The high-resolution gravimetric geoid of Italy: ITG2009

A new geoid computed with high-resolution for Italy, is presented in this paper. The computation of this gravimetric geoid is based on the most recent geopotential model: EGM2008 (Earth Gravity Model released in 2008). The method used in the computation of this new gravimetric geoid has been the Stokes integral in convolution form. The terrain correction has been applied to the gridded gravity anomalies, to obtain the corresponding reduced anomalies. Also the indirect effect has been taken into account. Thus, a new geoid model has been calculated and it is provided as a data grid in the Geodetic Reference System of 1980 (GRS80), distributed for the study area from 37° to 48° of latitude and 6° to 19° of longitude, on a 441 × 521 regular grid with a mesh size of 1.5′ × 1.5′. This new high-resolution geoid and the global geoid EGM2008; are compared with the geoid undulations measured for 11 points of the EUropean Vertical Network (EUVN) on Italy. The new geoid shows an improvement in precision and reliability, fitting the geoidal heights of these EUVN points with more accuracy than the global geoid. Moreover, this new geoid has a smaller standard deviation (12.5 cm) than that obtained by any previous geoid developed for Italy (and the surrounding area) up to date (Pavlis et al., 2008). This new model will be useful for orthometric height determination by GPS over this study area, because it will allow orthometric height determination in the mountains and remote areas, in which levelling has many logistic problems. This new model can be also interesting for other geophysical purposes, other than geodesy and the height measurements, because it can provide a constraint for the density distribution and the thermal state of lithosphere and the viscosity in the mantle. Such details can be inferred from a geoid model and the seismic velocity structure.