Compatibility of high-altitude aeromagnetic and satellite-altitude magnetic anomalies over Canada

Results from equivalent-source distributions derived jointly from high-altitude (average 4 km) aeromagnetic and Magsat-derived (average 400 km) magnetic anomalies over Canada indicate that long-wavelength components (500–2500 km) in these fields are extremely compatible with one another (with a correlation coefficient of 0.95). The jointly estimated anomaly field at the earth's surface can be used as a long-wavelength adjustment surface for regional near-surface magnetic anomaly compilations and in assessing the performance of other downward-continuation techniques. Because near-surface anomalies are not available over all regions of the world, we compare the jointly estimated anomaly field to the results of two different downward-continuation techniques: the evaluation of anomalies at the earth's surface from spherical harmonic coefficients derived from satellite-altitude data and the use of downward-continuation methods based on harmonic splines. Numerical and visual comparisons of these downward- continued fields with the jointly estimated anomaly field from the equivalent-source method indicate they are well correlated and could provide a useful method of deriving long-wavelength leveling surfaces for regional and worldwide magnetic anomaly maps.

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An equivalent source model of the satellite-altitude magnetic anomaly field over Australia

Earth and Planetary Science Letters ◽

10.1016/0012-821x(80)90266-6 ◽

1980 ◽

Vol 51 (1) ◽

pp. 189-198 ◽

Cited By ~ 43

Author(s):

M.A. Mayhew ◽

B.D. Johnson ◽

R.A. Langel

Keyword(s):

Magnetic Anomaly ◽

Source Model ◽

Anomaly Field ◽

Equivalent Source ◽

Satellite Altitude

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Simulating the Reiner Gamma Swirl and Magnetic Anomaly: The Impact of the Solar Wind Alpha Population

10.5194/egusphere-egu2020-6186 ◽

2020 ◽

Author(s):

Jan Deca ◽

Douglas J. Hemingway ◽

Andrey Divin ◽

Charles Lue ◽

Andrew R. Poppe ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Magnetic Anomaly ◽

Energy Flux ◽

Spatial Scales ◽

Magnetic Anomalies ◽

Lunar Orbit ◽

Near Surface ◽

Lunar Prospector ◽

The Impact

The Reiner Gamma swirl is one of the most prominent albedo features on the lunar surface. Its modest spatial scales and structure allows fully kinetic modelling. The region therefore presents a prime location to investigate the lunar albedo patterns and their co-location with magnetic anomalies. The precise relationship between the impinging plasma and the swirl, and in particular, how these interactions vary over the course of a lunar day, remains an open issue.Here we use the fully kinetic particle-in-cell code,&#160; iPIC3D, coupled with a magnetic field model based on Kaguya and Lunar Prospector observations, and simulate the interaction with the Reiner Gamma anomaly for all plasma regimes the region is exposed to along a typical orbit, including different solar wind incidence angles and the Moon's crossing through the terrestrial magnetosphere. We focus on the impact of the solar wind alpha population and construct energy and velocity distributions in key locations surrounding the interaction region of the anomaly.The energy flux profile provides a better match to the albedo pattern only when integrating over the full lunar orbit. Including He2+ as a self-consistent plasma species improves the brightness ratios between the inner and outer bright lobes, the dark lanes, and the mare background. However, substantial differences between the observed albedo pattern and the predicted flux remain.&#160; For example, the bright outer lobes are substantially brighter than predicted and the central portion of the anomaly is darker than predicted. This is likely due to an incomplete model of the near-surface field structure.Solar wind standoff can explain the large-scale correlation between the Reiner Gamma swirl and the co-located magnetic anomaly. In particular, the outer bright lobes emerge in the simulated weathering pattern only when integrating over the entire lunar orbit, although they are much weaker than observed. Both the proton and helium energy flux to the surface need to be taken into account to best reproduce the swirl pattern. A complete understanding of the solar wind interaction with lunar magnetic anomalies and swirl formation could be vastly improved by low altitude measurements of the magnetic field and solar wind.

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A Stable and High-Precision Downward Continuation Method of Magnetic Data

Applied Sciences ◽

10.3390/app112210881 ◽

2021 ◽

Vol 11 (22) ◽

pp. 10881

Author(s):

Zhiwen Zhou ◽

Jun Wang ◽

Xiaohong Meng ◽

Yuan Fang

Keyword(s):

High Precision ◽

Continuation Method ◽

Target Surface ◽

Lower Surface ◽

Downward Continuation ◽

Calculation Procedure ◽

Continuation Methods ◽

Magnetic Data ◽

Equivalent Source ◽

Original Observation

Downward continuation is an effective technique that can be used to transform the magnetic data measured on one surface to the data that would be measured on another arbitrary lower surface. However, it suffers from amplitude attenuation and is susceptible to noise, especially when the continuation distance is large. To solve these problems, we present a stable and high-precision downward continuation method combining the ideas of equivalent source technique, Tikhonov regularization, radial logarithmic power spectrum analysis, and constrained strategy. To implement this method, the observed data is used to construct the equivalent source in the study area, and the small amount of measured magnetic data at the lower surface (relative to the original observation surface) is employed to constrain the calculation procedure simultaneously. Then the magnetic data at the target surface can be obtained by using a forward calculation procedure instead of the risky downward continuation procedure. The proposed method is tested on both synthetic model data and real magnetic data collected in the South China sea. Various obtained results demonstrate that the method reported in this study has higher accuracy and better noise resistance than the traditional downward continuation methods.

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A Calculation Method of Magnetic Anomaly Field Distribution of Ellipsoid with Arbitrary Posture

International Journal of Pattern Recognition and Artificial Intelligence ◽

10.1142/s0218001421540318 ◽

2021 ◽

Author(s):

Song-tong Han ◽

Bo Zhang ◽

Xiao-li Rong ◽

Lei-xiang Bian ◽

Guo-kai Zhang ◽

...

Keyword(s):

Magnetic Field ◽

Finite Element ◽

Magnetic Anomaly ◽

Field Distribution ◽

Calculation Method ◽

Gravity Potential ◽

Anomaly Field ◽

Finite Element Software ◽

Wide Range ◽

Distribution Equation

The ellipsoidal magnetization model has a wide range of application scenarios. For example, in aviation magnetic field prospecting, mineral prospecting, seabed prospecting, and UXO (unexploded ordnance) detection. However, because the existing ellipsoid magnetization formula is relatively complicated, the detection model is usually replaced by a dipole. Such a model increases the error probability and poses a significant challenge for subsequent imaging and pattern recognition. Based on the distribution of ellipsoid gravity potential and magnetic potential, the magnetic anomaly field distribution equation generated by the ellipsoid is deduced by changing the aspect ratio, making the ellipsoid equivalent to a sphere. The result of formula derivation shows that the two magnetic anomaly fields are consistent. This paper uses COMSOL finite element software to model UXO, ellipsoids, and spheres and analyzes magnetic anomalies. The conclusion shows that the ellipsoid model can completely replace the UXO model when the error range of 1nT is satisfied. Finally, we established two sets of ellipsoids and calculated the magnetic anomalous field distributions on different planes using deduction formulas and finite element software. We compared the experimental results and found that the relative error of the two sets of data was within [Formula: see text]‰. Error analysis found that the error distribution is standardized and conforms to the normal distribution. The above mathematical analysis and finite element simulation prove that the calculation method is simple and reliable and provides a magnetic field distribution equation for subsequent UXO inversion.

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Interpretation of Long Wavelength Magnetic Anomalies

The Solution of the Inverse Problem in Geophysical Interpretation ◽

10.1007/978-1-4684-3962-5_11 ◽

1981 ◽

pp. 231-255 ◽

Cited By ~ 4

Author(s):

Paolo Gasparini ◽

Marta S. M. Mantovani ◽

Wladimir Shukowsky

Keyword(s):

Magnetic Anomalies ◽

Long Wavelength

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Magnetic anomalies at satellite altitude over continent-ocean boundaries

Tectonophysics ◽

10.1016/0040-1951(91)90251-m ◽

1991 ◽

Vol 192 (1-2) ◽

pp. 129-143 ◽

Cited By ~ 10

Author(s):

Kjell L. Hayling

Keyword(s):

Magnetic Anomalies ◽

Satellite Altitude

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A new type of cloud discovered from Earth in the upper Martian atmosphere

10.5194/epsc2021-7 ◽

2021 ◽

Author(s):

Jean Lilensten ◽

Jean-Luc Dauvergne ◽

Christophe Pellier ◽

Marc Delcroix ◽

Emmanuel Beaudoin ◽

...

Keyword(s):

High Altitude ◽

Magnetic Anomaly ◽

Dust Storm ◽

Large Scale ◽

Martian Atmosphere ◽

Ice Clouds ◽

Large Particles ◽

Night Side ◽

Cosmic Particle ◽

New Type

During the 2020 Mars opposition, we observe from Earth the occurrence of a non-typical large-scale high-altitude clouds system, extending over thousands of km from the equator to 50&#176;S. Over 3 hours, they emerge from the night side at an altitude of 90 (-15/+30) km and progressively dissipate in the dayside. They occur at a solar longitude of 316&#176;, west of the magnetic anomaly and concomitantly to a regional dust storm. Despite their high altitude, they are composed of relatively large particles, suggesting a probable CO2 ice composition, although H2O cannot be totally excluded. Such ice clouds were not reported previously. We discuss the formation of this new type of clouds and suggest a possible nucleation from cosmic particle precipitation.

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Analysis of Magnetic Anomaly Characteristics of Underground Non-Coplanar Cross-buried Iron Pipelines

Journal of Environmental and Engineering Geophysics ◽

10.2113/jeeg19-092 ◽

2020 ◽

Vol 25 (2) ◽

pp. 223-233

Author(s):

Pan Wu ◽

Minghui Wei

Keyword(s):

Magnetic Susceptibility ◽

Magnetic Anomaly ◽

Magnetic Dipole ◽

Geomagnetic Field ◽

Magnetic Anomalies ◽

Buried Pipelines ◽

Magnetic Declination ◽

Magnetic Inclination ◽

Basic Characteristics ◽

Geomagnetic Intensity

The non-coplanar cross-buried pipelines are a common way of pipeline wiring. In order to investigate the magnetic anomaly characteristics of the non-coplanar cross-buried pipelines and guide the site operation, the influences of a series of factors on the magnetic anomaly of the non-coplanar cross-buried pipelines are analyzed. Based on the principle of magnetic dipole construction, a forward model is established for the magnetic anomaly characteristics of the subsurface non-coplanar cross-buried pipelines. The basic characteristics of magnetic anomaly for the non-coplanar cross-buried pipelines are defined. The influences of geomagnetic parameters (geomagnetic intensity, geomagnetic inclination, and geomagnetic declination), pipeline parameters (thickness, magnetic susceptibility), and cross angle of pipelines on the characteristics of magnetic anomalies are analyzed. The results show that the shape of the total magnetic anomaly is mainly affected by the magnetic inclination, and the curve of magnetic anomaly at ± I site shows some symmetry. The amplitude is approximately linearly affected by the total geomagnetic field, magnetic declination, pipeline thickness, material magnetic susceptibility, and pipeline cross angle. There is a periodic change of the amplitude with the increase of geomagnetic inclination (−90°–>90°). The crest-trough distance is mainly affected by geomagnetic inclination, magnetic declination, thickness, magnetic susceptibility, and pipeline cross angle. A more accurate measurement can be achieved if the direction of the pipelines is roughly measured and then the number of measurement points is augmented near the intersection of pipelines and the measurement lines. Present work obtains the equivalent magnetic dipole units by segmenting pipelines. The magnetic anomaly characteristics of non-coplanar crossed iron pipelines are successfully simulated. The numerical results are in accordance with the experimental analysis.

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