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Re: "Earth Tides"

On Wed, 8 Apr 1998 16:03:15 -0700 Leigh Palmer said:

I get a dr of about 3 cm corresponding to a - 0.01 mgal change in
the gravitational field. Is the calculation more complicated than
just looking at the change with altitude above a sphere?

Yes, it is more complicated, because the tidal distortion does not lift you
off the sphere. It lifts the nearby mass up with you so you have to go up
higher to get the reduction. The only reasonable way I know to do this
is to imagine slipping in an extra layer of crustal rocks. So the bulk of
the correction comes from the fact that crustal rocks are less dense than
interior rocks. This is the standard way to do corrections for surface
topography and was developed by a man named Bougier (probably not spelled
right) and is known as a Bougier correction.