Induction in arbitrarily shaped oceans VI, oceans of variable depth

We present calculations of t he electric currents induced in a model ocean by the 24 hr Sq variation. The model has realistic bathymetry and represents a further step of a consistent approach to oceanic induction in which we have introduced various complexities in order of priority. The solution obtained is compared with our previously published results for the case of an ocean of realistic shape and uniform depth. It is found that the major shelf-seas considerably modify the pattern of elect ric current circu­ lation in the oceans of the southern hemisphere. The consistent nature of the method of matched outer and inner expansions which we have used is also discussed. It seems probable that other methods, not limited to finding an outer solution and consequently more complicated, will at best only produce an outer solution since, in practice, the relatively coarse mesh necessarily used in the computation of realistic global problems precludes a fine resolution of the coastal bathymetry. Finally , the meaning of the internal and external Legendre coefficients and their relationship to Sq over the oceans is briefly discussed.