The purpose of this paper is to evaluate an accuracy of the wet component of zenith tropospheric delay obtained by the data of six GNSS stations in comparison with radio sounding data. The determination of hydrostatic and wet components of zenith tropospheric delay was divided into several stages. In the first phase, with an appropriate site for data center processing GNNS-measurements averaged values of zenith tropospheric delay were selected. In the second step, using an analytical model of Saastamoinen, a hydrostatic component was calculated, with precisely measured (at the height of the antenna) value of atmospheric pressure. The third phase a wet component was determined as the difference between zenith tropospheric delay, derived from GNNS measurements and its hydrostatic component. The advantages of this approach in determining the tropospheric delay in comparison with other methods is continuity of GNNS observations and their independence of weather conditions. The obtained values were compared with the corresponding values determined according to the radio soundings, which were taken in this study as controls. As a result of processing of 120 vertical profiles of radio soundings, at six aerological stations and by the data from six GNSS stations the value of hydrostatic and wet component of zenith tropospheric delay was calculated for middle ten day period of January and July 2011 and 2013. Radio soundings data worked for two years, so a fairly lengthy and massive material is allowed to refine and evaluate reliable primarily the nature of the values of the hydrostatic component of tropospheric delay so as exactness of its determination directly will influence on exactness of establishment of moist component. In consequence of our calculations, the difference hydrostatic and wet components of the tropospheric zenith delays were obtained and their accuracy was assessed. These results serve as a basis for further improving of the accuracy of the wet component of GNSS-measurements, in particular, to determine the spatial and temporal changes and precipitable water vapor content in the atmosphere in the region, which is important for weather forecasting.
1. Zablotskyi F. D. GNSS-meteorologiia: [GNSS meteorology]. Navchalnyi posibnyk [tutorial]. Lviv: Lviv Polytechnic National University, 2013, pp. 95.
2. Zablotskyi F. D. Modeliuvannia vplyvu atmosfery na astronomoheodezychni vymiry v poliarnykh rehionakh [Modeling the influence of the atmosphere on astronomic and geodetic measurements in polar regions] dys. d-ra tekhn. nauk [Thesis of Doctor of Science]. Lviv: Lviv Polytechnic National University, 2002, pp. 267.
3. Kablak N. I. Ocinka vplyvu atmosfery u merezhi aktyvnyh referencnyh GNSS-stanciy [Assessing the impact of the atmosphere on a network of active references GNSS-stations]. Geodeziia, kartografiia i aerofotoznimannia [Geodesy, Cartography and Aerial Photography], 2010, issue. 73, pp. 17–21.
4. Kablak N. I. Dystantsiine zonduvannia vodianoi pary v atmosferi za dopomohoiu navihatsiinykh suputnykovykh system [Remote sensing of water vapor in the atmosphere using satellite navigation systems]. Geodeziia, kartografiia i aerofotoznimannia [Geodesy, Cartography and Aerial Photography], 2011, issue 75, pp. 31–35.
5. Kablak N. I. Monitorynh osadzhuvanoi vodianoi pary na osnovi obrobky GNSS-danykh [Monitoring precipitable water vapor from GNSS data processing]. Kosmichna nauka i tekhnolohiia [Space science and technology]. 2011, vol. 17, no. 4, pp. 65–73.
6. Kablak N. I., Klimyk V. I. Zastosuvannia GPS-sposterezhen dlia doslidzhennia volohosti atmosfery [Usage GPS-observations to research the humidity of the atmosphere]. Geoinformation monitoring of environment GPS and GIS technologies: X Jubilee International Scientific and Technical Symposium, 6-11 Sept., 2005, Alushta (Ukraine, Crimea). 2005, pp. 255–257;
7. Kashkin V. B., Petrov E. V. Otsenka troposfernoy zaderzhki signalov navigatsionnyih sistem GLONASS i GPS s ispolzovaniem sputnikovyih dannyih ATOVS o vertikalnyih profilyah atmosferyi [Estimation of tropospheric delay signals navigation systems GLONASS and GPS, using satellite data ATOVS vertical profiles of the atmosphere]. Izv. vuz. Fiz. [Proceedings of the higher educational institutions of Physics] 2010, No. 9 (2), рр. 27–29.
8. Sluzhba atmosfernyh doslidzhen pry universyteti Vajomingu, Internet resurs [Rezhym dostupu]: http://weather.uwyo.edu/upperair/sounding.html.
9. Boccolari M., Fazlagic S., Frontero P., Lombroso L., Pugnaghi S., Santangelo R., Corradini S., Teggi S. GPS Zenith Total Delays and Precipitable Water in comparison with special meteorological observations in Verona (Italy) during MAP-SOP. Annals of Geophysics, October 2002, Vol. 45, N.5, pp 599–608.
10. GNSS Data Center, Internet resurs [Rezhym dostupu]: http://igs.bkg.bund.de/file/productsearch/
11. Katsougiannopoulos S., Pikridas C., Rossikopoulos D., i. Ifadis M. and Fotiou A. Tropospheric Refraction Estimation Using Various Models, Radiosonde Measurements and Permanent GPS Data. PS5.4 – GNSS Processing and Applications, XXIII FIG Congress, Munich, Germany, October 8–13, 2006, pp. 15.
12. Mendes V.B. Modeling the neutral-atmosphere propagation delay in radiometric space techniques. Ph.D. dissertation, Department of Geodesy and Geomatics Engineering Technical Report № 199, University of New Brunwick, Fredericton, New Brunswick, Canada, 1999, p. 35.
13. Niell A. E. Global mapping functions for the atmosphere delay at radio wavelengths. Journal of Geophysical Research, 1996, Vol.101, no.B2, pp. 3227–3246.
https://doi.org/10.1029/95JB03048
14. Ning T. GPS Meteorology: With Focus on Climate Applications. Thesis For The Degree Of Doctor Of Philosophy. Department of Earth and Space Sciences Chalmers University of Technology Gothenburg, Sweden, 2012, pp. 82.
15. Saastamoinen J. Atmospheric correction for troposphere and stratosphere in radioranging if satellites. Geophysical monograph, 15, American Geophysical Union, Washington, 1972, pp. 247–252.
16. Schueler T. On Ground-Based GPS Tropospheric Delay Estimation: PhD Thesis. Munich: Universitaet der Bundeswehr, 2001, р. 364.