Re: Bulges

[John Mallinckrodt <ajmallinckro@CSUPomona.Edu>]

On Thu, 6 Mar 1997, David Bowman wrote:

> When I said that Jim didn't see the lunar tidal bulge signal in the time
> series  data that he had amassed for various continental shorelines I meant
> that he doesn't see the bulge signal in the times series *itself* in the time
> domain.  The reason that I suggested using ocean height data from a mid-ocean
> location was that then the bulge signal would not be such a tiny part of the
> overall motion and that the bulge signal would show up more clearly.
> ...

I understand what you are saying and I agree with you for the most part. 
It's only your implication that one needs to do some kind of fancy signal
analysis and even, perhaps, take a trip to Hawaii (not a bad idea, though) 
to ferret out a supposedly weak "bulge signal" from the noise that I take
exception to. 

Quite the contrary, I think you'll find that the overwhelmingly dominant
signature in the time signal at virtually *any* location on earth that has
tides is that of the moon's drive frequency beating against that of the
sun.  In every tide table I've ever looked at this signature is
immediately obvious.  Yes, there are phase shifts (in the Puget Sound the
tides are almost exactly *out* of phase with those in the Pacific just the
other side of the Olympic Penninsula) and harmonic distortions that cause
typical waveforms to vary markedly from place to place, but the average
time between successive high or low tides taken over any reasonable period
is about 12h 25min (half the apparent lunar period) and the tides go
through obvious cycles of varying heights about every 29 days, a very
clear signature of beating with the sun's drive frequency. 

John
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