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
| Member name | Institution |
|---|---|
| Zoltan Szuts, chair | University of Washington |
| Claudia Schmid, vice-chair | NOAA Atlantic Oceanographic and Meteorological Laboratory |
| Santha Akella | NASA Goddard |
| 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 |
| Eric Hackert | NASA Goddard |
| James Holte | Scripps Institution of Oceanography |
| Alicia Karspeck | National Center for Atmospheric Research |
| Kathryn Kelly | University of Washington |
| Marion Kersalé | University of Miami/NOAA Atlantic Oceanographic and Meteorological Laboratory |
| Matthias Lankhorst | Scripps Institution of Oceanography |
| Matthieu Le Hénaff | University of Miami/NOAA Atlantic Oceanographic and Meteorological Laboratory |
| 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.