TIDAL AND LOWER FREQUENCY CURRENTS ABOVE FIEBERLING-GUYOT

An intensive, yearlong deployment of current meter moorings was made over and around Fieberling Guyot (32.5 degrees N, 127.75 degrees W) in the North Pacific. The measurements are used to investigate tidal currents, the mean flow, and subinertial current fluctuations. The K-1 and O-1 diurnal tides were greatly amplified over the seamount, apparently through dynamics resembling nonlinear seamount-trapped waves. The diurnal tides interacted nonlinearly to induce constituents at the sum frequency (M(2)) and difference frequency (fortnightly) above the summit. Diurnal amplification was strongest at about 450 m, and it extended from the seamount center out over the flanks. The S-2 semidiurnal tide was not substantially amplified over the seamount. The mean flow was primarily along isobaths and was strongest about 50 m above the seamount rim. It was driven by tidal rectification, so that mean along-isobath velocity at a given location correlated well with the amplitude of the local fortnightly tide at that location. Accompanying the mean flow was a ''cold dome'' over the seamount that was presumably maintained by a balance of mean downward advection and eddy (tidal) radial heat transport. Lower frequency current fluctuations were enhanced near the seamount and were apparently driven by fluctuations in the ambient flow.