Category Archives: Cruises

Greetings from RSS James Cook!

By Rita Markina

The UK OSNAP team left Southampton on 12 July and is heading into the sub-polar North Atlantic. We will be working on the very eastern part of the OSNAP line from the Hebrides shelf via the Rockall basin to the Iceland Basin. This is the region where two major branches of warm and salty Atlantic waters flow into the Arctic, and we have various different oceanographic equipment on board to measure these ocean currents.

Picture 1: Map in the main lab showing the expedition region with the current location of the ship, mooring stations, and Argo deployments sites (ship’s position is updated daily). Photo from Rita Markina.

We will recover and redeploy several moorings that have been recording ocean properties continuously since Oct 2020. We will do a bunch of CTD stations where we will measure vertical profiles of ocean temperature, salinity, oxygen, fluorescence, pH and current velocity, and sample water at different depths for sensor calibration and chemical analysis of carbon, oxygen and nutrients. Apart from this, we will deploy three biogeochemical Argo floats which will measure CTD profiles and at least three (pH, nitrate, chlorophyll) out of the six biogeochemical Argo parameters (oxygen, chlorophyll, BBP, nitrate, pH and irradiance). These parameters are important to assess ecosystem health. There is also a brand-new bottom pressure recorder on board that we will deploy. A second recorder will be installed at the western basin during M148 led by our German colleagues from GEOMAR in August. The bottom pressure data on either side of the Atlantic will allow us to estimate the amount of water transported between the two instruments. More on this measurement system and how it works here: https://www.sonardyne.com/ocean-bottom-pressure-data-unlocks-amoc/

While our ship is moving north, the crew, technicians and science team prepare all the equipment, and those of us who are here for the first time are familiarising ourselves with the ship – which looks gorgeous. Check it out with this virtual tour: https://noc.ac.uk/facilities/ships/rrs-james-cook/rrs-james-cook-virtual-tour.

This morning we saw the dolphins! They came really close to the ship – curious about what we are up to (or just enjoying the waves).

Picture 2. Dolphins following RSS James Cook in the Irish Sea. Video from Rita Markina.

More details about our work and life on board are soon to come!

OSNAP GDWBC 11 July 2022

By Ellen Park

Life at sea is organized chaos.

Each day is incredibly valuable because sea time is so expensive.

As a result, prior to stepping foot on the boat, we had a detailed schedule outlining what operations, like mooring recovery/deployment or a CTD cast, would be completed on each day and their duration in a set order. But this order wasn’t really “set.” It was more realistically the ideal order of operations, assuming no major setbacks. Ultimately, forecasted weather and instrument malfunctions required us to be flexible, forcing us to prioritize certain operations over others due to factors like local conditions, limits on deck space, or transit time to stations.

To keep track of all these moving pieces, everyday a plan of the day (POD) was outlined by the chief scientist, Sheri White, for the upcoming workday. Conversations both amongst the science party and between the science party and the ship’s crew were essential for ensuring that all operations were conducted safely and smoothly and that both scientific agendas for OSNAP and OOI were met.

While the POD often changes multiple times (five times within one day once because of weather!), there are some aspects of life at sea that are constant.

Typically, most days start bright and early at 6am to prep the deck for a mooring deployment/recovery operation or preparation of the rosette for a CTD cast. After breakfast, mooring deployment/recovery or CTD casts begin. Mooring operations last anywhere from 2-6+ hours, depending on the height of the mooring and number of instruments attached. CTD casts on this cruise typically were 2-3 hours and went to 2,000-3,000 meters depth. Depending on the duration of the morning operation, we would break for lunch and afterwards continue or start a new operation. Occasionally, we conduct a few late night CTD casts after dinner, but for the most part all operations are complete by 18:00.

To help stay sane and entertained, people participate in a variety of evening activities after operations are completed. Some people workout in the onboard gym. Others read, play card games, or watch TV/movies in the lounge.

With the end of the cruise approaching, it is exciting to celebrate the accomplishment of achieving all the OSNAP and OOI objectives, despite the weather-related setbacks we encountered. This could not have been possible without the hard work from everyone on the ship’s crew and members of the science party. As we begin our transit to Reykjavik in the upcoming days, I know that I am looking forward to returning to land, but, at the same time, I will be a bit sad to leave the R/V Armstrong.

OSNAP GDWBC 07 July 2022

by Ellen Park

On our eight-day transit to the Irminger Sea, we completed a few calibration casts for instruments that will be deployed on the OSNAP moorings and saw some pretty incredible sunsets (see Figure 1).

Figure 1. OOI mooring buoys on the deck at sunset.  (Photo by Ellen Park)

Once we reached our target region, we got to work right away. First, we deployed all of the new components of the OOI Global Irminger Sea Array, which consists of a surface mooring, three subsurface moorings, and gliders. Then we moved on to recover the OSNAP Greenland Deep Western Boundary Current (GDWBC) moorings, which are all subsurface moorings. One of the key differences between the OOI and OSNAP moorings is how collected data are stored and recovered. OOI data are stored locally and also telemetered so that data can be accessed by the public in near real time. OSNAP data, on the other hand, are stored locally and cannot be accessed until the sensor is recovered and the data are downloaded.

Before recovering each mooring, we do a CTD cast roughly 0.5 nautical miles away from the mooring to provide an endpoint for each timeseries (see Figure 2). Not only can sensors drift overtime, but they also can become biofouled, which will affect the measured value (see Figure 3). Having an endpoint value is important because it allows us to correct the sensor data for these phenomena and provide more accurate results.

Figure 2. CTD going into the water. (Photo by Ellen Park)
Figure 3. Biofouled oxygen optode recovered from M1. (Photo by Heather Furey)

Many of the casts that we have done so far went below 2,000 m depth because we are interested in the GDWBC. Sensors deployed at these depths must be able to withstand harsh conditions and extremely high pressures. 10 m of water is roughly equivalent to 10 decibar of pressure (~1 atm). Therefore, at 2,000m depth, sensors experience 200 times the pressure that they experience at the surface. We could see the pressure effects on Styrofoam cups that we sent down with one of the deep CTD casts (see Figure 4).

Figure 4. Styrofoam cups before and after being sent to ~2,600 meters (Photo by Ellen Park)

We have roughly another week to finish up all of our operations before heading to Reykjavik, where we will leave the ship and fly home. During this time, we will finish recovering and deploying moorings and taking a preliminary look at the recovered two years’ worth of data!

OSNAP Greenland Deep Western Boundary Current (GDWBC) 01 July 2022

by Heather Furey

It’s been a minute.  The sun is shining, it is a perfect July day on the Irminger Sea.  After an eight-day transit, some amount of CTD casts, some amount of CTD sensor diagnostics, some amount of moored instrument calibrations, and a few glider deployments, we are finally getting to the guts of the work: the mooring deployments and recoveries. 

Lines all neat and at-the-ready on the side of WHOI’s Mooring Operations and Engineering (MOE) van.

It’s day 12 of 28. We are interweaving the OOI and OSNAP mooring operations.  It’s a workload that is in flux; we are up to ‘Plan C’ right now. Plans have changed due to weather days, both the good kind and the bad kind, and a glider recovery. The general plan is to deploy OOI moorings first, as we need to get the deck cleared of equipment before we will have space to recover a similar amount of gear.  After OOI moorings are deployed, we recover and then deploy OSNAP moorings, and once done, we recover OOI moorings.  That’s the idea, though Plan C has some deviations on that generalized plan. We have 2 out of 16 mooring operations complete so far.

Meanwhile, the galley staff keep cranking out great food, the crew are awesome as always, and we steam along from work task to work task, checking things off the list.

More later, Heather

Flowers kept in the galley, tended to by Harry Burnett, our Steward.

OSNAP Greenland Deep Western Boundary Current (GDWBC) 20-21 June 2022

by Heather Furey

So, we are off (Figure 1).  The sun is shining, it is a perfect June Cape Cod day.  Lines were cast about 20 minutes early; family and friends were left to rush to the dock to wave goodbye.

We are headed out to ‘tip jet central’, just east-northeast of the tip of Greenland where so many strong wind events are located. The winds scream across the Labrador Sea from the west, round the corner of Cape Farewell at the southern tip of Greenland, into the southwest Irminger Sea, forming strong cyclonic wind events.  We partner with Ocean Observatories Initiative (OOI) on this cruise, as they are headed to the same work region to turn around the Global Irminger Sea Array (https://oceanobservatories.org/array/global-irminger-sea-array/).  This OOI global array has four heavily instrumented moorings, two of which are in line with the OSNAP array, located between the Greenland Deep Western Boundary Current (GDWBC) moorings.

Figure 1. We are just starting out, having cast off the lines at about 16:10 EST from Dyers Dock at WHOI, in Woods Hole, Massachusetts.

The entire OSNAP line will be recovered and redeployed this summer – a feat that will require five different oceanographic cruises from three different institutions and five different science parties – led by UMiami, GEOMAR, NOC, Scripps, and WHOI.  The cruise details are listed here: https://www.o-snap.org/observations/research-cruises/.

Figure 2. The OSNAP array and hydrographic ‘line’. Mooring locations are represented by yellow dots; glider section, and a yellow line. Five cruises will service different portions of the array, circled and organized from blue to red by start date. The light green rectangle denotes the glider survey section, which is ongoing. (This ~2016 schematic has just a few differences from what is in the water right now, but in general, is correct.  I’m at sea, I’m using what I brought with me.)

The entire OSNAP mooring and CTD line across the Labrador Sea, Irminger Basin, Iceland Basin, and Rockall Trough is shown in Figure 2.  Each of the five cruises will service one of the circled regions.  We are headed to the Irminger Sea (blue) now, then the R/V Neil Armstrong will dock in Reykjavik and pick up the next science party, who will service moorings in the Iceland Basin (yellow), then back to Reykjavik, new science party, who will then service moorings east and west of southern Greenland (red).  Meanwhile, the folks aboard the British RSS Cook will service the Rockall Trough region (green), and the German RV Meteor will service the Labrador Basin array (orange). The glider array (light green), run by SAMS, continually measures ocean properties across the Rockall Plateau.

On this cruise, we will be recovering and redeploying (‘turning around’) four moorings and calibrating their instruments (see the blue circle in Figure 2 and M1, M2, M3, and M4 in Figure 3), in addition to the moorings at the OOI Irminger Array (see SUMO, HYPM, FLMA/B, and Glider Box in Figure 3). The work load will be about a 2/3 OOI, 1/3 OSNAP balance.  We share some of the science party: hydrographer Leah Houghton, the deck crew led by John Kemp, and help from other OOI members during our mooring deployment or recovery days when they have time.  And, in turn, we help OOI out during their work days as we can. 

Figure 3. Zoom-in of the work site and mooring locations east of the tip of Greenland.

We have just finished a test CTD cast and reworked the day-by-day cruise plan, which will likely be reworked a few more times as the days go by and actual events reshape the way we spend our time.  Just ahead are a couple of transit days to deep water, instrument prep, and then a few calibration casts.

More later, Heather

Transiting to the Irminger Sea

by Sarah Nickford, URI

Greetings from the R/V Neil Armstrong! I am a graduate student studying physical oceanography at the University of Rhode Island’s Graduate School of Oceanography. Originally, I planned on participating in the OSNAP-23 cruise to help calibrate and deploy oxygen sensors on some of the OSNAP moorings in the Labrador Sea as part of the newly funded Gases in the Overturning and Horizontal circulation of the Subpolar North Atlantic Program (GOHSNAP) awarded to my advisor, Dr. Jaime Palter, and her collaborators.

In the midst of the pandemic, I suddenly became an alternate for that cruise as science parties were slashed in half. After completing the 14-day self-isolation as an alternate, the entire science party tested negative for COVID-19 (phew) and the R/V Neil Armstrong began its voyage to the Labrador Sea. I resumed my “normal” pandemic day-to-day life until one morning, not long after, I was asked if I would be willing to complete another self-isolation period to be able to go to the Irminger Sea as a Hydrographer for the next OSNAP cruise. This cruise was a joint venture between OOI and OSNAP, with both OOI Irminger Node and OSNAP mooring turn-arounds. I had about a day to make a decision. Fond memories of my month aboard the SSV Corwith Cramer crossing the North Atlantic with Sea Education Association (SEA) helped me make up my mind. Ever since that voyage, I’ve been drawn to going to sea, where there is no land in sight. So, when the opportunity presented itself, I was eager to help out. I immediately was trained in Woods Hole and after the weekend, I entered my second self-isolation period of the summer. As I learned more about the cruise activities, I became increasingly excited. I suddenly had the opportunity to learn how to collect water samples, watch mooring turn-around operations and help document them, watch glider deployments, and help deploy an Argo float.

After the science party completed their 15-day self-isolation period, we finally arrived and settled into the R/V Neil Armstrong. We left Woods Hole, MA on Saturday August 8th at 0815 and the science team has been busy planning mooring operations, CTD deployments, and water sampling. Today is the fifth transit day and we are just past Canada, making a sharp turn north and heading to the Irminger Sea. So far, we’ve had incredibly clear skies in the evenings, creating the perfect conditions for beautiful sunsets and vibrant stargazing (great for viewing the Milky Way and the Perseid meteor shower!).

The first bit of science was on Saturday afternoon when we did a shallow water CTD cast to test how the CTD and associated machinery were working and so that the OSNAP Chief Scientist, Heather Furey, and I could practice water sampling. We have been orienting ourselves in the wetlab onboard and developing a sampling plan that fits the needs of both the OSNAP project and the OOI Irminger Array. After a CTD comes back on deck, we will be collecting water samples for the following parameters: dissolved oxygen, salt, DIC/TA, pH, nutrients, and chlorophyll. Each sample is taken at a specified depth, which can change depending on the water mass characteristics that we are sampling. We plan to do a CTD cast near each of the OSNAP moorings. This is useful for the calibration of the instruments on the new moorings and for what is called a “post-recovery caldip,” where the instruments from the recovered mooring are strapped to the CTD frame for one final dive to detect possible sensor drift over the two years they lived underwater collecting data. As we continue our transit, we are looking forward to the excitement that is soon to come.

A CTD just below the surface of the water. Before sending the CTD to the depths of the ocean, it must sit at the surface so that the instruments equilibrate with the surrounding water. After reaching its target depth, on its way back up to the surface, scientists monitoring the CTD close individual bottles at specified depths, capturing a sample of water from different water masses.

Reflections of the dwindling daylight on the surface of the ocean after departing Woods Hole.

MSM94 expedition on the RV Maria S. Merian

OSNAP/NIOZ Cruise Blog

OSNAP scientist, Femke de Jong, and a team of NIOZ scientists are currently at sea on a research cruise aboard the RV Pelagia. They will be servicing moorings and deploying drifters in the Irminger Sea. Follow their progress on the cruise blog posted here.

Aboard the R/V Atlantic Explorer east of Abaco, the Bahamas

by Bill Johns

At sea again!

No, not an OSNAP cruise this time, but in the balmy subtropics at 26°N.

I am leading a group from the University of Miami and NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) on this 18 day cruise, where we will recover and replace several deep moorings and collect hydrographic profiles near the ocean’s western boundary off the Bahamas as part of the RAPID/MOCHA program (http://www.rapid.ac.uk/rapidmoc/). One of our key goals is to monitor the strength of the Deep Western Boundary Current (DWBC) that carries deep waters formed in the subpolar region southward toward the equator, in the lower branch of the Atlantic Merdional Overturning Circulation.

Unlike our OSNAP cruises, we are wearing t-shirts on deck and scanning for the elusive “green flash” on clear days at sunset – a somewhat more comfortable existence to be sure, but as on all cruises the work is nonstop. We’ve experienced a short November gale on this cruise that shut down our sampling for awhile, but we are mindful of the fact that we’d much rather be here now than up in the high North Atlantic!

The last CTD recovery before shutting down our overboarding operations.

Even though the subpolar gyre seems far, far away, the data we are collecting on this cruise is a constant reminder of the connection between what is happening here in the subtropics and in the subpolar region. We can see clear evidence in the DWBC water mass properties of changes in the intensity of deep water mass formation in the North Atlantic over the past few decades. Although the RAPID program only started in 2004, the AOML group has been making measurements of the water mass composition of the DWBC here since the mid-80’s as part of their Western Boundary Time Series (WBTS) program. The biggest change occurred in 1995 when a new pulse of much colder and fresher (less salty) water originating from the Labrador Sea arrived at 26°N. This pulse followed a period of very strong cooling in the Labrador Sea starting about 9 years earlier that resulted in the deepest and densest formation of Labrador Sea Water in more than 60 years. The 9-year transit time for that pulse to arrive off the Bahamas means it couldn’t have all come in a fast-track pathway within the DWBC itself, but very likely followed one or more pathways through the ocean interior, for which there is other independent evidence. The peak of that event occurred in about 2003 off the

Bahamas, again just about 9 years after the peak of deep convection in the Labrador Sea in 1994. Since that time the waters in the DWBC off Abaco have gradually warmed, while deep convection in the Labrador Sea has generally decreased.

All that changed in 2014 with the onset of very strong cooling again across the subpolar gyre and extensive deep convection in the Labrador Sea – coincidentally (but auspiciously) timed with the start of OSNAP. If this turns out to be a sustained multi-year event, which it seems to have the makings of, then the next several years will be very interesting. Will this be a playback of the mid-90’s event, or will something different happen? We know the ocean is taking up a great deal of the excess carbon dioxide we are putting into the atmosphere, and that the deep water mass formation in the North Atlantic is a key element of that uptake. What we know much less about are the pathways and processes by which carbon is transported and stored in the ocean and he time scales of those deep ocean transport processes. Obviously we’ll have to wait a while to find out what happens, but the difference this time around is that we will have the OSNAP, RAPID, and other deployed AMOC arrays, as well as the fully-deployed Argo array, to help us out. THAT is progress.

Last OSNAP cruise of the season on RV Neil Armstrong is underway – Blog 1

September 12, 2018 

by Isabela Alexander-Astiz Le Bras 

Two weeks ago we left Reykjavik on the R/V Neil Armstrong for the last OSNAP cruise of the season, a five week expedition to the outskirts of Greenland. Our goal: “turn around” two sets of OSNAP moorings and taking as many CTD casts as possible. In fact, Chief Scientist Bob Pickart is well known for taking particularly large numbers of tightly spaced CTDs. 

Every group will say this, but I think our region is the most interesting of the OSNAP array. East of Greenland, cold and fresh water from the north meet warm and salty waters that originate in the Gulf Stream. This place is a turning point for the ocean’s global overturning circulation, which helps stabilize the earth’s climate, yet measurements here are severely lacking, partly due to the conditions I will describe here. 

You may already know all this, but I’ll start by getting you up to speed on oceanographer-speak just in case. Moorings are long wires dotted with instruments that are anchored to the sea floor and take measurements for as long as several years. We are picking up our moorings after a two year deployment and are only able to access the data in the instruments once they are on board. We are also deploying a new set of moorings to leave in the ocean for another two years. The moorings we are servicing range from 100m on the shelf to almost 3km long offshore!  

The CTD (conductivity, temperature, depth) rosette is the workhorse of oceanography. This instrumentation package measures temperature, salinity and pressure/depth as it is lowered through the water column by a winch on the ship. It also includes Niskin bottles that are closed at various depths to collect water that is used for calibration and ADCPs (Acoustic Doppler Current Profilers) that measure ocean velocity. Our CTD package also includes a set of chipods, which Jonathan Nash from OSU very generously loaned me for this cruise. Chipods measure temperature gradients at high speed (100 measurements per second), providing a quantification of turbulent processes over centimeter scales. As our CTD sections survey ocean properties at finer spatial resolution than the moorings, we use these to learn about detailed ocean dynamics and to ground-truth the mooring measurements. 

Our first priority on this cruise is to retrieve and re-deploy the OSNAP moorings. However, this can only be done in daylight and when it is calm enough to be lifting large objects in and out of the ocean. A group of mooring specialists from WHOI and the Armstrong’s deck crew physically deploy and retrieve the moorings while others (like myself) take notes. To take full advantage of being out here, anytime that we can’t do moorings, we are doing CTDs. And by we, I mean a small army of graduate students, postdocs and technicians who take 8 hour shifts round-the-clock to operate the CTD. Of course, none of this work is possible without the ship’s crew who get us where we need to go and keep us safe on our floating home for these 5 weeks. 

I thought I knew what to expect, having been to sea several times before and having spent the better part of the last year analyzing mooring data from the first deployment. I was also fully aware that we were heading into stormy seas pretty late in the “calm season”. After all, we think the currents we are studying are driven by the winds that zip along the coast of Greenland and flare up at its ominously named southern tip: Cape Farewell. 

During the first few days that reality set in as we rocked and rolled our way to our study site. For me at least, there is a difference between knowing its a stormy region and being tossed around in my bunk for 24 hours. Our chairs slid across the main lab as we gathered to discuss plans and even the most seaworthy in the crew held on tight as they staggered down the hallway. It didn’t always feel great, but it sure helped me internalize that this really is one of the windiest places on earth. 

Once on the continental shelf of Greenland, we were greeted by stunning views and large craggy icebergs that were well worth the weather. During the first OSNAP deployment (2014-2016), the inshore-most mooring, CF1, was hit by such an iceberg and the instruments sitting at 50m and 100m fell to the seafloor about a year after deployment. While marveling at their beauty and size, I wondered how such iceberg casualties were not more common. Luckily, we managed to recover CF1 this time as well, though yet again the 50m instrument was knocked down to 80m less than a year into the deployment. 

For the rest of our stay east of Greenland we alternated between mooring recoveries and deployments, doing CTDs through the night, and hiding behind the cliffs of Greenland when the weather turned. Our mooring operations were successful with the exception of one mooring on the shelf that has refused to surface thus far. We will be back for it as soon as we are done with the rest of the moorings, but it stands as a painful reminder that what we are doing here is difficult, and that the ocean is full of uncertainty and surprises. 

Two days ago we crossed through the beautiful Prince Christian Sound to start all over again west of Greenland. Armed with successful mooring operations east of Greenland, two sections of CTDs and two weeks of experience working as a team, I think we are ready to take on the Labrador Sea! 

Recovering the flotation sphere for mooring CF4 with an iceberg in the background. Pictured from left to right: Andrew Davies, Pete Liarikos, John Kemp and Brian Hogue.Photo by Isabela Alexander-Astiz Le Bras 

 

The last step of mooring deployment is dropping this anchor off the fantail to the seafloor.Photo by Isabela Alexander-Astiz Le Bras  

 

View of a glacier flowing into the Prince Christian Sound.