COMMENTS ON “INTERRELATIONSHIPS BETWEEN MAGNETIC ANOMALY COMPONENTS”

Geophysics ◽  
1959 ◽  
Vol 24 (2) ◽  
pp. 366-369 ◽  
Author(s):  
Aivars Celmins
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomaly ◽  
Simple Formula ◽  
Magnetic Anomalies ◽  
Horizontal Component ◽  
Two Dimensional ◽  
Interesting Behavior ◽  
Normal Magnetic Field

On page 748 of the above named paper, Affleck (1958) mentions an interesting behavior of magnetic anomalies which are caused by homogeneous magnetized two‐dimensional bodies. He states that in these cases the airborne magnetometer anomaly can be treated as either the vertical or horizontal component anomaly if the true magnetization is replaced by a pseudo‐magnetization of other direction and intensity. It may be of some interest to formulate this behavior more precisely, so much the more as the interdependence between the magnetization directions and the direction of a normal magnetic field can be expressed by a rather simple formula.

Anti-crossing of Landau levels of different two-dimensional subbands in GaAs in normal magnetic field

2001 ◽  
Vol 298 (1-4) ◽  
pp. 359-363
Author(s):  
D.Yu Ivanov ◽  
V.A Volkov ◽  
Yu.V Dubrovskii ◽  
E.E Takhtamirov ◽  
E.E Vdovin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Landau Levels ◽  
Two Dimensional ◽  
Normal Magnetic Field

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

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

<p>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.</p><p>Here we use the fully kinetic particle-in-cell code,  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.</p><p>The energy flux profile provides a better match to the albedo pattern only when integrating over the full lunar orbit. Including He<sup>2+</sup> 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.  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.</p><p>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.</p>

Pigeons at Magnetic Anomalies: The Effects of Loft Location

1992 ◽  
Vol 170 (1) ◽  
pp. 127-141 ◽  
Author(s):  
CHARLES WALCOTT
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Earth’S Magnetic Field ◽  
Homing Pigeons ◽  
Magnetic Gradient ◽  
Earth's Magnetic Field

Homing pigeons from our old lofts at Fox Ridge Farm in Lincoln, MA, were disoriented when released at places where the earth's magnetic field was irregular-so-called ‘magnetic anomalies’. The orientation of pigeons raised in our lofts at Cornell in Ithaca, NY, was unaffected by anomalies. Further experiments in Lincoln showed that sibling pigeons raised and trained to lofts only 2.5 km apart behaved differently when released at a strong magnetic anomaly. Pigeons from the loft situated in a magnetic gradient of 450 nT km−1 were disoriented at anomalies, whereas birds raised in a loft in a magnetic gradient of 88nT km−1 were well oriented. This suggests that the location of the home loft may play an important role in determining which cues pigeons use for their navigation, and that these cues are learned sometime after weaning from their parents at 4–6 weeks after hatching.

QUANTITATIVE INTERPRETATION OF VERTICAL MAGNETIC ANOMALIES OVER VEINS

Geophysics ◽  
1950 ◽  
Vol 15 (4) ◽  
pp. 667-686 ◽  
Author(s):  
Kenneth L. Cook
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomaly ◽  
Magnetic Induction ◽  
Vertical Component ◽  
Magnetic Anomalies ◽  
Quantitative Interpretation ◽  
Magnetic Intensity ◽  
Magnetic Inclination ◽  
Magnetic North ◽  
The Magnetic Field

By using ordinary magnetic induction methods of analysis, Haalck, Heiland, and others have developed formulas which express the magnetic anomaly over a vertical or inclined vein of tabular shape as a function of the susceptibility, dimensions, shape, and disposition of the vein, and of the strength and direction of the earth’s magnetic field. On the basis of these fundamental formulas, other formulas for the vertical component of the magnetic field are derived in the present paper for such veins in intermediate northern magnetic latitudes. Special emphasis is given to the orientation of the veins relative to the magnetic north direction. Several families of vertical magnetic intensity curves for veins with different strikes and dips are given. All theoretical curves for veins striking magnetic north are plotted in terms of a parametric unit so that, once plotted, they can be used repeatedly in different districts, provided a proper multiplying factor is chosen for the observed curve. The importance of the transverse horizontal magnetization effect under certain conditions of orientation is demonstrated. It is shown mathematically that small vertical magnetic anomalies are to be expected for thin veins striking east and dipping south at an angle equal to, or approximately equal to, the complement of the angle of magnetic inclination.

scholarly journals Detection of ferromagnetic objects in local magnetic anomaly of the Baltic Sea

2008 ◽  
Vol 15 (2) ◽  
pp. 77-82 ◽  
Author(s):  
Mirosław Wołoszyn
Keyword(s):  
Magnetic Field ◽  
Mathematical Model ◽  
Baltic Sea ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Mobile Platforms ◽  
The Baltic Sea ◽  
Magnetic Systems ◽  
The Baltic ◽  
The Mathematical Model

Detection of ferromagnetic objects in local magnetic anomaly of the Baltic Sea In geological researches several kinds of methods are applied to discovering the natural resources. Planes, helicopters and UAVs (UnmAnned Vehicle) are used in researches in large areas. The gravity, electromagnetic and magnetic methods, which are used in geological researches, are presented in this paper. The special attention was paid to magnetic systems installed on mobile platforms. The magnetic field of the Earth obtained from mathematical model was compared to the real magnetic field in the selected part of the Baltic Sea. The results of the calculations showed that the mathematical model of the Earth's magnetic field does not consider local magnetic anomalies. The strong local magnetic anomalies cause serious problems with detection of underwater objects. Special problems appear in the magnetic system on a helicopter, which are presented in this paper.

Intermediate‐scale magnetic anomalies of the Earth

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2817-2830 ◽  
Author(s):  
J. Arkani‐Hamed ◽  
D. W. Strangway
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Anomaly ◽  
Correlation Coefficients ◽  
Sedimentary Basins ◽  
Magnetic Anomalies ◽  
The Earth ◽  
Asymmetric Component ◽  
Anomaly Map ◽  
Well Correlation

Four separate magnetic anomaly maps of the earth are derived from magnetometer satellite data acquired at dawn and at dusk using two different altitude ranges. The magnetic anomalies on the two dawn maps (or dusk maps) are well correlated for spherical harmonics of degree less than 51, suggesting that the time varying external magnetic field and leveling noise have negligible effects on these harmonics. Dawn and dusk maps have an appreciable asymmetric component for harmonics of degree n ⩽ 5 and n = 15 and 17, arising from the quasi‐stable external magnetic field. Dawn‐dusk covariant harmonics of degree [Formula: see text] with signal‐to‐noise ratios greater than 1.5 correlate well. Correlation coefficients are higher than 0.75, implying that these harmonics can be repeatably derived. A global scalar magnetic anomaly map is derived based on these harmonics. The map is then converted to a magnetic susceptibility anomaly map by an inversion technique. The susceptibility anomalies delineate the ocean‐continent differences as well as the boundaries of tectonic provinces, modern uplifts, crustal rifts, and sedimentary basins.

Observation of the interaction between Landau levels of different two-dimensional subbands in GaAs in a normal magnetic field

JETP Letters ◽  
2000 ◽  
Vol 72 (9) ◽  
pp. 476-479 ◽  
Author(s):  
D. Yu. Ivanov ◽  
E. Takhtamirov ◽  
Yu. V. Dubrovskii ◽  
V. A. Volkov ◽  
L. Eaves ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Landau Levels ◽  
Two Dimensional ◽  
Normal Magnetic Field
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