الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.
iv
Table of Contents
Dedication………………………………………………………………………..The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.
iv
Table of Contents
Dedication………………………………………………………………………..The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.
iv
Table of Contents
Dedication………………………………………………………………………..The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.
iv
Table of Contents
Dedication………………………………………………………………………..The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.
iv
Table of Contents
Dedication………………………………………………………………………..The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.
iv
Table of Contents
Dedication………………………………………………………………………..The aim of this research is to develop a new precise and highresolution
geoid model for Egypt by refining the Global Geopotential
Models (GGMs) through a process named tailoring, where the existing
spherical harmonic coefficients of geopotential model are fitted to the
Egyptian gravity field by integral formulas using an iterative algorithm to
improve the accuracy of the obtained harmonic coefficients.
The satellite-only model GOCO05s (complete to degree and order
280) and ultra-high degree geopotential model EGM2008 (complete to
degree and order 2190) have been tailored to the Egyptian 5′×5′ mean
gravity anomalies in order to select the optimal model that can be used for
the reference gravity field for the new geoid model. The results show that
both EG1GOC5s and EGTM0818 tailored geopotential models give less
and better residual gravity anomalies, where the EGTM0818 tailored model
has been improved significantly by about 27% than the EGM2008 model
similarly, the EG1GOC5s tailored model better than the GOCO05s model
by about 17%.
Gravimetric and combined (gravity and astrogeodetic data) geoids
solutions for Egypt have been computed using both tailored geopotential
models in the remove-restore technique through Least-squares Collocation
(LSC). The computed geoids are fitted to the GPS/levelling stations. The
results show that no significant variance between the gravimetric and
combined geoids solutions exists. In addition, both combined geoids
solutions are given the same accuracy, where RMS ≈ ± 15 cm.
Finally, a comparison between GPS/levelling stations and both
NGRAV-A and NGRAV-B gravimetric geoids computed by using both
EG1GOC5s and EGTM0818 models, respectively, give nearly the same
external accuracy, where the RMS of the differences ± 13 cm for NGRAV-A
and ± 15 cm for NGRAV-B. Therefore, we recommend that both tailored
geopotential models as reliable models for geoid heights over Egypt.