Vertikaliosios refrakcijos eliminavimo metodika nematavus temperatūros gradiento

Abstract

The question is discussed how to eliminate the influence of vertical refraction from results of levelling when the vertical temperature gradient had been not measured. For this purpose the investigation data gained in Finland were used [2]. The correction concerning the levelling refraction within station is calculated by formula (2). For calculating the coefficient and temperature differences Δt the equation (3) is used. Its coefficients computed according to the similarity transformation of second degree are given in Table 1 and 2. The proposed methodology for computing corrections concerning the levelling refraction was used by establishing state vertical network of first class in Lithuania in 1998. Observations have been made in levelling lines Kazlų Rūda-Lazdijai and Jonava-Vilnius. Generally, the influence of levelling refraction on these lines is 1,23 and 1,24 mm. The final computations and investigations showed that this method only partly eliminates the negative influence of refraction.