The next stage of the OSNAP 2016 fieldwork

by Penny Holliday

RRS Discovery cruise today left Reykjavik on what surely must be the most beautiful day of the year so far. Sailing into glaring sunshine over blue sparkly water brings a optimistic lift to the heart of this Principal Scientist – it almost makes you think that we won’t need all of those extra days we have scheduled in case of delays due to bad weather… But the bad weather will probably come at some point, so I wont yet get too carried away with talking about calm conditions.

Most of us have spent a few days in Reykjavik, getting excited by seeing four research vessels in port at the same time (surely quite unusual?), gasping at the price of shopping, and admiring this stylish city in all it’s crazy-weather glory. But now we are glad to be getting going and getting on with the task ahead of us.

This cruise DY054 is the second UK OSNAP mooring refurbishment cruise of 2016. We’ll be retrieving some moorings and instruments that have been collecting deep ocean data for the past year, and sending a new lot of instruments back to replace them. We’ll also be releasing some ocean-exploring robots – floats that will spend two years following the coldest and deepest water so we can trace the many ribbons of currents that make up the southward-flowing circulation.

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Reykjvik

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Reykjavik

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R.V. Neil Armstrong

160727_RRSDiscovery_and_RVMariaSMerian

RRS Discovery and RV Maria S Merian

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RV Bjarni Saemundsson

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Reykjavik

Photos by Penny Holliday

Posted in News

Before the game starts

by Feili Li

It has been two days since we left Reykjavik and we are heading southwestward to the Irminger Sea, east of Greenland.   It will take about another day before we reach the location of the first CTD station near the Greenland side.   So before we get there, let me explain several things: who we are, why we are in the cold subpolar area, and what we are doing before getting to the working site.

We are a group of enthusiastic hard-working researchers coming from seven institutions and four countries on a research cruise aboard RRS Discovery.  Here the word “researcher” is preferable to “scientist” because we have an artist Mia and a photographer Amanda onboard – we are all doing research, just in diverse disciplines.  (If you are as interested in their work on the cruise as I am, stay tuned to our blog!)  Below are some nice photos of us.

One of the main goals of this research cruise is to retrieve data (sea water temperature, salinity, and current velocity) from the moored array as part of OSNAP, which has been sitting in the Irminger basin for another full year.  After the data retrieval, moorings will be redeployed and will be staying in the water for the next two years.  Processing of the data will begin shortly after they have been collected, although it may take several months to finish the processing and quality control of all these data.  With the data, we are one step further towards the first result about the overturning circulation in the subpolar North Atlantic.  It will provide unprecedented opportunities for understanding how water masses formed at high latitudes are tied to large scale Atlantic circulation that relates to climate change and variability.

Before getting to the site, we are generally free.  I feel like I have moved my office from Durham in North Carolina to the ship.  Except for training on CTD watch, I have been basically working on my laptop in a lab with a nice ocean view.  The boundary between work and life disappears:  eat, tea, work, eat, tea, work, eat, eat, eat … Yes, the boundary between the times you are eating and the times you are not eating also disappears.  But, soon, this will be substituted with days filled with lifting, walking, taking water samples, and that is when the real game starts.

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Photos credit:  Neill Mackay

Posted in News

At the Bight, and Oceanographer Heartbreak

OSNAP, Year 3 Leg 1, 56 42.45N 33 42.02W, 19-July-2016, At the Bight, and Oceanographer  Heartbreak.

by Heather Furey

So, we made it!  We are at the Bight.  I have to say though, troops are restless.  There are maprumors flying around the ship about when we’ll get back.  I have heard, ‘Not til Saturday 0600’, ‘Definitely Friday 2200, before the bars close’, and ‘Friday morning 0900’, as time estimates.  All ETAs reported just today, and all from reputable sources!  We are in the UNOLS ship schedule to hit the dock Saturday July 23rd, so anything earlier is, well, earlier.  Really, it just depends how fast we can get this set of nine CTD stations done.  There is a lot of motivation to get back Friday night.  We are in the middle of the third CTD cast as I write.

I saw the first sun I have seen in a long time this morning as we travelled south, though it is cold outside today. The ocean looks pretty much the same here as anywhere else, but underneath us is a totally different story.  We are over the south channel of the Bight now, a deep channel running east to west through the Reykjanes Ridge.  Here and the north channel of this fracture zone are the only deep passages from east to west through this mountain range for hundreds of kilometers to the south, and the very first passage through since the deep overflow current first formed and started flowing southward at the head of the Iceland Basin.

From the perspective of being at the south channel’s deepest point, the mountains rise 1200 workstationmeters to the south and at least 1400 meters to the north.  We have not passed over the highest point yet, so I have no multi-beam bathymetry data to know how shallow the northern mountain stands.  If I were out hiking, I would expect some strong mountain pass winds through such a gap due to orographic steering.  We think we might expect this here too in an oceanographic sense, water flowing strongly from east to west, funneled through this narrow gap.  A velocity profile will be available soon, once ‘the package’ is on deck.  (‘The package’ is the suite of water sample bottles, LADCP, which measures velocity, and CTD, which measures pressure, temperature and salinity.)

There are a couple of moorings out here now, one in each channel, that get pulled out summer of 2017, next year. Can’t wait to see what those data show, but they are so much more valuable for the velocity, temperature, and salinity data were collecting right now.  We are taking a reference section, from which we can get transport, and to which we may compare the two years of mooring velocity, temperature and salinity data later.

Back in the lab, though, folks are packing up.  Clean work tables?  Packed bags four days tablebefore we hit port?  Definitely, folks are ready to go home. And getting creative with how they spend their spare time (see map of Scotland). Food is still very good; I am impressed.  Swordfish with fresh chili pepper and red onion salsa, julienned carrots, with cabbage, and also squash?  I love vegetables, and the fact that there still exist freshly prepared vegetables weeks after leaving port is like gold to me.  Thank you, Mark and Wally.

Update:  Oceanographic Heartbreaker. The cooling on the hydraulic part of the deep tow winch failed at 0330 this morning (20 July), and we were not able to complete the section across the Bight.  It would have taken about six hours to fix, and we did not have enough time left.  We have some very valuable data in the form of a complete section across the southern channel, but it is a real disappointment!  Stuart, our Chief Scientist, states that in his experience things tend to fail at the end of a long trip, especially when trying to do a bit extra work.  Well, this is a case in point.   So we are headed back to the dock, ETA now about 1400 on Friday.  Cruise complete.

Posted in Cruises

Back on The Line

OSNAP Year 3 Leg 1, 17-July-2016, 58d 45.19N 30d 16.38W, Back on The Line.

by Heather Furey

We are nearing the end of this cruise. We have four more CTD stations to take on the OSNAP line, Pokeone ‘cal-dip’ (where instruments are attach to the CTD frame and calibrated in deep water), one mooring to deploy, having recovered its companion mooring in pea-soup fog this afternoon, and one final mooring to turn-around (both recover and deploy).  My head is on land today, laying out plans for hiking in Iceland when I get there, and for getting home to see my peeps.  I think it is because we went so close to Reykjavik when Greg got picked up by helicopter.

But, we are still at sea.

Here on board, a few things:  First, Wally’s Surprise was served at dinner tonight.  I can’t tell you what it was, because that would spoil the surprise for the next Leg’s science crew, but it was pretty darned good.  Excellent, in fact.  Second, some mystery person has been putting up Pokémon monsters hidden in plain sight around the ship.  Pokémon Go, here.  I do not have much to say about that, just that it is happening.

WallyNow that we are nearing the end of the scheduled science, we get a little time to play!  Most cruises have a few ‘weather days’ built in to the schedule, for things like gales, or getting personnel helicoptered off the ship, or equipment repair … whatever comes up.  See how the ship is sort of near the Bight Fracture Zone?  We seem to still have a breath of time left, and will use it to go back to the Bight!

Part of measuring the overturning circulation (O-SNAP=Overturning Circulation of the Subpolar North Atlantic Program) is measuring the bottom currents.  The Iceland-Scotland Overflow Water makes up the bottom current that flow southward from the shallow sill between Iceland and Scotland.  The dense overflow water sinks to the deep Iceland Basin and forms a boundary current travelling from north to south along the west side of the Iceland Basin, which is also the east flank of the Reykjanes Ridge.  But, this “flavor” water is also found in the western Atlantic Basin and it is still not quite known exactly how this water gets from one basin to the other.

This is where the fracture zones come in.  Fracture zones are deep breaks in the ridge, like missingship vertebrae in the spine of the North Atlantic.   Historically, if you open a research paper that is puzzling out this mystery, you would see a figure showing the deep ISOW water arrow following the eastern flank of the Reykjanes Ridge, turning into the western Atlantic through the Charlie Gibbs Fracture Zone further south.  This is the deepest and widest fracture zone in the Reykjanes-Mid-Atlantic Ridge system.    But these days, we think that some of (all of?) the shallower portion of the deep ISOW current flows through upstream cracks in the Reykjanes Ridge into the western Atlantic.  Makes sense to me.  How much?  Modelers have estimates, but no one has measured it.

The Bight is a shallower fracture zone upstream in an Iceland-Scotland-Overflow-Water sense.  We went there first in 2014, on the first OSNAP cruise, knowing that that no-one had ever taken CTD stations in this fracture zone.  Second time in all of history the Bight will be surveyed? Sign me up, let’s go!

P.S. Greg is on a plane home to Miami as I write, back to family and good care.  Safe and sound.

Posted in News

OSNAP Year 3 Leg 1, 15-July-2016, 61d 07.77N 28d 47.43W, steaming north.

by Heather Furey

We woke up this morning to the awful news of a van driving into a crowd celebrating Bastille Day in Nice.  Our French nationals onboard did not personally know anyone hurt.  So sad and so useless, the killing.

You might notice by the latitude and longitude above that we are no longer on the OSNAP line.  Two reasons: Firstly, at about 15:00 yesterday, we started to steam north to avoid the worst of an incoming gale.  We would have been down for weather anyway, so it was wise to outrun the worst of it.  Secondly, we are steaming to Reykjavik to rendezvous with an Icelandic Coast Guard helicopter.

This came about because a member of the science party injured his back a few Picture1days ago:  an old back injury that was seriously aggravated during an odd twist during the deck work of mooring recovery.  Early this morning, since there have been no signs of improvement, the captain decided that Greg needed better and more immediate medical attention. The captain consulted with the UK Coast Guard to see what the best course of action should be.  The UK Coast Guard contacted the Icelandic Coast Guard, and we are now en route to rendezvous 150 nautical miles from Reykjavik, the outer range for the rescue helicopter, where Greg will be ‘helivac’ed back to Reykjavik, a doctor, medical treatment, and home.    We are sad he is leaving us, but glad that he will be in less pain soon.  Eight more days under rolling seas with limited sleep would have been very unkind.

One thing about being at sea, everyone has a story.

Yesterday, I deployed the last of the RAFOS floats.  The captain had come to me earlier in the day with the idea that while we did not have time to complete CTD Picture2stations while outrunning the storm, we did have time to complete the RAFOS deployments. The deployments are quick: before coming onto station, the float, which has been previously tested and armed for mission, is loaded into a launching tube.  A starch ring, which will dissolve in water, is inserted into a piston release mechanism.  The bottom trap door on the launch tube is wired to the piston.  As we come onto station, the ship slows to about two knots speed.  The loaded launch tube is lowered into the water, the starch ring dissolves, the trap door at the bottom of the launch tube opens, and the glass float slips into the sea as we slowly steam away.  Although it takes some time to set up for deployment, the actual deployment takes just a few minutes.

 

It is my great pleasure to be allowed into ‘The Red Zone’, at the aft guard rails, to help with and oversee the deployment.  The ship’s crew helps me, and I am grateful for their necessary and able assistance.   While deploying the last of the RAFOS floats at the back rail, I had time to talk with the A/B, Will, who was helping me.  He came to this job after spending years in the UK Army as an explosive specialist.  He told me tales of crawling through the wire and pipe Heathertunnels under the city streets in Northern Ireland finding and disarming bombs planted by the IRA.  And of being in Afghanistan searching for land mines by poking a metal pole into the sand, describing the sound of the metal on metal clunk when he would find a mine.  He would then dig the live mine out of the sand, and disable it to ensure his own troops’ safe passage.  An explosives specialist, standing next to me, helping me launch armed-for-mission RAFOS floats into the abyss.  You just never know.

Posted in Cruises

Weather day

OSNAP, Year 3 Leg 1, 57 55.86N 25 6.19W, 09-July-2016, Weather day.

By Heather Furey

Yesterday, the sea was molten silver.  No organized swell, just a satin finish top, with the water satinseamoving underneath as though thickly boiling, heaving.  I like to go to sea for the work of it, and because I have a great job.  But the human details are what I enjoy most while out here.

Because this is an international program, each year, and sometimes each leg, the research program utilizes ships from different countries. People from everywhere staff the ships and ride as science crew. The most important thing for me is to try to pick apart dialects and accents.  We need to understand each other to successfully get our work done.  I find particular delight in the French accent, perhaps because I studied French in school for four years.  On board this year, I am trying to understand thick Scottish-, British-, and Chinese-accented English.  And French.  I miss our Dutch colleagues.  The Dutch nationals will all be on the next leg, boarding in Reykjavik for Leg 2 OSNAP, to ride the RRS Discovery’s return trip from Reykjavik to Southampton.

I notice, too, the way different groups hold cutlery.  Americans do not generally hold their knives while eating.  They move the knife to the fork hand to cut, then cut, then put the knife back down, move the fork back to the hand that just held the knife, and pick up the bite with their fork.  Scottish and British tend to hold on to both pieces of silverware all the time.  They push food onto their forks using their knives, and then lift the fork up to eat.  No transfer of knife to the other hand if cutting is required.  English in particular tend to eat with their fork upside-down, along with the knife in the opposite hand.

pantryBovrilCondiments on each ship are a playground.  ‘Heinz Salad Cream’?  ‘HP Sauce’?  ‘Golden Shredless’? ‘Robinson’s Barley Water’? ‘HP Fruity’? What are these?  ‘Bovril: The Original Beef Extract’? Am I supposed to put that on toast? It is stored in with the peanut butter, jams, and butter pats.  Why would I put beef extract on my toast?

Back to science and hot off the press, the very first batch of RAFOS floats, deployed in June 2014 off the R/V Knorr, has surfaced!  With this type of instrument, it is all about where the water goes, and not about how the water changes while moving past a stationary point (e.g., mooring).

Charlie-GibbsUsually the sample size is small, but, always, something new is learned.  So where did the floats that seeded the Iceland-Scotland Overflow Water in the deep Charlie-Gibbs Fracture Zone go over the past two years?  I have not had time to work up the trajectory data, but can show you the two-year displacement vector diagram I worked up this morning.  Deployment site is at the blue dot in the Charlie-Gibbs; black lines show the 2-year displacement; bullets denote sound source locations, bathymetry drawn at 1000, 2000, and 3000 meters.  The floats launched in the deepest currents off the East Reykjanes Ridge and off East Greenland in summer 2014 will surface late July and Mid-August, respectively.  The RAFOS results are starting to come in.  Stay tuned.

Posted in News

Another piece of a puzzle

By Tiago Bilo

After the 15th day at sea, scientists from University of Miami lead by Dr. William Johns had successfully deployed their fifth deep water mooring under the curious watch of Pilot Whales. This mooring is part of the set of nine moorings placed on the North Atlantic subpolar gyre, close to the fractures and rough topography of the Reykjanes Ridge (off the southern coast of Iceland).

As the RRS Discovery moves forward in completing its mission, we gather more and more important data that will help us to put the pieces of the circulation puzzle together. The size of the piece will depend on the puzzle of interest. Each equipment recover and deployment may represent a large piece to understand the circulation within a channel or fracture, or a tiny little piece of the Earth’s climate system.

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Deployment of one of the Heather’s (Woods Hole Oceanographic Institution, US) glider being watched by crew members and Scientists). Using yellow hard hats are SAMS scientists Loic (on the left) and Stuart (on the right).

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Pilot Whales carefully watching the RRS Discovery and the research activities

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University of Miami group (Greg, Tiago, Mark, Cobi) and John (RRS Discovery CPOS) deploying one of the moorings.

Posted in Cruises

New adventures in the North Atlantic on the RRS Discovery

by Loic Houpert

It’s been now more than a week that we left Glasgow on the RRS Discovery for the OSNAP cruise DY053. We entered the Iceland Basin yesterday to start the maintenance of the US moorings, after successfully turnover the SAMS moorings in Rockall Trough and recover Bowmore (the SAMS glider) on Rockall Plateau.

The RRS Discovery left Glasgow on Wednesday 29th June. The SAMS team (Estelle, John, Karen, Kamila, Stuart and myself) had the shortest trip to join the ship. Yunli, a technician from Ocean University of China, came from Qingdao (in China)! We also have a lot of people coming from the US. Bill Johns and his team (Adam, Cobi, Mark, Greg, Tiago and Dom) came from Miami, and Heather came from Woods Hole (in the Massachusetts). Dave, Chris, Steve, Andy, Jeff and Zoltan are all based at NOC (Southampton) and complete the science party of this scientific cruise.

The purpose of this OSNAP cruise is to service the Scottish and US moorings, deploy RAFOS floats, and deploy and recover gliders. All these observation are essential for us to better understand the ocean circulation and its role on the European and global climate. Moreover there is mounting evidence of the importance of the ocean circulation in the subpolar North Atlantic for the region’s marine ecosystem, the formation of hurricanes, and rainfall in the Sahel, and parts of the USA.

Part of the SAMS team (from left to right: myself, Stuart, Estelle, John) during recovery of one of the SAMS mooring, with Zlotan (a.k.a IT guru) and Mark (blue helmet)

Part of the SAMS team (from left to right: myself, Stuart, Estelle, John) during recovery of one of the SAMS mooring, with Zlotan (a.k.a IT guru) and Mark (blue helmet)

Happy selfie after the recovery of Bowmore, with our two glider experts (Estelle and Karen)

Happy selfie after the recovery of Bowmore, with our two glider experts (Estelle and Karen)

The RRS Discovery entering the Rockall Trough, with the Seaglider Bowmore (in pink) and a dophin-whale (thanks Dom for the crafting)

The RRS Discovery entering the Rockall Trough, with the Seaglider Bowmore (in pink) and a dophin-whale (thanks Dom for the crafting)

ea time for the Principal Scientific Officer of the cruise (Stuart, on the left) during the recovery of the first US mooring, lead by Bill (in the middle). Dom (on the right side) observed with attention the work on the back deck.

ea time for the Principal Scientific Officer of the cruise (Stuart, on the left) during the recovery of the first US mooring, lead by Bill (in the middle). Dom (on the right side) observed with attention the work on the back deck.

Posted in Cruises

New research published by Femke de Jong and Laura de Steur

press release

A new record in mixing of surface and deep ocean water in the Irminger Sea has important consequences for the Atlantic overturning circulation 

Scientists Femke de Jong and Laura de Steur of the NIOZ Royal Netherlands Institute for Sea Research have shown that the recent temperature changes in the Irminger Sea between Iceland and Greenland can be explained through regional ocean-atmosphere interaction during the cold winter of 2014-2015. This rejects a hypothesis that posed that increased meltwater from Greenland weakened deep water formation and caused the cold blob. The article by de Jong and de Steur is accepted by Geophysical Research letters and has appeared online.

Read more ›

Posted in News

CTD special

by Nora Fried and Patricia Handmann

Today this blog is focusing on one of the central Instruments of almost all oceanographic cruises: the CTD – Conductivity-Temperature-Depth sensor. One of the interests in oceanography is on the physical, chemical and biological properties of seawater. Most oft the work on board is accumulated around the CTD schedule. The CTD we use on this cruise went on around 70 dives until now, but what exactly is a CTD?

A CTD-rosette consists of a metal cage with a centrally installed sensor pack – the CTD. These sensors are measuring conductivity, temperature and pressure in real time being consistently pumped while passing through the water column. Salinity can be computed from conductivity, temperature and pressure. The maximum depth this instrument can resist is around 6000m. Since our cruise is passing through Labrador and Irminger Sea our deepest station until now is around 3800m deep.

Furthermore there are up to 24 Nisken water sampler bottles, which can hold up to 12 liter of seawater and bring them up to the surface. Additionally to the CTD sensors and the water sampler bottles we installed some more sensors on the CTD this cruise: we measure oxygen concentration, fluorescence, velocity of the surrounding water, distance to the bottom light penetration depth and the turbidity.

The whole CTD-rosette is mounted on a wire, which is connected to the vessels winch system to veer out the instrument into the water and heave it back to the deck. The wire is a cable at the same time and makes real time data transmission from the sensors to a computer on board possible. So temperature, salinity and pressure of the surroundings can be monitored the whole time.

Once a CTD Station is reached and the instrument is prepared the rosette can be deployed. Before deploying the bridge has to approve of the action, then the winch driver is informed by the CTD watch that the instrument can be deployed. The instrument is then veered out with a velocity of around one meter per second – so the CTD watch has to observe the altimeter and all the other instruments the whole time in order not to hit the ground.

Due to different properties of seawater in different depths, density oft the surrounding water is changing and the CTD is drifting with the currents – the pressure is different to the length oft the veered out rope. Therefore the winch is stopped at a depth of 10 to 15 meters to the ground in order not to hit the ground with the sensors. Once the instrument has reached the full depth the first water sampler is closed and the instrument is heaved back up to the surface and the sampler bottles are closed on different depths by the CTD watch.

Once the Instrument is back on deck, secured by ropes and washed, the work of the chemists and biologists starts. They take oxygen and nutrient samples and are the firsts to touch the sample bottles. When all samples are taken its time for the CTD watch to take salt samples – therefore sample bottles are filled and measured by a salinometer. Measuring the same properties with different measuring techniques can reduce the overall error.

Depending on the water depth the duration of a CTD cast can vary greatly. A station takes particularly long time if calibration or testing of additionally installed instruments is performed on the CTD rosette. Especially instruments that will be deployed on multi-year moorings need to be tested and calibrated before final deployment. Little CTD Systems called MicroCats are tested as described above. MicroCats measure temperature, conductivity and pressure just like the system installed on the rosette. In order to mount them on the rosette some sample bottles from the rosette are replaced by the MicroCats, and the CTD profiles of the rosette system gets compared to the Microcat profiles to calibrate after the cast. In order to get good calibration values, bottles are closed at five different depths with preferably constant salinity and temperature during the up-cast. For these depths the CTD is stopped for five minutes. Salinity of the sample bottles is determined by a salinometer and compared to the MicroCats-data afterwards. Moreover, the releasers of a mooring have to be tested for reliability before deployment. The releasers are activated by a specific hydrophone signal. These tests are essential to be able to recover the moorings with all the instruments after multiple years. Though a calibration-CTD takes longer, it provides some diversion during a CTD-watch and all in all we like our ‘Micro-Cats’.

In order to run the CTD around the clock, we are working in shifts of 4 hours at a time. At midnight the middle watch begins during which, one usually has some peace and quiet as most people on the ship are sleeping. To be regularly on deck at 2 a.m. and watch snowfall at night or the bright summer night sky at the Greenland coast is also an advantage of this shift.

A notably nice shift follows from 4 a.m. to 8 a.m. when sun is rising. A sunrise can be impressively beautiful at sea, appearing different every morning.

The 4 to 8 shift is then replaced by the so-called retirement shift from 8 a.m to 12 a.m. This shift is very close to a normal day.

Three to four students take care of the CTD during their watch time. This watch system is kept during the whole cruise and can make one sleep a lot during daytime. Also an ostrich steak with asparagus can happen to be your breakfast.

We already had rough weather during this cruise: nearly 7 meters of waves and around 34 kn of wind brought adventures like sliding through the CTD lab on a chair or not secured things on waltz to our trip. Even through these kinds of weather conditions the Maria S. Merian is able to perform CTD casts in a safe way. The sailors and the bridge show special skills and repeatedly perform extraordinary in order to bring the CTD-rosette back to deck without harming it.

Sometimes it also happens that something goes wrong during a CTD-station – Sensors stop working or seawater finds its way entering plugs or cables. Then it is time for error analysis by our CTD technicians. As soon as the CTD-rosette arrives on deck the troubleshooting starts.

Up until now we have had a successful and smooth cruise and hope to continue that way until Reykjavik.

Very hearty greetings from the dog watch der MSM54

 

Posted in News

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