Estimates of diurnal tidal volume transports through the Yucatan Channel

Abstract

A bottom-anchored, taut-wire mooring system, employing Richardson-type current meters, was used to obtain for 12.5 days from 6 June to 19 June 1969 direct current measurements at two depth-levels (72 m and 392 m) in the Yucatan Channel at a location of 21°33' north latitude and 85° 44.9' west longitude. Spectral analyses of the time series of current measurements indicated major energy peaks near the diurnal and semidiurnal tidal frequencies. The observations were analyzed harmonically by a least-squares procedure for the principal diurnal (K� and O�) and principal semidiurnal (M₂ and S₂) tidal currents. Results of statistical analyses indicated that only the harmonic coefficients for the diurnal tidal currents were statistically significant. The tidal currents during the period of observation accounted for approximately 35 percent of the total variance of the observed currents. The diurnally dominated tidal modulation of the observed currents was in agreement with astronomical conditions during the period of observation. The effects of mooring motion at tidal frequencies on the estimated harmonic coefficients for the diurnal tidal currents were rationally approximated by considering a quasi-linear model of the mooring response to small tidal perturbations of the horizontal velocity regime. Distortions in the amplitudes were found to be negligible with only slight distortions in the phases (a maximum of 17 degrees, for K�). ...