Time series of weekly and daily solutions for coordinates of permanent GNSS stations may indicate local deformations in Earth’s crust or local seasonal changes in the atmosphere and hydrosphere. The errors of the determined changes are relatively large, frequently at the level of the signal.
Satellite radar interferometry and especially Persistent Scatterer Interferometry (PSI) is a method of a very high accuracy. Its weakness is a relative nature of measurements as well as accumulation of errors which may occur in the case of PSI processing of large areas. It is thus beneficial to confront the results of PSI measurements with those from other techniques, such as GNSS and precise levelling.
PSI and GNSS results were jointly processed recreating the history of surface deformation of the area of Warsaw metropolitan with the use of radar images from Envisat and Cosmo-SkyMed satellites. GNSS data from Borowa Gora and Jozefoslaw observatories as well as from WAT1 and CBKA permanent GNSS stations were used to validate the obtained results. Observations from 2000–2015 were processed with the Bernese v.5.0 software. Relative height changes between the GNSS stations were determined from GNSS data and relative height changes between the persistent scatterers located on the objects with GNSS stations were determined from the interferometric results.
The consistency of results of the two methods was 3 to 4 times better than the theoretical accuracy of each. The joint use of both methods allows to extract a very small height change below the level of measurement error.
Cisak, J., Zak, L., Stepniak, K., Wielgosz, P., Kupko, V.S., Olijnyk, A.E., Liubzhyn, A. and Zanimonskiy, Y.M. (2014). Investigation of uncertainty of GNSS-based distance metrology using EPN double stations data. EUREF 2014 Symposium, Vilnius, Lithuania, 4–6 June 2014. http://www.euref.eu/symposia/2014Vilnius/P-10-Cisak.pdf
Dach, R., Hugentobler, U., Fridez, P. and Meindl, M. (Eds.) (2007). Bernese GPS Software Version 5.0. Astronomical Institute, University of Berne, Switzerland.
Feretti, A., Prati, C. and Rocca, F. (2000). Nonlinear subsidence rate estimation using permanent scatterers in differential SAR interferometry. IEEE Transactions on Geoscience and Remote Sensing, 38(5), 2202–2212.
Feretti, A., Prati, C. and Rocca, F. (2001). Permanent scatterers in SAR interferometry. IEEE Transactions on Geoscience and Remote Sensing, 39(1), 8–20.
Godah, W., Krynski, J. and Cisak, J., (2012). The use of GPS data at T-T Zone for the verification of the recent terrestrial reference frames considering possible geodynamic processes. Geoinformation Issues, 4, 1(4), 5–13.
Hastaoglu, K.O. (2016). Comparing the results of PSInSAR and GNSS on slow motion landslides,
Krynski, J. and Zanimonskiy, Y. (2005). Towards More Reliable Estimation of GPS Positioning Accuracy. A Window of the Future of Geodesy, IAG General Assembly, Sapporo, Japan, 30 June – 11 July 2003, Springer Verlag Berlin-Heidelberg, (ed.) F. Sansò, IAG Symposia, Vol. 128, 48–53.
Lyard, F., Lefevre, F., Letellier, T. and Francis, O. (2006). Modelling the global ocean tides: a modern insight from FES2004. Ocean Dynamics, 56, 394–415.
Massonet, D., Rossi, M., Carmona, C., Adagna, F., Peltzer, G., Feigl, K. and Rabaute, T. (1993). The displacement field of the Landers earthquake mapped by radar interferometry. Nature, 364(8), 138–142.
Neill, A.E. (1996). Global mapping functions for the atmosphere delay at radio wavelengths. J. Geophys. Res., 101(B2), 3227–3246.
Sawicki, L. (1960). The geological structure and morphology of the land in Warsaw (in Polish). Przegląd Geologiczny, 8 (12) 622.
Zebker, HA. and Goldstein, R.M. (1986). Topographic Mapping From Interferometric Synthetic Aperture Radar Observations. J. Geophys. Res., 91(B5), 4993–4999.
Zebker, H.A., Rosen, P.A., Goldstein, R.M., Gabriel, A. and Werner, C.L. (1994). On the derivation of coseismic displacement fields using differential radar interferometry: The Landers earthquake. J. Geophys. Res., 99(B10), 19617–19634. http://www.epncb.oma.be/