Akademik Veri Yönetim Sistemi
27th International Union of Geodesy and Geophysics (IUGG) General Assembly , Montreal, Kanada, 8 - 18 Temmuz 2019, ss.1
One of the most important products of the satellite gravimetry missions (e.g. GRACE, GOCE)
is the recovery of the Global Gravity Field Models (GGM). These GGM’s can be used for
geodetic (e.g. gravimetric geoid modelling) and geophysical purposes (e.g. understanding deep
Earth’s structure). However, before using them, the best-fitting GGM to the local gravity field
is investigated in comparison with independent in-situ observations of Earth gravity field
functionals. In this study, different from previous studies using GPS/leveling data, which may
possibly be affected by the vertical deformation and can be as high as 40 cm (Kilicoglu et al.,
2011), high precision absolute and vertical gravity gradient measurements carried out by
TUBITAK National Metrology Institute and General Directorate of Mapping within the frame
of Turkish Height System Modernization and Gravity Recovery Project over the 2016-2018
period have been used to choose best GGM model for whole Turkey among latest satellite-only
and combined GGM’s (2004-2018). Although, vertical gravity gradient measurements are
mainly carried out for the reduction of absolute gravity measurements from measurement point
to the absolute gravity benchmark, it is demonstrated that vertical gravity gradient data can also
be used for the validation of the GGMs as an independent in-situ data set. GOCE-TIM-R5 and
GOCE-DIR-R5 satelite only models are found to be almost equally the best satellite-only
models suggesting improvements over EGM2008 up to the spherical degree 270. The
significant improvements gained by GOCE models are observed particularly in high mountains
and coastal areas being maximum in the Eastern Black coast.