North Atlantic Ocean: Preliminary Description of Normal Modes

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Science  13 Oct 1972:
Vol. 178, Issue 4057, pp. 156-157
DOI: 10.1126/science.178.4057.156


The three lowest gravitational modes of free oscillation of the North Atlantic Ocean are estimated by numerical integration of Laplace's tidal equations. These modes have periods of approximately 21, 14, and 11 hours, and structures, respectively, of one, two, and three positive amphidromic systems. The phase distribution of the first mode resembles cotidal charts of the diurnal tide, and the period of the second mode is consistent with that inferred by Wunsch from tidal data in Bermuda and the Azores.