Comparison of two different methodologies for correcting refraction in vertical angles

The term atmospheric or geodetic refraction is the main factor that needed to be known in order to correct the vertical angles in high-precision geodetic applications. This term is found in the relevant surveying literature as mean to describe the alteration in the direction of the light curve as it propagates through the different layers of the lower part of the Earth’s atmosphere in the frame of standard surveying applications. So, what are the new things that the new article deals with? First substantial add is the analysis of the adjustment results of three more 3D geodetic networks with the TG method (totally, four 3D geodetic networks) in the TT1 tunnel at CERN as well as the comparisons of these results with the HLS measurements. However, the main task of this research work is the processing of the same geodetic data with the trigonometrical levelling network adjustment method (TLNA method) in order to detect and eliminate the effect of the refraction in the zenith angle measurements. A significant part of this research work after the result analysis is the comparison of the effectiveness of these two methods. Finally, after the analysis of the results of the two methodologies is proven that the TG method is more adequate than the TLNA method for such accurate measurements. With the TG method, the maximum difference between the nominal height differences of HLSystems and the calculated height differences after the 3D network adjustments with the corrected zenith angles is very promising and approaches the value of 50 μm.