A Feasible Way for Improving the Correction Accuracy of Neutral Atmosphere Refraction Delay

Based on the light of the requirements of space geodesy for the correction accuracy of neutral atmospheric refraction delay,it is necessary to put that the refraction delay correction value should change with the station and azimuth.Under the condition that the astronomical atmospheric refractive value can't be directly determined yet,the reason why the available various correction models can not meet the anticipated require- ment of accuracy and reduce the cut-off height angle for the dependency of the correction values on the model of atmospheric distribution are pointed out.On the special structure of the Lower Latitude Meridian Circle and the practice of determining astronomical refraction in Yunnan observatory,a new method for improving the correction accuracy of the atmo- spheric refraction delay is proposed:the determined data of the astronomical atmospheric refraction values with different azimuths are utilized to find the refractivity and the param- eters of mapping functions for modeling the atmospheric refraction delay correction,which changes with the observing stations and azimuths.Under the condition that the adoption of the atmospheric distribution model is avoided the implementation of this new method will improve the correction accuracy of the zenith delay within 1mm,that of the refraction delay of centimeter's magnitude,at low altitude angle,and reduce the cut-off height angle by degree 5 or less.