ON THERMALLY FORCED DEEP EQUATORIAL CIRCULATION IN A GCM

The thermohaline spinup of an equatorial ocean primitive equation GCM is investigated with a series of high-resolution numerical experiments . The author finds that a general problem of this class of models is u nrealistically weak deep stratification combined with an unphysical pa rameterization of diffusion using vertical and horizontal coefficients . Near the equator, this leads to a heat balance between vertical adve ction and meridional diffusion. This balance, in turn, permits alterna ting zonal jets on the equator. The jets disappear when the deep strat ification is improved to the extent that horizontal diffusion no longe r dominates vertical diffusion: Therefore, the deep jet structures fou nd in this and earlier studies are artifacts that are not related to o bserved equatorial deep jets.