The UK Overturning in the Subpolar North Atlantic Program (UK-OSNAP)

Lead Research Organisation: National Oceanography Centre
Department Name: Science and Technology

Abstract

UK-OSNAP: Summary

What is climate? The sun's energy is constantly heating the Earth in equatorial regions, while in the Arctic and Antarctic the Earth is frozen and constantly losing heat. Ocean currents and atmospheric weather together move heat from the equator towards the poles to keep the Earth's regional temperatures in balance. So climate is simply the heat moved by ocean currents and by the weather. Earth's climate is warming: the average temperature of the Earth is rising at a rate of about 0.75 degrees Centigrade per hundred years, caused by carbon dioxide in the atmosphere trapping heat that is normally lost to space. Can we forecast how climate might change in the future?

There is an old adage that rings true: "Climate is what you expect; weather is what you get". Hot weather in one summer does not tell us that climate is changing because the weather is so variable day-to-day and even year-to-year. We need to average over all the weather for a long time to decide if the climate is changing. We would like to know if the climate is changing before our descendants face the consequences, and that is where our project comes in. The ultimate ambition of climate scientists is nothing less than forecasting climate up to 10 years in advance.

Is this possible? After all we know weather forecasts become somewhat unreliable after three to five days. The answer is yes because of the ocean. Slow and deep currents give the ocean a memory from years to hundreds of years, and the ocean passes this memory onto the climate. If we know the condition of the ocean now, then we have a good chance of understanding how this will affect the climate in years to come.

We have set ourselves a huge task, but will be helped by colleagues in the US, Canada, Germany, Netherlands, Faroe Islands, Iceland, Denmark and Scotland. We will continuously measure the ocean circulation from Canada to Greenland to Scotland (the subpolar North Atlantic Ocean). This has never been attempted before. We have chosen the North Atlantic because the circulation here is important for the whole of Earth's climate. This is because in the high latitudes of the North Atlantic, and the Arctic Ocean that it connects to, the ocean can efficiently imprint its memory on the atmosphere by releasing the huge amounts of heat stored in it. In the UK we are on the same latitude as Canada and Siberia, and the Shetland Islands are further north than the southern tips of Greenland and Alaska, but the Atlantic Ocean circulation keeps the UK 5-10 degrees Centigrade warmer than those other countries.

We can measure across an entire ocean by deploying reliable, self-recording instruments. We will use moorings (wires anchored to the seabed and supported in the water by air-filled glass spheres) to hold the instruments in the important locations. Every year from 2014 to 2018 we will use ships to recover the moorings and the data, then put the instruments back in the water. We will also use exciting new technology. Autonomous underwater Seagliders will fly from the surface to 1 km depth on year long-missions surveying the ocean, from Scotland to 2000 km westward into the Atlantic. The Seagliders transmit their data to our lab every day via satellite, and the pilot can fly the glider remotely. Also there is a global fleet of 3000 drifting floats to continuously measure the top 1 km of the ocean. Satellites provide important measurements of the ocean surface. With these new measurements, we will find how the heat carried by the ocean changes through the months and years of the project, and we will use complex computer models to help explain what we find.

Planned Impact

Beneficiaries and how do they benefit?

Decadal and seasonal forecasters. Knowledge of the structure, behaviour and state of the sub-polar Atlantic is crucial to the skill of forecasting systems. OSNAP will provide observations to accurately form essential starting conditions, benefitting the UK Met. Office 'DePreSys' team.

UK, European and international climate modelers. The observations will provide valuable data to enable assessment, and subsequent refinement, of coupled ocean/climate models used for prediction. Modeling groups at UK Met. Office Hadley Centre and the UK National Centre for Ocean Forecasting will benefit. We will prepare tailored progress presentations for the Hadley Centre. Maximum benefit to the international climate modeling community will be ensured through links in the international OSNAP programme (US, Germany, Netherlands, Canada, France).

International and domestic climate policy and decision makers. Refinement of seasonal, decadal and climate models will contribute to increasingly reliable projections of future climate, thereby underpinning mitigation and adaptation strategies. International benefactors include future assessments by the Intergovernmental Panel on Climate Change (IPCC), which synthesises international modeling work for the policy-making community; and also the International Council for the Exploration of the Seas (ICES) and the Northwest Atlantic Fisheries Organization (NAFO). Domestic beneficiaries include the Depts. of Energy and Climate Change (DECC) and Environment, Food and Rural Affairs (DEFRA); the Foreign and Commonwealth Office (FCO) Polar Desk; and the Scottish Government whose territorial waters extend into the region. The combination of OSNAP results with data from other locations, notably RAPID-WATCH 26N and the Nordic Seas (EU projects NACLIM and THOR), will aid detection of large-scale change in the system likely to influence regional climate and require modified adaptation/mitigation policies.

We will manage our User Community List for climate policy-making for circulating notification and summaries of relevant publications. We will engage with users (known and new) and assist with the extraction, presentation and analysis of OSNAP data; we will make extensive use of a website. We will publish an annual Project Summary Briefing for the climate policy community, outlining project progress and key findings. We will work with the UK Marine Climate Change Impacts Partnership and the UK Climate Impacts Programme to ensure that findings are included in their reports including the 'Annual Report Card' and the AMOC Stakeholder Guidance Note. We will visit key policymakers throughout the project, and invite them to our Project's final UK meeting, shaping part of this meeting towards delivery of Project results within a user context.

Outreach. Ocean science is an exciting and engaging topic for the general public, particularly children. UK-OSNAP will showcase physical science and technology and inspire children in the science and engineering elements of the curriculum. The Scottish Ocean Explorer Centre in Oban will highlight the cutting edge technology with a particular focus on gliders, utilising live feeds of the incoming data and displays showing the tracks of the gliders. The highly-regarded oceans4schools.com website (Southampton) will carry regular features for pupils and teachers. The press offices of NERC, NOC, SAMS and U. Oxford will be kept appraised of newsworthy developments. We will exploit the publicity opportunities afforded by annual NOC & University Open Days. We will maintain cruise blogs targeted at non-scientific audiences.

We will disseminate findings by publication of articles in high-impact refereed journals and presentations at key international science conferences. We will develop a project website to act as a point of access for users of our results, reports and value-added data products.

Publications

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Benetti M (2019) Sources and Distribution of Fresh Water Around Cape Farewell in 2014 in Journal of Geophysical Research: Oceans

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Frajka-Williams E (2019) Atlantic Meridional Overturning Circulation: Observed Transport and Variability in Frontiers in Marine Science

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Gary S (2018) Seasonal Cycles of Oceanic Transports in the Eastern Subpolar North Atlantic in Journal of Geophysical Research: Oceans

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Holliday NP (2018) Subpolar North Atlantic Overturning and Gyre-Scale Circulation in the Summers of 2014 and 2016. in Journal of geophysical research. Oceans

Related Projects

Project Reference Relationship Related To Start End Award Value
NE/K010875/1 02/10/2013 31/10/2019 £2,188,097
NE/K010875/2 Transfer NE/K010875/1 01/11/2019 30/09/2020 £311,259
 
Title Show of Mia Taylor artwork at the Annihilation Event, Lethaby Gallery, London 
Description A set of watercolours paintings based on temperature and salinity profiles from the 2016 OSNAP cruise to the Irminger Sea. The work is by artist Mia Taylor (Winchester School of Art, University of Southampton) who came on the cruise to explore our science and research concepts from a non-scientific perspective. 
Type Of Art Artwork 
Year Produced 2017 
Impact The 6 day programme in the Lethaby Gallery will bring together a contrary group of artists, archivists, archaeologists, historians, technical experts and theorists from all over Europe. The scheduled events will operate as an experiment, an exchange, a chance to inhabit the Lethaby with a constellation of objects, machines, speculative processes and performances, an unprecedented opportunity for collisions and collusions. The event brings the science of OSNAP and the way we work at sea to a very diverse audience. 
URL http://annihilationevent.com/
 
Description In a departure from the prevailing scientific view, OSNAP has revealed that a deep-ocean process playing a key role in regulating Earth's climate is primarily driven by cooling waters west of Europe. These findings will help scientists better forecast changes to the weather and climate by improving understanding of the influence of the ocean upon them.

The study focused on part of the Atlantic meridional overturning circulation (AMOC), a system of ocean currents in the North Atlantic responsible for the transfer of huge amounts of heat from the ocean to northwest Europe, keeping its climate relatively mild. The prevailing scientific view, based on modelling studies, had been that most of the AMOC's overturning and variability occurs in the Labrador Sea, off Canada. Whereas this new research, published in the Journal Science, shows the overturning and variability actually happens in regions between Greenland and Scotland. There, warm, salty, shallow waters are carried northward from the tropics by currents and wind, sink and convert into colder, fresher, deep waters moving southward through the Irminger and Iceland basins.

Overturning variability in this eastern section of the ocean was seven times greater than in the Labrador Sea, and it accounted for 88 percent of the total variance documented across the entire North Atlantic over the 21-month study period. These findings, unexpected as they may be, can help scientists better predict what changes might occur to the Atlantic meridional overturning circulation and what the climate impacts of those changes will be. To aid predictions of climate in the years and decades ahead, we need to know where this deep overturning is currently taking place and what is causing it to vary.

Ocean overturning carries vast amounts of atmospheric carbon from human activity deep into the ocean, helping to slow global warming. The largest reservoir of this carbon from human activity is in the North Atlantic. Overturning also transports tropical heat northward, meaning any changes to it could have an impact on glaciers and Arctic sea ice. Understanding what is happening, and what may happen in the years to come, is vital.
Exploitation Route These observations will change the way we interpret the behaviour and development of climate models.
Sectors Environment

URL http://science.sciencemag.org/content/363/6426/456
 
Title OSNAP Array time series of overturning circulation 2014 to 2016 
Description Data from the full OSNAP array for the first 21 months (31-Jul-2014 to 20-Apr-2016) have been used to produce the 30-day mean Meridional Overturning Circulation, Meridional Heat Transport and Meridional Freshwater Transport time series across the section, along with the gridded property fields. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact This time series is a product that can be used to validate or challenge climate and ocean circulation models, as well as being an index of large scale ocean circulation 
URL https://www.o-snap.org/observations/data/
 
Title OSNAP CTD section 2014 cruise JR302 
Description 234 CTD profiles along the OSNAP/RAGNARROC and Extended Ellett Line sections (Canada - Greenland - Iceland - Scotland). Associated water samples for nutrients, oxygen, carbon were also collected, as were water velocity profiles, and underway measurements of upper ocean velocity, surface temperature and salinity, surface meteorology and bathymetry. 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact The data are used for quality assessment of Argo float profiles thereby helping to maintain the climate-research quality of the global upper ocean temperature and salinity data resource. 
URL http://cchdo.ucsd.edu/cruise/74JC20140606
 
Title OSNAP Moorings cruise dataset AR30-04 (Iceland Basin and Rockall Trough) 2018 
Description CTD casts, and moored instruments data (microcats, ADCP, current meters) 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact New measurements of transport of volume and properties through the eastern North Atlantic 
 
Title OSNAP Moorings cruise dataset DY053 (Iceland Basin and Rockall Trough) 2016 
Description CTD casts, ADCP data, underway instrument data including navigation moored instruments (microcats, ADCP, current meters) 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact New measurements of transport of volume and properties through the eastern North Atlantic 
URL https://www.bodc.ac.uk/projects/data_management/uk/uk-osnap/data_inventories/cruise/dy053/
 
Title OSNAP Moorings cruise dataset DY054 (Irminger Sea) 2016 
Description CTD casts, ADCP data, underway instrument data including navigation moored instruments (microcats, ADCP, current meters) 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact New measurements of transport of volume and properties in the Deep Western Boundary Current east of Greenland 
URL https://www.bodc.ac.uk/projects/data_management/uk/uk-osnap/data_inventories/cruise/dy054/
 
Title OSNAP Moorings cruise dataset DY078/79 (Rockall Trough and Iceland Basin) 2017 
Description CTD and water sample data, underway data from ship's instrumentation (met, bathymetry, ADCP), T, S and velcoity data from moored instruments in the Rockall Trough 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact 12 months of mooring data from the OSNAP eastern boundary array, and the 2017 occupation of the Extended Ellett Line 
URL https://www.bodc.ac.uk/resources/inventories/cruise_inventory/report/16375/
 
Title OSNAP Moorings cruise dataset KN221-2 (Iceland Basin and Rockall Trough) 2014 
Description CTD casts, ADCP data, underway instrument data including navigation 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact New measurements of transport of volume and properties through the eastern North Atlantic 
URL https://www.bodc.ac.uk/projects/data_management/uk/uk-osnap/data_inventories/cruise/kn221-2/
 
Title OSNAP Moorings cruise dataset MSM74 (Irminger Sea) 2018 
Description CTD data, T, S and velocity data from moored instruments in the Irminger Sea 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact New measurements of transport of volume and properties in the Deep Western Boundary Current east of Greenland 
URL https://portal.geomar.de/metadata/leg/show/344922
 
Title OSNAP Moorings cruise dataset PE399 (Iceland Basin and Rockall Trough) 2015 
Description CTD casts, ADCP data, underway instrument data including navigation moored instruments (microcats, ADCP, current meters) 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact New measurements of transport of volume and properties through the eastern North Atlantic 
URL https://www.bodc.ac.uk/projects/data_management/uk/uk-osnap/data_inventories/cruise/pe399/