ESS228
Prof. Jin-Yi Yu
Rossby Radius and the Equilibrium State
•For large scales (KHa « 1), the potential vorticity perturbation is mainly
associated with perturbations
in the mass field, and that the energy changes are in the potential and
internal forms.
•For small scales (KHa » 1) potential vorticity perturbations are associated
with the velocity field, and
the energy perturbation is mainly kinetic.
•At large scales (KH-1 » a; or KHa « 1), it is the mass field that is determined by the
initial potential vorticity,
and the velocity field is merely that which is in geostrophic equilibrium with the mass field. It is said, therefore, that the
large-scale velocity field adjusts to be in equilibrium with the large scale mass field.
•At small scales (KH-1 « a) it is the velocity field that is determined by the initial potential vorticity, and the mass field is merely that which is in
geostrophic equilibrium with the velocity
field. In this case it can be said that the mass field adjusts to be in
equilibrium with the velocity
field.
Mass
and Velocity
Energy
Partition
water number
deformation radius
