GNSS measurements

The aim of the work is to analyze the change of hydrostatic and wet component values of zenith tropospheric delay (ZTD), determined for all seasons of the year. For today, ZTD components are determined mainly as follows: hydrostatic component – by using one of existing analytical models, mostly Saastamoinen model, and wet component – from GNSS measurements using simulated value of hydrostatic component. Also, in this study we evaluated the accuracy of the obtained values of hydrostatic and wet ZTD components for similar components, determined by radio sounding.

The aim of the research is to diagnose the metrological characteristics of high-precision GNSS-observations by methods of non-classical error theory of measurements (NETM) based on Ukrainian reference stations. Methodology. We selected 72 GNSS reference stations, downloaded daily observation files from the LPI analysis center server, and created time series in the topocentric coordinate system. The duration of the time series is almost two years (March 24, 2019 - January 2, 2021).

The goal. Identify the relationship between seasonal temperature changes and vertical and horizontal displacements of GNSS control points based on data obtained by the automated monitoring system of the Dnipro HPP dam in the period from 2016 to 2020. Input data. The research used data of uninterrupted GNSS measurements obtained at 16 points of the Dnipro HPP dam from mid-2016 to mid-2020. Method.

The aim of this work is the research of the magnitude of the components change of the zenith tropospheric delay for the territory of Ukraine according to several-day terrestrial meteorological measurements, as well as the construction and study of the field of their change.  Method. The accuracy of the determination of the tropospheric delay and its components depends on the amount of meteorological data that can be used for its caclulation.

The purpose of the given work lies in the studies of the atmospheric precipitable water vapour (PWV), based on the processing of aerological and GNSS (Global Navigation Satellite System) measurements, as well as the comparing of PWV values, determined according to the data of aerological and GNSS stations, located both in temperate and tropical latitudes.

The results of long-term studies of landslide processes in the areas of operation of pumped storage power plant with the help of modern GNSS technologies are considered. The presence of deformation of the earth's surface, both in terms in plane and vertical, is revealed. Displacement of some points is a closed-return trajectory and not exceed a few millimeters. Another part of the points is characterized by the horizontal displacements with the presence of returning movements.

The purpose of this paper is determining the water vapor content calculated by the wet component of zenith tropospheric delay (ZTD) obtained by means of radio sounding data and GNSS observations. The investigation methodology is the following: the wet component of ZTD is defined as the difference between the total ZTD derived from GNSS measurements and the calculated hydrostatic component. Then the integrated and precipitable water vapor (PWV) is calculated by means of the wet component.

The paper illuminates the following questions according to the determination tropospheric delay: by the data of atmosphere radio sounding, by the data of the basic surface meteorological parameters only and by the data derived from  GNSS observations. Comparison of the results and estimation of accuracy have been carried out.