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Geomatics for the maintenance of the Internationl Terrestrial Reference Frames (ITRF) and for the analysis of national geodetic networks

Keywords: ITRF, IERS, Tie vectors, ETRF, RND, NRTK
Fig. 1. Geodetic measurements for the tie-vectors GPS-VLBI estimation at the IRA INAF observatories of Medicina (BO) and Noto (SR), Italy (Vittuari)
Fig. 2. Residual velocities in ETRF of GNSS permanent stations belonging the Rete Dinamica Nazionale (RDN), (picture by Gandolfi).

The realization of precise and reliable global geodetic reference frames is one of the innovations that have most contributed to the efficiency of positioning techniques, i.e. for monitoring surveys, land surveying and cadastral procedures, the stacking-out of large infrastructures, or for maritime, terrestrial and aerial navigation.

Starting from the initial applications exclusively conducted by research institutions, we can now observe a wide dissemination of the techniques of space geodesy for consumer applications, and it is sufficient to cite satellite car navigation systems or applications based on global positioning installed in smartphones or tablets PC.

The reference frame more accurate is the International Terrestrial Reference Frame (ITRF) maintained by the International Earth Rotation and Reference Systems Service (IERS). The update of ITRF, entirely depends on the voluntary effort of a large number of agencies and research infrastructures, this creates a fundamental relationship between public and private, national and global technical services. This reference frame is now the backbone also for the realization of national reference frames. For example, in Italy the Presidency of the Council of Ministers established by the Decree of 10 November 2011, the institution of the Rete Dinamica Nazionale (RDN) as official national reference frame, composed by 99 GNSS permanent stations.

A team of DICAM studied in collaboration with the Institute of Radio Astronomy (IRA-INAF) the ensemble of high-accuracy survey methodologies and geometrical/statistical procedures necessary for the measure of eccentricity vectors between the reference points (RP) of co-located geodetic instruments and a WG was established in 2003 within the IERS - IAG Sub-Commission 1.2. Moreover DICAM is involved both in real time GNSS network for NRTK positioning and for the RDN analysis by means of the most advanced scientific GNSS data processing packages.

Main Pubblications

Abbondanza C., Vittuari L., Sarti P., Negusini M.. (2007). An Analysis of Local Tie Vectors’ Temporal Evolution and Site Stability at Medicina Observatory through Terrestrial and GPS-based Observations. 18th European VLBI for Geodesy and Astrometry Working Meeting. Vienna. 12-13 April 2007. (vol. 79, pp. 188 - 183). ISSN 1811-8380. VIENNA: edited by J. Boehm, A. Pany, and H. Schuh (Austria).

Barbarella M., Cenni N., Gandolfi S., Ricucci L., Zanutta A., (2009), Technical and scientific aspects derived by the processing of GNSS networks using different approaches and software, ION GNSS 22th International Technical Meeting of the Satellite Division, 23- 25 September 2009, Savannah, GA, USA, 2677- 2688.

Barbarella M., Gandolfi G., Ricucci L, Zanutta A., (2009) The new Italian geodetic reference network (RDN): a comparison of solutions using different software packages; 03-p-gandolfi.pdf

Barbarella M., Gandolfi S., Ricucci L., 2010, Esperienze di calcolo della Rete Dinamica Nazionale, Bollettino SIFET (ISSN 1721-971X), 2010, 2, 27-43.

Bolli P., Montaguti S., Negusini M., Sarti P., Vittuari L., Deiana GL.. (2006). Photogrammetry, laser scanning, holography and terrestrial surveying of the Noto VLBI dish. International VLBI Service for Geodesy and Astrometry 2006 General Meeting Proceedings. Fourth IVS General Meeting. Concepción, Chile. January 9- 13, 2006. (vol. NASA/CP-2006-214140, pp. 172 - 176). -: NASA Conference Publication (US).

Dawson J., Sarti P., Johnston G. M., Vittuari L.. (2007). Indirect approach to invariant point determination for SLR and VLBI systems: an assessment. Journal of Geodesy. vol. 81(6-8), pp. 433 - 441 ISSN: 0949-7714. DOI

Gandolfi S., Tavasci L., Poluzzi L. (2016). Improved PPP performance in regional networks, GPS Solutions, 20 (3), pp. 485-497.

Sarti, P., Abbondanza, C., Legrand, J., Bruyninx, C., Vittuari, L., Ray, J., 2013, Intra-site motions and monument instabilities at Medicina ITRF colocation site, Geoph. J. Int., vol. 192, p. 1042- 1051, ISSN: 0956-540X, doi: 10.1093/gji/ggs092. pp. 1042-1051.

Sarti P., Sillard P., Vittuari L. (2004) - Surveying co-located Space Geodesy techniques for ITRF computation, Journal of Geodesy, vol.78, n.3 , Springer, 210-222. DOI 10.1007/s00190-004- 0387-0.

Vittuari L., Sarti P., Sillard P., Tomasi P., Negusini M.. (2005). Surveying the GPS-VLBI Eccentricity at Medicina: Methodological Aspects and Practicalities. IERS Technical Note. Proceedings of the IERS Workshop on site colocation. Matera. Italy, 23 - 24 October 2003. (vol. 33, pp. 38 - 48). ISBN: 3-89888-793.

Vittuari L., Gottardi G., Tini M.A. (2015). Monumentations of control points for the measurement of soil vertical movements and their interactions with ground water contents, «Geomatics, Natural Hazards & Risks », 2015, 6, pp. 439 - 453

Vittuari L., Tini M.A., Sarti P., Serantoni E., Borghi A., Negusini M., Guillaume S. (2016). A comparative study of the applied methods for estimating deflection of the vertical in terrestrial geodetic measurements, «Sensors», 2016, 16, pp. 1 – 14

Research projects

PRIN 2007: “Uso degli osservatori geodetici colocati VLBI-GPS per l'omogeneizzazione ed il confronto di serie storiche derivate da PS INSAR e livellazione geometrica, nello studio dei movimenti del suolo a scala regionale” (National PI A. Capra).

CISIS 2011 e 2012: Monitoraggio della Rete Dinamica Nazionale Italiana (RDN)

Accordo di collaborazione ARPAE-DICAM su: “Definizione sistema di riferimento per rilievi topografici e batimetrici lungo il litorale emiliano- romagnolo” .

CISIS 2011 2012 e 2016: Attività di monitoraggio Rete Dinamica Nazionale (RDN).