The Moon goes through a shorter declinational
cycle lasting 27.322 days.
More importantly, the relationship between the synodic and the declinational
cycle differs between the two locations: tides at Barbados are less influenced by the declinational
cycle, thus the tidal amplitude cycle (29.4 d) is in phase with the lunar cycle during much of the year, including the study period.
Analysis using simple multiples of astronomical cycles governing tides Perigean Spring Declinational
Period 7P = 192.88 13S = 191.95 14D = 191.25 solar days 0.53 years 60P = 1,653.27 1125 = 1,653.71 121D = 1,652.96 solar days 4.53 years 239P = 6,585.54 446S = 6,585.32 482D = 6,584.50 solar days 18.03 years Notes.
Luni solar semidiurnal constituent; it modulates amplitude and frequency of [M.sub.2] and [S.sub.2] for the declinational effect of the Moon and Sun, respectively.
Smaller lunar elliptic diurnal constituent; it helps to modulate the amplitude of the declinational [K.sub.1] for effect of the Moon's elliptical orbit.