ON ATMOSPHERIC INFLUENCES AT ASTROGEODETIC MEASUREMENTS IN POLAR REGIONS Fedir Zablotskyj Chair of Geodesy and Astronomy, State University “Lviv Polytechnic” 12, S.Bandera Str., 290646, Lviv, Ukraine fzablots@polynet.lviv.ua Abstract The paper outlines both author’s independent research and joint, with other scientists, studies of atmospheric influences on the results of angular and electronic distance measurements in polar regions and, in particular, in Antarctica. A short description of structure peculiarities of atmospheric boundary layer is given. A special attention was given to thermal stratification and caused by it influences on the results of astrogeodetic measurements. Investigation of astronomic refraction was conducted on the basis of aerological data. An integral of refraction was computed at different zenith angles for several Antarctic and Arctic stations. Refractive anomalies were calculated by means of refraction tables. The results of the theoretical and experimental investigations of the terrestrial vertical refraction in polar regions are given. Analysis of atmospheric influences on the electronic distance measurements were carried out by means of the refraction index calculation for light-and radio waves. The data of aerological soundings and meteorological gradients in the lowest atmospheric layers were used as initial materials. It should be noted that microwave distance measurements in Central Antarctica ensure a reliable accuracy in consequence of the very small air humidity. As regards the electronic distance measurements to satellites the existent models do not quite ensure the reliable results for laser- and microwave distance measurements in consequence of peculiarities of the meteorological parameter distributions in atmospheric lower layers in polar regions and in Central Antarctica, in particular. 1. Introduction The aim of the study was to determine an extent of atmospheric influences on the results of angular and electronic distance measurements in polar regions. It should be noted that a satisfactory precision of accounting of atmospheric influences is provided on the whole at the angular and electronic distance measurements to objects, located both in atmosphere and outside of it, at zenith distances less than 70°. Achievement of the precise results at large zenith distances, and especially in the near horizontal zone , is possible only at reliable representation of atmospheric stratification and first of all the boundary and lowest layers. It is accounted for by a heterogeneity of atmospheric structure and its dynamics and first of all by peculiarities of an air temperature and humidity distribution with a height. 2. Some peculiarities of the vertical distribution of air- temperature and humidity In polar regions according to long-terms mean monthly aerological sounding data it has been established that the vertical distribution of air temperature in the boundary layer is characterized mainly by the stable thermal stratification. In Antarctica two zones by meteorological peculiarities it should be marked out: • Antarctic coast zone - it may be present in general after meteorological data of the Mirnyj station as it characterizes more part of the Antarctic coast situated as effected of the gravity wind; • Central Antarctica – for it the most representative is the Vostok station. The mean capacity of the ground inversion layer amounts 240m over coast and in Central Antarctica – 720m. The ground inversion intensity makes up in average 2.8 and 17.1 °C per year accordingly and its recurrence reaches 75 and 98% [2]. The vertical temperature gradient in the lower 100-metres layer of the continent centre reaches the extremal values on the terrestrial globe ∼ 40-50°C/100m. Depending