Re: Tide article

[Jim Green <JMGreen@SISNA.COM>]

> Our tide clock was purchased in Los Angeles; it was not made "for"
> any particular location. Indeed, as I pointed out, the hand
> completes two cycles each "mean lunar day" which is not a function
> of location. Also as I mentioned, the clock keeps excellent *long
> term* track of the tides. To expand on what I said before, there
> are seasonal as well as biweekly variations that drive the tidal
> extremes temporarily away from the specific times predicted by the
> clock. But if the clock is, for instance, set to properly predict
> spring tides in July, it will be found to properly predict spring
> tides *every* July for years on end (as long as the timing
> mechanism functions properly and the batteries don't die.)

John, I will not "debate" you re this -- I have stated my understanding
from study and research -- well my student's research -- down the road from
John Denker.   The list -- as Sam Donaldson says -- can take it for what
they think it is worth.  I  think  that no one gives much of a damn about
this anyway.

NOAA gave us their raw strip chart recordings of the tidal data at the
Atlantic City Pier. (Come to think about  it, I think that I may still have
the rolls,  if anyone wants them. They were recorded by people at the
nearby FAA Tech Center (Fat City -- my how they hate that) ie Atlantic City
Airport).   We purchased  further data from NOAA (not necessary any longer
-- it is on the web for many many locations world wide)  The students
derived an equation for the vertical force v time at those locations (I
think -- maybe it was the potential) due to the Sun and Moon.  And plotted
both the tide and the force jointly on one strip chart.   (Some of the
details are now foggy as this was >ten yr ago)

Both our results and NOAA's calculations showed no correlation  of high
water  or Spring Tide to anything: Moon or Sun position, Moon or Sun
period, etc etc.  for any location (except for amphidromic points)

The cobbled force equation included contributions from the following:

     M2......12.42hr..Principal Lunar --  The period used by the NewZeland
site
     S2.......12.00.....Principal Solar..........
     N2.......12.66.....Lunar Elliptic...........
     K2........11.97....Luni-Solar Semi-Diurnal..
     K1........23.93....Luni-Solar Diurnal.......
     O1........25.82....Principal Lunar Diurnal -- I assume = John's Mean
Lunar Day
     P1.........24.07....Principal Solar Diurnal..
The above together with even the 19 yr Moon cycle -- mostly because the
students got carried away by the idea of accuracy

Now the variation John observes within one month or season is expected and
may just  be due to the variation of the period of the total force due to
the combination of the several periods of the Sun and the several periods
of the Moon.  If the claim is that the period between successive high
waters  is constant over  infinity, Puget Sound would seem to be a very
special place.  I did hear that someone sighted a sea  "thing" with a very
long neck  there.  (Come to think about it, it is conceivable that the
Sound resonates at one of the myriad of driving frequencies --Humm -- but
then  the tides there would be very high -- I donno)  But, if the 19yr
cycle is considered, I  would be very surprised if even the sea thing could
keep his  tide clock accurate over THIS time period even  with Eveready
Batteries.

Jim


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen