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Abrehdary, Majid
Publications (7 of 7) Show all publications
Saberi, A., Kabolizadeh, M., Rangzan, K. & Abrehdary, M. (2023). Accuracy assessment and improvement of SRTM, ASTER, FABDEM, and MERIT DEMs by polynomial and optimization algorithm: A case study (Khuzestan Province, Iran). Open Geosciences, 15(1), Article ID 20220455.
Open this publication in new window or tab >>Accuracy assessment and improvement of SRTM, ASTER, FABDEM, and MERIT DEMs by polynomial and optimization algorithm: A case study (Khuzestan Province, Iran)
2023 (English)In: Open Geosciences, ISSN 2391-5447, Vol. 15, no 1, article id 20220455Article in journal (Refereed) Published
Abstract [en]

Satellite digital elevation models (DEMs) are used for decision-making in various fields. Therefore, evaluating and improving vertical accuracy of DEM can increase the quality of end products. This article aimed to increase the vertical accuracy of most popular satellite DEMs (i.e., the ASTER, Shuttle Radar Topography Mission [SRTM], Forest And Buildings removed Copernicus DEM [FABDEM], and Multi-Error-Removed Improved-Terrain [MERIT]) using the particle swarm optimization (PSO) algorithm. For this purpose, at first, the vertical error of DEMs was estimated via ground truth data. Next, a second-order polynomial was applied to model the vertical error in the study area. To select the polynomial with the highest accuracy, employed for vertical error modeling, the coefficients of the polynomial have been optimized using the PSO algorithm. Finally, the efficiency of the proposed algorithm has been evaluated by other ground truth data and in situ observations. The results show that the mean absolute error (MAE) of SRTM DEM is 4.83 m while this factor for ASTER DEM is 5.35 m, for FABDEM is 4.28, and for MERIT is 3.87. The obtained results indicated that the proposed model could improve the MAE of vertical accuracy of SRTM, ASTER, FABDEM, and MERIT DEMs to 0.83, 0.51, 0.37, and 0.29 m, respectively. 

Place, publisher, year, edition, pages
De Gruyter Open, 2023
Keywords
Iran; Khuzestan; Decision making; Forestry; Particle swarm optimization (PSO); Polynomials; Surveying; Topography; Tracking radar; Accuracy assessment; Accuracy Improvement; ASTER digital elevation model; Digital elevation model; Digital elevation model accuracy assessment; Digital elevation model accuracy improvement; Modeling accuracy; Optimization algorithms; Shuttle radar topography mission; accuracy assessment; algorithm; ASTER; digital elevation model; optimization; Shuttle Radar Topography Mission; Errors
National Category
Geophysical Engineering Remote Sensing
Identifiers
urn:nbn:se:hv:diva-19828 (URN)10.1515/geo-2022-0455 (DOI)000940164300001 ()2-s2.0-85149312990 (Scopus ID)
Note

CC-BY 4.0

The authors are grateful to the Research Council of Shahid Chamran University of Ahvaz for financial support (SCU.EG1400.26151).

Available from: 2023-11-08 Created: 2023-11-08 Last updated: 2024-01-03Bibliographically approved
Sjöberg, L. & Abrehdary, M. (2022). Combination of three global Moho density contrast models by a weighted least-squares procedure. Journal of Applied Geodesy, 16(4)
Open this publication in new window or tab >>Combination of three global Moho density contrast models by a weighted least-squares procedure
2022 (English)In: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 16, no 4, p. -339Article in journal (Refereed) Published
Abstract [en]

Due to different structures of the Earth’s crust and mantle, there is a significant density contrast at their boundary, the Moho Density Contrast (or shortly MDC). Frequently one assumes that the MDC is about 600 kg/m3, but seismic and gravimetric data show a considerable variation from region to region, and today there are few such studies, and global models are utterly rare. This research determines a new global model, called MDC21, which is a weighted least-squares combination of three available MDC models, pixel by pixel at a resolution of 1° × 1°. For proper weighting among the models, the study starts by estimating lacking standard errors and (frequently high) correlations among them. The numerical investigation shows that MDC21 varies from 21 to 504 kg/m3 in ocean areas and ranges from 132 to 629 kg/m3 in continental regions. The global average is 335 kg/m3. The standard errors estimated in ocean regions are mostly less than 40 kg/m3, while for continental regions it grows to 80 kg/m3. Most standard errors are small, but they reach to notable values in some specific regions. The estimated MDCs (as well as Moho depths) at mid-ocean ridges are small but show significant variations and qualities. © 2022 Walter de Gruyter GmbH, Berlin/Boston 2022.

Place, publisher, year, edition, pages
De Gruyter Open, 2022
Keywords
Errors; Structural geology; Contrast models; Global models; Least Square; Least-square combination; Least-square procedure; Moho; Moho density contrast; Mohorovičić discontinuity; Standard errors; Weighted least-squares; Pixels
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hv:diva-18511 (URN)10.1515/jag-2022-0004 (DOI)000790948400001 ()2-s2.0-85130804668 (Scopus ID)
Note

 This study was supported by project no. 187/18 of the Swedish National Space Agency (SNSA).

Available from: 2022-10-31 Created: 2022-10-31 Last updated: 2022-11-03Bibliographically approved
Abrehdary, M. & Sjöberg, L. (2021). A New Moho Depth Model for Fennoscandia with Special Correction for the Glacial Isostatic Effect. Pure and Applied Geophysics, 178(3), 877-888
Open this publication in new window or tab >>A New Moho Depth Model for Fennoscandia with Special Correction for the Glacial Isostatic Effect
2021 (English)In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 178, no 3, p. 877-888Article in journal (Refereed) Published
Abstract [en]

In this study, we present a new Moho depth model in Fennoscandia and its surroundings. The model is tailored from data sets of XGM2019e gravitationl field, Earth2014 topography and seismic crustal model CRUST1.0 using the Vening Meinesz-Moritz model based on isostatic theory to a resolution of 1° × 1°. To that end, the refined Bouguer gravity disturbance is determined by reducing the observed field for gravity effect of topography, density heterogeneities related to bathymetry, ice, sediments, and other crustal components. Moreover, stripping of non-isostatic effects of gravity signals from mass anomalies below the crust due to crustal thickening/thinning, thermal expansion of the mantle, Delayed Glacial Isostatic Adjustment (DGIA), i.e., the effect of future GIA, and plate flexure has also been performed. As Fennoscandia is a key area for GIA research, we particularly investigate the DGIA effect on the gravity disturbance and gravimetric Moho depth determination in this area. One may ask whether the DGIA effect is sufficiently well removed in the application of the general non-isostatic effects in such an area, and to answer this question, the Moho depth is determined both with and without specific removal of the DGIA effect prior to non-isostatic effect and Moho depth determinations. The numerical results yield that the RMS difference of the Moho depth from our model HVMD19 vs. the seismic CRUST19 and GRAD09 models are 3.8/4.2 km and 3.7/4.0 km when the above strategy for removing the DGIA effect is/is not applied, respectively, and the mean value differences are 1.2/1.4 km and 0.98/1.4 km, respectively. Hence, our study shows that the specific correction for the DGIA effect on gravity disturbance is slightly significant, resulting in individual changes in the gravimetric Moho depth up to − 1.3 km towards the seismic results. On the other hand, our study shows large discrepancies between gravimetric and seismic Moho models along the Norwegian coastline, which might be due to uncompensated non-isostatic effects caused by tectonic motions.

Place, publisher, year, edition, pages
Springer, 2021
Keywords
Delayed glacial isostatic adjustment, Moho depth, satellite altimetry, Vening Meinesz-Moritz, Fennoscandia
National Category
Geophysics
Identifiers
urn:nbn:se:hv:diva-16498 (URN)10.1007/s00024-021-02672-8 (DOI)000618126300001 ()2-s2.0-85101470074 (Scopus ID)
Available from: 2021-05-21 Created: 2021-05-21 Last updated: 2022-11-17Bibliographically approved
Abrehdary, M. & Sjöberg, L. (2021). Moho density contrast in Antarctica determined by satellite gravity and seismic models. Geophysical Journal International, 225(3), 1952-1962
Open this publication in new window or tab >>Moho density contrast in Antarctica determined by satellite gravity and seismic models
2021 (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 225, no 3, p. 1952-1962Article in journal (Refereed) Published
Abstract [en]

As recovering the crust-mantle/Moho density contrast (MDC) significantly depends on the properties of the Earth’s crust and upper mantle, varying from place to place, it is an oversimplification to define a constant standard value for it. It is especially challenging in Antarctica, where almost all the bedrock is covered with a thick layer of ice, and seismic data cannot provide a sufficient spatial resolution for geological and geophysical applications. As an alternative, we determine the MDC in Antarctica and its surrounding seas with a resolution of 1°x 1° by the Vening Meinesz-Moritz gravimetric-isostatic technique using the XGM2019e Earth Gravitational Model and Earth2014 topographic/bathymetric information along with CRUST1.0 and CRUST19 seismic crustal models. The numerical results show that our model, named HVMDC20, varies from 81 kg m-3 in the Pacific Antarctic mid-oceanic ridge to 579 kg m-3 in the Gamburtsev Mountain Range in the central continent with a general average of 403 kg m-3. To assess our computations, we compare our estimates with those of some other gravimetric as well as seismic models (KTH11, GEMMA12C, KTH15C and CRUST1.0), illustrating that our estimates agree fairly well with KTH15C and CRUST1.0 but rather poor with the other models. In addition, we compare the geological signatures with HVMDC20, showing how the main geological structures contribute to the MDC. Finally, we study the remaining glacial isostatic adjustment effect on gravity to figure out how much it affects the MDC recovery, yielding a correlation of the optimum spectral window (7< n <12) between XGM2019e and W12a GIA models of the order of ~0.6 contributing within a negligible \pm 14 kg m-3 to the MDC. 

Place, publisher, year, edition, pages
Oxford University Press, 2021
Keywords
Structural geology, Geological structures; Geophysical applications; Glacial Isostatic Adjustments; Gravitational model; Mid oceanic ridges; Numerical results; Satellite gravity; Spatial resolution, Seismology
National Category
Geophysics
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-17514 (URN)10.1093/gji/ggab069 (DOI)2-s2.0-85114994287 (Scopus ID)
Note

This study was supported by project no. 187/18 of the Swedish National Space Agency (SNSA)

Available from: 2021-09-30 Created: 2021-09-30 Last updated: 2021-09-30
Abrehdary, M. & Sjöberg, L. E. (2020). Estimating a combined Moho model for marine areas via satellite altimetric: gravity and seismic crustal models. Studia Geophysica et Geodaetica, 64, 1-25
Open this publication in new window or tab >>Estimating a combined Moho model for marine areas via satellite altimetric: gravity and seismic crustal models
2020 (English)In: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 64, p. 1-25Article in journal (Refereed) Published
Abstract [en]

Isostasy is a key concept in geoscience in interpreting the state of mass balance between the Earth's lithosphere and viscous asthenosphere. A more satisfactory test of isostasy is to determine the depth to and density contrast between crust and mantle at the Moho discontinuity (Moho). Generally, the Moho can be mapped by seismic information, but the limited coverage of such data over large portions of the world (in particular at seas) and economic considerations make a combined gravimetric-seismic method a more realistic approach. The determination of a high-resolution of the Moho constituents for marine areas requires the combination of gravimetric and seismic data to diminish substantially the seismic data gaps. In this study, we estimate the Moho constituents globally for ocean regions to a resolution of 1° × 1° by applying the Vening Meinesz-Moritz method from gravimetric data and combine it with estimates derived from seismic data in a new model named COMHV19. The data files of GMG14 satellite altimetry-derived marine gravity field, the Earth2014 Earth topographic/bathymetric model, CRUST1.0 and CRUST19 crustal seismic models are used in a least-squares procedure. The numerical computations show that the Moho depths range from 7.3 km (in Kolbeinsey Ridge) to 52.6 km (in the Gulf of Bothnia) with a global average of 16.4 km and standard deviation of the order of 7.5 km. Estimated Moho density contrasts vary between 20 kg m-3 (north of Iceland) to 570 kg m-3 (in Baltic Sea), with a global average of 313.7 kg m-3 and standard deviation of the order of 77.4 kg m-3. When comparing the computed Moho depths with current knowledge of crustal structure, they are generally found to be in good agreement with other crustal models. However, in certain regions, such as oceanic spreading ridges and hot spots, we generally obtain thinner crust than proposed by other models, which is likely the result of improvements in the new model. We also see evidence for thickening of oceanic crust with increasing age. Hence, the new combined Moho model is able to image rather reliable information in most of the oceanic areas, in particular in ocean ridges, which are important features in ocean basins.

Keywords
Moho density contrast, Moho depth, satellite altimetry, uncertainty, Vening Meinesz-Moritz
National Category
Geophysics
Research subject
ENGINEERING, Geodesy
Identifiers
urn:nbn:se:hv:diva-14873 (URN)10.1007/s11200-019-1067-0 (DOI)000500877200001 ()2-s2.0-85076399462 (Scopus ID)
Funder
Swedish National Space Board, 187/18
Available from: 2020-01-29 Created: 2020-01-29 Last updated: 2021-02-09Bibliographically approved
Abrehdary, M., Sjöberg, L. E. & Sampietro, D. (2019). Contribution of satellite altimetry in modelling Moho density contrast in oceanic areas. Journal of Applied Geodesy, 3(1), 33-40
Open this publication in new window or tab >>Contribution of satellite altimetry in modelling Moho density contrast in oceanic areas
2019 (English)In: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 3, no 1, p. 33-40Article in journal (Refereed) Published
Abstract [en]

The determination of the oceanic Moho (or crust-mantle) density contrast derived from seismic acquisitions suffers from severe lack of data in large parts of the oceans, where have not yet been sufficiently covered by such data. In order to overcome this limitation, gravitational field models obtained by means of satellite altimetry missions can be proficiently exploited, as they provide global uniform information with a sufficient accuracy and resolution for such a task. In this article, we estimate a new Moho density contrast model named MDC2018, using the marine gravity field from satellite altimetry in combination with a seismic-based crustal model and Earth's topographic/bathymetric data. The solution is based on the theory leading to Vening Meinesz-Moritz's isostatic model. The study results in a high-accuracy Moho density contrast model with a resolution of 1° × 1° in oceanic areas. The numerical investigations show that the estimated density contrast ranges from 14.2 to 599.7 kg/m3 with a global average of 293 kg/m3. In order to evaluate the accuracy of the MDC2018 model, the result was compared with some published global models, revealing that our altimetric model is able to image rather reliable information in most of the oceanic areas. However, the differences between this model and the published results are most notable along the coastal and polar zones, which are most likely due to that the quality and coverage of the satellite altimetry data are worsened in these regions.

Keywords
Aneroid altimeters; Coastal zones; Seismology, GMG2014; Isostasy; MDC2018; Moho Density Contrast; Satellite altimetry; Vening Meinesz-Moritz, Satellites
National Category
Geophysics
Research subject
ENGINEERING, Geodesy
Identifiers
urn:nbn:se:hv:diva-13120 (URN)10.1515/jag-2018-0034 (DOI)2-s2.0-85055655330 (Scopus ID)
Available from: 2018-11-13 Created: 2018-11-13 Last updated: 2020-01-27Bibliographically approved
Abrehdary, M. & Sjöberg, L. (2019). Recovering Moho constituents from satellite altimetry and gravimetric data for Europe and surroundings. Journal of Applied Geodesy, 13(4), 291-303
Open this publication in new window or tab >>Recovering Moho constituents from satellite altimetry and gravimetric data for Europe and surroundings
2019 (English)In: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 13, no 4, p. 291-303Article in journal (Refereed) Published
Abstract [en]

In this research, we present a local Moho model, named MOHV19, including Moho depth and Moho density contrast (or shortly Moho constituents) with corresponding uncertainties, which are mapped from altimetric and gravimetric data (DSNSC08) in addition to seismic tomographic (CRUST1.0) and Earth topographic data (Earth2014) to a resolution of 1° × 1° based on a solution of Vening Meinesz-Moritz' theory of isostasy. The MOHV19 model covers the area of entire European plate along with the surrounding oceans, bounded by latitudes (30 °N–82 °N) and longitudes (40 °W–70 °E). The article aims to interpret the Moho model resulted via altimetric and gravimetric information from the geological and geophysical perspectives along with investigating the relation between the Moho depth and Moho density contrast. Our numerical results show that estimated Moho depths range from 7.5 to 57.9 km with continental and oceanic averages of 41.3 ± 4.9 km and 21.6 ± 9.2 km, respectively, and an overall average of 30.9 ± 12.3 km. The estimated Moho density contrast ranges from 60.2 to 565.8 kg/m3, with averages of 421.8 ± 57.9 and 284.4 ± 62.9 kg/m3 for continental and oceanic regions, respectively, with a total average of 350.3 ± 91.5 kg/m3. In most areas, estimated uncertainties in the Moho constituents are less than 3 km and 40 kg/m3, respectively, but they reach to much more significant values under Iceland, parts of Gulf of Bothnia and along the Kvitoya Island. Comparing the Moho depths estimated by MOHV19 and those derived by CRUST1.0, MDN07, GRAD09 and MD19 models shows that MOHV19 agree fairly well with CRUST1.0 but rather poor with other models. The RMS difference between the Moho density contrasts estimated by MOHV19 and CRUST1.0 models is 49.45 kg/m3.

Keywords
Geodesy; Gravimetric analysis, Altimetry; Europe; Isostasy; Moho density contrast; Moho depth; MOHV19; Vening Meinesz-Moritz, Uncertainty analysis
National Category
Geophysics
Research subject
ENGINEERING, Geodesy
Identifiers
urn:nbn:se:hv:diva-14456 (URN)10.1515/jag-2019-0011 (DOI)2-s2.0-85067414113 (Scopus ID)
Available from: 2019-10-01 Created: 2019-10-01 Last updated: 2020-01-10Bibliographically approved
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