At present there is no accepted explanation of this relationship. Indeed, there are question whether the observations reprsent basic characteristics of vent processes or simply reflect the influence of tidal currents on the measurement apparatus. 4.640 Mf lunar fortnightly 13.66 d 4.174 Tidal analysis involves interpreting long duration records to establish the phase and amplitude of these constituents at a particular location.
Harmonic analysis is used, i.e., constructing a least squares fit to waveforms of known frequency.
Figure 1 shows the tidal forcing due to the first four constitutents all with phase of zero. The matlab script, tidebuild.m illustrates the progressive contributions of the components starting with the dominant M2 tide. Tidal forcing from M2, K1, S2 and O1 tidal constituents. In order for sea lvel to change fluid must move from place to place giving rise to tidal currents. In a general sense, tidal currents are related to the first derivative of the tidal amplitude.