Time-periodic quasigeostrophic motion under dissipation and forcing

The quasigeostrophic equation is a prototypical geophysical fluid model. In this paper, we consider time-periodic motions of this model under dissipat ion and time-dependent wind forcing. We show that when the wind forcing is time-periodic and the spatial square-integral of the wind forcing is bounde d in time, the full nonlinear quasigeostrophic (QC) model has time-periodic motions, under some conditions on the beta parameter, Ekman number, viscos ity and the domain size. (C) 1999 Published by Elsevier Science Inc. All ri ghts reserved.