TY - JOUR
T1 - ETH-GQS
T2 - An estimation of geoid-to-quasigeoid separation over Ethiopia
AU - Belay, Ephrem Y.
AU - Godah, Walyeldeen
AU - Szelachowska, Malgorzata
AU - Tenzer, Robert
N1 - Funding Information:
The 2 nd and 3 rd authors' works were conducted in the framework of the statutory project “Problems of Geodesy and Geodynamics” of the Institute of Geodesy and Cartography (IGiK), Warsaw, financially supported by the Polish Ministry of Science and Higher Education . Dr. Tenzer was supported by the Hong Kong GRF RGC project 15218819 : “The modernization of height datum in the Hong Kong territories”.
Publisher Copyright:
© 2021 The Authors
PY - 2022/1
Y1 - 2022/1
N2 - The determination of accurate orthometric or normal heights remains one of the main challenges for the geodetic community in Ethiopia. These heights are required for geodetic and geodynamic scientific research as well as for extensive engineering applications. The main objective of this study is to estimate the geoid-to-quasi geoid separation (GQS) in Ethiopia (ETH-GQS). Such separation would be required for the conversion between geoid and quasigeoid models, which is mandatory for the determination of accurate geodetic heights in mountain regions. The airborne free-air gravity anomalies and the topographic information retrieved from the SRTM3 (Shuttle Radar Topography Mission of a spatial resolution 3 arc-second) digital elevation model were used to compute the ETH-GQS model according to the Sjöberg's strict formula for the geoid-to-quasigeoid separation. The ETH-GQS was then validated using GNSS-levelling data as well as geoid heights determined from different Global Geopotential Models (GGMs), namely the EGM2008, EIGEN-6C4 and GECO. The results reveal that the standard deviation of differences between the geoid heights obtained from the EIGEN-6C4 model and the geometric geoid heights obtained from GNSS-levelling data were improved by ∼75% (i.e. from ∼24 to ∼6 cm) when considering GQS values obtained from the ETH-GQS.
AB - The determination of accurate orthometric or normal heights remains one of the main challenges for the geodetic community in Ethiopia. These heights are required for geodetic and geodynamic scientific research as well as for extensive engineering applications. The main objective of this study is to estimate the geoid-to-quasi geoid separation (GQS) in Ethiopia (ETH-GQS). Such separation would be required for the conversion between geoid and quasigeoid models, which is mandatory for the determination of accurate geodetic heights in mountain regions. The airborne free-air gravity anomalies and the topographic information retrieved from the SRTM3 (Shuttle Radar Topography Mission of a spatial resolution 3 arc-second) digital elevation model were used to compute the ETH-GQS model according to the Sjöberg's strict formula for the geoid-to-quasigeoid separation. The ETH-GQS was then validated using GNSS-levelling data as well as geoid heights determined from different Global Geopotential Models (GGMs), namely the EGM2008, EIGEN-6C4 and GECO. The results reveal that the standard deviation of differences between the geoid heights obtained from the EIGEN-6C4 model and the geometric geoid heights obtained from GNSS-levelling data were improved by ∼75% (i.e. from ∼24 to ∼6 cm) when considering GQS values obtained from the ETH-GQS.
KW - Airborne gravity data
KW - Ethiopian vertical control network
KW - Geoid-to-quasigeoid separation
KW - GNSS-Levelling
KW - Orthometric and normal heights
UR - http://www.scopus.com/inward/record.url?scp=85122157851&partnerID=8YFLogxK
U2 - 10.1016/j.geog.2021.09.006
DO - 10.1016/j.geog.2021.09.006
M3 - Journal article
AN - SCOPUS:85122157851
SN - 2589-0573
VL - 13
SP - 31
EP - 37
JO - Geodesy and Geodynamics
JF - Geodesy and Geodynamics
IS - 1
ER -