Coupled patterns between fields of dynamic height and bottom pressure in the Japan/East Sea

Vertical coupling between shallow and deep mesoscale eddy processes in the southwestern Japan/East Sea is investigated using acoustic travel-time and bottom pressure measurements from a two-year deployment of an array of pressure-gauge-equipped inverted echo sounders. Canonical correlation analysis is applied to the simultaneously measured data to extract the coupled modes. The upper layer exhibits a migration of the Ulleung Warm Eddy, and correspondingly the deep potential vorticity in the Ulleung Basin adjusts in magnitude and sense to conserve potential vorticity. Coupling between meanders of strong upper currents and abyssal flows has been observed previously in the Gulf Stream during the Synoptic Ocean Prediction experiment. The evidence from our study strongly suggests that such coupling occurs also under much weaker flows.