InSAR observations and analysis of the Medicina Geodetic Observatory and CosmoSkyMed images
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InSAR observations and analysis of the Medicina Geodetic Observatory and CosmoSkyMed images Davod Poreh1 · Saied Pirasteh2 Received: 7 May 2020 / Accepted: 16 June 2020 © Springer Nature B.V. 2020
Abstract We have observed some discrepancies between installed geodetic instruments including global positioning systems (GPS) and very long baseline interferometry (VLBI) in the Medicina Geodetic Observatory (MGO). This study overcomes the above-mentioned discrepancies. We analysed several CosmoSkyMed images utilizing the interferometric synthetic aperture radar (InSAR) technique to improve the understanding of 3D surface displacements. The MGO is in a rural area, and the radar coherence is low; therefore, the coverage of permanent scatterers (PS) is limited. In ascending mode, the closest scatterer to the MEDI GPS station shows that the surface displacements are as large as 0.72 ± 1.45 mm/year along the line of sight (LOS) direction. The GPS height projected on the LOS vector shows a rate of 0.92 ± 0.04 mm/year of displacements. In descending mode, the closest scatterer to MEDI shows that the displacement is at a rate of − 0.1 ± 0.51 mm/ year along the LOS direction, and the MEDI projected on the LOS vector is at a rate of 0.91 ± 0.002 mm/year. In this study, the deformation rates and their standard deviations stress that the GPS and PS-InSAR have different values. Despite a large (32-m-diameter parabolic antenna) VLBI telescope, we do not observe a single PS on the telescope for ascending and descending passes due to the frequent movements of the VLBI telescope in different directions. Keywords Medicina · Subsidence · Interferometric synthetic aperture radar (InSAR) · GPS · PS
* Saied Pirasteh [email protected] Davod Poreh [email protected] 1
Dipartimento di Ingegneria Elettrica edelle Tecnologie dell’Informazione, Universita degli Studi di, Napoli Federico II, Via Claudio, 21, 80125 Naples, D.P., Italy
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Department of Surveying and Geoinformatics, Faculty of Geosciences and Environmental Engineering (FGEE), Southwest Jiaotong University, Chengdu 611756, S.P., China
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1 Introduction Medicina Geodetic Observatory (MGO) is a radio astronomy observatory and a global positioning system (GPS) with a very long baseline interferometry (VLBI) and a satellite laser ranging (SLR) co-location site of International Terrestrial Reference Frame (ITRF) (Altamimi et al. 2008). The 32-m VLBI antenna installed in the MGO is part of the International VLBI Service for geodesy and astronomy (IVS) network (Schlüter and Behrend 2007). In addition to VLBI, the MGO is also equipped with one SLR, a superconducting gravimeter (Zerbini et al. 2010), and two continuous GPS stations, including MEDI and MSEL. MGO is one of only 40 geodetic sites in the world where GPS, SLR, and VLBI are present. For the ITRF, it is essential to understand how the GPS reference frame changes concerning the VLBI and SLR. To connect the GPS to the VLBI and SLR observations, physical surveys must be conducte
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