Monday 31 March 2014

A well deserved break


Working at sea is an incredible experience, however you do return to land with a renewed appreciation for solid ground, green grass and a horizon filled with topography, glorious topography! It was with these motivations that a group of us jumped at the opportunity to spend a little time in Chile's famous Torres del Paine National Park. 

The fabulous Torres del Paine (photo by Heather)
The peaks of the Torres (photo by Jesse)

We left the ship painfully early on Wednesday morning to catch a bus up to a charming port town near the park called Puerto Natales. Here we were able to hire tents, sleeping bags and mats, and fill our bags with food for the adventure ahead. From Puerto Natales it was another bus journey into the park. The view out the window got steadily more incredible. Jagged peaks loomed in the distance and the sunshine blazing down highlighted vibrant lakes and stark outcrops of rock.  The ferocious wind whipped up the lakes sending clouds of spray up high in the air towards soaring condors. We drove past herds of llamas grazing with spindly legged young and flocks of rheas with wind ruffled feathers.



Once in the park the bus dropped us at the edge of Lake Pehoe where we hopped on a catamaran (because what else does an oceanographer do with a day off the ship?). Lake Pehoe is a vibrant turquoise thanks to sediment washed down from glaciers. The boat ride was pretty choppy thanks to the strong winds, but by now we are all experienced seamen and hung off the top deck absorbing the magnificent view of the mountains in the sunshine.

The catamaran on Lake Pehoe (photo by Jesse) 
Ocean cruises are not all hard work - the team enjoy some relaxed time on the water

The view from the catamaran (photo by Heather)


The catamaran dropped us at a campsite on the shore of Lake Pehoe and at the feet of the Torres del Paine range. We quickly set up camp, no easy job in such windy conditions! After dinner we sat at the lake shore and stargazed until it clouded over and the first few drops of rain started to fall. It was quite a wild and rainy night, but most of us slept very soundly, enjoying a bed which wasn't swaying and rolling beneath us.

Andrew had won the lottery for a tent to himself... but unfortunately this rather backfired. The zips on his rented tent refused to close and he was left with a rather draughty bed for the night! We also chose to store our food supplies in his tent and poor Andrew was awoken by a small gang of mice munching their way through our chow. Not the most peaceful nights sleep!

Kim and Siobhan set up camp for the night

Mike in his element!


The next day things slowly cleared up into another stunning day of sunshine. We spent the morning walking, aiming for a view of the massive Grey Glacier and taking in the astounding landscape. We started our return to the ship early in the afternoon, refreshed and invigorated – bring on the next leg of the cruise!



Part II begins!


Apologies for the radio silence dear readers! We have been making the most of having solid ground beneath our feet and have had little time to update you.

We arrived back into Punta Arenas on Tuesday morning and quickly availed ourselves of the numerous delights that access to land allows; fresh fruit and veg, shops and walks to name a few! Groups of us set off on various adventures out into the magnificent Patagonian wilderness, while others made the most of the relative luxury of this charming port town.

Sadly our call into port also meant some goodbyes. Katy and the VMP team packed up their stuff and waved us goodbye to take the broken VMP back to the UK for some much needed TLC. The ship just won't be the same without Katy, Alex, Paul and John, their lovely company will be sorely missed.

The VMP-ers relax after all the hard work and wait for the flight home! Alex, Jon and Paul
Mike Meredith...we'll miss him!


We were also sorry to have to bid Mike M farewell. Mike has been an invaluable member of the team, patiently training us for the work ahead and imparting some of his vast oceanographic wisdom. We all owe Mike a huge THANK YOU!

So what lies ahead? Leg two of the cruise will take us around the Scotia Sea, starting back down at the top of Drake Passage to complete the sampling we had to abandon due to the bad weather a week ago. This leg should only take a day or two, and after that we steam south east and towards the Weddell Sea. At this point we need everyone to keep their fingers crossed that the sea ice will not have encroached too far north and stop our work here. We are hoping to recover and redeploy some moorings. Moorings are clusters of oceanographic instruments, such as thermometers and current meters, which are attached to chains and held in place by a sturdy anchor at the sea bed and buoyant glass spheres just below the surface. We are nervously studying satellite images of the site, watching the sea ice creep ever closer and praying to the weather gods that the mooring site will stay ice free. After that be will begin another oceanographic section that tracks northwards from the Weddell Sea up towards South Georgia. Here we will be taking seawater samples for the DIMES tracer, CFCs and other halocarbons, carbon, alkalinity, nutrients and barium as well as taking the standard plethora of physical observations (ie temperature, salinity, conductivity, current speeds etc). After this section we will head west towards the Falkland Islands along the North Scotia Ridge with the cruise ending in Port Stanley at the end of April.
Check out our ship track animation for a route map (see link on the right)!

So keep tuned folks, more adventures lie ahead!


Note:
With Katy now back in blighty she will be taking up the role of 'UK correspondent'. Internet access from the ship is a little temperamental so we have been emailing our posts to Katy's mum to upload for us (thanks!) but now Katy will be taking on this vital role, as well as continuing to share her thoughts and experiences on the endeavour. 

Animated Ocean

Here are the links to the two animations which we made whilst waiting to dock in Punta Arenas....enjoy!

https://www.youtube.com/edit?o=U&video_id=P_rQqz73IlQ

https://www.youtube.com/watch?v=4sOxPreKod0

Tuesday 25 March 2014

Land Ahoy!

Well here we are docked up in Punta Arenas. The Chilean pilots and customs folk are onboard sorting out the paper work for our disembarkation. It’s been a relaxed few days as we steadily steamed around the Argentinian point and through the eastern Magellan straits. Yesterday, a group of us got creative with stop-movie animations, which we will post up on You Tube soon – so keep an eye out!



Some nice skies on our journey back to Punta Arenas (photo by Heather)

Ollie, Siobhan and Katy catch some sunshine on the monkey island yesterday (photo by Ellen)

We are scheduled to stay here for a few days while some equipment is craned on and off the back deck. Some science equipment from the previous cruise is being taken off and the JCR is to be re-stocked with fuel (we take on 900 tonnes of fuel!) and fresh fruit and veg to ward off scurvy.

Dolphins outside Punta Arenas as we waited for the high winds to calm down so that we could get into port (photo by Tom)

The VMP is packed up ready to be sent back to Southampton and Paul, Jon, Katy and Mike are flying home tomorrow. The rest of the team are set to continue for the second leg of the cruise, which will take them back south into the Weddell Sea, where more exciting science and icy adventures are bound to happen. Siobhan and co. will keep up the blog – so don’t tune out yet.


The pilot boat comes out to meet the James Clark Ross (photo by Ellen)
The crew get to work unloading equipment from the back deck.




Saturday 22 March 2014

Watery Reflections


 Hello all! We are still bobbing about like a cork, waiting for the waves to calm so that we can squeeze in a little bit more science before having to return to Punta. With fuel-bunkering and port facilities booked in for the 24th, after about 3pm this afternoon we will have to begin the two day steam back to Chile.

We still have some 6-7 m waves to ride!

Yesterday, I telephoned my grandparents who, both in their mid-nineties, live just up the road from a beautiful little bay called Cwm-Yr-Eglwys in West Wales. I was wondering how long it would take for some of the water molecules thrashing about in Drake Passage to reach that little bay back at home. As a rough guess the surface waters would probably take tens of years to reach the UK, winding their way around the ocean gyres. For deep waters, to complete an overturning loop of the globe and pop up somewhere near the UK, we’re talking a much longer time – something like 1000 years. And, did you know that because there are more molecules in a glass of water than there are glasses of water in the sea (!), if I emptied a cup of water into the Southern Ocean now and then scooped a cup of water out of the Welsh sea twenty years later, I would most likely grab some of the original molecules!

Whilst on the phone, my nanny, Joy, described how as a girl, her mother used to read her ‘The Rime of the Ancient Mariner’ by Coleridge. She reminisced about how she had imagined what it must be like to watch the great albatrosses soaring across the waves. And there one was – right outside my cabin window. It was one of those moments when a hand from the past reaches out and grabs you, and I realized (again) how fortunate I am to have made this amazing journey.

View over the back deck of the JCR

So here is a snippet of the poem, along with a super sketch by Heather (who is from Somerset where, according to Wordsworth, the inspiration for the poem was seeded as he walked through the Quantock Hills with Coleridge. They were discussing the book ‘The World by Way of the Great South Sea’ by Captain George Shelvocke, which Wordsworth was reading at the time….):


Albatross Sketch by Heather

And now the STORM-BLAST came, and he
Was tyrannous and strong:
He struck with his o'ertaking wings,
And chased us south along.

With sloping masts and dipping prow,
As who pursued with yell and blow
Still treads the shadow of his foe,
And forward bends his head,
The ship drove fast, loud roared the blast,
And southward aye we fled.

And now there came both mist and snow,
And it grew wondrous cold:
And ice, mast-high, came floating by,
As green as emerald.

And through the drifts the snowy clifts
Did send a dismal sheen:
Nor shapes of men nor beasts we ken—
The ice was all between.

The ice was here, the ice was there,
The ice was all around:
It cracked and growled, and roared and howled,
Like noises in a swound!

At length did cross an Albatross,
Thorough the fog it came;
As if it had been a Christian soul,
We hailed it in God's name.

It ate the food it ne'er had eat,
And round and round it flew.
The ice did split with a thunder-fit;
The helmsman steered us through!

And a good south wind sprung up behind;
The Albatross did follow,
And every day, for food or play,
Came to the mariner's hollo!

In mist or cloud, on mast or shroud,
It perched for vespers nine;
Whiles all the night, through fog-smoke white,
Glimmered the white Moon-shine.'

'God save thee, ancient Mariner!
From the fiends, that plague thee thus!—
Why look'st thou so?'—With my cross-bow
I shot the ALBATROSS.
Albatrosses enjoying the high winds!

Friday 21 March 2014

Dispatches from the tracer lab


White tipped waves surge by the ship and the deck beneath us groans and rolls as we struggle to keep our feet. Buffeted by the stormy swell, the JCR jumps and judders as titanic waves crash over her bow. Out the tracer lab window our view oscillates wildly between the ominous sky and the angry sea. We are getting our first glimpse of the true nature of Drake Passage.

With the deck awash with a violent sea and sampling deemed unsafe we have, regretfully, put a halt to science for the day, and the scientists have beat a hasty retreat to the bar. That is except the dogged tracer team, still hard at work in the grand search for tracer. We are slaving away feeding a backlog of samples into the great tracer machine.

So lets talk about the DIMES tracer. I think we have said already that our tracer is trifluoro methyl sulphur pentafluoride (CF3SF5)..... But why did we choose such a mouthful of a tracer? Well it is important that the tracer is inert and that it does not occur naturally. We need to be sure that what we measure can only have come from our release and is not added from another source or lost through interactions with other compounds in the ocean. This tracer can be detected in very low concentrations (1 milligram in a cubic kilometer) which makes it perfect for such a long running experiment. It also meant that we only had to release 76 kg of CF3SF5 and are still able to detect it in the vast ocean today.

The tracer was released back in 2009 in the south-east Pacific, upstream of Drake Passage. Since then we have returned every year to observe how our blob of tracer has dispersed. East of Drake Passage the ocean floor is relatively smooth and we observed only small amounts of vertical (diapycnal) mixing. However when the tracer passed through Drake Passage it underwent a 20-fold increase in its vertical spread (diapycnal dispersion). We attribute this to interactions between the fast flowing circumpolar currents with the rough topography of Drake Passage. This result is incredibly exciting and helps explain how water deep in the ocean returns to the surface.

The equipment that measures the concentration of DIMES tracer in each water sample looks like a mad science experiment: funny shaped glassware filled with bubbling liquid, a tangle of wires and pipes in every direction, a vat of liquid refrigerated to -69 °C, radioactive warning stickers, a general abundance of levers and buttons, and even an old-school machine that draws wiggles onto graph paper. It looks fantastic. And a bit crazy.


The machine which measures the concentration of tracer....it spits and bubbles away!


How it works is somewhat more .straightforward. The tracer prefers to be a gas rather than a liquid, so nitrogen is bubbled through the seawater sample and the tracer migrates from the water into the gas bubbles. The gas bubbles are then piped it into a part of the instrument called a trap which is a curve of pipe sitting at -69 °C. Inside the trap is a molecular sieve that captures the tracer while letting the rest of the gas flow on through. Like the holes in a colander, compounds of a certain size (the pasta in this metaphor) are trapped while everything else (the metaphorical water) drains away. After 10 minutes of bubbling the temperature of the trap is raised to 80 °C, which releases the tracer and injects it into a gas chromatograph. The gas chromatograph produces a graph with a bump on the line; the area of this bump corresponds to the amount of tracer in the sample. Et voila, we have a measurement of the tracer from the sample!


The nitrogen bubbles act to release the tracer molecules from the seawater sample.
The results from the gas chromatograph - the peaks indicate the amounts of different molecules. Spot the tracer?!


As it is the final year of the DIMES field program, the bulk of the tracer blob is probably up in the sunshine somewhere near Cape Town. Consequently, we are now only finding small amounts of tracer in Drake Passage. However coming back here is still important so that we catch the 'tail' of the tracer blob (although our graphs look less impressive).

We now await a lessening of Poseidon's wrath and another batch of samples to feed our instrument...


A happy Siobhan working the machine - it takes about and hour to run four seawater samples, and with 24 bottles coming with the CTD every 4 hours or so it's a struggle to keep up!

Thursday 20 March 2014

Under Pressure

Over the last 10 hours the atmospheric pressure has been dropping and dropping: it seems that we have some bad weather on the way! The sea is getting pretty choppy and the wind has picked up to steady 35 knots, with 50 knot peaks. Science has stopped while we wait for the swell to calm again. It’s getting difficult to walk down the corridors in a straight line as the ship sways from side to side and the chairs in the lab are beginning to spin around. Everyone is carefully tying computers and equipment to desks and table legs. Well, I guess this is what Drake Passage is famous for – high seas and strong winds. On the plus side the downtime is allowing us to catch up with analysing the backlog of water samples that have collected over the last few days.

Speaking of pressure changes, yesterday we conducted a little experiment. We wanted to see what kind of pressures our instruments experience as they reach 4000 m below the sea surface. Meet Ripley – our cruise mascot and willing guinea pig. The left hand photos below show her yesterday morning (normal size) with Katy and Siobhan. Lovingly tattooed by all the team, she is made of polystyrene, which is essentially a collection of air bubbles. Just after these photos were taken, our heroine was strapped (in Ellen’s laundry bag) to the CTD frame and sent to the watery depths….

The right hand pics show how she came back to us:


Ridley is strapped tightly to the CTD frame


As Ripley was lowered deeper and deeper into the ocean, the pressure difference between the surrounding water and the air inside the polystyrene caused the head to gradually implode. At 4000 m, Ripley would have experienced about 100 tons of water sitting on top of her - that’s enough to give any one a headache! Compare it to the way your ears sometimes pop just a few meters down in the swimming pool.

Conveniently, Ripley bore a scar on her right cheek, which was exactly 5 cm long before she bravely sunk to the bottom of the sea. We had a sweepstake to guess how long the scar would be on her return., which was 2.8 cm. The proud winner was Prof. Mike Meredith. (He did perhaps have an advantage, having previously sent polystyrene cups to various water depths and measured how much they shrunk by – it’s good to know that careful scientific observation does work). A close second was Hugh who guessed 2.6 cm.



Would we implode if we followed Ripley down 4000 m in the ocean? Our lungs would collapse but since we're made mostly of water, which is almost incompressible, we would probably remain the same shape. I’m not sure we would be quite as robust as Ripley however, who now proudly sits in the main lab keeping her patch-free beady eye on us!

Special thanks to Jesse for the help with this post.

Wednesday 19 March 2014

Turbulent Times


It’s Tuesday evening here on the RRS James Clark Ross. The CTD is currently in the water, having been lowered on a wire and winch to about 3700 m. With 24 bottles poised to snap shut on as it returns to the surface, capturing seawater from lots of different depths, and bringing back lots more samples for us to analyse.

Ewa and Heather watch the temperature and salinity data from the CTD as it travels to the bottom of the sea (photo by Richard)

The CTD brings back 24 precious water samples (photo by Richard)


The crew get the CTD safely stowed on deck (photo by Richard)

Heather gets ready to extract the water samples from the CTD (photo by Richard)

Unfortunately things haven’t been running quite so smoothly for the VMP-team…one of the instruments conked out due to a problem with the computer board or ‘brains’ of the instrument. After a day on the tech’s operating table, we realized that we didn’t have the spare part needed to get it up and running again. However, it’s not all bad news as we do have a second ‘back-up’ instrument.

VMP stands for vertical microstructure profiler, and it is the instrument (often referred to more succinctly as ‘the yellow-bog brush’) that measures how turbulent the seawater is. We have two types of VMP instruments on board – an untethered VMP and a tethered VMP. Despite not being attached to the ship (and therefore more likely to get lost!), we tend to use the untethered VMP because it can reach much deeper in the ocean – up to 6000 m compared to 2000 m for the tethered instrument. These deep mixing observations are particularly important for DIMES because it is near the seabed where deep currents flow over underwater mountains and cause lots of mixing and turbulence.


The untethered VMP is deployed – when in the water, the rope and hook are released. The probes, which face downwards into the water, are protected by a metal cage, which also holds two iron weights. The yellow casing provides buoyancy whilst most the electronics are housed inside the black tube. The two brushes help the instrument to fall at the correct speed (photo by Richard).

The nose of the VMP instruments host very sensitive probes, which measure fluctuations in temperature and velocity of the surrounding water. From these data we can quantify how vigorously ocean is being mixed up and stirred on tiny (i.e. cm) scales. The probes act a bit like the needle on a record player – picking up tiny variations in the ocean, and playing us back a story about the small scale physics which are going on. Whilst the tethered instrument is always attached to the ship by a strong wire, the untethered instrument is left to it’s own devices. Once deployed from the side of the ship, it slowly sinks because it is ballasted by two heavy iron weights. We program the instrument to drop these weights at a chosen pressure (depth), after which the VMP becomes buoyant and rises back to the surface. It’s sometimes a bit tricky choosing a release depth. Some information about how deep the seabed is can be gleaned from an echo sounder on the ship, and we also use the surface current direction and strength to predict where and how far the profiler will drift. A whole cast takes about 3 hours. Once the profiler pops back up at the surface, we steam towards it, hook in back on board and download the data. A red flag, flashing light, radio communications, and often a curious flock of albatrosses all help in spotting it after a dive.

Jon hooks the untethered VMP out of the water after it’s dive – it takes a bit of practice! (photo by Rich)     
The VMP is safely back on deck, ready for the data to be downloaded (photo by Rich).


The tethered VMP (or bog-brush). In the background Paul and Jon prepare the wire on which it is attached (photo by Katy).

There are several reasons why mixing in the Southern Ocean is of interest to the scientists. As well as heat exchange between the oceans, this mixing brings nutrients from the deep ocean to the surface – nutrients needed by phytoplankton (or tiny plants which live in the surface of the ocean). In addition to being the base of the ocean food chain, phytoplankton plays a key role in the Earth’s climate system. Like land-plants, phytoplankton remove the carbon dioxide generated by burning fossil fuel carbons from the atmosphere and lock it up in the deep ocean. Ocean mixing also affects the global concentration of atmospheric CO2 because the rate at which it is taken up by the ocean ‘sponge’ is sensitive to the rate at which deep and surface waters are exchanged. Measuring all these factors will help to quantify the rate of climate change. The VMP mixing data also complements the data from the DIMES tracer nicely - it provides 'on-the spot' estimates of the vertical mixing present in the ocean, in contrast to the time and space averaged values determined from the yearly spread of the tracer (dye).

Monday 17 March 2014

Things continue to go swimmingly!


Bright sunshine out here on the southern seas! The sparkling skies are slowly melting the ice on deck, and the air temperature has rocketed up to a toasty 1.9 degrees Celsius... pass the suncream! The ocean is a bright, sparkling blue, and the vast horizon is dotted with soaring royal albatrosses and the occasional hourglass dolphin leaping about.


Hourglass dolphins having a whale of a time (photo by Hugh)

We have now reached station 16 of the 30 planned observation stations - about half way through the section.


The map on the right shows an enlargement of the region inside the red box on the world map. The background colours indicate how deep the seabed is –Drake Passage is like a deep canyon in between South America and Antarctica through which the Antarctic Circumpolar Current (ACC) flows. The red shows the journey of the James Clark Ross as we head north along the section (the red star indicates our current position). Each of the black dots is the location of a planned observation station.

Professor. Mike Meredith, helping to collect the water samples from the CTD, after it has returned from a 2 mile trip to the bottom of the ocean.

We are well ahead of schedule, thanks to the amazing weather, slick crew, Andrew’s heroic leadership and all the equipment behaving itself. The upshot is, we have the time to squeeze in some extra science over the upcoming days. Hurrah! Currently, we are planning additional stations between about 57 and 56 degrees South, which will provide some high-resolution measurements across the Polar Front. The Polar Front is a region of fast flowing current within the main Antarctic Circumpolar Current (ACC). The exact position of the front swings and meanders around from month to month - it’s a bit like the oceanic equivalent of the atmosphere’s jet stream. Because of the fast flowing water and sharp temperature gradients associated with the Polar Front we expect lots of interesting physics to be happening here – particularly on smaller scales (< 10 km). After all this hard work, the Sunday roast on the menu tonight will be much appreciated!


A vertical slice through the ocean that runs south to north along our observation stations.


A vertical slice through the ocean that runs south to north along our observation stations. These data were collected in 2011 – temperature and salinity data have been collected along this section annually since 1992 giving us a great record. However, measurements of how the ocean is mixed in this region, which we are collecting with the tracer and the VMP, have only been recorded recently by the DIMES project. The black contours show density surfaces (isopycnals) - note how they tilt up sharply at the Polar Front, where there is a sharp change in water temperature. The isopycnals slope-up at the Polar Front because of the effect of the spinning Earth on the faster current flow here. It’s similar to the way the water surface in a bowl of spinning water banks up against the side.



The lovely sunset last night – red sky at night, shepherd’s delight! (photo by Heather)

Finally: a big HAPPY BIRTHDAY to DIMES veteran Neill Mackay (we know you wish you were here!)