
Ocean gyres
-----------


Baroclinic instability is a ubiquitous process in the ocean, as well as the
atmosphere. Ocean eddies play an important role in modifying the
hydrographic structure and current systems of the oceans. Coarse resolution
models of the oceans cannot resolve the eddy field and yield rather broad,
diffusive patterns of ocean currents. But if the resolution of our models is
increased until the baroclinic instability process is resolved, numerical
solutions of a different and much more realistic kind, can be obtained.

:numref:`ocean-gyres` shows the surface temperature and
velocity field obtained from MITgcm run at :math:`\frac{1}{6}^{\circ}`
horizontal resolution on a *lat-lon* grid in which the pole has
been rotated by 90° on to the equator (to avoid the
converging of meridian in northern latitudes). 21 vertical levels are
used in the vertical with a ‘lopped cell’ representation of
topography. The development and propagation of anomalously warm and
cold eddies can be clearly seen in the Gulf Stream region. The
transport of warm water northward by the mean flow of the Gulf Stream
is also clearly visible.

  .. figure:: figs/atl6.png
    :width: 100%
    :align: center
    :alt: ocean-gyres
    :name: ocean-gyres

    Instantaneous temperature map from a :math:`\frac{1}{6}^{\circ}` simulation of the North Atlantic. The figure shows the temperature in the second layer (37.5 m deep).
