Exploration of the residual topography effect on some functionals of the gravity field

Abstract

The topographical masses, considering their distribution and variations in density, have a measurable influence on Functionals of the Gravity Field (FGF). In this paper, the effect modeled by the Residual Terrain Model (RTM) exerted on the height anomaly, on the gravity anomaly, and on the deflections of the vertical components was explored. The SRTM30 PLUS and DTM2006.0 Digital Elevation Models (DEM), based on a high-pass filter were used in the context of RTM technique. Chile is a natural laboratory for studies in geodynamics considering the characteristics of its topography and crustal structure. Several studies consider the analysis of FGF described in the geopotential space. However, investigations linking the residual effects of topography on these FGF have not yet been reported. Thus, this paper seeks to include this analysis considering two different regions of Chile: the 1st and 8th regions, which have very different crustal characteristics. The results reveal the importance of the contribution of RTM in modeling the high-frequencies of the Earth's gravity field. The values of height anomaly obtained were between 1 m and -1 m, while the gravity anomalies were between 100 mGal and -100 mGal, whereas the deflections of the vertical components reach values between -20 and 18 arcseconds in different topographic settings. The study shows the possibility of retrieving large part of the omission errors in Global Geopotential Models (GGM) by using the RTM technique. Furthermore, the stability of different FGF in relation to the variation of the radius of integration, in the context of the Stokes-Pizzetti formulation was explored. © 2012 Sociedade Brasileira de Geofísica.