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Re: New Moon, Perigee, and Solstice
From: Trevor Kenchington
Date: 2003 Dec 30, 02:07 +0000
From: Trevor Kenchington
Date: 2003 Dec 30, 02:07 +0000
Rodney,
Of course the frequency of tidal waves is not affected by basin
morphology (except where shallow-water effects produce assorted
harmonics in addition to the tide at the frequency of the driving
force). However, it is not only amplitude that is affected by real
basins and would be by the seabed in a theoretical, global ocean of
uniform depth. The phase angles are strongly affected also but, perhaps
more important, so is the nature of the wave. In most areas, tides
predominantly take the form of standing waves and very commonly Kelvin
waves (thus forming amphidromic systems), rather than progressive waves
heading in a westerly direction around the globe.
That is true in the real Southern Ocean (which is open clear around all
360 degrees of longitude, with a relatively constant depth) as it is in
the open expanses of the real Pacific Ocean. As best as I can comprehend
the conclusions of tidal specialists, it would also be true of the
hypothetical global ocean too.
Trevor Kenchington
You wrote:
> The depth would certainly have an effect on surface waves as you say,
> but it would affect the amplitude, not the frequency. The solution
> would still be at the frequency of the driving force in the steady
> state.
>
> That is the actual case now, with all the extra complications. It would
> not be less so if the complications were removed.
--
Trevor J. Kenchington PhD Gadus@iStar.ca
Gadus Associates, Office(902) 889-9250
R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251
Nova Scotia B0J 2L0, CANADA Home (902) 889-3555
Science Serving the Fisheries
http://home.istar.ca/~gadus
