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David Hoyte asked:

>         On the matter of complex cycles in tidal movements: I was
> at one time involved with computer programs to identify cyclic
> interactive processes, such as a cement kiln. The program gave the
> plot of amplitude-vs.-frequency for each variable in the process:
> cause and effect could be identified by their similar frequencies.
>
>         Programs of this type were in an advanced state of develpment
> by Prof. Ashikaga at University of Tokyo, in 1985.
>
>         Tidal movements in the ocean were commonly used as a test for
> these programs: Are these same programs now used as the primary
> method for the analysis of tides, do you know?

I do not know what methods are now used to extract the parameters of the
various sine-wave tidal constituents from tide-gauge records. I assume
that hydrographer's use statistical analysis software of some kind but I
cannot confirm that, let alone say what software is used.

It shouldn't be a very demanding process. The frequency of each
constituent is known so it is just a matter of getting the best fit to
the data by adjusting amplitudes and phase angles. The only real problem
is that you should use 18+ years of data, with heights of tide measured
at frequent (hourly?) intervals through that time, which makes for a
fair amount of data. That was a mind-numbing process before modern
computer capabilities but might only be a few minutes work with a
desk-top machine.


Trevor Kenchington


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Trevor J. Kenchington PhD                         Gadus@iStar.ca
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