Determining the astronomical refraction and building the radio wave refractive delay model measured (I) - Observation principle and feasibility

The research history of the astronomical refraction and the cause of formation of the radio wave atmospheric refractive delay are reviewed,and the fact that there are differences in measured values of the refraction in different directions at different stations are described briefly.Based on the observation principle of measuring the angular refraction and modeling the local refraction, several major obstacles resulting in no direct measurement for the refraction since always are analyzed,necessary conditions now possessed to remove these obstacles are presented.These can ensure success in building the astronomical refraction model measured and the radio wave refractive delay corrective models varied with change in observing stations and observational directions.