Analysis of methods for determining the refraction coefficient in the atmospheric surface layer

In the instructions for modern geodetic instruments, it is recommended to introduce an amendment for the refraction, taking into account the “standard” refraction coefficient k = 0,13÷0,2. In fact, in the surface layer of the atmosphere, the refractive index can range from –6 to 6. Various classical methods of determining refraction are analyzed. Conclusions based on experimental work made by various researchers are presented. Using the results of numerous studies of various methods for determining vertical refraction, it can be concluded that all classical (static) methods do not provide a high degree of reliability to determine the refraction. An exception is the method of determining refraction at a neutral temperature stratification of the atmosphere, when the time interval is not very long. For this reason, their practical application is extremely limited. To improve the accuracy of determining refraction, it is necessary to take into account the turbulence of the atmosphere, that is, to use dynamic measurement methods that take the fluctuations of the electromagnetic wave passing through the path into account.