Assistant Professor Hilary I. Palevsky, Boston College, Department of Earth and Environment, was a presenter at the National Science Foundation’s Geosciences Directorate Division of Ocean Sciences 2020 Frontiers in Ocean Sciences Symposium, which was held virtually on 18 June 2020.  In her presentation, New Insights into the Ocean Carbon Cycle for Novel Platforms and Partnerships, Palevsky told of ways she has used and plans to use OOI data from the Irminger Sea Array to advance understanding of the global biological pump. Watch her presentation, beginning at 56:54.

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Twelve scientists from Woods Hole Oceanographic Institution (WHOI) will board the R/V Neil Armstrong on 8 August 2020 for about a month-long expedition to OOI’s Irminger Sea Array. The journey includes an eight-day transit to reach the array, where they will recover and replace ocean observing equipment that has ridden out arduous conditions in a region known for intense winter wind events (peak speeds of 50-55 knots).

Iceland is separated from the east coast of Greenland by the Denmark Strait, roughly a distance of some 250 miles. The Irminger Sea is south of the strait, stretching from Iceland down to the latitude of Cape Farewell at Greenland’s southern tip. This region is important to the Atlantic Ocean circulation and sensitive to global climate change.

Supported by wind power and solar cells, the Irminger Sea Array consists of moorings that serve as home for sensors that measure air-sea fluxes of heat, moisture and momentum, and physical, biological and chemical properties throughout the water column. The observations of the moorings are enhanced by open-ocean gliders that sample within and around the triangular array, feeding data back to the moorings which relay data to shore via satellite telemetry. Gliders also sample the upper water column near the Apex Profiler Mooring to complement the moored profiler data and extend coverage to the air-sea interface.

This month-long expedition is the seventh time the OOI team has traveled to the array, specifically to replace and repair equipment that is vital to maintaining a continuous flow of data from this important site.

“This is a difficult region to sustain surface observations, yet such observations are critical to improving our understanding of air-sea exchanges and deep convection that drives the Atlantic overturning circulation” said Al Plueddemann, project scientist for the OOI Coastal and Global Scale Nodes (CGSN).

WHOI Research Scientist Sebastien Bigorre will serve as the chief scientist for the expedition.

 COVID Complications

The scientific party went into a 14-day quarantine on 21 July to ensure that everyone could safely board the ship.  They were tested for COVID-19 prior to quarantine and will be tested again prior to departure.  Masks and social distancing will be practiced onboard until another two-week period of health is achieved. At that point, mask wearing may be loosened as the scientific team and crew members will, in effect, be their own social bubble as they live, work, and share the space of the 238 foot-long vessel.

[caption id="attachment_16416" align="alignleft" width="300"] During a past expedition to the Irminger Sea Array, the crew deploys a near surface instrument frame to the array. Credit: Allison Heather, WHOI[/caption]

Explained Derek Buffitt, program manager for the Coastal and Global Scale Nodes, operated from Woods Hole Oceanographic Institution, which includes oversight of the Irminger Sea Array, “COVID-19 created plenty of new logistical challenges for an expedition of this length and distance.  We had to address contingencies such as what to do if someone presented COVID symptoms while at sea. WHOI’s marine operations office, working with agents and government representatives, confirmed health and safety protocols within the foreign ports along the planned vessel track.  This was to ensure our personnel could receive the care needed in an emergency and in a timely manner.”

Such contingencies were necessary steps, in addition to many months of preparation, to ensure the equipment to be deployed is ready, tested, and packaged for transporting to the ship.

Watch this space, and social media, as we follow along on this important expedition.

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The University-National Oceanographic Laboratory System (UNOLS), which coordinates oceanographic ships’ schedules, recommended on 17 March 2020 that cruise activities be paused for 30 days due to the COVID-19 pandemic. On 30 March UNOLS extended its guidance to suspend research cruises to July 1 2020. This action is designed to protect the health and safety of the crews and scientific parties.

The planned spring operation and maintenance (O&M) cruise to the Endurance Array in March was affected by the original 30-day guidance. The upcoming O&M cruises for the Pioneer, Irminger, and Papa Arrays aboard R/V Neil Armstrong and R/V Sikuliaq are impacted by this latest guidance.

The OOI is working with UNOLS and ship operators to find potential opportunities to complete the scheduled cruises and conduct needed maintenance on the arrays.  In the meantime, there’s been no interruption in OOI data. OOI data continue to be collected and made available for use by the scientific and educational communities.

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“Just like lightning,” in one-minute presentations, 15 scientists shared amazing ways they are using OOI data in scientific investigations and in the classroom. This round of lightning talks capped the Ocean Observatories Initiative Facility Board’s (OOIFB) Town Hall at the 2020 Ocean Sciences Meeting on 20 February, demonstrating the multiple and creative ways OOI data are being used to answer key science questions in a changing environment.

The presentations ranged from how students are using real-life and real-time OOI data to advance their understanding of scientific principles to how researchers are using OOI data to identify the presence of marine life by sound to how modelers are making OOI data more accessible and useable.

“We were simply thrilled by the depth, breadth, and range of applications of OOI data shown during this lightning round,” Kendra Daly, chair of the OOIFB.  “We were pleased so many presenters were willing to accept the challenge. This enthusiastic response clearly shows that OOI data are being used to help answer important science questions.”

Brief summaries of the talks are presented below.

Advancing science

Isabela Le Bras, Scripps Institution of Oceanography, reported on a recent article in Geophysical Research Letters, where she and her colleagues describe how they used data from the Irminger Sea Array moorings (2014–2016) to identify two water masses formed by convection and showing that they have different rates of export in the western boundary current. Upper Irminger Sea Intermediate Water appears to form near the boundary current and is exported rapidly within three months of its formation. Deep Irminger Sea Intermediate Water forms in the basin interior and is exported on longer time scales. The subduction of these waters into the boundary current is consistent with an eddy transport mechanism. The eddy transport process is more effective for the waters cooled near the boundary current, implying that cooling near boundary currents may be more important for the climate than has been appreciated to date.

Since 2017, Clare Reimers and Kristen Fogaren, Oregon State University, have been working to assess seasonal variability in benthic oxygen consumption and the contribution of benthic respiration to the development of hypoxic conditions in the northern California Current, using time series data from the OOI Endurance Array. Reimers and Fogaren measured benthic oxygen consumption rates using in situ eddy covariation techniques and ex situ core incubations, during a series of ten cruises that allowed sampling near the Endurance Oregon Shelf and Inshore stations, in all seasons. During these cruises, the researchers used real-time data provided by the Endurance Array to optimize the settings for their eddy covariance deployments. They are now examining property-relationships in discrete bottom water samples collected during the cruises and using data from OOI assets to help separate influences of mixing and biochemical processes in the water column and sediments. The researchers are also synthesizing benthic flux measurements and placing these rates in the context of cross-shelf glider measurements and benthic node time series.

Adrienne Silver, University of Massachusetts Dartmouth provided details about how she is using Pioneer Array data to learn more about the influence of warm core rings on Shelf break circulation.  Results from a 40-year Warm Core Ring census show a regime shift in warm core ring formation at 2000, with the number of rings doubling from an average of 18 rings per year (during 1980-1999) to 33 rings per year (during 2000-2019). This regime shift creates a large increase in the amount of warm salty water being transported northward toward the shelf from the Gulf Stream. The preferred pathway of these rings, or the Ring Corridor seem to indicate their proximity to the shelf break and the Pioneer array during their lifetime. The goal of Silver’s project is to understand how these warm core rings affect the shelf break exchange while traveling along the shelf. A large focus of the study will be on the salinity intrusion events which might be sourced from these warm core rings.

Liz Ferguson, CEO and founder of Ocean Science Analytics, is using data from OOI’s Coastal Endurance and Regional Cabled Arrays to determine the variables that are most useful for assessing the ecosystem of this region and obtaining baseline information on marine mammal acoustic presence for use in monitoring.   Using long term physical and biological data provided by these arrays, Ferguson is assessing long-standing shifts in the ecology of this coastal and offshore environment by associating physical oceanographic variables with the vocal presence of marine mammals using the broadband hydrophone data. Temporal changes in the occurrence of marine mammal species such as killer whales, sperm whales and dolphins can be used as an indicator of ecosystem shifts over time. She is analyzing passive acoustic data provided by the OOI arrays to determine the presence of vocally active marine mammal species, identify their spatial and temporal use of these sites, and combining this information with the physical oceanographic variables to assess the ecological characteristics associated with marine mammal occurrence.

Sam Urmy of the Monterey Bay Aquarium Research Institute (MBARI) also is using OOI acoustical data in his research.  Using an upward-looking echosounder and a high-frequency hydrophone at MBARI’s Monterey Accelerated Research System, Urmy showed how small animals in the epipelagic and mesopelagic altered their behavior in response to predators.  These responses included abrupt dives during bouts of foraging by dolphins, changes in depth to avoid predatory fish schools, and dramatic alterations to daily vertical migratory behavior. Continual observations of the mesopelagic with active and passive acoustics are revealing several dynamic predator-prey interactions in an ecosystem that is typically thought of as relatively slow and static.

Veronica Tamsitt of the University of New South Wales used the OOI’s Southern Ocean mooring and the Southern Ocean Flux Site (SOFS, in the Southeast Indian) to study the Sub Antarctic Mode water (SAMW) formation. Tamsitt’s and her colleagues findings were reported in the Journal of Climate in March 2020. Using data from the two mooring locations, the researchers were able to compare and contrast characteristics and variability of air-sea heat fluxes, mixed-layer depths, and SAMW formation. The researchers found that inter mixed-layer depth anomalies tended to be intermittent at the two moorings, where anomalously deep mixed layers were associated with anomalous advection of cold air from the south, and conversely shallow mixed layers correspond to warm air from the north. Both the winter heat flux and mixed-layer depth anomalies, however, showed a complex spatial pattern, with both positive and negative anomalies in both the Indian and Pacific basins that Tasmitt and colleagues relate to the leading modes of climate variability in the Southern Ocean.

Editor’s note: The Southern Ocean Array was decommissioned in January 2020.  Its data, however, are still available for use by researchers, students, and the public.

Bringing OOI data into the classroom

Sage Lichtenwalner, Department of Marine and Coastal Sciences at Rutgers, The State University of New Jersey reported on the progress of the Ocean Data Labs Project. This project is a Rutgers-led effort to build a “Community of Practice” to tap into the firehose of OOI ocean data to support undergraduate education. To date, the project has hosted four “development” workshops that introduced participants to the OOI, conducted data processing with Python notebooks, and shared effective teaching strategies, in addition to a series of introductory workshops and webinars.  As part of the development workshops, 56 university, college, and community college faculty designed 19 new “Data Explorations,” featuring web-based interactive “widgets” that allow students to interact with pre-selected data from the OOI. The project also sponsors a series of webinars, a fellowship program, and is compiling a library of resources (including coding notebooks, datasets, and case studies in teaching) to help the community.

Cheryl Greengrove, University of Washington Tacoma, summarized an article in the March issue of Oceanography that she and colleagues from across the United States wrote detailing ways to integrate OOI data into the undergraduate curriculum. The wealth of freely-accessible data provided by OOI platforms, many of which can be viewed in real or near-real time, provides an opportunity to bring these authentic data into undergraduate classrooms. The TOS article highlights existing educational resources derived from OOI data that are ready for other educators to incorporate into their own classrooms, as well as presents opportunities for new resources to be developed by the community. Examples of undergraduate introductory oceanography OOI data-based lessons using existing interactive online data widgets with curated OOI data on primary productivity, salinity, and tectonics and seamounts are presented, as well as ways to use OOI data to engage students in undergraduate research. The authors provide a synthesis of existing tools and resources as a practical how-to guide to support new resource development and invite other educators to develop and implement new educational resources based on OOI data.

Matthew Iacchei, Hawaiʻi Pacific University, presented how he has been integrating OOI data explorations to supplement his upper division oceanography lecture and labs with real data from around the world. Last semester, he had students explore patterns of dissolved oxygen and impacts of anoxia at the coastal endurance array in Oregon and compare that data to dissolved oxygen data the students collected in Kāneʻohe Bay, Hawaiʻi. This semester, students are working through two exercises with OOI data as part of their primary productivity lab (perfect, as it is now online!). Students will compare vertical profiles from Hawaiʻi with seasonal variations across the world, and will compare latitudinal drivers of primary production using data from a time-series from the Southern Ocean Array.

Strengthening OOI data usability

Wu-Jung Lee, a senior oceanographer at the Applied Physics Laboratory, University of Washington, is using data collected by the OOI to develop new methodologies for analyzing long-term ocean sonar time series. In a project funded by the National Science Foundation, she and her colleagues show that unsupervised matrix decomposition techniques are effective in discovering dominant patterns from large volumes of data, which can be used to describe changes in the sonar observation. Their preliminary analysis also show that the summaries provided by these methods facilitate direct comparison and interpretation with other ocean environmental parameters concurrently recorded by the OOI. A parallel effort that spun out of this project is an open-source software package echopype, which was created to enable interoperable and scalable processing of biological information from ocean sonar data.

As part of the Rutgers Ocean Modeling Group, in conjunction with University of California Santa Cruz, John Wilkin and Elias Hunter are delivering a high-resolution data assimilative ocean model analysis of the environs of the Pioneer Coastal Array, including a systematic evaluation of the information content of different elements of the observing network. The project uses the Regional Ocean Modeling System with 4-Dimensional Variational data assimilation. To produce a comprehensive multi-year (2014-2018) analysis required them to assimilate all available Pioneer CTD data, with quality checks, in a rolling sequence of data assimilation analysis intervals. They used three days of data in each analysis, which required queries to with a time range constraint and relevant platform (i.e. glider, profiler, fixed sensor), migrating  all Pioneer CTD data (wire following profilers, gliders, fixed sensors, plus ADCP velocity) to an ERDDAP server. The simple graphing capabilities in ERDDAP allow quick browsing of the data to trace quality control or availability issues, and ERDDAP provides a robust back-end to other web services to create more sophisticated graphical views, or time series analysis. Using the ERDDAP Slide Sorter tool, they operate a quick look Control Panel to monitor the data availability and quality.

Mitchell Scott and colleagues Aaron Marburg and Bhuvan Malladihalli Shashidhara at the University of Washington, are studying how to segment macrofauna from the background environment using OOI data from the Regional Cabled Axial Seamount Array. Their long-term goal is to use an automated approach to study species variation over time, and against other environmental factors. Their initial step focuses specifically on scale worms, which are very camouflaged, making them difficult to detect. To address this, the researchers initially used a deep learning model, called U-Net, to detect and localize the scale worm locations within an image. To address the high rate of false positives using this model, they added an additional classifier (a VGG-16 model) to verify the presence of scaleworms.  This combined, applied approach proved feasible for scale worm detection and localization. Yet because the environment of the Axial Seamount is so dynamic due to the growth and decay of chimneys at the site and resulting changes in bacteria and macrofauna present, they found the performance of the model decreased over time.

Weifeng (Gordon) Zhang of Woods Hole Oceanographic Institution has been using Pioneer Array data to understand the physical processes occurring at the Mid-Atlantic Bight shelf break, including the intrusion of Gulf Stream warm-core ring water onto the shelf and the ring-induced subduction of the biologically productive shelf water into the slope sea. His findings were reported in a Geophysical Research Letters paper where data from the Pioneer Array moorings and gliders demonstrated the anomalous intrusion of the warm and salty ring water onto the shelf and revealed the subsurface structure of the intrusion. Zhang also shared findings reported in the Journal of Geophysical Research: Oceans where data from the Pioneer Array showed a distinct pattern of relatively cold and fresh shelf water going underneath the intruding ring water. These results show the subduction of the shelf water into the slope sea and a pathway of shelf water exiting the shelf. In both instances, Zhang and his colleagues used computer modeling to study the dynamics of these water masses. These two studies together suggest that shelf break processes are complex and require more studies in the region.

Hilary Palevsky of Boston College presented results from an ongoing project funded by the National Science Foundation’s Chemical Oceanography program, using biogeochemical data from the OOI Irminger Sea Array. Analysis of dissolved oxygen data on OOI Irminger Sea gliders and moorings from 2014-2016 showed the importance of biogeochemical data collected over the full seasonal cycle and throughout the entire water column, due to the influence of subsurface respiration and deep winter convection on biological carbon sequestration. The OOI Irminger Sea array is the first source of such full-depth year-round data in the subpolar North Atlantic. To quantitatively evaluate the annual rate of carbon sequestration by the biological pump and the role of deep winter convection, Palevsky and colleague David Nicholson of the Woods Hole Oceanographic Institution collaborated with OOI to improve the calibration of oxygen data at the Irminger Sea array by modifying the configuration of glider oxygen sensors to enable calibration in air each time the glider surfaces, which improves the accuracy and utility of the data collected both from gliders and from moorings. Palevsky presented preliminary results demonstrating successful glider air calibration at the Irminger array in 2018-2019 as well as work by student Lucy Wanzer, Wellesley College, demonstrating the importance of well-calibrated oxygen time series data to determine interannual variability in rates of subsurface respiration and deep winter ventilation in the Irminger Sea.

 

 

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The spring 2020 OOI Endurance Operations and Management (O&M) turn cruise has been delayed for at least 30 days due to travel and personnel restrictions imposed to stem the spread of the virus COVID-19.

The 16-day cruise was set to depart on 31 March from Newport, Oregon aboard the R/V Sikuliaq to service the array off the Oregon and Washington coasts. The R/V Sikuliaq is part of the US academic research fleet managed by UNOLS (the University-National Oceanographic Laboratory System). UNOLS imposed a 30-day suspension in fleet operations on 13 March to help ensure the safety of the ship’s crew and science party and to mitigate the risk of virus spread. Rescheduling of activities will commence once the situation stabilizes and UNOLS sees a path forward to re-start research vessel operations safely.

Upcoming O&M cruises for the Pioneer, Irminger, and Papa Arrays also are scheduled aboard UNOLS vessels (R/V Neil Armstrong and R/V Sikuliaq). These cruises fall outside of the UNOLS current 30-day suspension so cruise preparation continues.

We do not anticipate that cruise schedule changes will affect the collection nor dissemination of OOI data, which will continue to be available for users here.

 

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[media-caption type="image" path="https://oceanobservatories.org/wp-content/uploads/2019/09/Array-236x300.jpg" link="#"]Fig. 1. Irminger-5 surface buoy after deployment in June 2018. Damage to the direct covariance flux sensor (center of tower) is evident.[/media-caption]

The recently completed OOI mooring service cruise on the R/V Neil Armstrong (2-25 Aug 2019) established a significant milestone – the Irminger Sea Global Surface Mooring was sustained for over a year and returned high quality data. To our knowledge, this is the first surface mooring with instrumentation to compute bulk air-sea fluxes of heat, moisture and momentum that has operated through a full annual cycle in this region.

It is now recognized (e.g. de Jong and de Steur, 2016, Geophys. Res. Lett., 43, 7106–7113, DOI: 10.1002/2016GL069596) that extreme heat loss in the Irminger Sea results in deep water formation, which ultimately influences the strength of the Atlantic Meriodonal Overturning Circulation and has important climate implications. The strong heat loss in the region is largely driven by episodic cold-air outbreaks from the southern tip of Greenland (Josey et al., 2019, Geophys. Res. Lett., 46. DOI: 10.1029/2018GL080956).

[media-caption type="image" path="https://oceanobservatories.org/wp-content/uploads/2019/09/Winds1-300x212.jpg" link="#"]Fig. 2. Satellite scatterometer winds (QuikSCAT) during a cold-air outbreak (right; from Vage et al., 2008))[/media-caption]

Cold-air outbreaks are associated with high winds, sub-freezing temperatures, and large, steep waves (Vage et al., 2008, J. Phys. Oceanogr., 38(3), DOI: 10.1175/2007JPO3678.1), which create very difficult conditions for sustained observations at the air-sea interface.  The situation is further complicated by the occasional passage of icebergs, which could impact the buoy. The lack of continuous time series data through the winter season capable of identifying episodic events has hindered understanding of air-sea interaction in the Irminger Sea.

The biggest risks to sustained operation of the OOI Irminger Sea mooring were determined to be icing on the buoy tower & freezing of sensitive instrument components.  Icing could not be controlled, but potential impacts could be mitigated, for example by shutting down the wind turbines to reduce the likelihood of broken blades. However, a turbine shut-down also meant reduced power generation.  Freezing of the precipitation sensor was controllable using a built-in heater, but at the cost of additional power.

[media-caption type="image" path="https://oceanobservatories.org/wp-content/uploads/2019/09/Buoy-300x169.jpg" link="#"]Fig. 3a. Buoy cam pictures showing tower icing.[/media-caption]

The CGSN operations team took on the challenge by monitoring weather forecasts for conditions conducive to icing, adding cameras to the buoy tower to detect icing, and implementing a power management strategy during storms. When icing conditions were forecast, the wind turbines were shut down to reduce the likelihood of damage, while some mooring components were simultaneously shut down to save power. Power to high priority instruments (including the bulk meteorology system) and the precipitation sensor heaters was maintained. The strategy was effective, but the difficulty of sustained observations was still evident: The direct-covariance flux package was damaged upon deployment and did not return useful data. The buoy sustained damage to the wind vane, a solar panel and a wind turbine during the winter storms. This compromised power generation capability eventually led to an eight-day data gap in June 2019 due to sustained low wind and overcast skies.

[media-caption type="image" path="https://oceanobservatories.org/wp-content/uploads/2019/09/Winds-2-300x225.png" link="#"]Fig. 4. Time series of METBK meteorological parameters spanning the full deployment period. Left panel: Air (red) and sea surface (blue) temperature, relative humidity and barometric pressure. Right panel: East (red) and north (blue) wind, shortwave (red) and longwave radiation, and precipitation.[/media-caption] [media type="image" path="https://oceanobservatories.org/wp-content/uploads/2019/09/Winds-3-300x225.png" link="#"][/media]

Despite the challenges, the buoy bulk meteorology system operated for 420 days of the 428-day deployment (8 June 2018 – 9 Aug 2019) and returned a wealth of scientific data. One-minute records from the bulk meteorology sensors show wind speeds up to 25 m/s and air temperatures as low as -5 C associated with cold -air outbreaks that likely dominate the cumulative wintertime heat loss, as described by Josey et al. (2019).  The availability of the first annual cycle of surface meteorology, in conjunction with subsurface data from the OOI Irminger Sea array and the Overturning in the Subpolar North Atlantic Program (OSNAP) array, provide the potential for new insights into the nature of deep mixing, carbon sequestration and deep-water formation in the region.

[media-caption type="image" path="https://oceanobservatories.org/wp-content/uploads/2019/09/team-640x360.jpg" link="#"]Fig. 5. Photo of the Irminger-5 buoy about to be recovered from the R/V/ Armstrong in August 2019. A close look shows damage to the wind turbine and solar panel on the left side.[/media-caption] Read More
[media type="image" path="/wp-content/uploads/2019/07/HopkinsPaper-1.jpg" link="#"][/media]

Data from the Ocean Observatories Initiative (OOI) Global Irminger Sea Array contributed to the longest continuous record of total volume transport of water in the Deep Western Boundary Current. This current, in the subpolar North Atlantic, travels southwest along the continental slope off of Greenland and is considered a significant part of the global climate system.

In a recent Journal of Geophysical Research Letters: Oceans paper, Dr. Joanne Hopkins at the National Oceanography Center in Southampton, U.K., and collaborators used data from two U.S. OOI flanking moorings, along with three U.S. Overturning in the Subpolar North Atlantic Program (OSNAP) East Greenland Current array moorings, and five U.K. OSNAP moorings to study the total amount of water moved by the current over a period of two years, as well as its daily and seasonal variability.

The data used for this paper was gathered over 22 months between 2014 and 2016, while all 10 of the moorings were in the water for the same period. Previous research to determine transport estimates at this latitude have been limited by a sparse number of direct and sustained measurements, relying instead on measurements over 9.5 months, 60 days, and “snapshot” or repeated summertime hydrographic sections.

Hopkins et al estimate that the Deep Western Boundary Current transports an average of 10.8 × 106 m3 of water per second with variation in time. In addition, the transport variability shifts from high to low frequencies with distance down slope. While the results did suggest an increase in transport since 2005-2006, they did not conclude that there was a significant long-term trend, given the limitations of previous data sets.

The location of the OOI Global Irminger Sea array was selected as part of an effort by the scientific community to place moorings in areas that have been historically under-sampled and subject to high winds and sea states that make frequent ship-based measurements difficult. The OOI Data Portal provides access to data from the Irminger Sea Array dating back to the initial installation in September 2014.

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Late last year, more than 30 researchers from countries spanning the Atlantic met in Southampton, UK at the National Oceanography Centre to foster coordination of research efforts focused on the Irminger Sea region. Of central importance to the workshop was to bring in young investigators.

[media type="image" class="external(onlynecessaryiflinkopensdifferentsite)" path="/wp-content/uploads/2018/04/IMG_1270-e1523556889622-300x225.jpg" alt="30 Researchers at the National Oceanography Centre" link="#"][/media]

“The Irminger Sea workshop provided me with an incredibly valuable opportunity to meet and develop connections with others working in this region, and to gain a better understanding of the current state of our knowledge and areas of active research in the Irminger Sea and broader subpolar North Atlantic,” reflects Hilary Palevsky, Postdoctoral Scholar at the Woods Hole Oceanographic Institution. “This was especially important for me at this stage in my career to have the opportunity to make these sorts of connections with people whom I had only previously known from reading their published papers.”

The Irminger Sea region, west of Greenland, is a region of high wind and large surface waves, strong atmosphere-ocean exchanges of energy and gases, CO2 sequestration, high biological productivity, an important fishery, and the location of one of the OOI Global Arrays.

“Many of the participants were already using OOI data, and those that weren’t were eager to learn more about the data and improve the time series going forward,” says Mike Vardaro, OOI Data Manager. “I returned with many recommendations to improve data collection, processing, and distribution as well as requests for data, including inquiries about cruise opportunities and how to add to OOI infrastructure or deploy in the OOI area.”

Some of the key recommendations noted were easier bulk download, expansion of ERDDAP, and improved quality control of DO, NUTNR, and PCO2A sensor data.

The overarching objective of the workshop was to coordinate international efforts to observe, study, and better understand the Irminger Sea region.

“The second Irminger Sea workshop saw the fruit being borne of the collaboration between OOI and OSNAP,” says Bob Weller, OOI Global Array PI. “At the first workshop that collaboration resulted in siting the OOI moorings in line with the OSNAP array and adding instrumentation to achieve common sampling. This proved to be very successful.  Further, the sampling of the air-sea fluxes and the biology and biogeochemistry at OOI Irminger drew high level of interest and provided the data for a number of papers and joint analyses now underway.”

Check out the O-SNAP blog post written by workshop steering committee member Penny Holliday from the National Oceanography Centre.

Workshop foci were:

  • Summaries of present and planned observational, empirical, theoretical, and model-based efforts focused on the physics and biogeochemistry of the Irminger Sea region;
  • Presentation of results from recent observational campaigns;
  • Identification of key questions and hypotheses related to the physics and biogeochemistry of the region; discussion of sampling strategies to address those questions, including coordination of present, planned and new observational efforts;
  • Plans for collaborative analyses and publications;
  • Data sharing in support of coordination and collaboration.

 
Day one of the workshop featured presentations to share results of existing studies and plans for future studies and analysis. A full list of presentations can be found in the workshop report.

On the second day, participants worked in small groups to tackle specific discussion questions with the aim of catalyzing collaborative research, analyses, and publications.
 
Some questions included:

  • Does convection in the Labrador Sea and Irminger Sea have different behavior?
  • What are the drivers of extreme convection events?
  • What are the controls on productivity, the spring bloom, and ecosystems?
  • How do freshwater anomalies (from Arctic) propagate around the subpolar gyre?
  • What is the impact of the freshwater on oceanic and atmospheric variability?

 
Key outcomes of the workshop included:

  • Strong support for multi-disciplinary observations made by OOI platforms including the gliders
  • Strong support for continued efforts to collect surface meteorology and air-sea fluxes through challenging winter conditions, thus support for OOI to improve surface buoy
  • Reliance on OOI Irminger Sea Array continuing allowing Dutch LOCO mooring and German CIS mooring time series to now be collected by OOI going forward.
[button link="/wp-content/uploads/2018/04/Irminger_Sea_Workshop_Report_25Jan18_final.pdf"]Download Workshop Report[/button] Read More

Increased risk of a shutdown of ocean convection posed by warm North Atlantic summers

Marilena Oltmanns*, Johannes Karstensen and Jürgen Fischer

Abstract: A shutdown of ocean convection in the subpolar North Atlantic, triggered by enhanced melting over Greenland, is regarded as a potential transition point into a fundamentally different climate regime1,2,3. Noting that a key uncertainty for future convection resides in the relative importance of melting in summer and atmospheric forcing in winter, we investigate the extent to which summer conditions constrain convection with a comprehensive dataset, including hydrographic records that are over a decade in length from the convection regions. We find that warm and fresh summers, characterized by increased sea surface temperatures, freshwater concentrations and melting, are accompanied by reduced heat and buoyancy losses in winter, which entail a longer persistence of the freshwater near the surface and contribute to delaying convection. By shortening the time span for the convective freshwater export, the identified seasonal dynamics introduce a potentially critical threshold that is crossed when substantial amounts of freshwater from one summer are carried over into the next and accumulate. Warm and fresh summers in the Irminger Sea are followed by particularly short convection periods. We estimate that in the winter 2010–2011, after the warmest and freshest Irminger Sea summer on our record, ~40% of the surface freshwater was retained.

[button class="block" link="https://www.nature.com/articles/s41558-018-0105-1"]Full Article found can be on Nature Magazine Website[/button] [button class="block" link="/array/global-irminger-sea/"]More details on the OOI Irminger Sea Array design and data products[/button] [feature]

Do you have a recent publication using OOI data? Let us know!
Simply send a note to the HelpDesk with the digital object identifier (DOI) of your publication.[/feature] Read More