Simple models for Atlantic diurnal tides

Gill's (1979,Proceedings of the Royal Society of London,A367, 549–571) narrow-canal Atlantic-Southern Ocean model fails for diurnal tides. Suggested modifications are flow through the open end of the Atlantic at 60°N, a Southern Ocean ‘broad’ for the coastal-trapped diurnal tide at high latitudes, and hence escape around South Africa of the southward-progressing component of the Atlantic tide (implying no resonances). Idealized models suggest that even the Drake Passage is ‘broad’. The large Southern Ocean tide progresses westwards along the Antarctic coast, almost as though South America were absent, but a small part is diffracted northwards. The Atlantic tides are small and therefore relatively sensitive to the diffracted wave, to the different K1 and O1 natural wave-numbers, and to earth-tide effects.