4. Recommendations
- Studies should define the AMOC in density coordinates because it is
more closely aligned with the AMOC’s climatic influence, and thus why
we care about the AMOC. There are also additional benefits like the
streamfunction is more continuous in density space, and that it
retains more information of the three-dimensional circulation
including correctly positioning the maximum AMOC in the subpolar North
Atlantic.
- Observational arrays at all latitudes (e.g., RAPID, OSNAP,
SAMOC) should produce AMOC values in density coordinates to provide
consistency between arrays (e.g., Fig. 2e). We acknowledge the added
degree of difficulty in measuring the AMOC in density coordinates at
these observational arrays – it requires knowledge of the full
density and velocity fields across the basin. To provide consistency
through time, there is a benefit to publishing both density space and
depth space AMOC values at the existing arrays.
- The modeling community (especially the CMIP community) should
establish the density space AMOC streamfunction as a standard output
variable from their models, as is currently true of the depth-space
AMOC streamfunction.
- Studies should remap the density-space AMOC into depth coordinates
(Fig. 2c, f) so that the streamfunction can be easily interpreted by
non-experts.
- Studies should identify the geographic region and time scale for any
AMOC metric. Comparing results that use different coordinate systems,
metrics, and data sources requires isolating differences between these
three variables. Being specific at which latitude the AMOC is
diagnosed, projected, and reconstructed is critical to clearly
explaining the driving mechanisms behind AMOC variability and change.
This point is also important when comparing proxies or model output to
available estimates.
- The maximum AMOC in depth coordinates is likely insufficient to
summarize AMOC variability, and could be very sensitive to the data
used. This is especially true for studies that highlight: (a) AMOC
dynamics, (b) the role of watermass transformation, (c) the importance
of the horizontal circulation, and/or (d) AMOC variability at higher
latitudes.