> Dear GMT users,
> I am looking for more information about the grdfft -T option.
> 1) How does it decide where to use the water and infill densities?
From grdfft.c:
They get used in differences. infill (ri) water (rw) load (rl) mantle (rm)
rigidity_d = (youngs_modulus *te*te*te)/(12.0*
(1.0 - poissons_ratio*poissons_ratio))
d_over_restoring_force = rigidity_d/((rm -ri)*normal_gravity)
airy_ratio = -(rl -rw)/(rm -ri)
> 2) The example in the Reference manual pages uses -C4000. Does this mean 4km
> beneath the surface? This seems like an odd exercise, does anyone know a
> reason for this?
-C Upward (for zlevel > 0) or downward (for zlevel < 0)
continue the field zlevel meters.
The -C option is for upward or downard continuation of the field. -C4000
upward continues the field 4000 meters, which is about the depth of the ocean
in the example - so the output field should be as if it was at the surface of
the ocean.
> 3) How does it compare to other programs such as AIRYROOT?
No idea. Don't have "airyroot".
> 4) Any suggestions for references that explain this a bit further?
Geodynamics: Applications of continuum physics to geological problems
by Turcotte & Schubert, 1982, John Wiley, New York
(textbook for course in tectonophysics that I took a few years ago)
Ben Horner-Johnson
ben@earth.nwu.edu