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calc_geoid_corr

Called by:  correct_ttime for each phase.

Includes:   iscloc.h

External:   Array of deltas at which the correction is incremented delta_step[].

Input arguments:
Latitude of the current solution.
Pointer to a phase structure

Calls:   height_above_mean_sphere from this file.

Structure members updated:   None.

Return:   Travel time correction in seconds for height of geoid above mean sphere.

Corrects for the difference in distance travelled between a ray in a spherical Earth, as assumed by the tables, and in a more accurately shaped Earth.  Multiplies the height above the mean sphere of both the station and the source by an average velocity that depends on the distance between the two.  This velocity is stored at 10 delta intervals in the array delta_step[], declared at the top of this file.



height_above_mean_sphere

Called by:  calc_geoid_corr for station and source.

Input arguments: Latitude in radians.

Structure members updated:   None.

Return:   Height above mean sphere in km.