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| The original machine made by lord Kelvin |
The functioning of Kelvin's tide predicting mechanism, and the way in which the various constituents contribute to the tide, are illustrated in this JAVA applet contributed by Bill Casselman of the University of British Columbia. In the simulated mechanism seven constituents are summed: M2, S2, N2, K1, O1, P1 and K2. The initial phases are all set to zero (upper pulleys) or 180o (lower). The amplitudes can be selected from the pull-down menu to match those from one of seven ports.
(c) American Mathematical Society
Click to activate. Horizontal lines on the graph are spaced 1 foot apart. The vertical bars mark off 24-hour days.
In this simulation the constituents all start out in phase; the typical aspect of the tidal record for the port does not appear until after a simulated week or two.
The following constituent amplitudes were used in the simulation:
M2 S2 N2 K1 O1 P1 K2
Matarani, Peru 0.995 0.274 0.225 0.514 0.279 0.167 0.101 ft
Recife, Brazil 76.2 27.5 5.3 4.3 5.0 1.4 8.1 cm
Yamato Wan, Kuril Islands 0.59 0.23 0.11 0.95 0.79 0.31 0.06 ft
New York NY 2.104 0.437 0.469 0.321 0.170 0.104 0.127 ft
Otomari, Sakhalin Island 0.656 0.312 0.102 0.719 0.715 0.240 0.095 ft
Cordova, Alaska 4.712 1.599 0.957 1.615 1.001 0.530 0.463 ft
Ras at Tannura, Saudi Arabia 1.951 0.651 0.416 0.471 0.380 0.142 0.231 ft
Fakfak, Indonesia 0.54 0.17 0.10 0.31 0.19 0.10 0.46 m
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The constituent amplitudes for Recife are courtesy of the Banco Nacional de Datos Oceanográficos, Diretoria de Hidrografia e Navigação, Marinha do Brasil. Other amplitudes courtesy of the National Ocean Service, thanks to Tom Kendricks.