scholarly journals Multiscale techniques for 3D imaging of magnetic data for archaeo‐geophysical investigations in the Middle East: the case of Tell Barri (Syria)

2019 ◽  
Vol 26 (4) ◽  
pp. 379-395 ◽  
Author(s):  
Giovanni Florio ◽  
Federico Cella ◽  
Luca Speranza ◽  
Raffaele Castaldo ◽  
Raffaella Pierobon Benoit ◽  
...  
Keyword(s):  
Middle East ◽  
3D Imaging ◽  
Magnetic Data ◽  
Geophysical Investigations ◽  
Multiscale Techniques

scholarly journals Magnetometer data from the GRACE satellite duo

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Nils Olsen
Keyword(s):  
Mean Squared Error ◽  
Incident Angle ◽  
Magnetic Data ◽  
Grace Data ◽  
Magnetometer Data ◽  
Geophysical Investigations ◽  
Grace Satellites ◽  
Grace Satellite ◽  
The Difference ◽  
Grace Mission

AbstractThis paper describes and discusses the preprocessing and calibration of the magnetic data taken by the navigational magnetometers onboard the two GRACE satellites, with focus on the almost 10 years period from January 2008 to the end of the GRACE mission in October 2017 for which 1-Hz magnetic data are available. A calibration of the magnetic data is performed by comparing the raw magnetometer sensor readings with model magnetic vector values as provided by the CHAOS-7 geomagnetic field model for the time and position of the GRACE data. The presented approach also accounts for magnetic disturbances produced by the satellite’s magnetorquer and for temperature effects, which are parametrized by the Sun incident angle. The root-mean-squared error of the difference between the calibrated data and CHAOS-7 model values is about 10 nT, which makes the GRACE magnetometer data relevant for geophysical investigations.

scholarly journals Observations of equatorial ionization anomaly over Africa and Middle East during a year of deep minimum

2017 ◽  
Vol 35 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Olawale Bolaji ◽  
Oluwafisayo Owolabi ◽  
Elijah Falayi ◽  
Emmanuel Jimoh ◽  
Afolabi Kotoye ◽  
...  
Keyword(s):  
Middle East ◽  
Continuity Equation ◽  
Equatorial Electrojet ◽  
Data Acquisition System ◽  
Magnetic Data ◽  
Electron Content ◽  
Deep Minimum ◽  
Total Electron ◽  
Equatorial Ionization Anomaly ◽  
Low Latitudes

Abstract. In this work, we investigated the veracity of an ion continuity equation in controlling equatorial ionization anomaly (EIA) morphology using total electron content (TEC) of 22 GPS receivers and three ground-based magnetometers (Magnetic Data Acquisition System, MAGDAS) over Africa and the Middle East (Africa–Middle East) during the quietest periods. Apart from further confirmation of the roles of equatorial electrojet (EEJ) and integrated equatorial electrojet (IEEJ) in determining hemispheric extent of EIA crest over higher latitudes, we found some additional roles played by thermospheric meridional neutral wind. Interestingly, the simultaneous observations of EIA crests in both hemispheres of Africa–Middle East showed different morphology compared to that reported over Asia. We also observed interesting latitudinal twin EIA crests domiciled at the low latitudes of the Northern Hemisphere. Our results further showed that weak EEJ strength associated with counter electrojet (CEJ) during sunrise hours could also trigger twin EIA crests over higher latitudes.

scholarly journals A wavenumber-domain iterative approach for 3D imaging of magnetic anomalies and gradients with depth constraints

2019 ◽  
Vol 16 (6) ◽  
pp. 1032-1047
Author(s):  
Yatong Cui ◽  
Lianghui Guo
Keyword(s):  
Large Scale ◽  
3D Imaging ◽  
Three Dimensional ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Iterative Approach ◽  
Quantitative Interpretation ◽  
Wavenumber Domain ◽  
Large Scale Data ◽  
Scale Data

Abstract Three-dimensional magnetic inversion, based on the least-square and regularization algorithm in the space domain, is an important tool for quantitative interpretation of magnetic data. However, the common 3D inversion approaches usually require great numbers of forward and inversion calculations and cause low efficiency for inverting large-scale data. Three-dimensional imaging is an alternate rapid tool for qualitative and quantitative interpretation of magnetic data. In this paper, we present a wavenumber-domain iterative approach for 3D imaging of magnetic anomalies and gradients, which could increase imaging efficiency and is suitable for rapidly imaging large-scale data. The wavenumber-domain formulas for forward modeling and imaging of total magnetic anomaly, three magnetic components, magnetic gradients and magnetic full-tensor gradients are deduced and provided. A depth-scale factor and the constraints of magnetic interface are included into the imaging formulas to enhance depth resolution. An iterative algorithm is adopted for the imaging to reduce the fitting error and improve the imaging accuracy. Tests on synthetic and real data from the Sichuan basin, China, verified the feasibility of the presented approaches.

Design and calibration of an IVEM for general 3-dimensional imaging of non-diffracting materials

1992 ◽  
Vol 50 (2) ◽  
pp. 1040-1041
Author(s):  
Neil Rowlands ◽  
Jeff Price ◽  
Michael Kersker ◽  
Seichi Suzuki ◽  
Steve Young ◽  
...  
Keyword(s):  
3D Imaging ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3 Dimensional ◽  
3D Microstructure ◽  
Image Translation ◽  
Digital Correlation ◽  
On Line ◽  
Mechanical Stage ◽  
Projection Angle

Three-dimensional (3D) microstructure visualization on the electron microscope requires that the sample be tilted to different positions to collect a series of projections. This tilting should be performed rapidly for on-line stereo viewing and precisely for off-line tomographic reconstruction. Usually a projection series is collected using mechanical stage tilt alone. The stereo pairs must be viewed off-line and the 60 to 120 tomographic projections must be aligned with fiduciary markers or digital correlation methods. The delay in viewing stereo pairs and the alignment problems in tomographic reconstruction could be eliminated or improved by tilting the beam if such tilt could be accomplished without image translation.A microscope capable of beam tilt with simultaneous image shift to eliminate tilt-induced translation has been investigated for 3D imaging of thick (1 μm) biologic specimens. By tilting the beam above and through the specimen and bringing it back below the specimen, a brightfield image with a projection angle corresponding to the beam tilt angle can be recorded (Fig. 1a).

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