La geodesia fisica è un ramo della geodesia che si occupa dello studio dei fenomeni fisici che influenzano la forma e le dimensioni della Terra.
L'obiettivo principale della geodesia fisica è quello di comprendere e quantificare variazioni nella gravità terrestre, deformazioni della crosta terrestre ed effetti delle maree per migliorare la nostra conoscenza della forma e della dinamica della Terra.
Nell’ambito della Geodesia Fisica, la sezione è impegnata nello studio del campo di gravità della terra, attraverso osservazioni terrestri o da satellite. In particolare sono oggetto di ricerca il calcolo dell’ondulazione del geoide e le sue applicazioni, in particolare nella stima geodetica della Mean Dynamic Topography (MDT) e delle correnti geostrofiche e la livellazione GNSS.
La valutazione degli effetti dei cambiamenti climatici lungo le coste richiede una appropriata definizione del sistema di riferimento delle quote fisiche, in relazione quindi al campo di gravità terrestre, e non può quindi prescindere dalla accurata conoscenza della superficie del geoide.
Articoli su Riviste Scientifiche:
In 2014, the Jeddah Municipality made a call for an estimate of a centimetric precision geoid model to be used for engineering and surveying applications, because the regional geoid model available at that time did not reach a sufficient precision. A project was set up to this end and dedicated sets of gravity and Global Positioning System (GPS)/levelling data were acquired in the framework of this project. In this paper, a thorough analysis of these newly acquired data and of the last available Global Gravity Field Models (GGMs) has been done in order to obtain a geoid undulation estimate with the prescribed precision. In the framework of the Remove–Compute–Restore (RCR) approach, the collocation method was used to obtain the height anomaly estimation that was then converted to geoid undulation. The remove and restore steps of the RCR approach were based on GGMs, derived from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) and Gravity Recovery and Climate Experiment (GRACE) dedicated gravity satellite missions, which were used to improve the long wavelength components of the Earth’s gravity field. Furthermore, two different quasi-geoid collocation estimates were computed, based on gravity data only and on gravity plus GPS/levelling data (the so-called hybrid estimate). The best solutions were obtained with the hybrid geoid estimate. This was tested by comparison with an independent set of GPS/levelling geoid undulations that were not included in the computed solutions. By these tests, the precision of the hybrid geoid is estimated to be 3.7 cm. This precision proved to be better, by a factor of two, than the corresponding one estimated from the pure gravimetric geoid. This project has been also useful to verify the importance and reliability of GGMs developed from the last satellite gravity missions (GOCE and GRACE) that have significantly improved our knowledge of the long wavelength components of the Earth’s gravity field, especially in areas with poor coverage of terrestrial gravity data. In fact, the geoid models based on satellite-only GGMs proved to have a better performance, despite the lower spatial resolution with respect to high-resolution models (i.e., Earth Gravitational Model 2008 (EGM2008)).
DOI
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