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Bagherbandi, Mohammad, ProfessorORCID iD iconorcid.org/0000-0003-0910-0596
Publications (10 of 64) Show all publications
Amin, H., Sjöberg, L. E. & Bagherbandi, M. (2020). A global vertical datum defined by the conventional geoid potentialand the Earth ellipsoid parameters. In: : . Paper presented at EGU General Assembly 2020, Vienna, Austria, 3-8 May.
Open this publication in new window or tab >>A global vertical datum defined by the conventional geoid potentialand the Earth ellipsoid parameters
2020 (English)Conference paper, Oral presentation with published abstract (Other (popular science, discussion, etc.))
Abstract [en]

According to the classical Gauss–Listing definition, the geoid is the equipotential surface of the Earth’s gravity field that in a least-squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s Global Gravity Models (GGM). Although nowadays, the satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the Mean Earth Ellipsoid (MEE). In this study, we perform joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface, and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite componentof a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e. mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea-level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2s-2 and the semi-major and –minor axes of the MEE,a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of the GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3s-2.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31485 (URN)
Conference
EGU General Assembly 2020, Vienna, Austria, 3-8 May
Available from: 2020-01-18 Created: 2020-01-18 Last updated: 2020-03-04Bibliographically approved
Jouybari, A., Bagherbandi, M. & Nilfouroushan, F. (2020). Assessment of Different GNSS and IMU Observation Weights on Photogrammetry Aerial Triangulation. In: : . Paper presented at FIG Working Week 2020 Amsterdam, the Netherlands, 10–14 May 2020. Amsterdam: FIG
Open this publication in new window or tab >>Assessment of Different GNSS and IMU Observation Weights on Photogrammetry Aerial Triangulation
2020 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Nowadays, the Global Navigation Satellite System (GNSS) and Inertial Navigation System (INS) are playing a prominent character in high accuracy navigation applications. Beside camera calibration and tie points which are crucial, GNSS shift and drift errors, which caused by either unknown GNSS antenna-eccentricity, atmospheric effect, GNSS and INS observation qualities, unsolved datum correction between coordinate systems and far away GNSS reference stations from the project area, are important factors in bundle block adjustment ultimate accuracy. In this study, the influence of different a priori observation uncertainties of GNSS and Inertial Measurement Unit (IMU) using block- Aerial Triangulation (AT) method is examined. We investigate the effect of IMU and GNSS uncertainties on the final AT results using Trimble Inpho Match-AT software by evaluating the checkpoints RMS residual and employing a statistical t-test for determining the number of images with the gross error. In our study area, the most trustworthy observation uncertainties was 0.2, 0.2, 0.2 meter for East, North, and Height of the GNSS components respectively, and 0.007, 0.007, 0.009 for Omega, Phi, and Kappa for the IMU orientations, respectively.

Place, publisher, year, edition, pages
Amsterdam: FIG, 2020
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:hig:diva-32246 (URN)
Conference
FIG Working Week 2020 Amsterdam, the Netherlands, 10–14 May 2020
Available from: 2020-04-29 Created: 2020-04-29 Last updated: 2020-05-04Bibliographically approved
Bagherbandi, M. & Gido, N. A. A. (2020). How isostasy explains continental rifting in East Africa?. In: : . Paper presented at EGU General Assembly 2020, Vienna, Austria, 3-8 May.
Open this publication in new window or tab >>How isostasy explains continental rifting in East Africa?
2020 (English)Conference paper, Poster (with or without abstract) (Other (popular science, discussion, etc.))
Abstract [en]

The principle of isostasy plays an important role to understand the relation between different geodynamic processes. Although, it is difficult to find an exact method that delivers a complete image of the Earth structure. However, gravimetric methods are alternative to provide images of the interior of the Earth. The Earth’s crust parameters, i.e. crustal depth and crust-mantle density contrast, can reveal adequate information about the solid Earth system such as volcanic activity, earthquake and continental rifting. Hence, in this study, a combine Moho model using seismic and gravity data is determined to investigate the relationship between the isostatic state of the lithosphere and seismic activities in East Africa. Our results show that isostatic equilibrium and compensation states are closely correlated to the seismicity patterns in the study area. For example, several studies suggest that African superplume causes the rift valley, and consequently differences in crustal and mantle densities occur. This paper presents a method to determine the crustal thickness and crust-mantle density contrast and consequently one can observe low-density contrast (about 200 kg/m3 ) and thin crust (about 30 km) near the triple junction plate tectonics in East Africa (Afar Triangle), which confirms the state of overcompensation in the rift valley areas. Furthermore, the density structure of the lithosphere shows a large correlation with the earthquake activity, sub-crustal stress and volcanic distribution across East Africa.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31487 (URN)
Conference
EGU General Assembly 2020, Vienna, Austria, 3-8 May
Available from: 2020-01-18 Created: 2020-01-18 Last updated: 2020-01-20Bibliographically approved
Amin, H., Bagherbandi, M. & Sjöberg, L. E. (2020). Quantifying barystatic sea-level change from satellite altimetry, GRACE and Argo observations over 2005–2016. Advances in Space Research, 65(8), 1922-1940
Open this publication in new window or tab >>Quantifying barystatic sea-level change from satellite altimetry, GRACE and Argo observations over 2005–2016
2020 (English)In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 65, no 8, p. 1922-1940Article in journal (Refereed) Published
Abstract [en]

Time-varying spherical harmonic coefficients determined from the Gravity Recovery and Climate Experiment (GRACE) data provide a valuable source of information about the water mass exchange that is the main contributor to the Earth’s gravity field changes within a period of less than several hundred years. Moreover, by measuring seawater temperature and salinity at different layers of ocean depth, Argo floats help to measure the steric component of global mean sea level (GMSL). In this study, we quantify the rate of barystatic sea-level change using both GRACE RL05 and RL06 monthly gravity field models and compare the results with estimates achieved from a GMSL budget closure approach. Our satellite altimetry-based results show a trend of 3.90 ± 0.14 mm yr−1 for the GMSL rise. About 35% or 1.29 ± 0.07 mm yr−1 of this rate is caused by the thermosteric contribution, while the remainder is mainly due to the barystatic contribution. Our results confirm that the choice of decorrelation filters does not play a significant role in quantifying the global barystatic sea-level change, and spatial filtering may not be needed. GRACE RL05 and RL06 solutions result in the barystatic sea-level change trends of 2.19 ± 0.13 mm yr−1 and 2.25 ± 0.16 mm yr−1, respectively. Accordingly, the residual trend, defined as the difference between the altimetry-derived GMSL and sum of the steric and barystatic components, amounts to 0.51 ± 0.51 and 0.45 ± 0.44 mm yr−1 for RL05 and RL06-based barystatic sea-level changes, respectively, over January 2005 to December 2016. The exclusion of the halosteric component results in a lower residual trend of about 0.36 ± 0.46 mm yr−1 over the same period, which suggests a sea-level budget closed within the uncertainty. This could be a confirmation on a high level of salinity bias particularly after about 2015. Moreover, considering the assumption that the GRACE-based barystatic component includes all mass change signals, the rather large residual trend could be attributed to an additional contribution from the deep ocean, where salinity and temperature cannot be monitored by the current observing systems. The errors from various sources, including the model-based Glacial Isostatic Adjustment signal, independent estimation of geocenter motion that are not quantified in the GRACE solutions, as well as the uncertainty of the second degree of zonal spherical harmonic coefficients, are other possible contributors to the residual trend.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Climate change, Sea-level budget, Decorrelation, Barystatic sea-level change, Steric sea-level change
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31978 (URN)10.1016/j.asr.2020.01.029 (DOI)000533504300004 ()2-s2.0-85079432165 (Scopus ID)
Note

Funding: CSIRO, NASA, NOAA

Available from: 2020-03-02 Created: 2020-03-02 Last updated: 2020-06-05Bibliographically approved
Shirazian, M., Jazireeyan, I. & Bagherbandi, M. (2020). Reality measure of the published GPS satellite ephemeris uncertainties. Journal of Spatial Science
Open this publication in new window or tab >>Reality measure of the published GPS satellite ephemeris uncertainties
2020 (English)In: Journal of Spatial Science, ISSN 1449-8596Article in journal (Refereed) Epub ahead of print
Abstract [en]

The international GNSS service (IGS) started publishing the precise ephemeris files in the form of the standard products #3, version C (the sp3c files) in which the GPS satellite orbits and clocks and their uncertainties were available since 2004. Incorporating these uncertainties into the GPS observation equations results in a better stochastic model of the processing system. The reality of these uncertainties is questioned and studied in this paper. Precise point positioning (PPP) model, statistical tests and variance component estimation (VCE) techniques are employed for this study. The results confirm the efficiency of the proposed method in the assessment of reality of the published ephemeris uncertainties.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2020
Keywords
PPP, VCE, precise ephemeris, uncertainties
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-32221 (URN)10.1080/14498596.2020.1746702 (DOI)000532108500001 ()2-s2.0-85085043262 (Scopus ID)
Available from: 2020-04-24 Created: 2020-04-24 Last updated: 2020-06-02Bibliographically approved
Gido, N. A. A., Amin, H., Bagherbandi, M. & Nilfouroushan, F. (2020). Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data. In: : . Paper presented at EGU General Assembly 2020, Vienna, Australia, 3-8 May.
Open this publication in new window or tab >>Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data
2020 (English)Conference paper, Oral presentation with published abstract (Other (popular science, discussion, etc.))
Abstract [en]

Monitoring environmental hazards, due to natural and anthropogenic causes, is one of the important issues, which requires proper data, models, and cross-validation of the results. The geodetic satellite missions, e.g. the Gravity Recovery and Climate Experiment (GRACE) and Sentinel-1, are very useful in this aspect. GRACE missions are dedicated to model the temporal variations of the Earth’s gravity field and mass transportation in the Earth’s surface, whereas Sentinel-1 collects Synthetic Aperture Radar (SAR) data which enables us to measure the ground movements accurately. Extraction of large volumes of water and oil decreases the reservoir pressure, form compaction and consequently land subsidence occurs which can be analyzed by both GRACE and Sentinel-1 data. In this paper, large-scale groundwater storage (GWS) changes are studied using the GRACE monthly gravity field models together with different hydrological models over the major oil reservoirs in Sudan, i.e. Heglig, Bamboo, Neem, Diffra and Unity-area oil fields. Then we correlate the results with the available oil wells production data for the period of 2003-2012. In addition, using the only freely available Sentinel-1 data, collected between November 2015 and April 2019, the ground surface deformation associated with this oil and water depletion is studied. Due to the lack of terrestrial geodetic monitoring data in Sudan, the use of GRACE and Sentinel-1 satellite data is very valuable to monitor water and oil storage changes and their associated land subsidence over our region of interest. Our results show that there is a significant correlation between the GRACE-based GWS change and extracted oil and water volumes. The trend of GWS changes due to water and oil depletion ranged from -18.5 to -6.2mm/year using the CSR GRACE monthly solutions and the best tested hydrological model in this study. Moreover, our Sentinel-1 SAR data analysis using Persistent Scatterer Interferometry (PSI) method shows high rate of subsidence i.e. -24.5, -23.8, -14.2 and -6 mm/year over Heglig, Neem, Diffra and Unity-area oil fields respectively. The results of this study can help us to control the integrity and safety of operations and infrastructure in that region, as well as to study the groundwater/oil storage behavior.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31486 (URN)
Conference
EGU General Assembly 2020, Vienna, Australia, 3-8 May
Available from: 2020-01-18 Created: 2020-01-18 Last updated: 2020-01-20Bibliographically approved
Gido, N. A. A., Amin, H., Bagherbandi, M. & Nilfouroushan, F. (2020). Satellite Monitoring of Mass Changes and Ground Subsidence in Sudan’s Oil Fields Using GRACE and Sentinel-1 Data. Remote Sensing, 12(11), Article ID 1792.
Open this publication in new window or tab >>Satellite Monitoring of Mass Changes and Ground Subsidence in Sudan’s Oil Fields Using GRACE and Sentinel-1 Data
2020 (English)In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 12, no 11, article id 1792Article in journal (Refereed) Published
Abstract [en]

Monitoring environmental hazards, owing to natural and anthropogenic causes, is an important issue, which requires proper data, models, and cross-validation of the results. The geodetic satellite missions, for example, the Gravity Recovery and Climate Experiment (GRACE) and Sentinel-1, are very useful in this respect. GRACE missions are dedicated to modeling the temporal variations of the Earth’s gravity field and mass transportation in the Earth’s surface, whereas Sentinel-1 collects synthetic aperture radar (SAR) data, which enables us to measure the ground movements accurately. Extraction of large volumes of water and oil decreases the reservoir pressure and form compaction and, consequently, land subsidence occurs, which can be analyzed by both GRACE and Sentinel-1 data. In this paper, large-scale groundwater storage (GWS) changes are studied using the GRACE monthly gravity field models together with different hydrological models over the major oil reservoirs in Sudan, that is, Heglig, Bamboo, Neem, Diffra, and Unity-area oil fields. Then, we correlate the results with the available oil wells production data for the period of 2003–2012. In addition, using the only freely available Sentinel-1 data, collected between November 2015 and April 2019, the ground surface deformation associated with this oil and water depletion is studied. Owing to the lack of terrestrial geodetic monitoring data in Sudan, the use of GRACE and Sentinel-1 satellite data is very valuable to monitor water and oil storage changes and their associated land subsidence over our region of interest. Our results show that there is a significant correlation between the GRACE-based GWS anomalies (ΔGWS) and extracted oil and water volumes. The trend of ΔGWS changes due to water and oil depletion ranged from –18.5 ± 6.3 to –6.2 ± 1.3 mm/year using the CSR GRACE monthly solutions and the best tested hydrological model in this study. Moreover, our Sentinel-1 SAR data analysis using the persistent scatterer interferometry (PSI) method shows a high rate of subsidence, that is, –24.5 ± 0.85, –23.8 ± 0.96, –14.2 ± 0.85, and –6 ± 0.88 mm/year over Heglig, Neem, Diffra, and Unity-area oil fields, respectively. The results of this study can help us to control the integrity and safety of operations and infrastructure in that region, as well as to study the groundwater/oil storage behavior.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
groundwater; GRACE; hydrological model; oil depletion; land subsidence; InSAR
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-32371 (URN)10.3390/rs12111792 (DOI)
Available from: 2020-06-03 Created: 2020-06-03 Last updated: 2020-06-03Bibliographically approved
Sjöberg, L. E. & Bagherbandi, M. (2020). Upper mantle density and surface gravity change in Fennoscandia, determined from GRACE monthly data. Tectonophysics, 782-783, Article ID 228428.
Open this publication in new window or tab >>Upper mantle density and surface gravity change in Fennoscandia, determined from GRACE monthly data
2020 (English)In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 782-783, article id 228428Article in journal (Refereed) Published
Abstract [en]

Precise gravity measurements have been repeatedly observed in Fennoscandia since the 1960-ties, first by relative gravimeters, then by absolute gravimeters, for studying the temporal change of gravity related with the on-going glacial isostatic adjustment (GIA). The results of such studies are vital for understanding GIA processes and tuning GIA and Earth structure models.

This study uses monthly repeated data from the twin satellite mission GRACE for 164 months between 2003 and 2016 for estimating the temporal change of surface gravity, its ratio (f) to the land uplift rate as well as the upper mantle density related with the viscous mass flow in the mantle. The maximum negative change of gravity is estimated to −1.8 μGal/yr, and f is estimated to −0.172 ± 0.018 μGal/mm.

The solutions for f from the three independent techniques (relative, absolute and satellite gravity observations) were found to agree statistically without significant biases, and they were merged in a joint solution to −0.166 ± 0.004 μGal/mm, corresponding to a mean upper mantle mass flow density of 3402.5 ± 95 kg/m3, which decreases towards the uplift center.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Fennoscandia, Glacial isostatic adjustment, Gravity change, Mantle density, Postglacial rebound
National Category
Geophysics Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:hig:diva-32213 (URN)10.1016/j.tecto.2020.228428 (DOI)000531065200005 ()2-s2.0-85083816750 (Scopus ID)
Available from: 2020-04-23 Created: 2020-04-23 Last updated: 2020-05-25Bibliographically approved
Amin, H., Sjöberg, L. & Bagherbandi, M. (2019). A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters. Journal of Geodesy, 93(10), 1943-1961
Open this publication in new window or tab >>A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters
2019 (English)In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 93, no 10, p. 1943-1961Article in journal (Refereed) Published
Abstract [en]

The geoid, according to the classical Gauss–Listing definition, is, among infinite equipotential surfaces of the Earth’s gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.

Keywords
Geodetic reference system, Geoid potential W0, Global vertical datum, Mean Earth ellipsoid, Reference ellipsoid
National Category
Climate Research Geophysics Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-30666 (URN)10.1007/s00190-019-01293-3 (DOI)000495245100009 ()2-s2.0-85073812763 (Scopus ID)
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-11-28Bibliographically approved
Gido, N. A. A., Bagherbandi, M. & Sjöberg, L. E. (2019). A gravimetric method to determine horizontal stress field due to flow in the mantle in Fennoscandia. Geosciences Journal, 23(3), 377-389
Open this publication in new window or tab >>A gravimetric method to determine horizontal stress field due to flow in the mantle in Fennoscandia
2019 (English)In: Geosciences Journal, ISSN 1226-4806, Vol. 23, no 3, p. 377-389Article in journal (Refereed) Published
Abstract [en]

Mass changes and flow in the Earth's mantle causes the Earth's crust not only to movevertically, but also horizontally and to tilt, and produce a major stress in the lithosphere.Here we use a gravimetric approach to model sub-lithosphere horizontal stress in theEarth's mantle and its temporal changes caused by geodynamical movements likemantle convection in Fennoscandia. The flow in the mantle is inferred from tectonicsand convection currents carrying heat from the interior of the Earth to the crust. Theresult is useful in studying how changes of the stress influence the stability of crust.The outcome of this study is an alternative approach to studying the stress and itschange using forward modelling and the Earth's viscoelastic models. We show that thedetermined horizontal stress using a gravimetric method is consistent with tectonicsand seismic activities. In addition, the secular rate of change of the horizontal stress,which is within 95 kPa/year, is larger outside the uplift dome than inside.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
horizontal stress, mantle convection, mass change, stress field, tectonics
National Category
Geophysics
Identifiers
urn:nbn:se:hig:diva-27317 (URN)10.1007/s12303-018-0046-8 (DOI)000469221700002 ()2-s2.0-85054552297 (Scopus ID)
Available from: 2018-06-24 Created: 2018-06-24 Last updated: 2019-08-22Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0910-0596

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