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1. Fram Strait

2. GSR Greenland Scotland Ridge

3. OSNAP Overturning in the Subpolar North Atlantic Program

4. NOAC North Atlantic Changes

5. RAPID-MOCHA-WBTS Rapid Climate Change Meridional Overturning Circulation Heat-flux Array Western Boundary Time Series

6. MOVE Meridional Overturning Variability Experiment

7. 11°S

8. SAMBA-SAMOC South Atlantic Meridional Overturning Circulation



Overturning in the Subpolar North Atlantic Program
Overturning in the Subpolar North Atlantic Program
Contributing institutes Canada: Bedford Institute of Oceanography (DFO), Memorial University

China: Ocean University of China and Qingdao National Laboratory for Marine Science and Technology

France: IFREMER, CNRS, Laboratoire d’Océanographie Physique et Spatiale

Germany: GEOMAR Helmholtz Centre for Ocean Research Kiel

Netherlands: Royal Netherlands Institute, Utrecht University

UK: National Oceanography Center Southampton (NOC), University of Edinburgh, Scottish Association for Marine Sciences (SAMS), University of Liverpool

USA: Duke University, Rosenstiel School of Marine and Atmospheric Science (RSMAS), Scripps Institution of Oceanography (SIO), and Woods Hole Oceanographic Institution (WHOI)
Overall representative M. Susan Lozier,
Feili Li,

For the sub-arrays and their representatives see
Data Representative Richenda Houseago-Stokes, Britisch Oceanographic Data Centre, UK,

Brief description of the TMA

The OSNAP TMA is designed to provide a continuous record of the full-water column, trans-basin fluxes of heat, mass and freshwater in the subpolar North Atlantic. The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). For more information see

There is mounting evidence from measurements and models of the importance of the transports of heat and salt by the North Atlantic Subpolar Gyre (SPG) for impacts on North Atlantic, European and global climate via temperature, precipitation and wind strength, and also on marine ecosystems, hurricanes, even rainfall in the Sahel, the Amazon and parts of the US. The SPG behaves substantially differently from the Subtropical Gyre, and their mechanisms and timescales for transport and storage of heat and freshwater are very different. The SPG is inadequately measured, and no ocean general circulation or climate model represents it accurately. UK-OSNAP aims to generate new knowledge and understanding of the SPG, to improve predictions of the contribution of the SPG to climate.

Figure 1

Fig. 1: OSNAP observing system: From west to east: Canadian shelfbreak array and German 53°N western boundary array; US West Greenland boundary array; US/UK East Greenland boundary array; Netherlands western Mid-Atlantic Ridge array; US eastern Mid-Atlantic Ridge array; Chinese glider survey in the Iceland Basin; UK glider survey over the Hatton-Rockall Bank; UK Scottish Slope current array. See also

Figure 2

Fig. 2: OSNAP array superposed on climatological salinity along the OSNAP West and East lines. Color shading is 2005-2012 mean salinity from WOA13; black dashed lines are isopycnals of 27.5, 27.75, 27.8, and 27.88 kg m-3. OSNAP mooring locations (vertical gray lines) and glider domain (shaded white box) are indicated. Vertical black lines over the western flank of the Reykjanes Ridge illustrate three moorings as part of the RREX.

Data products: volume transport time series

Figure 3

Fig. 3: MOC and Ekman transport across the OSNAP section. Black, yellow, and blue lines represent the 30-day mean estimates from the full section, OSNAP West, and OSNAP East, respectively, for MOC (solid lines) and Ekman transport (dashed lines). Shading indicates uncertainty in the 30-day means. Uncertainty in the Ekman transports is too small for display. Thin gray lines show the 10-day low-pass filtered daily means for the full OSNAP section. From Lozier et al. (2019)

Transport data can be downloaded here

The DOI is 10.7924/r4z60gf0f at

The array instrument data are available at

Observation period 2014 - ongoing
Observed quantities Temperature, salinity, velocity
Current/past funding sources Physical Oceanography Program of the U.S. National Science Foundation; the United Kingdom’s Natural Environment Research Council programs UK-OSNAP, the Extended Ellett Line, and ACSIS (National Capability). European Union 7th Framework Programme (FP7 2007-2013) under grant 308299 (NACLIM) and the Horizon 2020 research and innovation program under grants 727852 (Blue-Action), 308299 (NACLIM), 678760 (ATLAS), and 633211 (AtlantOS). French Centre National de la Recherche Scientifique. China: National key research and development projects (2016YFA0601803) and the Fundamental Research Funds for the Central Universities (201424001). Support for the 53°N array by the RACE program of the German Ministry BMBF. Canada: Fisheries and Oceans Canada’s (DFO’s) Atlantic Zone Off-shelf Monitoring Program (AZOMP).


Lozier M. S. 1,*, F. Li1,*, S. Bacon2, F. Bahr3, A. S. Bower3, S. A. Cunningham4, M. F. de Jong5, L. de Steur5,†, B. deYoung6, J. Fischer7, S. F. Gary4, B. J. W. Greenan8, N. P. Holliday2, A. Houk9, L. Houpert4, M. E. Inall4,10, W. E. Johns9, H. L. Johnson11, C. Johnson4, J. Karstensen7, G. Koman9, I. A. Le Bras12, X. Lin13, N. Mackay14,‡, D. P. Marshall15, H. Mercier16, M. Oltmanns7, R. S. Pickart3, A. L. Ramsey3, D. Rayner2, F. Straneo12, V. Thierry17, D. J. Torres3, R. G. Williams18, C. Wilson14, J. Yang3, I. Yashayaev8, J. Zhao3,§ (2019)

A sea change in our view of overturning in the subpolar North Atlantic, Science, 363, 6426, DOI: 10.1126/science.aau6592

For more publications see