Definitions for "Geostrophic"
Wind Horizontal wind in the upper atmosphere that moves parallel to isobars. Results from a balance between pressure gradient force and Coriolis force.
balance of pressure gradient and the Coriolis force. In the southern hemisphere, a northward geostrophically balanced current has sea level higher to the west. Similarly, an anti-clockwise eddy has elevated sea level in the centre. Slowly-varying (ie over several days) currents are invariably close to being geostrophic, so by measuring either the current velocity or the slope of sea level, the other can be calculated.
Referring to the balance, in the atmosphere, between the horizontal Coriolis forces and the horizontal pressure forces. See geostrophic wind, geostrophic equilibrium, geostrophic balance.