Diurnal-period currents trapped above Fieberling Guyot: observed characteristics and model comparisons

Current measurements at depths of 19, 115, 264 and 464 m above the summit of Fieberling Guyot (32??28???N, 127??47???W) for 13 months in 1989 show that the diurnal tides are strongly amplified. The measured variances for K1, P1 and O1 at the 115 m depth were 810, 140 and 80 times larger than the variances of the respective estimated barotropic tides. The diurnal currents closer to the summit were also strongly amplified, through the variance ratios were 40-50% of the ratios observed at 115 m. The diurnal band currents were only amplified at the precise tidal frequencies; the bandwidth of the response was less than 0.0002 cph. The discrete character of the response suggests that only currents with large spatial scales will be amplified. The characteristics of the amplified diurnal currents are compared to those predicted by a model for Fieberling Guyot of seamount-trapped waves driven by the barotropic tide. The amplitudes of the responses at this one site on the seamount compare favourably to the predicted. ?? 1994.