Brad deYoung, Robin Matthews and Mark Downey
Physics and Physical Oceanography
Memorial University, Newfoundland
11 January 2017
This fall we deployed an ocean glider into the Labrador Sea. Our goal was to make measurements of the oxygen and carbon dioxide gas properties in the Labrador Sea. There are presently two deep-sea moorings in the Labrador Sea, separated by about 40 km off the shelf in 3500m of water. The K1 mooring was deployed by German researchers from GEOMAR in Kiel; the Seacycler mooring was deployed by Dalhousie researchers as part of the VITALS research program. We wanted to map the gas and water properties between and around the moorings. The glider operated from the surface down to 1000 m depth, flying along a 100 km extended line that connects the two moorings.
Our original plan was to deploy the glider directly in the Labrador Sea from a research ship and then recover it from a ship in the Labrador Sea, so that we would get the most out of the batteries in the glider. Battery-power is time, and time is money of course. We wanted to get the most out of our battery investment. As it turned out, the availability of ships did not line up with our schedule. As a result we had to deploy from the shore in southern Labrador, the closest port to the Labrador Sea. For recovery, southern Labrador would not work because by December all the ports are closed because of ice. So we had to fly the glider to the south and recover from the island of Newfoundland.
The deployment in September required driving 1400 km from our lab, in St. John’s Newfoundland, to Cartwright Labrador, about a day and a half of driving that requires taking a ferry from Newfoundland across the Labrador Straits to Labrador. We deployed the glider using a 63 foot boat operated by a local fisherman. Operating from small boats does have some advantages, making it easier to get the glider into the water. Even in September the weather was intense. On the afternoon of the deployment, winds over the shelf reached 55 knots and the sea was about 8 m or 25 feet.
Mark Downey getting the glider ready for deployment with the Gannett Islands in the background.
The glider did move across the shelf fairly smoothly (see below) although you can see from the track that there was a period when the glider was too shallow and got caught in a strong southward current and was pulled southwards. Once off the shelf and the glider could dive to its full 1000m depth thus was able to make better progress and only took a few weeks to reach the mooring stations. The glider operated in the Labrador Sea very well and flew for three months operating along the extended line between the two moorings.
The intent was to fly the glider straight across the shelf but strong currents, and a little mixup in the depth of the glider, led to an unintended loop to the south.
In November we began making plans for the recovery. We carefully watched the battery usage. Each day the glider would use about 0.5 percent of the battery. That meant that in principle we could have 200 days at sea but in practice we want to recover with 15-20% of the battery left in case there are delays on recovery or the battery is not as ‘full’ as we think it is. We made a plan to fly the glider along the shelf edge where the water is deep and where there is a strong shelf break current moving southwards. The southward current meant that we gained an extra 10-20 km of progress. We determined that it would take about 40 days to fly the return route and so headed the glider southwards in mid-November (see track below). As the track shows, the glider made its way southward very well in spite of a few hiccups. At times we would lose regular contact because the winds (greater than 50 knots – 80 km/hr) and sea-state (well above 10 m – 30 feet) were such that the antenna was not always working properly. We also had some problems bringing the glider back across the shelf when it appeared to lose track of its direction a bit, perhaps related to problems with how the glider corrects for the current that it experiences as it flies.
Return path of the glider from the Labrador Sea a trip that took about 40 days and led to the successful recovery of the glider just off Heart’s Content, Newfoundland
We planned to bring the glider back to one of the deep bays on the north coast of Newfoundland – Trinity Bay. These bays are somewhat sheltered and because they are deep the glider could wait there for us, patiently going back and forth in the deep water. The glider arrived at our target location off Heart’s Content, Newfoundland on Christmas day. We programmed it to fly a little triangle offshore (see figure) and then went out in a small boat to recover it. On the day of the recovery the pilot for our mission (Robin) was in the UK and so while he maintained contact with the glider we got the boat ready and then went out looking for the glider. The day before we had a storm with strong winds and the day after we had a strong winds again and so we had a narrow window for the recovery. It was winter and windy but we had no problems as we knew precisely where the glider was. The glider was just where we expected to find it and the weather cooperated. Now we get to explore the data and plan for our next deployment in the Labrador Sea.
The glider (located just below the boom in the center of the picture) was just where we expected it to be on a somewhat windy and very cold data. The glider looked just as bright and clean as on its deployment some four months earlier.
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 rumors 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 meters 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 before 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.
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 days 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 stations while outrunning the storm, we did have time to complete the RAFOS buy nexium online 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 tunnels 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.
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 can you buy levitra at walmart 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.
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).
Pilot Whales carefully watching the RRS Discovery and the research activities
University of Miami group (Greg, Tiago, Mark, Cobi) and John (RRS Discovery CPOS) deploying one of the moorings.
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)
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)
http://cymbaltasupports.com first US mooring, lead by Bill (in the middle). Dom (on the right side) observed with attention the work on the back deck.” width=”692″ height=”519″ /> 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.
This doesn’t sound new: Having bad data is worse than having no data! Anyone who had to deal with ‘fishy’ numbers coming out from instrument will agree.
A strong motivation is driving Dalhousie team of scientists to work around the clock on collecting and processing water samples in order to produce QC data for e.g. oxygen sensors on CTD rosette, SeaCycler, a surface-profiling mooring, and other moorings. Only the sensor float of SeaCycler itself is populated with 13 (!) different sensors, which require in situ calibration. While some water samples can be processed straightaway in the chemistry lab onboard, the rest will be sent home and analyzed at Dalhousie University in Halifax, NS, Canada.
So what’s happening in the lab?
GEOMAR and Dalhousie provided two titration systems for the analysis of oxygen samples onboard. Chemistry behind the method was described by Winkler back in 1888 and with certain modifications it remains a gold standard for oxygen measurements for more than a century now. However two systems utilize their own detection method (voltammetry vs. colorimetry), sample volume and concentration of reagents. Despite all the differences, an agreement in oxygen values between two systems is impeccable. The results are truly encouraging for both GEOMAR and Dalhousie teams who rely on their systems in the assessment of instruments’ performance.
Chlorophyll and CDOM (Coloured Dissolved Organic Matter) samples are partly processed onboard and preserved for later analysis. The same concerns nutrients and the carbonate system probes.
Once the chemists have done their job, it’s up to the deployed instruments to show what is hidden in the blue and cold waters of the Labrador Sea. See CERC.OCEAN website for more information about the SeaCycler mooring.
Fig.1: Work routine: Dasha and Kat are running two independent Winkler oxygen systems in parallel.
Fig.2: A filtering station for Chlorophyll, CDOM and nutrients gets ready for the next batch of samples.
The VITALS (Ventilation, Interactions and Transports Across the Labrador Sea) research network is funded to study how the deep ocean exchanges carbon dioxide, oxygen, and heat with the atmosphere through the Labrador Sea. To address this topic, a multi-instrumented, deep-ocean mooring has been deployed to measure and collect oceanographic parameters in the Labrador Sea.
The mooring contains a surface-profiling “SeaCycler” at its top, with 9 x MicroCAT CTD’s and two RDI ADCP’s below it. SeaCycler is ideally suited for VITALS research due to its unique ability to profile the upper ocean making numerous simultaneous measurements near the surface.
The deployment was very successful and early engineering results are encouraging.
At the time of writing, SeaCycler has completed:
12 profiles to the surface from a parking depth of 154m,
Is moored in 3526m of water located mid-way between Greenland and Newfoundland, Canada,
Has sent 72 data files to shore,
and has profiled a total vertical distance of 3.3 km underwater.
Unless new commands are sent, the system is programmed to profile every 20 hours for the next year.
The average water temperature in the upper 150m is currently 3.9 °C.
SeaCycler – A Short Description:
Fig 1, SeaCycler Mooring Components
SeaCycler is a moored, deep-ocean, surface-piercing profiler with two-way satellite communication. This means it’s anchored to the sea floor and cycles (or “profiles”) oceanographic sensors through the upper 150m of the ocean collecting measurements on the way (see Fig 1).
At the top of the profile, it surfaces a satellite telemetry system to transfer data to shore and receive new commands. After communication, it returns its profiling elements to a depth resistant to bio-fouling and safe from surface hazards such as ships and storm waves.
Primary to SeaCycler’s success is its ability to profile a sizable sensor suite (currently 11 sensors) using substantial buoyancy to resist mooring knock-over from ocean currents while conserving battery-stored energy to permit over 500 x 150m profiles throughout year-long deployments.
SeaCycler senses surface conditions and will abort profiles prematurely if wave loading exceeds an adjustable limit. Profiling movement is controlled by a unique drive system which powers an underwater winch that has built-in compliance and no rotating seals or slip-rings to enhance reliability.
The weather was good with light winds and 1 to 2m waves. We started early in the day as winds were forecasted to pick up. A quick site survey revealed flat bathymetry and good water depths.
SeaCycler components were deployed in the usual “MechFloat-tow, CommFloat, SensorFloat, MechFloat-slip” fashion (B-L of Fig 2), which worked well.
The buy ativan online A-Frame was used to deploy most mooring components including the MechFloat. The CommFloat was slipped by hand and a slewing crane deployed the anchors.
A capstan winch was used to pay out cable and deck cleats were used to slip mooring loads.
The deployment took less time than expected and resulted in an estimated 3-hour tow to achieve station. It was decided to omit 1 x 5m length of chain and deploy immediately to avoid the long tow. The final mooring location was about 2 nm further from the AR7W line than originally planned.
The ship was maneuvered to follow the mooring’s top floats until they submerged. A nice gentle tow was observed. No mooring beacon hits were received after submergence.
Fig. 3, Mooring top floats being towed by a sinking anchor.
Hydro-acoustic triangulation was not performed at this time and instead, the ship was relocated for K1 deployment. The ship returned to the SeaCycler site later that evening, but triangulation was not performed since a SeaCycler surfacing had already occurred providing a more accurate GPS location fix.
Mooring Position & Anchor Fall-Back:
The 2400kg double-quad steel anchor was slipped in 3526m of water and eventually settled on the bottom 1016m to the South-East. It took 38 minutes for the top of the mooring to submerge after anchor release. This equates to a SeaCycler descent rate of .48 m/s, which is well within acceptable limits.
The final mooring position is determined by averaging CommFloat GPS location fixes shown in Figure 4. The central “Best” point indicates the profile with least amount of “Extra Cable Out”.
Fig 4, CommFloat GPS locations for the first 10 profiles
The entire SeaCycler Team at Dalhousie University and Scripps Institution of Oceanography would like to thank the Maria S. Merian’s Captain Ralf Schmidt for his support and excellent ship handling skills and our Chief Scientist, Dr. Johannes Karstensen from GEOMAR-Kiel for his support and acceptance of our operation into his OSNAP West project. We also acknowledge the support of the VITALS project of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Excellence Research Chair in Ocean Science and Technology for supporting this deployment.
Many thanks are also given to Christian Begler, Gerd Niehus and Uwe Papenburg for their valuable advice and help on deck and to the many students and ship’s crew for their excellent mooring handling skills and provision of delicious food.
It was a pleasure to meet and work with the entire MSM54 team. We sincerely thank you for your help and assistance and opportunity to sail together.
Figure 1: Mooring launch locations (white squares at 53N array, the central Labrador Sea and west Irminger Sea) and CTD stations (small yellow squares). This picture is from Johannes Karstensen (chief scientist of the cruise) with permission.
Another promising year for measuring Atlantic Meridional Overturning Circulation starts with cruise Maria S. Merian 54 (MSM 54), which departed St. John’s, Canada on 12th May and will end on 7th June in Reykjavik, Iceland. During this cruise, we will deploy seven moorings at the exit of the Labrador Sea near 53N, and two deep ones at the entrance near the west Greenland coast (Figure 1, right). These moorings serve to measure the magnitude and variability of the deep western boundary current as well as the connection of deep layer transport between entrance and exit of the Labrador Sea. Besides, direct measurements of the convective activity will be accomplished with mooring deployments in the central Labrador Sea (K1 and SeaCycler) and the central Irminger Sea (CIS). These observations will collectively contribute to our understanding of how the boundary current (both strength and property) varies with time, and the how these buy kamagra online changes are related to the convections.
Along the cruise, we will be conducting 90 CTD casts, crossing the Labrador Sea and west Irminger Sea. We are excited to expect a thick, cold and fresh Labrador Sea Water layer comparable to the ever-observed deepest convection in 1994.
Now we have been at sea for 5 days. The weather was not as good as what I have hoped: it was windy and cold during the first 3 days and got foggy afterwards. Hopefully the weather is getting better so that we can have everything progressed as scheduled.
Just BTW: Food is great on MSM (Figure 2). People are nice (Figure 2). I wish I could speak some German.
At the port of St. Johns, Canada on May 12th before cruise started. by Sijia Zou
With two other students (Christina Schmidt on the left and Patricia Handmann on the right) from GEOMAR (photo credit to Marilena Oltmanns). The flying hair in this photo tells you how important it is to wear a hat on the ship.
One of the great dinners on board (half chicken!!).
by Johannes Karstensen, chiefscientist MSM54 expedition
The ocean-class German research ships are rarely seen in Germany. They follow a route that is composed by many individual expeditions and converting the ships travel into a long, long journey; for Maria S Merian this journey takes place primarily in the North Atlantic and it transition into the Arctic Ocean. As a consequence – the scientists have to travel to where the ship is and have to bring with them (again by ship, but container ships) the equipment that is needed for the experiments to be performed at sea.
Without equipment brought by the scientists the Maria S Merian is not at all an empty ship – she carries a lot of equipment, required by almost all groups that make use of the ship, such as cranes, work shops, communication devices, instrumentation. However, most important – the ship is manned with a skilled, experienced and simply great crew, providing all support to not only conduct experiments at sea but to find a comfortable atmosphere which makes life at sea easy for us, the non-seamen.
In the last ten years I have been six times to St. Johns, Canada – all times to enter a ship (two times the Maria S Merian) for expeditions to the Labrador Sea. Typically I arrive 3 to 4 days before the cruise starts, just to be here when the ship arrives and to help loading and setting up equipment. The arrival of the ship is always special; for example people often eagerly wait to be back to shore, leaving the steadily moving platform behind – but to discover that the movement continues even on land for the next couple of days. St. Johns is a convenient harbour for us, just 1.5 days transit to one of our main working areas (the “53°N array”) – but it is also a nice little town settled around a large natural harbour bay.
Caption: View from Battery Park on St. Johns harbour. The two research ships (easy to identify by the “A” formed crane mounted at the stern, are the Irish Celtic Explorer (keft) and the German Maria S. Merian (right). credit: J. Karstensen
We, a science crew of 20 people, need for the installations and experiments planned during this trip (called MSM54) an amount of material that came in 7 containers. We fixed 4 containers to the ships deck but the rest of the material is now distributed in the labs.
The science crew is composed of five people from Canada’s Dalhousie University, one person from Duke University in the US, and 14 persons from GEOMAR in Germany. We are a mix of students (9), from PhD to BSc, technicians (7), and full scientists (4). A lot of the work that will be done is very technical – installing quite heavy equipment that ultimately serves us to conduct our experiments at sea generating data that is of use for our scientific investigations. What we are really after is to better understand how our ocean regulates climate – for example by taking up heat and other substances in specific regions, such as the Labrador Sea, where large amounts of near surface water sink to sometime deeper than 2000m depth, and from where it spreads far into the ocean interior.
What regulates the sinking process and how does the water spread in the ocean interior are some of the questions we want to answer. The 53°N-Array has been first installed in 1997, long before I came to Kiel to work in this region. It is a unique time series not only because it is operational since so long, but because it has been well designed from the beginning. Setting up a time series has similarities in buying a house – the only thing that matters is the location!
On this trip we will recovery many instruments that were installed during the last service of the array in 2014. For that cruise we started, guess where? – in St. Johns, correct! but on the French Research Vessel NO Thalassa. Not only the two of us who participated in the Thalassa expedition are now very excited to see how well the instrumentation had worked over the last two years. In 2018 we plan to come to the Labrador Sea again to service the “53°N-Array” – and I hope I can one more time join the long, long journey of the RV Maria S Merian.
‘Go with the flow’: Research on the currents in the subpolar North Atlantic
This past July chief scientist Laura de Steur and the crew of the Pelagia set out to take measurements of the subpolar gyre as part of NACLIM and OSNAP research programs. Research conducted on this cruise, and as part of these programs, is important in understanding the “role of the ocean in our climate and future climate change.” Learn more about their work this summer, and ongoing research, in this film created over the course of the cruise.