Meridional Overturning Variability Experiment

Investigators: U. Send, M. Lankhorst

Introduction

The meridional overturning circulation in the Atlantic Ocean carries much of the ocean's meridional heat flux. Yet, until recently, no monitoring system had existed to measure the transport of this overturning circulation. Speculations are abundant about variability, slowing, or potential collapse of this system, with the ensuing impacts on northern hemisphere climate.

Featured article: "Atlantic Overturning Circulation Questions Abound" - EOS Meeting Report, 2018

In 2000, the German CLIVAR program initiated the monitoring array MOVE in the subtropical west Atlantic. MOVE is part of NOAA's Sustained Global Ocean Observing System, among whose objectives are to develop techniques and programs for monitoring the circulation and mass, heat, and freshwater transports of major current systems. Depending on the intensity, width, and depth extension of the current system to be observed, different approaches and technologies now exist which allow implementation and maintenance of "transport reference sites" such as MOVE. For broad-scale and full-depth circulations, a recently demonstrated method consists of fixed-point installations with moored and bottom-mounted instruments to obtain horizontally and vertically integrated measurements.

MOVE project sites

The present MOVE array includes two "geostrophic endpoint moorings" (MOVE1 and MOVE3), and one traditional current meter mooring on the slope (MOVE4). The goal of this installation is to measure fluctuations in transport across the section between the Lesser Antilles (Guadeloupe) and the Mid-Atlantic Ridge, using dynamic height and bottom pressure differences between the moorings to estimate the geostrophic transport.

The core system of moorings in the MOVE project has occasionally been augmented with additional components, including acoustic thermometry, RAFOS floats, and additional bottom pressure sensors for comparison with GRACE satellite data. Earlier configurations have also included up to four additional sites (seven total), which have since been discontinued.

Research Highlight

The figure below shows the time series of North Atlantic Deep Water (NADW) volume transport, calculated from pressure gradients at the MOVE section endpoints, plus the continental slope transport from the current meters on the western MOVE moorings. The southward (negative) transport shows large interannual variability, and as the length of the time-series grows, evidence of decadal-scale variability has begun to emerge. This variability constitutes the science interest of the project.

NADW layer (1200-4950 m) volume transport, computed as the sum of the "boundary" and "internal" components with an additional constant offset as per Kanzow et al. (2006). This figure is based on Send et al. (2011; Fig. 2), with minor updates to processing and extension of the data records with more recent measurements. The plot shows a time series that has been smoothed with a 120-day low-pass filter. The data shown in this figure can be downloaded here.

Publications

  • Biló, T.C., Perez, R.C., Dong, S., Johns, W., and Kanzow, T.: Weakening of the Atlantic Meridional Overturning Circulation abyssal limb in the North Atlantic. Nat. Geosci., 2024. doi: 10.1038/s41561-024-01422-4.
  • D. L. Volkov, D. A. Smeed, M. Lankhorst, S. Dong, B. I. Moat, J. Willis, W. Hobbs, T. Biló, W. Johns, and L. Chomiak: Meridional overturning circulation and heat transport in the Atlantic Ocean [in "State of the Climate in 2022", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 104 (9), S181-S184, 2023.
  • Sebastien Bigorre, Ray Graham, Matthias Lankhorst: NTAS-21 Mooring Turnaraound Cruise Report. Technical Report, Woods Hole Oceanographic Institution, Dec. 2022. doi: 10.1575/1912/66127.
  • Rebecca Hummels, Bill Johns, Sabrina Speich, Renellys Perez, Peter Brandt, Matthias Lankhorst, Uwe Send: The AMOC in the Tropical Atlantic. In: CLIVAR Exchanges, Special Issue: Tropical Atlantic Observing System (TAOS). CLIVAR Exchanges, no. 82, 2022. doi: 10.36071/clivar.82.2022.
  • W. Johns, S. Speich, R. Perez, P. Brandt, U. Send, and M. Lankhorst: The AMOC in the Tropical Atlantic. Pp. 87-96 in: Tropical Atlantic Observing System (TAOS) Review Report (coord. lead authors: W. Johns and S. Speich). CLIVAR, document no. 202101, 222 pp., May 2021.
  • Gokhan Danabasoglu, Frederic S. Castruccio, R. Justin Small, Robert Tomas, Eleanor Frajka-Williams, and Matthias Lankhorst: Revisiting AMOC transport estimates from observations and models. Geophysical Research Letters, 48, e2021GL093045, 2021. doi: 10.1029/2021GL093045.
  • Barbara Berx, Denis Volkov, Johanna Baehr, Molly O. Baringer, Peter Brandt, Kristin Burmeister, Stuart Cunningham, Marieke Femke de Jong, Laura de Steur, Shenfu Dong, Eleanor Frajka-Williams, Gustavo J. Goni, N. Penny Holliday, Rebecca Hummels, Randi Ingvaldsen, Kerstin Jochumsen, William Johns, Steingrimur Jónsson, Johannes Karstensen, Dagmar Kieke, Richard Krishfield, Matthias Lankhorst, Karin Margetha H. Larsen, Isabela Le Bras, Craig M. Lee, Feili Li, Susan Lozier, Andreas Macrander, Gerard McCarthy, Christian Mertens, Ben Moat, Martin Moritz, Renellys Perez, Igor Polyakov, Andrey Proshutinsky, Berit Rabe, Monika Rhein, Claudia Schmid, Øystein Skagseth, David A. Smeed, Mary-Louise Timmermans, Wilken-Jon von Appen, Bill Williams, Rebecca Woodgate, and Igor Yashayaev: Climate-Relevant Ocean Transport Measurements in the Atlantic and Arctic Oceans. Pp. 10-11 in Frontiers in Ocean Observing: Documenting Ecosystems, Understanding Environmental Changes, Forecasting Hazards. E.S. Kappel, S.K. Juniper, S. Seeyave, E. Smith, and M. Visbeck (eds.). A Supplement to Oceanography 34(4). doi: 10.5670/oceanog.2021.supplement.02-04.
  • D. L. Volkov, S. Dong, M. Lankhorst, M. Kersalé, A. Sanchez-Franks, C. Schmid, J. Herrford, R. C. Perez, B. I. Moat, P. Brandt, C. S. Meinen, M. O. Baringer, E. Frajka-Williams, and D. A. Smeed: Meridional overturning circulation and heat transport in the Atlantic Ocean, [in "State of the Climate in 2020", chapter "Global Oceans"]. Bull. Amer. Meteor. Soc., 102 (8), S176-S179, 2021.
  • Jannes Koelling, Uwe Send, and Matthias Lankhorst: Decadal strengthening of interior flow of North Atlantic Deep Water observed by GRACE satellites. J. Geophys. Res. Oceans, 125, 2020. doi: 10.1029/2020JC016217.
  • D. L. Volkov, C. S. Meinen, C. Schmid, B. Moat, M. Lankhorst, S. Dong, F. Li, W. Johns, S. Lozier, R. Perez, G. Goni, M. Kersalé, E. Frajka-Williams, M. Baringer, D. Smeed, D. Rayner, A. Sanchez-Franks, and U. Send: Atlantic meridional overturning circulation and associated heat transport, in "State of the Climate 2019", Bull. Amer. Meteor. Soc., 101, S1–S429, 2020. doi: 10.1175/2020BAMSStateoftheClimate.1.
  • M. Lankhorst and U. Send: Uncertainty of North Atlantic Current observations from altimetry, floats, moorings, and XBT. Progress in Oceanography, 187, 2020. doi: 10.1016/j.pocean.2020.102402.
  • E. Frajka-Williams, I. J. Ansorge, J. Baehr, H. L. Bryden, M. P. Chidichimo, S. A. Cunningham, G. Danabasoglu, S. Dong, K. A. Donohue, S. Elipot, P. Heimbach, P. N. Holliday, R. Hummels, L. C. Jackson, J. Karstensen, M. Lankhorst, I. A. Le Bras, S. M. Lozier, E. L. McDonagh, C. S. Meinen, H. Mercier, B. I. Moat, R. C. Perez, C. G. Piecuch, M. Rhein, M. A. Srokosz, K. E. Trenberth, S. Bacon, G. Forget, G. Goni, D. Kieke, J. Koelling, T. Lamont, G. D. McCarthy, C. Mertens, U. Send, D. A. Smeed, S. Speich, M. van den Berg, D. Volkov, C. Wilson: Atlantic Meridional Overturning Circulation: Observed Transport and Variability. Front. Mar. Sci., 6:260, 2019. doi: 10.3389/fmars.2019.00260.
  • A. Bower, S. Lozier, A. Biastoch, K. Drouin, N. Foukal, H. Furey, M. Lankhorst, S. Rühs, and S. Zou: Lagrangian Views of the Pathways of the Atlantic Meridional Overturning Circulation. J. Geophys. Res. Oceans, 124, 2019. doi: 10.1029/2019JC015014.
  • Köhler, J., G.S. Völker, and M. Walter: Response of the Internal Wave Field to Remote Wind Forcing by Tropical Cyclones. J. Phys. Oceanogr., 48, 317–328, 2018. doi: 10.1175/JPO-D-17-0112.1.
  • M. O. Baringer, J. Willis, D. A. Smeed, B. Moat, S. Dong, W. R. Hobbs, D. Rayner, W. E. Johns, G. Goni, M. Lankhorst, and U. Send: Meridional overturning and oceanic heat transport circulation observations in the North Atlantic Ocean. [In "State of the Climate in 2017", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 99 (8), S91-S94, 2018.
  • E. Frajka-Williams, M. Lankhorst, J. Koelling, and U. Send: Coherent Circulation Changes in the Deep North Atlantic From 16°N and 26°N Transport Arrays. J. Geophys. Res. Oceans, 2018. doi: 10.1029/2018JC013949.
  • M. O. Baringer, D. A. Smeed, J. Willis, M. Lankhorst, W. R. Hobbs, S. Dong, G. McCarthy, D. Rayner, W. E. Johns, G. Goni, and U. Send: Meridional overturning and oceanic heat transport circulation observations in the North Atlantic Ocean. [In "State of the Climate in 2016", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 98 (8), S84-S88, 2017.
  • S. Elipot, E. Frajka-Williams, C. Hughes, S. Olhede, and M. Lankhorst: Observed basin-scale response of the North Atlantic Meridional Overturning Circulation to wind stress forcing. Journal of Climate, vol. 30, pp. 2029-2054, 2017. doi: 10.1175/JCLI-D-16-0664.1.
  • M. O. Baringer, M. Lankhorst, D. Volkov, S. Garzoli, S. Dong, U. Send, and C. S. Meinen: Meridional overturning circulation observations in the North Atlantic Ocean. [In "State of the Climate in 2015", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 97 (8), S84-S87, 2016.
  • M. O. Baringer, G. McCarthy, J. Willis, M. Lankhorst, D. A. Smeed, U. Send, D. Rayner, W. E. Johns, C. S. Meinen, S. A. Cunningham, T. O. Kanzow, E. Frajka-Williams, and J. Marotzke: Meridional overturning circulation observations in the North Atlantic Ocean. [In "State of the Climate in 2014", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 96 (7), S78-S80, 2015.
  • M. O. Baringer, G. McCarthy, J. Willis, M. Lankhorst, D. A. Smeed, U. Send, D. Rayner, W. E. Johns, C. S. Meinen, S. A. Cunningham, T. O. Kanzow, E. Frajka- Williams, and J. Marotzke: Meridional overturning circulation observations in the North Atlantic Ocean. [In "State of the Climate in 2013", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 95 (7), S67-S69, 2014.
  • J. Köhler, C. Mertens, M. Walter, U. Stöber, M. Rhein, and T. Kanzow: Variability in the internal wave field induced by the Atlantic Deep Western Boundary Current at 16°N. Journal of Physical Oceanography, vol. 44 (2), pp. 492-516, 2014. doi: 10.1175/JPO-D-13-010.1.
  • G. Danabasoglu, R. Curry, P. Heimbach, Y. Kushnir, C. Meinen, R. Msadek, M. Patterson, L. Thompson, S. Yeager, and R. Zhang: 2013 US AMOC Science Team Annual Report on Progress and Priorities. Report 2014-4, US CLIVAR Project Office, 2014, 162 pp.
  • IPCC, 2013 (section 3.6.3): Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Eds.: T.F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
  • M. O. Baringer, W. E. Johns, G. McCarthy, J. Willis, S. Garzoli, M. Lankhorst, C. S. Meinen, U. Send, W. R. Hobbs, S. A. Cunningham, D. Rayner, D. A. Smeed, T. O. Kanzow, P. Heimbach,E. Frajka-Williams, A. Macdonald, S. Dong, and J. Marotzke: Meridional overturning circulation and heat transport observations in the Atlantic Ocean [in "State of the Climate in 2012", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 94 (8), Aug. 2013, S65-S68.
  • Kanzow, T., U.Send, M. Lankhorst, A.Biastoch, C.Boening: Comparison of the Atlantic Meridional Overturning Circulation (AMOC) at two latitudes - 16°N and 24°N. Abstract THOR/AMOC conference, Hamburg, September 2012.
  • Kanzow, T., M. Lankhorst, E. Frajka-Williams, U. Send, S. A. Cunningham, R. Bingham, J. Karstensen, and C. W. Hughes: Meridional coherence and divergence of the Atlantic Meridional Overturning Circulation (AMOC). Conference Proceedings. 2012 US AMOC PI Meeting, Boulder, CO. Sponsored by U.S. CLIVAR Project Office.
  • Elipot, S., E. Frajka-Williams, C. Hughes, S. Olhede, M. Lankhorst: Basin-wide response of the North Atlantic Meridional Overturning Circulation to wind stress forcing. Conference Proceedings. European Geosciences Union. 2012 EGU General Assembly, Vienna, Austria.
  • Kanzow, T., M. Lankhorst, E. Frajka-Williams, U. Send, S. A. Cunningham, R. Bingham, J. Karstensen, and C. W. Hughes: Meridional coherence and divergence of the Atlantic Meridional Overturning Circulation (AMOC). Conference Proceedings. European Geosciences Union. 2012 EGU General Assembly, Vienna, Austria.
  • M. O. Baringer, S. A. Cunningham, C. S. Meinen, S. Garzoli, J. Willis, M. Lankhorst, A. Macdonald, U. Send, W. R. Hobbs, E. Frajka-Williams, T. O. Kanzow, D. Rayner, W. E. Johns, and J. Marotzke: Meridional overturning circulation observations in the subtropical North Atlantic [in "State of the Climate in 2011", chapter "Global Oceans"]. Bulletin of the American Meteorological Society, 93 (7), S78-S81.
  • M. Srokosz, M. Baringer, H. Bryden, S. Cunningham, T. Delworth, S. Lozier, J. Marotzke, and R. Sutton: Past, Present, and Future Changes in the Atlantic Meridional Overturning Circulation. Bulletin of the American Meteorological Society, vol. 93, Nov. 2012, pages 1663–1676. doi: 10.1175/BAMS-D-11-00151.1.
  • Colin Schultz: Moored instruments show decadal drop in AMOC strength. Eos Trans. AGU, Vol. 93, No. 8, 2012. doi: 10.1029/2012EO080013.
  • Nicola Jones: Atlantic current slowdown. Nature Climate Change, Vol. 2, Pages 22-23, 2012. doi: 10.1038/nclimate1362.
  • Uwe Send, Matthias Lankhorst, Torsten Kanzow: Observation of decadal change in the Atlantic Meridional Overturning Circulation using 10 years of continuous transport data. Geophysical Research Letters, Vol. 38, L24606, 2011. doi: 10.1029/2011GL049801.
  • H.-H. Gennerich, H. Villinger: Deciphering the ocean bottom pressure variation in the Logatchev hydrothermal field at the eastern flank of the Mid-Atlantic Ridge. Geochemistry Geophysics Geosystems, Vol. 12, Q0AE03, 2011. doi: 10.1029/2010GC003441.
  • Matthias Lankhorst, David Fratantoni, Michel Ollitrault, Philip Richardson, Uwe Send, Walter Zenk: The Mid-Depth Circulation of the Northwestern Tropical Atlantic Observed by Floats. Deep-Sea Research Part I, Vol. 56, No. 10, 2009. Pages 1615-1632. doi: 10.1016/j.dsr.2009.06.002.
  • T. Kanzow, U. Send, M. McCartney: On the variability of the deep meridional transports in the tropical North Atlantic. Deep-Sea Research Part I, Vol. 55, Issue 12, Dec. 2008, Pages 1601-1623. doi: 10.1016/j.dsr.2008.07.011.
  • Matthias Lankhorst: Analyses of the Circulation in Intermediate and Shallow Water Masses of the North Atlantic with Lagrangian and Profiling Methods. Dissertation, Christian-Albrechts-Universität, Kiel, Germany, 2007.
  • Michel Ollitrault, Matthias Lankhorst, David Fratantoni, Philip Richardson, Walter Zenk: Zonal intermediate currents in the equatorial Atlantic Ocean. Geophysical Research Letters, vol. 33, L05605, 2006. doi: 10.1029/2005GL025368.
  • Torsten Kanzow, Uwe Send, Walter Zenk, Alan D. Chave, Monika Rhein: Monitoring the integrated deep meridional flow in the tropical North Atlantic: Long-term performance of a geostrophic array. Deep Sea Research Part I: Oceanographic Research Papers, Volume 53, Issue 3, March 2006, Pages 528-546. doi: 10.1016/j.dsr.2005.12.007.
  • Martin Scharffenberg: Analyse hochaufgelöster Zeitserien der Wassermassenvariabilität im tropischen Nord-West-Atlantik. Diplomarbeit (German diploma thesis). Christian-Albrechts-Universität, Kiel, Germany, 2005.
  • Torsten Kanzow, Frank Flechtner, Alan Chave, Roland Schmidt, Peter Schwintzer, Uwe Send: Seasonal variation of ocean bottom pressure derived from Gravity Recovery and Climate Experiment (GRACE): Local validation and global patterns. Journal of Geophysical Research, Vol. 110, C09001, 2005. doi: 10.1029/2004JC002772.
  • Hauke Schmidt: Anwendung von Satellitenaltimetrie zur Verbesserung von integralen in situ Transportmessungen. Diplomarbeit (German diploma thesis). Christian-Albrechts-Universität, Kiel, Germany, 2004.
  • Torsten Kanzow: Monitoring the Integrated Deep Meridional Flow in the Tropical North Atlantic. Dissertation, Christian-Albrechts-Universität, Kiel, Germany, 2004.
  • Matthias Lankhorst: Klassifizierung charakteristischer Eigenschaften von Float-Trajektorien in unterschiedlichen dynamischen Regionen. Diplomarbeit (German diploma thesis). Christian-Albrechts-Universität, Kiel, Germany, 2003.
  • Uwe Send, Torsten Kanzow, Walter Zenk, Monika Rhein: Monitoring the Atlantic Meridional Overturning Circulation at 16°N. CLIVAR Exchanges, Vol. 7, No. 3/4, September 2002, Pages 31-33.

Published Datasets

    Note: MOVE is part of the international OceanSITES program. Complete, quality-controlled, processed data sets are made available via the OceanSITES Global Data Assembly Center public THREDDS catalog [see 'MOVE' directories].

  • Lankhorst, Matthias; Bigorre, Sebastien; Send, Uwe (2023): Water temperature, salinity, and oxygen data from CTD and water sampling taken from NOAA Ship Ronald H. Brown, cruise RB-22-04, in the Northwestern Tropical Atlantic from 2022-10-09 to 2022-10-24 (NCEI Accession 0276368). NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/1m7m-kn39.
  • Kanzow, Torsten; Carrilho Bilo, Tiago; Lankhorst, Matthias; and Mauritzen, Cecilie (2023): Guyana Abyssal Gyre Experiment (GAGE) current meter mooring ocean velocity records obtained between February 2000 and April 2002 at 16°N. University of Miami Libraries. Dataset. doi: 10.17604/5jd9-7f77.
  • Lankhorst, Matthias; Send, Uwe (2021): Water temperature, salinity, and oxygen data taken by CTD and water sampling from the NOAA research vessel Ronald H. Brown, cruise RB-20-07, in the Northwestern Tropical Atlantic from 2020-12-04 to 2020-12-10 (NCEI Accession 0228396). NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/3y1g-c542.
  • Lankhorst, Matthias; Plueddemann, Al; Send, Uwe (2021): Water temperature, salinity, and oxygen taken by CTD and water sampling from the NOAA Ship Ronald H. Brown, cruise RB-20-06, in the Northwestern Tropical Atlantic from 2020-10-11 to 2020-10-25 (NCEI Accession 0229563). NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/dvya-by96.
  • Lankhorst, Matthias; Zenk, Walter (2019): RAFOS Float Trajectories from the MOVE Project in the Tropical Atlantic in 2000 and 2001. PANGAEA, doi: 10.1594/PANGAEA.897147.
  • Lankhorst, Matthias; Send, Uwe; Bigorre, Sebastien (2019): Water temperature, salinity, and other data from CTD and water sampling taken from the research vessel Pisces, cruise PC-18-03, in the Northwestern Tropical Atlantic from 2018-06-03 to 2018-06-16 (NCEI Accession 0183583). Version 1.1. NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/7qe1-mn83.
  • Lankhorst, Matthias; Send, Uwe; Bigorre, Sebastien (2018): Water temperature, salinity, and other data from CTD and water sampling taken from the research vessel Endeavor, cruise EN573, in the Northwestern Tropical Atlantic from 2016-01-26 to 2016-02-11 (NCEI Accession 0174795). Version 1.1. NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/s041-ht47.
  • Lankhorst, Matthias; Send, Uwe; Plueddemann, Albert (2018): Water temperature, salinity, and other data from CTD and water sampling taken from the research vessel Ronald H. Brown, cruise RB1009, in the Northwestern Tropical Atlantic from 2010-11-29 to 2010-12-16 (NCEI Accession 0174724). Version 1.1. NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/X9DC-5G86.
  • Lankhorst, Matthias; Send, Uwe; Plueddemann, Albert (2018): Water temperature, salinity, and other data from CTD and water sampling taken from the research vessel Ronald H. Brown, cruise RB0903, in the Northwestern Tropical Atlantic from 2009-06-19 to 2009-07-01 (NCEI Accession 0174710). Version 1.1. NOAA National Centers for Environmental Information. Dataset. doi: 10.25921/FXDB-1818.
  • Lankhorst, Matthias; Send, Uwe; Plueddemann, Albert (2017): Water temperature, salinity, and other data from CTD and water sample data taken from research vessel Oceanus, cruise 449/1, in the Northwestern Tropical Atlantic, from 2008-07-18 to 2008-07-28 (NCEI Accession 0167644). Version 1.1. NOAA National Centers for Environmental Information. Dataset. doi: 10.7289/V5W0945G.

Acknowledgements

This project is made possible with funding from the NOAA Climate Program Office. Initial funding came from the German Bundesministerium fuer Bildung und Forschung.
Data disclaimer: All data shown here come without warranty, express or implied. Use at your own risk, with appropriate caution.
Last Modified: 2024-04-22

Data/Website inquiries: jsevadjian@ucsd.edu