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Articles

1979: Vol. LVI, No. 2

Some Comparisons of Response and Harmonic Tide Predictions

Submitted
August 7, 2015
Published
2015-07-10

Abstract

Empirical tests compared response and harmonic tide predictions for Atlantic City and Pensacola (semidiurnal and diurnal tidal regimes respectively). Three years of hourly heights were analyzed by both methods in the frequency range of one to six cycles per day. The results were used to predict another three-year period, the predictions were subtracted from the observations, and energy calculations were made for the frequency bands in each of the six tidal species. Once more, response methods were somewhat better, but the differences are small compared to the total (unpredictable) continuum. The study disclosed: (1) the need to include third-order nonlinear interactions of diurnal tides in response predictions for some stations, (2) the need for National Ocean Survey to examine carefully its rejection limit in analyzed amplitudes of 0.03 foot and a practice of inferring T2 regardless of its amplitude, and (3) the need to examine an annual modulation of M2 presumably due to some local seasonal effect.