Refining the estimate of the Italian quasi-geoid.

In this paper the latest Italian quasi-geoid estimation in presented. Comparing to the previous version of the quasi-geoid, ITALGEO99, in this computation new data have been taken into account, relating to gravity and the terrain and sea bed altimetric description. In particular an up-to-date DTM has been realised on the basis of the NASA SRTM 3’’ product, integrating it with other national and international data bases. The gravity data base has been significantly integrated and extended in its geographical boundaries. The recent global geopotential models, based on the space missions CHAMP and GRACE, have been considered, even if the best results have been achieved with the same model used for ITALGEO99, GPM98CR. The quasi-geoid estimation has been computed using the well-known “remove-restore” procedure. The precision of the estimated gravimetric quasi-geoid, ITALGEO05, has been assessed with the recently updated IGM GPS/leveling data, attesting an improvement comparing to the previous estimation.