A discussion for GPS atmospheric refraction delay observational models

Abstract：Aim at the requirement of GPS on correction precision of neutral atmospheric refraction delay, the paper expatiated the necessity that the refraction delay correction value should be different with the station and azimuth.In the instance of astronomic atmospheric refraction value can't be directly determined, we point out that the current correction models depend on atmosphere distributing model, can't arrive at the prospective precision and reduce cut-off angle in observation.The paper gave a new method for advancing the correction precision of refraction delay.It's principle is: using the actual surveying datum of astronomical atmospheric refraction value which is from zenith to lower elevation angles along certain the azimuth in the station, and then, make certain the refractivity and parameters in the mapping function.In this way, correction model of atmospheric refraction delay can be constituted, which is different with the station and azimuth.In circumstances of non-adopting any atmospheric distributing model, the method may improve observational precision of lower elevation angles to centimeter's magnitude, zenith delay's precision to 1mm, and reduce cut-off angle to 5 degree or less.

Keyword：neutral atmosphere;refraction delay;observational model;