The following slides are from a brief overview of Arctic Ocean Models Intercomparison Project (AOMIP)
prepared for the Arctic Ocean Science Board (AOSB) meeting at Kiruna, Sweden the 29-31 March 2003.
Encouraged by the AOSB Chair, the slides include speculative comments (outside AOMIP) concerning
possible dynamics of Arctic change.
To view, please scroll, then use your browser 'back' to end.
|The next slide shows seasonal variation of modeled transport across the Norway-Spitzbergen opening.|
|The next three slides are from Steiner et al., to appear in Ocean Modelling. The first shows streamfunction.|
|The next few slides compare modeled flows at 500m characterising Atlantic Layer circulation.|
What is striking is that even the gross sense of circulation is ambiguous despite effort (as nearly as possible) to
provide common forcing. What have we learned? Are some of the models (about half?) simply wrong? Or do the
diversity of model results suggest that actual mid- and deep-circulation is highly sensitive to applied forcing?
Here we digress to speculative comments. The suggestion is that ocean models generally are wrong because they
are based on classical mechanical ideas without influence from statistical physics. Another lecture (click for lecture)
on these pages elaborates. Below we only consider consequences. Using the IOS model within AOMIP protocols,
the left panel compares with other AOMIP models. Flow is broadly but weakly cyclonic. The right panel shows
the difference when only the eddy viscosity term is directed toward higher entropy rather than toward rest.
The statistical dynamical forcing resulting in the right panel (above) is suggested to better represent the mid-
and deep-Arctic flows even when external forcing tips more anticyclonic or cyclonic. We can use this to synthesize
pictures of the Arctic that don't depend upon computer models. Light blue arrows suggest circulation in and
above the halocline; red arrows indicating flow below the halocline. Flow in and above the halocline responds
to differences of wind forcing, the next two figures comparing anticyclonic and cyclonic forcing regimes. Note
the red arrows do not change.
It may be objected that, if the subhalocline circulation does not change, how have major changes in
sub-halocline water masses come about? The suggestion is that only subtle changes at a very limited
number of key locations (diffluences) alter water masses within a nearly unchanging circulation.