try to warm up before heading back out into the cold!!

But it’s not just the people on board the JCR who have had to deal with the cold; the equipment has to as well. With such cold temperatures we’ve really been testing our instruments to the limit – the CTD and VMP regularly freeze in the short distance between the deck and the labs inside where they’re kept, and our autonomous underwater vehicles (Seagliders and Autosub) have both experienced sea ice forming on their communications antennae! Even our radiosonde launches haven’t escaped without some hitches; one balloon was launched as a gust of nearly 50 knots blew across the ship, catching the balloon and driving it into the mainframe of the ship, resulting in one burst radiosonde.

Overall, however, our data collection is proceeding at some pace – we have now completed over 180 microstructure profiles, 70 CTDs and 25 radiosonde launches, as well as 2 Seaglider deployments and recoveries and a 2nd Autosub mission in progress as this blog is written. We are currently collecting data to the west of Pine Island Glacier at the ice shelf of Thwaites Glacier, where we hope to find some Weddell seals for the seal biologists to tag. The nights are beginning to creep in slowly, with longer periods of relative darkness – the moon is now visible overnight too.

Weather in Antarctica

Antarctica is the coldest continent on Earth; snow and ice cover 98% of the land surface! Recently, satellite data recorded a new record low temperature of below -90°C on the vast East Antarctica ice sheet. Fortunately for us we’re visiting in summer and not venturing beyond the (relatively) warm waters of Pine Island Bay.

How cold is it for us? Our position feed also shows the latest weather observations from the ship. Most of these are direct from the automatic weather station situated at the top of the ship, but when the weather gets really interesting, manual observations are recorded. Three days ago we had windspeeds of 37 knots and it was -10 degrees, adding up to a windchill well below -20°C! For this reason everyone working on deck is kitted out in thermal layers, hats, gloves and thick working overalls. You can see from the forecast below (provided by the US Antarctic Mesoscale Prediction System), that the reason for this cold weather is the very strong winds coming from the antarctic continent (the wind arrows have barbs at their tail end that indicate wind strength – each full bar is 10 knots). You can also see how cold the air is inland!

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Since cold air is heavier than warm air, it flows downhill, creating rivers of fast moving air down the steep mountains near the coast. These are known as Katabatic winds, and can be very violent around Antarctica, where the combination of very cold air and steep mountains combine to produce some very dramatic winds. These downslope winds push sea ice away from the coast, creating a gap in the ice known as a polynya that can persist into the depths of the Antarctic winter. These areas of open water are often filled with life, allowing sunlight to reach water that would otherwise be beneath thick sea ice, and providing access to the ocean for penguins, seals and other animals during the winter months. Fortunately for us, the sea ice has been scarce due to the relatively warm weather, allowing easy access to the ice front. You can view our current weather conditions in this excellent visualisation of current conditions.

What about snowfall? Perhaps surprisingly, much of Antarctica is very dry with very little snow falling each year- parts of East Antarctica are described as a polar desert, and the famous dry valleys near the McMurdo research base are perhaps the most extreme desert on the planet! The region where we are now is more prone to snowfall. Large areas of low pressure often move towards Pine Island Glacier having formed over the Southern Ocean; you can see an example in the forecast above, indicated by the winds circling around a point near the centre of the image. These low pressure systems carry lots of moisture and can lead to significant snowfalls over the glacier and surrounding areas, particularly close to the coastline. In summer snowfall events are typically less common and so although we are likely to see some snow, it shouldn’t disrupt our science work on deck!

Icebergs ahead!

by Povl Abrahamsen
In October 2011 a NASA airplane flying over Pine Island Glacier observed a large crack going all the way across the ice. This was the first sign that the glacier was about to calve a large iceberg into the Amundsen Sea. Glaciers are large rivers of ice – the ice flows very slowly from the interior of Antarctica where it falls as snow, down to the coast. When the ice reaches the sea, it will float; the floating part it is called an ice shelf. And eventually bits will break off as icebergs, which drift out to sea, where they gradually break up and melt.

Since the crack on Pine Island Glacier was first observed, it got wider and wider, until the new iceberg finally broke free in November 2013. After picking up speed, the iceberg moved at around 4 km per day, until it ground to a halt in early December. The iceberg is almost 450 m thick; most of the ice is under the surface, and a corner of the iceberg hit a part of the seabed that is around 400 m deep. Slowly the iceberg turned around that corner, until it finally started moving again in mid-January 2014. At the moment the iceberg is still moving. We are trying to keep an eye on it with satellite images, like the picture below, which shows some of the iceberg’s past outlines. Although the JCR can break its way through sea ice, the iceberg is much larger and heavier than the ship, so we will have to steer around it – and hopefully get a nice view of the iceberg from a safe distance!

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Satellite image of Pine Island Bay, taken on 26 Jan. 2014. Pine Island Glacier is in the bottom right. The dark areas are open water, the lighter parts are ice: there is ice on much of the land, floating freshwater ice (ice shelves and icebergs – both formed from snow) and sea ice (frozen seawater).

Seagliders are go!

Overnight we sailed east of Burke Island, with ice caps in sight on both
sides of the ship at some points, collecting new ocean depth data and
more CTD data. We have left the sea ice behind now, and whilst we’ve
seen fewer seals and penguins, a couple of killer whales were spotted
last night!

Today started with sunset merging beautifully into sunrise (without the
sun dipping below the horizon), and there is now blue sky and calm seas
– a good start to our first Seaglider deployment! Although it’s sunny
and calm, it’s very cold outside – the temperature is hovering around -5
degrees C + wind chill!

All preparations on deck went smoothly, and the Seaglider will now
travel east-west just south of Burke Island for the next couple of
weeks, collecting temperature, salinity, dissolved oxygen and
chlorophyll data. 

Like the CTD data, this information can help us identify water that’s
come from different places – for example, except for the surface layer
there are no processes that will change the salinity, until that water
mixes with water of a different salinity. We’re interested in this so
that we can see the path that the ‘warm’ (2 degrees C) water takes after
it has come onto the continental shelf, as well as identifying where the
meltwater from the glacier is.
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Below the Antarctic Circle!

We are now out of normal communications satellite range, and are reliant on our Iridium phones for any essential messages (and this blog!). The Antarctic Circle is defined as 66 degrees 33′ S, and we crossed this latitude late evening (around 10pm) on the 31st January – so we are now officially in Antarctic waters!

 JCR position

One of the important tasks before we arrive in our study region is to check that all our equipment is performing as expected. After a two day postponement due to weather (we had quite a bit of swell, with a maximum recorded roll of about 30 degrees to port!), we ran a CTD cast, tested one of our VMPs (Vertical Microstructure Profilers) and released a radiosonde. Throughout the cruise we’ll have special blog posts describing what each of these pieces of equipment do, but today we’ll briefly describe a CTD.

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A CTD being deployed from the JCR in the Weddell Sea, January 2012.

CTD stands for Conductivity-Temperature-Depth, and these are the three main measurements that this sensor takes, providing salinity, temperature and depth. The sensors are also able to collect dissolved oxygen and chlorophyll measurements, and these are attached to a ‘rosette’, which consists of 24 10-litre bottles that can be shut at any specified depth to collect water samples. These water samples are then measured for salinity, dissolved oxygen and Helium-Tritium concentrations, and these can be used to verify the readings that the sensors provide. All of these measurements give us vital information about where the water has come from and how these water masses interact.

It is definitely becoming evident we’re travelling further south; we started spotting our first icebergs yesterday, and they’re becoming a much more frequent sight. However, straight after our CTD cast, the visibility reduced dramatically and we’re currently sailing through fog with snowfall! There’s already a shallow covering on the colder surfaces on the ship.

We expect to arrive on the shelf edge of the Amundsen Sea in the early hours of Sunday morning (2nd Feb), and then our science will begin!! CTD measurements will be taken all the way down to the front of the ice shelf, and we’re hoping to spot some seals along the way too. If all goes to plan, we should be arriving in front of Pine Island Glacier next Friday or Saturday!

We’ll try to update this blog as frequently as we can, but it is unlikely we’ll be able to send photos out from the field until our return to normal communications. Until then, we’ll try our best to describe the views! You can also see previous photos from the Antarctic 
field season and follow our location from our meteorological data here.

‘World’ Wide Web at Sea

As you can see, blog updates have already become sparse! This is partly due to the hectic work schedule of the few days of a scientific cruise – setting all the first equipment up and securing everything down – but also due to difficulties with internet connection!

The internet on the ship doesn’t come through cables like in your houses – we get it through a satellite! The total bandwidth for the whole ship is 128Kbps, that’s slower than your smartphone can connect! That whole bandwidth is shared between four phones, four fully internet enabled computers, and everyone’s emails – each phone can conceivably use up to 32Kbps, so if someone is having a catch up with their family, everyone else’s internet slows down!

Where we’re going in the Amundsen Sea is so far south (and west) that we’re out of the range of the satellites that provide the internet. This means that from Friday 31st January we’ll have no emails, no phones and no internet for 30 days! We have three special satellite phones though that we can use in case of emergencies, and we might be able to send through some plain text blog posts for you on them too. Another place to find more information and general blog posts about life on the ship is the Radio Officer’s blog; www.gm0hcq.com.

Why are we going to Pine Island Glacier?


Pine Island Glacier is changing rapidly – observations from satellites and airborne measurements show that it is thinning and retreating. But atmospheric warming is not the main suspect here, instead it’s a combination of the ocean, climate and local geology to blame! Relatively warm circumpolar deep water (still close to freezing point though!) is transported onto the continental shelf in this area of Antarctica, and is responsible for melting the lower part of the ice shelf (see the picture below from the fantastic Antarctic Glaciers website).

Schematic showing what's going on at Pine Island Glacier (from AntarcticGlacier.org)

Schematic showing what’s going on at Pine Island Glacier (from AntarcticGlacier.org)


Notice how the bedrock is sloping off downwards on the right hand side? That’s another reason why Pine Island Glacier’s retreat is now considered irreversible – the bottom of the glacier is below sea level, so once the ocean starts moving the glacier backwards, it’s easier for the glacier to just keep moving downhill.

The research on the cruise focusses firstly on how this water gets on to the continental shelf and secondly what is happening at the front of the ice sheet. Seagliders and Autosub can both be controlled by computers and after they are launched from the ship they will target specific areas of the ocean that interest researchers. We will also be putting oceanography instruments on a number of seals in the area – the seals dive deep underwater and by tagging them we can record data over a longer period of time than the 30 days of the cruise. The tags will fall off naturally when the seals shed their fur.

We’re very keen to discover why Pine Island Glacier is thinning and retreating. If we can understand the processes causing the glacier to melt we can try to find out whether the ice loss will speed up or maintain it’s current rate. This knowledge will help us make better predictions for future sea level rise.