ETH-GQS: An estimation of geoid-to-quasigeoid separation over Ethiopia

Ephrem Y. Belay; Walyeldeen Godah; Malgorzata Szelachowska; Robert Tenzer

doi:10.1016/j.geog.2021.09.006

ETH-GQS: An estimation of geoid-to-quasigeoid separation over Ethiopia

Ephrem Y. Belay
, Walyeldeen Godah
, Malgorzata Szelachowska
, Robert Tenzer

Research output: Journal article publication › Journal article › Academic research › peer-review

5 Citations (Scopus)

Abstract

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.

Original language	English
Pages (from-to)	31-37
Number of pages	7
Journal	Geodesy and Geodynamics
Volume	13
Issue number	1
DOIs	https://doi.org/10.1016/j.geog.2021.09.006
Publication status	Published - Jan 2022

Keywords

Airborne gravity data
Ethiopian vertical control network
Geoid-to-quasigeoid separation
GNSS-Levelling
Orthometric and normal heights

ASJC Scopus subject areas

Geophysics
Earth-Surface Processes
Computers in Earth Sciences

More information

10.1016/j.geog.2021.09.006

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@article{4ed700e4a6d241d9880e9b427a347a88,

title = "ETH-GQS: An estimation of geoid-to-quasigeoid separation over Ethiopia",

abstract = "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 Sj{\"o}berg'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.",

keywords = "Airborne gravity data, Ethiopian vertical control network, Geoid-to-quasigeoid separation, GNSS-Levelling, Orthometric and normal heights",

author = "Belay, \{Ephrem Y.\} and Walyeldeen Godah and Malgorzata Szelachowska and Robert Tenzer",

note = "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: {\textcopyright} 2021 The Authors",

year = "2022",

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doi = "10.1016/j.geog.2021.09.006",

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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 - https://www.scopus.com/pages/publications/85122157851

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 -

ETH-GQS: An estimation of geoid-to-quasigeoid separation over Ethiopia

Abstract

Keywords

ASJC Scopus subject areas

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