And finally ....

The cruise finished on schedule on the 3rd June and the next scientific cruise is now underway on the RRS James Cook.  Overall 96% of the data that we had hoped for was recovered from the RAPID array of moorings.  A figure with which we were very pleased.  We are very grateful to everyone on board: officers, crew, technicians and scientists who all worked together to achieve this result.

Before we left the ship we were able to make our first preliminary estimate of the 26°N AMOC time series from October 2012 to March 2014.   There was much excitement amongst the scientists on board as Ben completed the calculation and showed us the preliminary results.     All of the data now needs to checked carefully and we need to incorporate the data from our colleagues in Miami.  After this is done the complete calculation of the new times series will be made public on our website, probably by the end of September.

However, we can now announce the winner of our competition to estimate the value of our preliminary calculation for the period from 1st October 2012 to 30th September 2013 (Please note the final value will be different once  we incorporate data from our colleagues in Miami).      The entries are summarised in the figure below.    Estimates ranged from 15.1 Sv to 19.4 Sv with an average of 17.2 Sv.  So most of you thought that it would be a little less than the long term average (17.5 Sv).

Distribution of entires (red) compared with the annual averages from
the eight years starting from April 2004.  The distribution of annual averages
has been normalised to enable the comparison.

 - Third place was Stuart Cunningham 17.0 Sv

 - Joint second were Sarah Hughes and the Master of the RRS James Cook Peter Sarjeant with 16.7 Sv

 - But one person estimated the exact value of 16.5 Sv.   Well done Bablu Sinha!

Recreation at Sea

Playing cricket on the back deck of the RRS James Cook.  Darren, Eleanor, Nick, and Lola (and a few more outfielders).  Photo by Ben Moat.

This post is a bit overdue, since we're now all back on land.  However, it fits well with the "life at sea" portion of the blog.  [ pics to be added shortly! ]

When we are at sea for 6 weeks, we typically work longer hours than on land.  For certain types of cruises (e.g. hydrographic sections), the science work is going on 24-hours a day.  Since this cruise was a moorings cruise, we would have more intense working days, followed by passage days where data processing and analysis continued in the lab, but less time was spent on deck or making measurements.  We are permitted to work no longer than 12 hour days, 7 days a week.

Paul, Dave, Chris, Steve and Martin, on the  bow.

6 weeks is a rather long time to be spent with the 22 crew, 7 scientists and 7 technicians.  Fortunately, British ships are reasonably well-equipped for recreation.  The RRS James Cook has a bar, a lounge, a video room and a library, all on the level above the main lab.   On the lower accommodation level, there is also a gym with treadmill, rowing machine, reclining bike, weights and a sauna.  The bow is a comfortable spot for a bit of sun or to watch the sunset or stars.  And a popular area for tea is outside the coffee shop, on the starboard side, just aft of the main lab, where a few extra chairs have been placed.

David, Neela and Lola playing dominos.

The bar is stocked with the daily allotment of wine and beer.  Folks are allowed to purchase a certain number of units per day, when off-duty.  There are also a variety of games to be played: dominos, scrabble, Trivial Pursuit and a popular sea farers card game: cribbage.  One night during the cruise we had a pub quiz, organised by Carl.  Another night was the RPC "request the pleasure of the company", where David Smeed as chief scientist, paid for the beers and invited everyone along.

The Twister board, made out of an old sheet.  The "dice" didn't work very well, so we ended up with a different solution.  Photo by Lola.

On Lola's birthday, we made a Twister board out of an old sheet.  The spinner was a piece of cardboard, with a beer bottle in the middle.  For some more active entertainment, Nick made a cricket bat, and Lola and I spent a while making some balls out of rags and duct tape (gaffer tape).  20 balls made for about an hour and a bit of fun on the ship.  So while there is lots to be done, there are also plenty of options for evening entertainment, or spots of free time between the more intensive moorings days.

The gym on the Cook.  Photo by Lola.

The lower levels of the ship

There are 5 engineers on the ship, and the electrician: (back row, left to right) Mick (2nd engineer), Charlie (Motorman), Lawrie (3rd engineer), Mic (3rd engineer) and (front row), George (the chief) and Pete (the electrician).

A post by Lola and Eleanor

From our first few weeks of the cruise, all we knew about the engineers and engine room was that they drink lots of tea and they play loud music while dancing and working somewhere down below.  However, the engineers are responsible for keeping the ship watertight, powered (electrics and hydraulics), and liveable (they are in charge of the AC, fridges, plumbing, sewage and freshwater production).  Every so often, an alarm will sound in the living spaces of the ship.  This means the engineer on duty has 3 minutes, night or day, to get to the control room and acknowledge the alarm.  

The deck plans show that the engine rooms cover an entire deck beneath the lower accommodation, though it also extends vertically through different spaces on the ship.  There are myriad doors and staircases dotted about that lead down into engine room spaces.  This means that when we need an engineer to fix things, they sometimes pop out like magic from unexpected places.  This all gives a rather mysterious impression to the engine room.  So when George (the “chief”) offered to take us on a tour, we gladly accepted.

One of the engines.

The main entrance to the engine room is through one of the hidden doors and staircases at the back of the engineers changing room (where you wouldn’t normally venture).  At the bottom of the stairs is the control room.  The control room has windows over the four engines which power the ship.   Normally, the ship has two engines running, a third on standby and fourth that the engineers can service.   Each of the four engines provides about 1700 kW, with a total average fuel consumption of 11 tonnes per day.   These engines, when running, are about 90 deg C, and when on standby are still at 80 deg C.  The exhaust temperatures are about 300 deg C.  The room with the engines in it was hot and noisy.

Lola, going into the small space with the porthole onto the propeller.

A view of the port-side propeller.

You may expect an engine room to be super dirty, full of grease and oil, but surprisingly, it was very clean. Even though we were climbing over pipes and under cables, ducking through low clearance spaces, and around bits of machinery, we didn’t end up filthy.  Towards the bow of the ship, we visited the workshop, sewage room, purifier room, water tanks and the salt water intake for science.  When we visited, the engineers were servicing one of the purifiers (which purifies the fuel before its burning).  In this space, the engineers can typically be found dancing while working to loud music.  From here, we took a different staircase back up to the rest of the ship.  

Engineers don't like having their photos taken.  Lawrie, Mick and Charlie.

What does it take to create a 10 year time series of ocean circulation? Saying thank you 240 times

Darren, Steve, Dave, Chris and Colin.  Between them they have spent 2,014
days at sea on RAPID cruises.  That is more than one year each!
(Photo: Ben Moat)

We are now into the last two weeks of our expedition on the RRS James Cook and if all goes well we will soon have retrieved the data that will complete the first decade of observations of the overturning circulation.  What has it taken to reach this milestone?    Darren has been scouring our reports to answer this question.

On board James Cook we have 22 officers and crew, 7 technicians, 5 scientists and 2 graduate students.  Thirty-six people in all.   But since the start of the project a staggering total of 240 people have participated in UK-RAPID research cruises.   Thirty of these were students gaining their first experience of research at sea and 13 were visitors from other research centre with whom we collaborate.   With a total of 533 ship-days at sea this represents about 30 man years of work at sea.

Many of those who have sailed with RAPID have completed one cruise (141 people) or two cruises (43 people) and 49 have done three or more cruises.  But there are seven individuals who have been to sea many times for the RAPID project, between them they have done almost as many RAPID cruises (121 person-cruises) as all the other technicians and scientists put together (139 person-cruises)  Everyone who has sailed has contributed to the success of the program but the expertise and commitment of these seven has been outstanding.

The RAPID project Magnificent Seven are:

 - Dave Childs and Steve Whittle have been on 16 cruises each.
 - Stuart Cunningham, Colin Hutton, Rob McLachan and Darren Rayner have sailed 17 times
 - Chris Crowe tops our chart and is currently sailing on his 21st RAPID cruise

Thank you to everyone who has sailed with us, all 240 of you!

RAPID is a collaboration between the UK and the US.      This post is about the UK cruises and UK personnel on US ships only.    We are equally grateful to all our American colleagues but don't have all the information for their personnel.

Over the Mid-Atlantic Ridge

A post by Lola Pérez Hernández

As Eleanor said in the last post we have been crossing the Mid-Atlantic Ridge (MAR). The MAR is a subsea mountain range that divides the Atlantic into eastern and western basins.  The MAR rises in some points up to 1000 m from the surface. From a geological point of view the MAR is where the oceanic crust gets renewed on a long time basis. The RAPID project has several moorings over the MAR. Can you imagine why? Apart form being in the middle of the ocean, having this mountain chain through the whole Atlantic Ocean affects the deep-flow. This is the case for the Antarctic Bottom Water (AABW).  The AABW is formed in the Southern Ocean around Antarctica and flows northwards along off the east coast of South America and then along the west side of the MAR in the North Atlantic.    The AABW is cold and we can trace the path that it follows by looking at the temperature of the water

Topography of the Atlantic Ocean,
colour indicates the depth in metres

Temperature of the Atlantic water at 4,500m depth, 

the arrows indicate the flow of Antarctic Bottom Water.

Shrinking cups

Recovering the CTD after a cast.  The CTD itself is the horizontal silver instrument at the level of the guys' hands.  The vertical cylinders are a mix of instruments and bottles.  (Photo by Ben Moat)

Today we were working at the Mid-Atlantic Ridge.  This underwater mountain range runs from north to south in the Atlantic.  While some of the work today was on landers, we also did a CTD cast, where we send an instrument which senses the temperature and salinity of the ocean to the seabed and then pull it back up on a long wire.  This wire is about 6 kilometers long, so when the instrument is down near the seabed, there is nearly 6 kilometers of water sitting on top of it.  The weight of this water creates a unique environment for creatures living at the bottom of the sea.  It also presents an engineering challenge to instruments and sensors that we use to measure the ocean.  They need to be able to withstand incredible pressures.

Adding the cups to the CTD frame.  (Photo by Lola)

One of the fun ways to observe the effect of the pressure at the bottom of the ocean is to see their effect on polystyrene (styrofoam--for Americans) cups.  Before leaving Southampton, I took 50 cups to my daughters' nursery and school.  The children decorated their cups, and then gave them back to me.  These cups flew with me to Trinidad, and then sailed with us to the Bahamas and across the Atlantic to the Mid-Atlantic Ridge.  Today, our CTD cast was finally in the daytime (usually they start or end at night).  So Lola and I stuffed the cups with a bit of paper, and then put them into some tights.  These tights were then attached to the CTD frame with cable ties (many cable ties) and they went on an adventure to the bottom of the sea.

The CTD frame going out to sea, with the cups attached.  For the oceanograhers out there, if you notice there's a bit more on the frame that usual, the large silver cylinders are acoustic releases.  These are tested at the depths they'll be operating at before they're used for the moorings.  The smaller silver cylinders are MicroCATS (the one with the 5 circles cutout of it).  These are compared against the wired CTD sensor to improve their accuracy.

If we were to send a balloon to the bottom of the ocean, it would shrink as the weight of the water squeezed the air inside it.  When it came back up and the weight of the ocean is no longer squeezing the balloon, the air would expand again, and the balloon would look like nothing happened to it.  Polystyrene is a little bit like a balloon.  It has lots of little air bubbles in it.  Under high pressure, like 6 kilometers of water, these air bubbles collapse.  But unlike a balloon, when the cups come back up to the surface and the pressure is released, the cups don't expand again.  They are more rigid, and the keep their collapsed, squeezed out shape, permanently.   The air bubbles have popped and the cups have shrunk.


You can see the results here--teeny tiny cups where the drawings and writing of the children are now miniature.

Lots of teeny tiny cups.  The big white one is what they started out as.

Tiny cups can be used for thimbles, or tea parties.

Tomorrow, we continue with the Mid-Atlantic Ridge west side, and then a few days later will travel to the east side of the Mid-Atlantic Ridge.

You can read more about ocean pressure on Deep Sea News: http://deepseanews.com/2014/05/how-to-shrink-a-styrofoam-cup-and-other-side-effects-of-deep-ocean-pressure/ (leaves this website)

Moorings work is well underway

A view of the back deck of the RRS James Cook.  (Photo by Ben Moat)

We’ve been busy with gathering our sensors from the moorings which were deployed 18 months ago, and then left recording data until now.  Since Wednesday, when we started out with the PIES recovery, there hasn’t been much of a break.  You can see some of the work below.

So, what is a day's work on a research cruise like this one?  This is a moorings cruise, which is a little different than some cruises.  Here, when we're talking about a mooring, we are referring to a large anchor or weight, with wire and flotation attached.  The flotation is like underwater balloons, but because of the weight of water, they are made of strong material like steel or glass.  The anchor holds it to the seabed, while the flotation helps keep the wire upright.  Along the wire, we attach different instruments or sensors to record information about the ocean.  I'll see if I can find a picture of one of these--a diagram really, to show what it looks like.  Since some of the tall moorings are in water which is 5 kilometers deep, the mooring itself is 5 kilometers long.  This would be difficult to take a picture of!

Looking for a mooring which has been released.  Since we are sometimes a good distance away, we need binoculars to spot the flotation on the surface of the water.

When we're working on the moorings, we typically start by "listening" to the mooring using some acoustics from the ship.  We “ping” a particular sequence of sounds that mooring is listening for, and it responds.  From the response, we can tell how far away it is.  When the ship is in a good position, we then send a command to tell the mooring to drop its anchor.  Depending on how tall it is, and how far from the surface the top instrument is, we can see the floatation almost immediately.

Some of the wildlife that can be found on a mooring.  Here is a worm or "polychaete" from one of the floats.

We then wait to make sure the whole thing is on the surface and nicely laid out.  We don’t want to come in too quickly, because some of the mooring could come up underneath the ship, which would be a problem.  Once it’s all up, the ship gets into position and the top float is hooked using something that looks like a grappling hook with a line (rope) attached.  The mooring is then slowly pulled in by the double-barrel winch, while the guys on the back deck (the technicians) take instruments off it one by one.  Sometimes the instruments come up with some animals or algae growing on them (see the green stuff in the picture).

This is an RCM11 current meter--it measures how fast the water is moving past it using acoustics.  You can see it also became a nice home for some algae (the green, furry stuff).

One of the tall moorings—5 km tall, since it’s in 5 km of water, can take a good 6 hours to recover.  During this time, we’re out on deck in the heat (27 deg C), humidity (80%) and sun, which can be quite tiring.  We have plenty of sunscreen, but somehow, I think everyone will end up with a tan before the trip is over.

After the mooring is redeployed (sent back out again with fresh instruments and batteries and wire), the night's work begins.  The mooring position on the seabed is triangulated using the same acoustics to range from the ship.  The ship is moved to three different locations so that we can figure out where the mooring landed on the bottom.  Then we do some ship-based work---sending down a sensor on a wire and back up again---to calibrate the sensors which are left out.  In the morning, we start again with the moorings.

Martin, Lola, Darren and Paul, looking at the bathymetry around WBAL.

Yesterday, we were planning to release and recover a mooring which we call WBAL.  The L stands for lander, since it’s a small mooring with just a bottom pressure and temperature recorder on it.  We ranged it, and then released it, then went up to the bridge to wait for it.  It was in just 500 m of water, but after an hour, and more ranging that confirmed it hadn’t moved, we left it to complete some other work.  We tried, briefly, to see it in the swath bathymetry system, but with no luck.

Today, Darren got a message from his Argos alerts that the WBAL beacon—a satellite receiver on the top float of WBAL—that it was on the surface and a few miles south of us.  So instead of the work we had planned for this afternoon, we’re setting out to recover the mooring.  We don’t know yet why it didn’t come up as it should’ve yesterday, but we’ll hopefully know soon.  Perhaps there was some fouling (what we call the overgrowth by plants or animals) on the releases and it couldn’t drop it’s anchor immediately.

We have a few more days at this intense pace before we head out for the Mid-Atlantic Ridge.  It’ll take a few days to get there, where we can regroup, check data further, calibrate some more instruments, and get ready for the next bit of work.