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gfdl's home page > people > John Dunne >
Notes from Dec 17
The primary goal of this sub-meeting was to update interested parties on the development of the coarse resolution ocean model in MOM4 for Biogeochemical and Earth System Modeling, called OM1p5, and to solicit suggestions for improving the simulation.
Development progress:
- 1) GM set to 600.
- 2) NCAR vs OMIP forcing experiments showed only problems with very
strong southern ocean winds in the NCAR dataset. No effect on NADW
formation was observed
- 3) Ross/Weddell seas - Added 75S - 78S row (now 120x65x28). This
gives a much more realistic description of these areas, particularly
in the representation of the shelves and Ross Sea polyna.
- 4) Roughened topography - increased Ridges/trough contrast by 300 m,
added Kerguelen, Chatham Rise, S. Orkney Isles. This had remarkably
little effect on results.
- 5) Working with th tip of South America in the effort to increase
ACC transport also had little effect. Shaving off the west cell
increase the transport by 0.9 Sv, while removing both cells increased
the transport by 1.1 Sv over the standard run. We decided to keep
the west-shave modification as it gives a velocity point over water.
- 6) Experiments with the ice configuration of: Turning angle (0
versus 25), shaving Greenland and removing Iceland all had little
effect on NADW formation. None of these modifications were adopted.
- 7) Higher salt restoring in GIN Seas was experimented with in
order to increase NADW formation. This had only a small effect.
- 8) There was some suggestion that it is the Pacific circulation
that is driving the stoppage of NADW circulation.
- 9) Comparison with OM1-Prince2 shows significant improvement in
North Pacific circulation, and while OM1 is too warm in the deep,
OM1p5 is too cold (due to the dominance of Southern Ocean ventilation).
Next Steps:
- 1) We are currently waiting for an NCAR climatology. As OM3-omip
has the same problem as OM1p5, and CM2 has the opposite problem of too
strong NADW, we believe that the forcing is the problem.
- 2) We are currently waiting for an NCAR climatology.
- 3) Gnanadesikan has promised to do some further parameterization experiments.
Dunne's full powerpoint presentation can be downloaded here