Yellow robots

by Clare Johnson

There are now two more bright yellow robots ‘swimming’ in the North Atlantic Ocean. On Friday we deployed an Argo float (picture below). These yellow tubes containing a host of complex electronics are designed to dive to 2000m, sit there for 10 days drifting with the water, then to rise back to the surface. Every time the floats dive/rise they measure the temperature and salinity of the water, and every time the floats are at the surface they transmit this data and their position via satellite back to scientists on land. They then dive back to 2000m and repeat the cycle over and over again until they run out of life. There are around 3880 Argo floats all over the world monitoring various oceans and transmitting the data back to scientists.

The second yellow robot deployed was a glider (picture below). This glider is a different make than those deployed/recovered on the Discovery cruise, with slightly different capabilities. However, it works in a near identical way: using buoyancy changes to dive to 1000 m and then rise back to the surface again measuring the temperature and salinity of the water as it goes. At the surface in the same way as an Argo float the glider transmits the data and its position to scientists on land. The difference between a glider and an Argo float is that scientists can ‘talk’ to a glider whilst it is out in the ocean, give it instructions and determine in what direction the glider should go in. So while the Argo float is happily left to its own devices, the glider has a piloting team in America and China checking it is ok and deciding where it should go next.

The big advantage of autonomous instruments like Argo floats and gliders is that they can collect a huge amount of data when scientists and ships are not at sea. Particularly they give us valuable information about inaccessible areas – for example the subpolar North Atlantic in winter when the weather is often too bad for ship work. To me it feels as if the development of gliders within the last few years is an exciting step forward for marine science. However, when it is my turn to pilot and the glider gets into difficulty at 4am in the morning and texts me to say that there is a problem that I need to get up and sort out immediately, I am less enthusiastic!!! The glider that we recently deployed should be collecting data between Scotland and south of Iceland for the next 6-12 months before it is picked up.

PS In case anyone is wondering why some gliders are yellow and others bright pink, both colours are thought to be as visible as possible in the ocean so it is a matter of choice to which colour you go for!

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Pic 1: An Argo float being deployed off the back of Pelagia. Thanks to Colin for the photo.

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Pic2: The Slocum Glider with proud scientists Heather and Dalai just before it was carefully lowered over the side.

How to catch yourself a mooring

On this research cruise we are deploying and (hopefully!) recovering 13 moorings from west of Scotland out across the Atlantic to the longitude of Iceland. In non-oceanographer speak (we are excellent at jargon which I’m trying my best to avoid) moorings are a set of instruments which are left in the ocean for a period of time, in our case a year. These instruments are attached at different depths to a wire kept vertical by floats and stopped from floating away by a weight on the seabed. They say that pictures are worth a thousand words so there’s a diagram below!

One of the things that makes us scientists nervous (but excited at the same time!) is getting these moorings back after they’ve been in the inhospitable ocean for such a long time. Will they come to the surface? Will all the instruments still be there? Will they have data on? Have I momentously screwed up and accidently programmed the instruments wrong or forgotten to press start?!

The moorings are tethered to the weight on the seabed by a closed hook attached to a sound receiver. When we want to recover the mooring we send a series of sound pulses to the receiver which opens the hook and the mooring (hopefully!) floats to the surface. Although we know the latitude and longitude of the mooring we don’t want to be too close in case the wire gets tangled in the ships propeller. Once we think the mooring is on the surface we slowly move closer with several people on deck trying to spot it. It’s sobering to realise how difficult it is to see even several large yellow floats in anything other than a flat calm ocean. Once the mooring is spotted and the ship has edged along-side, a crew member throws a grappling hook over a recovery rope attached to the mooring and hauls the first small float on board. The rest of the mooring can then be connected to a winch enabling it to be slowly and carefully brought on board. The mooring wire which is up to 2km long on some of these moorings is rolled onto drums and every time an instrument or float comes on board the winch is stopped and the instrument/float removed. All in all the process takes around three hours. So far we have successfully recovered six moorings; it will be a while before we know the full details of the data, but from our quick looks it looks as if we have some really interesting things to keep us busy over the next few months. 😀

PS the weather is better than yesterday but the sea is taking longer than we expected to calm down again.

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Diagram of the simplest mooring in the Rockall Trough. The water depth is nearly 2000m (2km) and it is not to scale!

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Crew member throwing a grappling hook over the mooring recovery line in order to be able to attach it to a winch and recover it. The throw was successful first time and got a round of applause!

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Mooring being recovered. Shown are the mooring wire, floats and an instrument that measures current speed and direction.

Rock and Roll

by Clare Johnson

It’s been fairly lively today as the wind picked up overnight. The first clue was the forecast pinned to the board showing strong wind speeds (coloured red – never a good sign) in our bit of ocean. The second was the galley (kitchen) staff tying down all the chairs in the mess (eating area) and putting signs on the two fridges reminding us to use the catches to hold them shut.

Everything on a ship is designed to cope with the motion: from catches on all the drawers in your bedroom so they can’t open and close as the ship rolls, to tables being attached to the floor so they can’t ‘fly’ across the room if the ship gives a particularly violent roll. There are tennis balls on the legs of the dining chairs to give them better grip and help them (and you!) not to slide across the floor whilst eating, and all tables and benches have lips and sticky mats. It also helps to remember not to fill your soup bowl or mug too full! However, even with adaptions life on a moving ship is more difficult. There’s a saying: ‘one hand for you and one for the ship’. You have to lean against something to work at a bench, computer mice have a mind of their own, and it’s a bit too high risk to have a cuppa anywhere near anything you don’t want to get wet!!

Having said that we managed to carry on some work today thanks to the skill of the crew and officers and turning ourselves into the waves to get a more stable position whilst on a sampling station. We are also all aware that the weather here can be a LOT worse than this, and are thankful that we’re not seeing the record breaking waves that Penny and others saw in 2000 in this area – 96 foot I am told by a scientist who was also on board that day! Eek! I’m also very grateful that life didn’t get too lively until after I’d got my sea legs. We’ll all be pleased to wake up to calmer seas tomorrow though!

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Washing machine effect in the portholes as water sloshes in and around the outside. Thanks to Heather for capturing it.

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Roll of the ship and waves passing by. This wasn’t one of our larger rolls when water came over the deck and I was too busy holding on inside!

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Tennis balls to help the dining chairs and you stay put during meal times.

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View from the bridge in the late afternoon when things were beginning to calm down a bit.

Greetings from Pelagia!

by Clare Johnson

As the scientists from RRS Discovery are enjoying being back on land, we are eight days into our scientific cruise on board a Dutch research vessel, RV Pelagia, named after a type of colourful jellyfish. We are a mixed bunch: scientists from the UK, China and US who are all interested in the circulation of the subpolar North Atlantic. Although we’re in nearly exactly the same bit of ocean that Discovery was in less than two weeks ago, the approach of this trip is different. Penny and the team on Discovery made measurements of temperature and salinity at a single point in time at many different locations between Scotland and Iceland. The aim of this trip is to supplement this brilliant dataset with a series of measurements every 30 minutes for at least three years across the entire width of the Atlantic! This should allow us to see how variable important currents are, whether they are weaker or stronger at different times of the year and for us to calculate how much heat and salt is entering the Nordic Seas and Arctic Ocean to the north.

So how do we do this? Well, we don’t expect scientists to be out making measurements continuously for the next 5 years – there would be a mutiny especially as the North Atlantic is not somewhere you want to be in winter! Instead instruments are attached to a wire that is tethered to the seabed using a heavy weight such as several old railway wheels. Last summer we deployed these ‘moorings’ at around 50 locations between Scotland and Canada. Since then they have (hopefully!) stayed where we deployed them, not been damaged by trawlers and dutifully made measurements of current speed and direction as well as water temperature and salinity every 30 minutes. This trips main aim is to (hopefully!) recover the first 13 of these moorings (and the associated valuable yearlong datasets), and re-deploy new instruments to continue the measurements for the next 12 months. Then next summer we’ll be back to (hopefully!) pick these instruments up, get the data off them and put the next lot of instruments in and so on until 2017. I say ‘hopefully’ a lot because although we try and minimise the risk of instruments and moorings failing there is a lot that can go wrong with things that are in the ocean for a year… We have recovered and replaced four moorings in the past week so so-far it’s going pretty well. Fingers crossed it continues to do so!

Photos by Clare Johnson and Loïc Houpert

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RV Pelagia docked at the National Oceanography Centre in Southampton

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John squeezing the SAMS kit into a small van

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Mooring kit on the NOC quayside before loading onto Pelagia

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Deployment of a mooring west of Scotland. The rusty chain tethers the instruments to the seabed whilst the orange floats keep the wire and instruments vertical in the water.

One cruise ends on Discovery and another one starts on Pelagia

by Penny Holliday

Well I’m finally home after 3 weeks away on RRS Discovery. I’m very pleased to be home with my family, feeling the warm June sun here in Southampton, but already missing some of the friends that I shared cruise DY031 with. The end of the Extended Ellett Line section was marked by our shared sense of achievement, and, excitingly, a few runs on the ship’s rescue boat just offshore from the SAMS lab near Oban. For those of us who dont usually get to play in small boats this was a huge treat. The rescue boat was driven by Evelyn, the third mate, who patiently took us all on joy rides around the bay. It was a grey and tranquil morning, and we could see people from SAMS waving to us on the beach. It was slightly odd for all the SAMS scientists onboard to be so close to home but knowing that we had a long journey to Liverpool to off-load our gear and leave the ship.

But we did eventually reach Liverpool on a cold and wet Wednesday lunchtime. The day was spent packing, tidying, cleaning and finishing the data processing. Eventually on Thursday we were able to see our stuff off the ship into vans and lorries and to start the journey home.

We are in touch with other NOC and SAMS OSNAP scientists who left Southampton on the day we were playing in boats off SAMS. They are on a Dutch ship, the Pelagia, sailing to exactly where we have been on the OSNAP/Ellett Line, to service some moored instruments that we left in the ocean a year ago. I’m hoping that during the course of their cruise they will be able to send us some updates on their OSNAP work to post on this blog. Watch this space!

Photos by Penny Holliday and Karen Wilson

Like ships passing in the night

by Geoff Stanley

This research cruise between Iceland and Scotland is my first time at sea, which makes me a bit of a rarity amongst the science team. What’s more, this cruise has nothing to do with my own research (which is theoretical work on the rather far away Southern Ocean); I’m here to help out with the physics team, and learn more about observational oceanography. I’ve quickly come to appreciate some of the challenges faced by physical oceanographers for which we theory types don’t often give much credit.

I’ll focus on the physical difficulties. Stefan and I are on the night watch, from midnight until 8am, plus four more hours of more flexible (not on official watch) work until noon. When we were told this we immediately began adjusting our sleep schedules to suit — but we did so in opposite directions. With great willpower, Stefan rigorously went to sleep earlier and earlier each day until the day before the watch started, he went to sleep at 3pm. (See the graph below.)

Initially I tried the same, forcing myself to wake early the next day, but a dash of seasickness caused me to retire to my bunk in the mid afternoon and take a nap. So much for that. Okay, new strategy: stay up late. That’s easier than falling asleep early when you’re not tired, right?

Maybe this would have worked, but after two late nights we ploughed into another storm as we left the Irish Sea and entered the North Atlantic (May 31). I woke just in time for lunch (what an entrance), then returned to my cabin where the uneasy pitching of the ship rocked me back to sleep. But the storm only got worse, and waking a few hours later after far too much sleep, my best defence against seasickness — horizontal unconsciousness — would no longer activate. Still, Gale Force 8 winds cut through my determination to stay up ridiculously late and I fell back asleep as soon as I could. Stefan, meanwhile, would cope with these horrendous calamities when he woke at 2am and forced his mind to swim miles through seasickness and wake-in-the-wee-hours delirium. Like two ships passing in the night, Stefan was travelling 8 time zones west around the Earth and I 16 hours east, and there were days when we almost never saw the other.

My second strategy tattered as well, I now planned more simply: sleep as much as possible in the next two days before my midnight shift began, and power through on reserve. It sort of worked, but the next few days I was on a see-saw between sleeping 3pm-11pm as I should, and being so exhausted at the end of the shift that I caved at 8:30am. Eventually though, I steadied out. All in all, I think Stefan was the wiser.

For all that, the night watch had some benefits, such as seeing the sun rise over Iceland (photo below). I was holding out on this blog post for a long-exposure photograph of magnificent light-pollution free stars (swaying drunkenly, you might say, by the motion of the ship), but alas we were clouded over every night.

The last week of the cruise has been fabulous, and I’ve felt like a normal human being. But now we’re at the end of the cruise and we face the opposite problem: how to get back 8 time zones east. In comparison, and with our calm seas, this should be a piece of cake.

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Stefan and Geoff’s sleep schedules during their transformation to night-people.

Pulling up the CTD while the sun rises over Iceland, on June 3.