The effect of absolute humidity on GPS-positioning accuracy
Received: February 15, 2018
Lviv Polytechnic National University

Objective. Investigate the effect of absolute humidity on the GPS accuracy for different durations of observation. Methods. The GPS observations with different durations over spring-autumn period at 17 permanent stations in France and 8 stations in Switzerland were chosen for initial data. These observations used four GPS networks with a different number of points (from 5 to 8) and lengths of vectors (average length varied from 5.1 to 48.6 km). Values of absolute humidity were determined using the average values of air temperature, atmospheric pressure, and relative humidity, obtained from 06:00 to 22:00. For our investigation we selected only those days when absolute humidity varied significantly. The observations were processed by the Trimble Business Center software, changing the duration of the observations (1, 2, 4 hours). In total, 1,200 sessions were processed. By comparing the values of true coordinates of the network points and those determined by the results of observations, we obtained the RMS (root-mean-square) errors of the positions of the points. Results. The analysis of RMS position errors showed that there is a tendency for deterioration of the point’s position accuracy in the network when the absolute humidity is increasing. The values of the RMS, obtained at the lowest and highest values of absolute humidity, for all networks and the different durations of observations were compared. Thus, when the absolute humidity changed from 7,0 g/m3 to 13,8 g/m3 for the observation duration of 4 hours, the average values of RMS increased 1.6 times (from 4.4 mm to 7.0 mm), for the sessions of 2 hour duration the value of RMS increased 1.8 times (from 4.7 mm to 8.3 mm), and for a 1 hour duration – 2.1 times (6.1 mm to 13.0 mm). Scientific novelty and practical significance. The environment of satellite signals propagation remains one of the main sources of errors, in particular in the troposphere, which, in essence, "forms" the weather. Although today more attention is focused on weather forecasting using satellite navigation systems, there is also an inverse problem. The study suggests meteorological conditions, specifically absolute humidity, should be considered to increase the accuracy of GPS-measurements. The obtained results of the studies are quite reliable, since a large amount of data is used. It is advisable to choose the days for GPS observations, when the moisture content is minimal (no higher than 12 g/m3). From a practical point of view – the possibility of using observable meteorological parameters obtained from the weather forecasts are feasible.

  1. Absoliutna volohist [absolute humidity. [Wikipedia, the free encyclopedia]. Available at:
  2. Antonovich K. M., Frolova E. K. Sovmestnoe ispol'zovanie meteodannyh nazemnyh i ajerologicheskih nabljudenij pri obrabotke sputnikovyh izmerenij [The use of meteorological data from terrestrial and aerial observations in the processing of satellite measurements]. Vestnik SGGA. 2003, issue 8, pp. 8–13.
  3. Azizov A. A., Gajkovich K. P., Kashkarov S. S., M. B. Chernjaeva Ispol'zovanie signalov navigacionnyh ISZ dlja opredelenija parametrov atmosfery [Use of navigation satellite signals to determine atmospheric parameters]. Izv. VUZov. Radiofizika [Radiophysics and Quantum Electronics], 1997, T. XLI, no. 9, pp. 1093–1110.
  4. Devis M. S., Businger S., Herring T. A. et al. GPS meteorology: remote sensing of atmospheric water vapor using the Global Positioning System. J. Geophys. 1992, v. 97, pp. 15787–15801.
  5. Hofmann-Wellenhof В., Lichtenegger Н., Collins J. Global Positioning System. Theory and Practice. Wien; N.Y.: Springer-Verlag, 1994, 356 p.
  6. Hutorova O. G., Vasil'ev A. A., Hutorov V. E. O perspektivah issledovanija neodnorodnoj struktury troposfery s pomoshh'ju seti priemnikov GPS-GLONASS [On prospects of investigation of the nonhomogeneous troposphere structure using the set of GPS-GLONASS receivers]. Optika atmosfery i okeana [Atmospheric and Oceanic Optics]. 2010, 23, no. 6, pp. 510–514
  7. Ivanov V. A., Rjabova N. V., Zuev A. V., Kislicyn A. A., Ershov P. M. Vlijanie klimaticheskih i geofizicheskih javlenij na pomehoustojchivost' priema radionavigacionnyh signalov sistem GLONASS/GPS [Influence of climatic and geophysical phenomena on noise immunity reception of radio navigation signals of GLONASS/GPS systems]. II Vserossijskie Armandovskie chtenija. Radiofizicheskie metody v distancionnom zondirovanii sred. Materialy V Vserossijskoj nauchnoj konferencii [Materials of the All-Russian Scientific Conference] (Murom, 26-28 June 2012). Murom: Izd. poligraficheskij centr MI VlGU, 2012, 567 p.
  8. Kablak N. I. Monitorynh osadzhenoi vodianoi pary na osnovi obrobky HNSS-danykh [Monitoring of the besieged water vapor on the basis of the processing of GNSS data]. Kosmichna nauka i tekhnolohiia [Space Science and Technology]. 2011, T. 17, no. 4, pp. 65–73.
  9. Kablak N. I. Suchasni pidkhody do vyznachennia ta vykorystannia troposfernykh zatrymok GNSS syhnaliv [Questions of definition that uses of tropospheric delays of GNSS-signals at the present stage of development of satellite technologies are considered]. Heodeziia, kartohrafiia i aerofotoznimannia [Geodesy, Cartography and Aerial Survey”]. 2009, issue 72, pp. 22–27
  10. Kovorotnyj A. L., Kivva F. V., Goncharenko Ju. V., Gorobec V. N., Gorb A.I. Sravnitel'nyj analiz modelej dlja ocenki polnogo vlagosoderzhanija troposfery nad Har'kovskim regionom posredstvom GPS-izmerenij [The comparative analysis of models for estimation of the total moisture content of the troposphere through the GPS measurements over Kharkov]. Radiofizyka ta elektronika [Radiophysics and electronics]. 2014, T. 5(19), no. 4, pp. 21–26
  11. Mendes V. B., Langley R. B. Tropospheric Zenith Delay Prediction Accuracy for Airborne GPS High-Precision Positioning. Proceedings of The Institute of Navigation 54th Annual Meeting, Denver, CO, U.S.A., 1–3 June 1998, pp. 337–347.
  12. Schueler T. On Ground-Based GPS Tropospheric Delay Estimation Dissertation. T. Schuelеr. Schriftenreihe 73, Studiengang Geodäsie und Geoinformation Universität der Bundeswehr München, February 2001. Available at:
  13. Vahnin A. V. Primenenie meteorologicheskoj informacii v navigacionnyh sistemah GLONASS/GPS: Magisterskaja dissertacija [Application of meteorological information in navigation systems GLONASS. GPS: Master's thesis]. Vahnin Anton Vjacheslavovich. Sankt-Peterburg, 2012, 68 p
  14. Zablotskyi F. D. HNSS-meteorolohiia [GNSS meteorology]. lviv Polytechnic Publishing House, 2013, 96 p.
  15. Zablotskyi F., Palianytsia B., Matviienko L., Turchyn N. Sukha i hidrostatychna skladovi zenitnoi troposfernoi zatrymky [On the dry and hydrostatic component of zenith tropospheric delay]. Suchas. dosiahn. heodez. nauky ta vyr-va: zb. nauk. pr. Zakh. heodez. t-va UTHK [Modern achievements of geodetic science and industry: Coll. Science pr. UTHK Western geodetic company]. Lviv Polytechnic Publishing House, 2011, issue II, pp. 92–95.