IMPROVING EGM2008 BY GPS AND LEVELING DATA AT LOCAL SCALE

Abstract

The development of the Earth Gravitational Model 2008 (EGM2008) model is a
significant contribution for modeling the Earth’s gravity and geoid. Recently, it can
be confidently used versus geometric models following a simple refinement
procedure. Several studies show that, EGM2008 can reach the accuracy of regional
or local geoid models after modeling the differences between the GPS-leveling
geoid heights and EGM2008 derived geoid heights at identified control points. The
study focuses on a corrector surface fitting (CSF) approach based on radial basis
functions (RBF) as improvement procedure for EGM2008. A detailed mathematical
model and solution algorithm of the proposed model is given, and it has been
applied in different test areas covering the city borders of Bursa, Konya, Denizli and
Gaziantep in Turkey. Accuracy of the improved model was evaluated in scattered
check points within test regions. The geoid heights of all check points obtained by
GPS-leveling measurements were compared with the geoid heights obtained from
improved model. The discrepancies between the calculated and measured geoid
heights were analyzed and discussed.