The deep open ocean exhibits energetic space-time variability phenomena that are the counterpart of atmospheric weather systems. The internal weather of the sea occurs on the scale of the internal deformation radius (depth times the ratio of buoyancy to Coriolis frequencies), with features called “mesoscale” fronts and eddies, although the dynamical analogy is with the atmospheric synoptic scale [Charney and Flierl, 1980; Robinson, 1983]. Space scales range from tens to hundreds of kilometers and time scales from days to months; features extend from surface to bottom intensified in the upper ocean main thermocline.
Mesoscale effects include the intermittent energization of regions; the shifting of currents; the location of air-sea interaction events; the transport, entrapment and dispersion of such things as heat, chemicals, nutrients, larvae, and pollutants; and the alteration of sound propagation. Forecasting the internal weather of the sea is important scientifically and practically and is now feasible [Mooers et al, 1987; Robinson, 1987] due to rapid, recent advances in physical oceanography and related technologies, especially satellites and computers. We have established a forecast system for the Gulf Stream Meander and Ring (GSM&R) region, called GULFCAST, that provides predictions one week ahead in real time and on an ongoing basis.