Description and validation of the new data to determine a geoid model in Algeria

Abstract

Since 2000, the era of dedicated satellite gravity missions such as CHAMP, GRACE and GOCE has revolutionized our knowledge on the Earth’s gravity field and its changes in time. They will be mapping the Earth’s gravity field with significantly increasing accuracy and spatial resolution. Several new Global Earth Gravity Models were released. These lead to substantial improvements of our knowledge of the long wavelength part of the Earth’s gravity field, and thereby of the long-wavelengths of the geoid. However, the up-to-date, accuracy of the global geoid modelling is a few decimetres and sometimes it may be significantly higher in areas lacking accurate gravity like Algeria, which is not sufficient for many scientific and engineering applications. So, high resolution and accurate local geoid models are still necessary for the most practical purposes. Furthermore, the SRTM has improved tremendously our knowledge of the topography for about 80 percent of the Earth’s land surface and consequently, the new high resolution SRTM global DEM was generated.The computation of the local geoid model via remove-restore technique requires different types of data: good quality gravimetric measurements, an optimum geopotential model, a high resolution digital terrain model, and leveled GPS data. But before integrating them, we must describe and validate these data.