A practicable method of correction for atmospheric refraction in precise EDM trigonometric leveling

Atmospheric refraction is the main factor to affect the precision of the precise EDM trigonometric leveling.Its influence must be reduced by means of adding a correction to the observational result according to the refraction coefficient.This paper introduces a practicable method of calculating atmospheric refraction coefficient-synthesis inversion method.Making use of the results of the direct and reversed EDM trigonometric leveling directly,we can inverse calculate the refraction coefficients which are corresponding to direct and reversed observation.