Task Team 2: AMOC State, Variability, and Change

The team is charged with assessing the current state and past variability of the AMOC using existing observations, data assimilation models, and proxy data. 

View TT2 Near- and Long-Term Priorities


US AMOC Task Team 2 Members
Zoltan Szuts, chair University of Washington
Claudia Schmid, vice-chair NOAA Atlantic Oceanographic and Meteorological Laboratory
Molly Baringer NOAA Atlantic Oceanographic and Meteorological Laboratory
Amy Bower Woods Hole Oceanographic Institution
James Carton University of Maryland
Timothy DelSole George Mason University
Gustavo Goni NOAA Atlantic Oceanographic and Meteorological Laboratory
James Holte Scripps Institution of Oceanography
Alicia Karspeck National Center for Atmospheric Research
Kathryn Kelly University of Washington
Matthias Lankhorst Scripps Institution of Oceanography
Susan Lozier Duke University
Sudip Majumder NOAA Atlantic Oceanographic and Meteorological Laboratory
Renellys Perez University of Miami/NOAA Atlantic Oceanographic and Meteorological Laboratory
Peter Rhines University of Washington
Irina Rypina Woods Hole Oceanographic Institution
Fiamma Straneo Woods Hole Oceanographic Institution
Luanne Thompson University of Washington
Xiao-Hai Yan University of Delaware
Rong Zhang NOAA Geophysical Fluid Dynamics Laboratory


Near-term priorities

Discussions have identified thematically organized questions on which immediate progress can be made based on lack of consensus between different approaches.

AMOC Characteristics

  • Depth extent of AMOC cells
  • Level of high-frequency variability
  • Dominant timescales of variability
  • Long-term trends of overturning strength 

Coherence between gyres

  • Role of planetary waves varies between models in terms of patterns, timing, and forcing
  • Balance between high-latitude wind versus buoyancy forcing (observations or models)
  • Subtropical/Southern ocean connectivity, including geostrophic reference level
  • Nature of coherence in the upper AMOC branch, as related to observational coverage (well-resolved temperature and upper ocean circulation versus poorly sampled salinity and deep ocean)
  • Impact of eddies and indirect (and unknown) water parcel pathways, and their resulting transfer between gyres.
  • Relation between Eulerian and Lagrangian perspectives of coherence

 Methodological improvements for comparison and synthesis

  • Consistent metrics to compare models and observations, including observational methods and assumptions, and whether calculated in depth or density space
  • Quantifying uncertainty in data products
  • More explicit synthesis of Eulerian and Lagrangian descriptions of overturning, especially as influencing advective fluxes of climatically relevant quantities (heat, freshwater, carbon, etc.)

Long-term priorities

  • Use new and existing observations in combination with modeling experiments to refine our understanding of the present and historical circulation (and related transports of heat and freshwater as well as flow pathways) in the North and South Atlantic.
  • Observational studies should focus on mechanisms and pathways that identify and explain coherent and incoherent signals between different study sites, thereby reaching consensus on which signals represent the large-scale AMOC versus more localized circulation patterns.
  • Synthesize modeling and observational evidence to build scientific consensus on the variability and change of the AMOC over the last 50 years, using and defining observable proxies as appropriate.
  • Efforts within the data assimilation community should focus on reaching a consensus on the evolution of the AMOC over the last 50 years, consistent with other lines of observational evidence.