Basem Elsaka

Basem Elsaka
University of Bonn | Uni Bonn · Institute of Geodesy and Geoinformation (IGG)

BSc., MSc., PhD.

About

45
Publications
10,036
Reads
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244
Citations
Additional affiliations
August 2017 - present
University of Bonn
Position
  • Academic and Technical Staff Member
July 2016 - July 2017
January 2014 - July 2015
King Abdulaziz City for Science and Technology (KACST)
Position
  • Consultant

Publications

Publications (45)
Article
Full-text available
In December 2019, the latest generation transportable superconducting gravimeter (SG) iGrav-043 purchased by the University of Bonn was installed in the Walferdange Underground Laboratory for Geodynamics (WULG) in the Grand Duchy of Luxembourg. In this paper, we estimate the calibration factor of the iGrav-043, which is essential for long-term grav...
Article
Full-text available
Numerous studies for improving gravity field determination from future gravity missions beyond the GRACE/GRACE-FO missions have been proposed during the last decade. In this contribution, full-scale simulated observations of four satellite missions, namely Bender-, Cartwheel-, Helix- and Pendulum-type, in addition to GRACE-FO as a reference mission...
Article
Full-text available
In this contribution, two gravimetric geoid models for Egypt; EGY-LGM2019 and EGY-FGM2019 are developed using the least-squares collocation and the Fast-Fourier Transformation methods, applying Remove-Restore procedure. Different datasets are used in terms of gravity anomalies obtained from GOCE-based SPW-R5 and EGM2008 models, and from 1015 terres...
Article
Full-text available
This contribution provides a comparison between the Gaussian and decorrelationfilters asderived from GRACE products (RL05) estimated by the official GRACE Science Data Systemcentres (GFZ, CSR and JPL) as well as the ITSG-GRACE2016 solutions over Egypt. Theoutcome of this study will help infinding out which of these centres provides improved tempora...
Article
Full-text available
Gravity Recovery and Climate Experiment (GRACE) and its Follow-on (GRACE-FO) satellite missions could provide monthly gravity solutions representing the change in groundwater at both global and river basin scales. In this contribution, two full years of the sixth’s release of GRACE-FO (RL06) decorrelation filtered (DDK1 – DDK8) products estimated b...
Article
Full-text available
Reducing the gravity field raw data influenced by drift effect is remarkable as a pre-processing correction step. Most of the research groups deal with the drift effect as a linear function when reducing the drift effect from the gravimeters raw data. This would be suitable for short time period of gravity data. However, for a long time period this...
Article
Full-text available
Sinking of the Nile Delta region of Egypt is one of urgent issues to be investi-gated due to its vital importance to numerous perspectives such as economic, environmental and social impact on the whole Egyptian territory. This con-tribution represents one of the project outcomes entitled “Evaluation of Nile Delta Sinking Hypothesis Using the Global...
Article
Full-text available
The gravity field and steady-state ocean circulation explorer (GOCE) satellite mission has provided numerous Global Geopotential Models (GGMs) with different processing methodologies and model accuracies. In the current contribution, the latest releases of GOCE-based GGMs are evaluated on the regional scale using the available terrestrial GPS/Level...
Article
Full-text available
An improved hybrid gravimetric geoid model for Egypt, EGY-HGM2016, has been recently computed implementing the least-squares collocation (LSC) method through the remove-compute-restore (RCR) procedure. The computation of EGY-HGM2016 involves different datasets in terms of gravity anomalies determined from the GOCE (gravity field and steady-state oc...
Article
Full-text available
The global geopotential models (GGMs) derived from the gravity field and steady-state ocean circulation explorer (GOCE) mission provide important information about Earth gravity functionals (e.g., geoid heights, gravity anomalies, and disturbances). Among gravity functionals, we utilize geoid heights which have been determined from several recent G...
Article
Full-text available
The Global Geopotential Models (GGMs) of GOCE (Gravity Recovery and steadystate Ocean Circulation Explorer) differ globally as well as regionally in their accuracy and resolution based on the maximum degree and order (d/o) of the fully normalized spherical harmonic (SH) coefficients, which express each GGM. The main idea of this study is to compare...
Article
Full-text available
We compute the secular tectonic motion of the Arabian plate, based on two different sets of Global Navigation Satellite System (GNSS) observations. The first set is formed by continuous GNSS (cGNSS) observations from 10 stations that are being operated since 2000 and have a data time span of at least 3.5 years. The cGNSS is supplemented with a seco...
Article
Global Geopotential Models (GGMs) provide important information about the Earth gravity field in terms of precise gravity anomaly, gravity disturbance and geoid height on global and regional scales. The GGMs based on the Gravity Recovery and steady-state Ocean Circulation Explorer (GOCE) satellite gravity mission provided by the International Cente...
Poster
Full-text available
A newd eveloped gravimetric quasi-geoid, ( known as KSAG0) by Remove-Compute-Restore techniques (RCR), provided by the GRAVSOFT software, using gravimetric free air anomalies. The data consists of1145 terrestrial gravity field anomalies ( observed by ARAMCO Saudi Arabian Oil Company) and 2470 Gravity measurements ( from BGI Bureau Gravimétrique Int...
Article
Full-text available
This contribution investigates two different ways for mitigating the aliasing errors in ocean tides. This is done, on the one hand, by sampling the satellite observations in another direction using the pendulum satellite mission configuration. On the other hand, a mitigation of the temporal aliasing errors in the ocean tides can be achieved by usin...
Conference Paper
Full-text available
The Red Sea is a semi-enclosed basin and exchanges water with the Gulf of Aden through the strait of Bab-el-Mandeb at the southern part of the sea. Its circulation is affected by the Indian Monsoon through its connection via the Gulf of Aden. Two distinctive (in summer and in winter) seasonal signals represent the water exchange. To understand the...
Conference Paper
Full-text available
The gravity field over the Kingdom of Saudi Arabia (KSA), in terms of gravity anomalies, are estimated from the final releases of GOCE-based global Geopotential models ( GOCE-combined models); go_cons_gfc_dir_r4 (DIR4), go_cons_gfc_dir_r5 (DIR5) and GOCE-only models; go_cons_gfc_tim_r4 (TIM4) and go_cons_gfc_tim_r5 (TIM5). These models are compared...
Conference Paper
Full-text available
The free air gravity anomalies over Saudi Arabia (KSA) has been estimated from the final releases of GOCE-based global geopotential models (GGMs) compared with the terrestrial gravity anomalies of 3554 sites. Two GGMs; EGM08 and Eigen-6C3 have been applied. The free-air anomalies from GOCE-based, ∆gGGM, have been calculated over the 3554 stations i...
Conference Paper
Improving the spatial sampling isotropy is considered as a major issue in designing future missions, dedicated to pursue the task of GRACE (Gravity Recovery And Climate Experiment), from which the multi-orbits satellite configuration seems to be a suitable choice since it reduces the temporal aliasing and has the potential to provide a better spati...
Book
Full-text available
The free air gravity anomalies over Saudi Arabia (KSA) has been estimated from the final releases of GOCE-based global geopotential models (GGMs) compared with the terrestrial gravity anomalies of 3554 sites. Two GGMs; EGM08 and Eigen-6C3 have been applied. The free-air anomalies from GOCE-based, ∆gGGM, have been calculated over the 3554 stations i...
Chapter
Full-text available
The project “Future Gravity Field Satellite Missions” (FGM) was a logical consequence of two previous phases in Theme 2 “Observation of the System Earth from Space” in the BMBF/DFG (Federal Ministry of Education and Research/German Research Foundation) Research and Development Programme GEOTECHNOLOGIEN.
Conference Paper
Full-text available
The Wavelets Multi-Resolution Analysis (WMRA) has been used in geodesy to filter, refine, decompose, and analyze earth observations. This technique can be applied for simultaneous analysis of induced inaccurate and non-homogeneous geodetic data. In this paper, we apply the WMRA to decompose the computed regional gravimetric geoid for Saudi Arabia (...
Article
Increasing the spatial sampling isotropy is a major issue in designing future missions dedicated to continue the task of the Gravity Recovery And Climate Experiment (GRACE) mission. From various possible future satellite gravimetry scenarios, the two-pair multi-orbit satellite configuration (Bender-type in the sequence), consisting of a coupled sem...
Conference Paper
The gravity field models from the GRACE and GOCE missions have increased the knowledge of the earth’s global gravity field. The latter GOCE mission has provided accuracies of about 1-2 cm and 1milli-Gal level in the global geoid and gravity anomaly, respectively. However, determining all wavelength ranges of the gravity field spectrum cannot be onl...
Conference Paper
Full-text available
Due to the inaccuracies and non-homogeneity in the gravity observations, computed gravimetric geoid over Saudi Arabia requires filtering. In this investigation, the Wavelet Multi-Resolution Analysis (WMRA) has been used to refine, decompose, analyze, and reconstruct the gravimetric geoid at different levels. By this approach, spatially correlated e...
Conference Paper
Full-text available
The performance of the Bender-type scenario (one single pair of GRACE-type twins in a polar orbit with another pair flying in a relatively lower inclination of 60 degree, Bender et al., 2008) to improve the regional recovery of water storage signals is examined. We created here one full year of simulated observations of the GRACE and Bender configu...
Article
Full-text available
Improving the gravity field recovery in terms of error levels and more isotropic noise distribution by adding cross-track and radial information to the satellite observables has been investigated through a number of studies by a variety of satellite constellations, i.e. satellite pairs that orbit the Earth in alternative configurations than the cur...
Article
Full-text available
There are two spurious jumps in the atmospheric part of the Gravity Recovery and Climate Experiment- Atmosphere and Ocean De-aliasing level 1B (GRACEAOD1B) products, which occurred in January-February of the years 2006 and 2010, as a result of the vertical level and horizontal resolution changes in the ECMWFop (European Centre for Medium-Range Weat...
Article
Full-text available
Monthly solutions of the current GRACE mission are affected by the aliasing problem. In fact, sub-monthly temporal sampling may reduce the temporal aliasing errors but this will be done at the cost of reduced spatial sampling. Reducing the effects of temporal aliasing can be achieved by setting two pairs of satellites in different orbital planes. I...
Article
Full-text available
The goal of this contribution is to focus on improving the quality of gravity field models in the form of spherical harmonic representation via alternative configuration scenarios applied in future gravimetric satellite missions. We performed full-scale simulations of various mission scenarios within the frame work of the German joint research proj...
Data
Full-text available
The twin-satellite mission GRACE has provided a new type of information for Earth sciences by the estimation of numerous static and time-variable gravity field models. However, derived gravity field estimations from GRACE are still non-optimal in term of the error levels and isotropy. The error behavior of GRACE gravity estimations is mostly due to...
Article
Temporal and mean gravity field models derived from the twin-satellite, leader–follower mission GRACE have provided a new type of information for Earth sciences. In this contribution, we study the potential of various alternative satellite formations for gravity field determination in the post-GRACE era in a simulation environment. In particular, t...
Article
Full-text available
Today, the analysis of the Earth's time-variable gravity field plays a key role in Earth system research. The GRACE observables provide an almost direct measurement of the mass that is redistributed at or near the surface of the planet. Yet, important questions such as closing the sea level budget from GRACE, altimetry and steric data still pose a...
Thesis
Full-text available
In this thesis, the concept of satellite formation flight (SFF) is studied by means of simulated satellite observations. With various formation types enabling inter-satellite measurements in various directions (e.g. along-track, cross-track or radial), the principal tasks in global gravity field recovery are tackled: the determination of the static...
Data
Full-text available
Abstract The choice of the repeat periods of the satellite revolutions plays an important rule on the accuracy of the gravity field solutions. This can be noticed in the different gravity solutions of the real GRACE mission due to its different repeat periods (since the mission has no altitude control in orbit). In this study, we investigate the ef...
Presentation
Full-text available
The concept of satellite formation flights for investigating the Earth’s gravity field is discussed. Various proposals have been made in the past and simulation tests have been successfully performed, in most cases to moderate upper spherical harmonic (SH) degrees. In this contribution we will focus on the improvement of the static gravity field fo...
Data
Full-text available
The concept of satellite formation flights for investigating the Earth's gravity field is discussed. Various proposals have been made in the past and simulation tests have been successfully performed, in most cases to moderate upper spherical harmonic (SH) degrees. In this contribution we will focus on the improvement of the static gravity field fo...
Data
Full-text available
A study of the Earth’s gravity field recovery from Satellite-to-Satellite Tracking (SST) data of simulated formation flight missions is presented. New scenarios of multiple formation flights with polar and near-circular satellites’ orbits will be examined. This is done by the combination of various satellite configurations such as GRACE-type scenar...
Article
Full-text available
A study of the Earth's gravity field recovery from Satellite-to-Satellite Tracking (SST) data of simulated formation flight missions is presented. New scenarios of multiple formation flights with near-polar and near-circular satellites' orbits will be examined. This is done by the combination of various satellite configurations such as GRACE-type s...
Data
The recovery of the global gravity field using the utility of Satellite-to-Satellite Tracking (SST) data is applied. A formation flight of multiple orbits of simulated GRACE-like observations (each orbit in this study consists of a twin satellites) of near-polar, near-circular and small eccentric orbit characteristics are investigated. In a first s...

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