Effect of ASTER DEM on the prediction of mean gravity anomalies: a case study over the Auvergne test region

Abstract

A precise gravimetric geoid determination requires height information and terrestrial gravity data with high accuracy and resolution. The height data is utilized for predicting mean free-air gravity anomalies as well as computing the topographic, atmospheric and downward continuation effects which are fundamental components of any geoid model. Nowadays the Digital Elevation Model (DEM) obtained from the Shuttle Radar Topography Mission (SRTM) has been widely used when an accurate regional DEM does not exist. In addition the DEM generated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was newly released by researchers from Japan and United States. In this study the effect of ASTER DEM on the estimating mean free-air gravity anomalies in geoid determination were investigated in the Auvergne test area where one of its regions exhibits one of the most rugged topography over the world. The numerical results show that ASTER DEM gives worse statistics than SRTM DEM with respect to the accuracy of the height. Using ASTER DEM introduces discrepancies (compared to SRTM DEM) in the range of −4 to 10 mGal in the interpolation of free-air gravity anomalies. It is also proven that the geoid differences due to the use of ASTER DEM are a few centimeters, which remain below the accuracy level of the external GPS-levelling data.

Comparison of Aster and SRTM Digital Elevation Models at One-Arc-Second Resolution Over Turkey

“…Thus a corrector surface is used to remove systematic errors between data before detailed discussion. Corrector surfaces which area from a simple linear model to more sophisticated similarity transformation model can be found in literature (Kotsakis and Sideris, 1999;Abbak, 2014). Such a comparison is based on a traditional method as follows,…”

Kabuk yoğunluğu değişiminin PITE (Birincil Dolaylı Topografik Etki) üzerindeki etkisi

“…SRTM projesinden üretilen 1 saniye çözünürlüklü sayısal yükseklik modeli bu çalışmada SRTM1 olarak adlandırılmıştır. SRTM1 modelinin tüm yeryuvarında düşey doğruluğu 16 m iken, çalışma bölgemizde doğruluğu 3 m'den daha iyidir (Abbak, 2014). Bu model yatay ve düşey datum olarak sırasıyla WGS84 elipsoidini ve EGM96 jeoidini referans alır (Bildirici ve ark., 2007;Bildirici ve Abbak, 2020).…”