Estimation of the Gravity Field and Sea Surface Heights from Heterogeneous Data in the Central Mediterranean

Abstract

The gravity field approximation for the Central Mediterranean is attempted using (a) seagravimetry, (b) bias and tilt adjusted satellite altimetry, (c) bathymetry and mean heights and (d) a “tailored” spherical harmonic coefficient set complete to degree 360 (IfE88). A number of numerical tests is carried out to check the compatibility of the different data types. The Least Squares Collocation (LSC) and the parametric LSC methods are used to predict subsets of the data types(a) and for (b) from subsets of the same data types. The above tests show that the combination of such different data sets gives the optimal approximation of the gravity field in terms of the standard deviation (s.d.) of the observed minus predicted values. Using as input data in the parametric LSC method the data types (a) and (b) (in un-adjusted form) and after the removal of the terrain effect and the contribution of the geopotential model used, an accuracy ±4.3 mgal for gravity anomalies and ±0.04 m for geoidal heights is achieved.