Research of oscillations in the components of zenith tropospheric delay during the year in Ukraine

The aim of this work is to study the fluctuations of the components of the zenith tropospheric delay during the annual period according to the ground meteorological measurements in Ukraine. Methodolodgy. The surface values of meteorological values at the stations: Lviv, Kyiv, Kharkiv and Odesa, obtained in 2019 with an interval of 3 hours were used for the research. A total amount of 2020 measurements at each of the stations has been presented. The calculation of the components of the zenith tropospheric delay was performed according to the Saastamoinen formula. According to the calculated values of the components, graphs of changes in the dry and wet components of the zenith tropospheric delay for each of the stations during constructed. Subsequently, the monthly average and annual average values of the components were calculated and compared with each other. Results. Based on studies of changes in delay values at four Ukrainian meteorological stations for the period of 2019, it was found that the monthly average values of ZHD component are higher at stations whose altitude is lower. The wet component of ZWD during the year acquires the biggest values in summer. Annual fluctuations of the dry component of ZHD have a much smaller amplitude than the wet ZWD. The amplitude of the change in the total delay is determined by the amplitude of the change of the wet component, which at different stations is almost two times bigger than the amplitude of the change of the dry component, although ZWD is only up to 10% of ZTD. Thus, the variations in the total tropospheric delay, which indirectly reflects the weather and climatic processes due to variations in the wet component. Scientific novelty and practical significance consist in identifying the features of the annual change in the components of tropospheric delay at stations in different climatic and weather conditions. The performed research can be used in the tasks of monitoring of large hydraulic structures by GNSS methods to create regional models of the atmosphere and further studies of tropospheric delay, as they relate to its changes in space and time.