Natural Science Forum / Earth Science / Oceanography / April 2007

I have a set of harmonics, amplitudes and phases, for local tide prediction.
I was going to have a go at constructing the formula
h(t) = H0 + sum( H(i) * cos( w(i) * t + phase (i)))
in a maths application with the angular velocities
28.984 ,30.000 ,28.440, 15.041, 13.943 degree/hour etc
But how to sysnchronise the virtual generator with real world tides ?
Run the formula for "5 years" say and find the highest high, lowest low,
lowest high, highest low, rare event like a double low and match to such
single events in the real world , or how ?
Is there a set of more precise numbers for the above angular velocities, I
can only find that set of precision on the web.
Over the months comparing the 2 local on-line, near real-time tide plots
http://www.pol.ac.uk/ntslf/pltdata_tgi_ntslf_v2.php?code=Bournemouth&span=1
and
http://www.pol.ac.uk/ntslf/pltdata_tgi_ntslf_v2.php?code=Portsmouth&span=1
the Bournemouth one , around springs, always deviates strongly from the
predicted, in shape rather than just barometric or storm effects. Is that
likely due to extensive sea defense works around the Bournemouth area and
marine gravel dredging a bit farther away, having disturbed the harmonics ?