Formulation and validation of a global laterally varying topographical density model

Abstract The distribution of masses within topography is extremely important for the evaluation of a rigorous geoid model. Most present day models of topographical density are either determined via gravity field inversions or have too coarse a resolution to be useful on a regional level. The ideal solution would be to have a 3-dimensional (3D) density model but such a dataset does not currently exist and would be quite complicated and expensive to develop. As a substitute, a 2-dimensional (2D) topographical density model is presented here through the application of a high resolution lithological map. By assigning probable surface density values and error estimates to the lithologies based on geological data, the Global Lithology Model (GLiM) is transformed into a laterally varying topographical density model (UNB_TopoDens). This model is then validated against present-day global and regional topographical density models. Apart from some water and ice covered regions, the UNB_TopoDens model agrees with all regional and global models at our disposal with the differences all falling within the 95% confidence region associated with the UNB_Topodens model. UNB_TopoDens is the first laterally varying topographical density model with associated error estimates that spans the globe at a 30″ x 30″ resolution and is therefore extremely useful for investigations of the crust and mantle, isostasy, gravimetric studies and various other disciplines.