Tide Lagging and Priming

 What is the relationship between transits of the moon and the timing of the associated high tides on Maui?

Here is a plot for 2023:


Shown above are the tide lags for both upper transits (blue) and lower transits (hollow red).

Positive lags mean high tide trails the transit.  We might think of this as the "normal" result, since the ocean system shouldn't be expected to respond to the moon's movements instantaneously.  A negative lag means the transit actually occurred after the high tide.  

Positive lags predominate, as you can see.  The typical lag range is about 4 hours, with the mean lag for the year being about 2 hours.  

Here is a closer look:


As you can see, lags tend to decrease around the times of full and new moons.  This is called "priming".  For an simple example of priming see the Professor Tony Phillips example in the Reference blog.  


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