Remote monitoring of the atmosphere is designed to obtain information about the state of the atmosphere. The principle of the remote monitoring system of the atmosphere is based on the registration and processing of spacecraft radio signals of the Global Navigation Satellite Systems (GNSS). The wet tropospheric delay component of the electromagnetic signal (Δρ sup(tropo) sub(w)), which is derived from the GNSS observations data analysis, is used to calculate the water vapour content in the atmosphere. It is well known, that this parameter is critical to meteorologists, because the water vapour content in the atmosphere is a key parameter in the construction of numerical weather modelling. In this article the IWV - Integrated Water Vapour has been estimated and the expected accuracy of its determination on the basis of the operational GNSS data processing from reference station network ZAKPOS and the results of aerologic sensing of the atmosphere are given.

Along with the development of the technological possibilities, the Global Positioning Satellite System (GNSS) is increasingly used in geodetic measurements. Using GNSS, measurements are performed in horizontal plane as well as for point elevation determination. The aim of the article is to demonstrate that the GNSS measurements’ static mode has a high accuracy. To achieve the aim the following objectives were set: 1) to perform global positioning measurements in Class I national leveling network, 2) to calculate the elevation above the sea level, 3) to evaluate the accuracy of performed GNSS measurements. The following research methods were used: static measurement method and analytical method for comparison of the obtained data.

The article presents the research study of the current state and condition of the geodetic base (polygonometric) network for Kaunas city and region as well as the aspects of its compiling. The geodetic base compiled in the post-war years is considered to be of high quality and is used nowadays. The still existing polygonometric network is seldom studied and thus it remains little known. For the purpose of defining the current state of the geodetic base networks, the search for the points in Karmėlava neighbourhood of Kaunas region has been provided. From the total number of 22 points to be searched, five (i.e. 22 percentage) were determined, but only four points (i.e.18 percentage) were appropriate for measurements. The majority of the points has been destroyed during the construction of the residential buildings or roads, or after the reconstruction works. The measurements have been taken by Trimble R6, by RTK method, 10 times for each point. The most reliable value of the measured geodetic points X and Y were defined as well as the errors of the mean square for one measurement and of the average. The results of the survey (100 respondents) showed that the majority of the professionals apply the points of the polygonometric network when making measurements. However, the problems related to a rather rear usage of the network and the aggravated search of the polygonometric points were encountered. A significant part of the professionals suggested the restoration of the polygonometric network.