f Production and Use of Global Topography Models in Gravity Compilations

Over the last ten years GETECH has undertaken a number of continutal scale gravity compilation projects for Africa, South America, Europe, South East and North Central Asia. In all the total number of land and marine gravity stations involved exceeds 12 million (4,500,000 land and 7,700,000 marine). An integral part of each of these compilations has been the construction of a digital terrain model which improves on available models, namely the ETOPO5 grid or variations on it. Such a topographic model enables us to calculate full Bouguer anomalies by overcoming the processing problems concurrent with gravity stations having no preserved elevation information and in the calculation of terrain corrections which are aften not measured or recorded with the gravity data received.