scholarly journals ORBITAL NOISE OF THE EARTH CAUSES INTENSITY FLUCTUATION IN THE GEOMAGNETIC FIELD

2003 ◽  
Vol 03 (01) ◽  
pp. L63-L72 ◽  
Author(s):  
H. S. LIU ◽  
R. KOLENKIEWLCZ ◽  
C. WADE
Keyword(s):  
Geomagnetic Field ◽  
Noise Spectrum ◽  
Outer Core ◽  
The Past ◽  
The Earth ◽  
Spectral Peaks ◽  
Relative Paleointensity ◽  
Intensity Fluctuations ◽  
Composite Curve ◽  
Insight Into

Orbital noise of Earth's obliquity can provide an insight into the core of the Earth that causes intensity fluctuations in the geomagnetie field. Here we show that noise spectrum of the obliquity frequency have revealed a series of frequency periods centered at 250-, 100-, 50-, 41-, 30-, and 26-kyr which are almost identical with the observed spectral peaks from the composite curve of 33 records of relative paleointensity spanning the past 800 kyr (Sint–800 data). A continuous record for the past two million years also reveals the presence of the major 100 kyr periodicity in obliquity noise and geomagnetic intensity fluctuations. These results of correlation suggest that obliquity noise may power the dynamo, located in the liquid outer core of the Earth, which generates the geomagnetic field.

scholarly journals Archaeomagnetic studies at Schmidt institute of physics of the earth, Russian Academy of Sciences: history and main results

2019 ◽  
pp. 123-136
Author(s):  
I. E. Nechasova ◽  
O. V. Pilipenko
Keyword(s):  
Field Intensity ◽  
Geomagnetic Field ◽  
Main Magnetic Field ◽  
International Studies ◽  
The Past ◽  
Russian Academy Of Sciences ◽  
The Earth ◽  
Geomagnetic Field Intensity ◽  
Academy Of Sciences ◽  
Schmidt Institute

The archaeomagnetic studies carried out at the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS) provided an important contribution to the international studies of the main magnetic field of the Earth for the past few thousand years. Extensive data on the intensity of geomagnetic field in the past 8000 years were obtained. Four most representative and long time series of the data have been constructed for Eurasia for the Iberian Peninsula, the Caucasus, Central Asia, and Siberia. Unique studies having no analogues in international research have been carried out into rapid variations in the geomagnetic field intensity with characteristic times starting from several tens of years. Based on the analysis of the international data on the ancient geomagnetic field, the spectrum of the variations in the geomagnetic field intensity with the periods ranging from decades to millennia was established and the characteristics ofthe variations whose superposition can describe the pattern of the changes of the geomagnetic field intensity were determined. It was found out that variations with different characteristic times have a differently directed drift, and the “main oscillation” with a characteristic time of 8000 years has an eastern drift.

Preliminary paleomagnetic results from PS97 cores from the Drake Passage for the past 110 ka

2020 ◽  
Author(s):  
Jiabo Liu ◽  
Norbert Nowaczyk ◽  
Xufeng Zheng ◽  
Qinsong Liu ◽  
Helge Arz
Keyword(s):  
Southern Ocean ◽  
Geomagnetic Field ◽  
Sediment Cores ◽  
Drake Passage ◽  
Mono Lake ◽  
The Past ◽  
Asymmetric Pattern ◽  
Relative Paleointensity ◽  
Globally Distributed ◽  
Northern And Southern Hemispheres

<p>Paleomagnetic records reconstructed from globally distributed marine sediments have greatly improved our understanding of long-term paleosecular variations and geomagnetic excursions. Nevertheless, questions regarding to the development of the geomagnetic field anomaly in the Southern Atlantic Ocean and the asymmetric geomagnetic field between Northern and Southern Hemispheres are not yet satisfactorily resolved. Paleomagnetic data, particularly from the Southern Hemisphere, is needed to better define the global geomagnetic field configurations spanning paleosecular variations and excursions. In this study, three sediment cores (PS97-085, PS97-84, PS97-079) recovered from the Drake Passage, Southern Ocean were subjected to detailed rock magnetic and paleomagnetic investigations. Preliminary age models were obtained by correlating their magnetic susceptibility to the ẟ<sup>18</sup>O master record from Dome C, Antarctica. In addition, rock magnetic records of the studied PS97 cores were further correlated to that of core PS67/197-1 with AMS <sup>14</sup>C age constraints. The results from PS97 cores are thus continuously covering the past about 110 ka. Rock magnetic results indicate titanomagnetite is the dominant magnetic carrier in the studied PS97 cores. Relative paleointensities (RPI) derived from these PS97 cores are comparable with the regional relative paleointensity records and the South Atlantic paleointensity stack (SAPIS). Additionally, anomalous inclinations at about 41 ka and 35 ka, observed in core PS97-085, are coeval with the Laschamps and the Mono Lake excursions, respectively. This study provides new paleomagnetic records from the Southern Ocean, though further age constrains are needed to consolidate the paleomagnetic interpretations. The up to now obtained paleomagnetic records, together with previous studies from the Southern Ocean, are aiming to clarify the asymmetric pattern of non-dipole geomagnetic field between Northern and Southern Hemispheres.</p>

Relative paleointensity of the geomagnetic field during the past 0.8 Ma from Nihewan Basin, Hebei Province, China

2004 ◽  
Vol 49 (9) ◽  
pp. 948-952 ◽  
Author(s):  
Yong Wang ◽  
Zhenqing Chi ◽  
Tehquei Lee ◽  
Longrui Min ◽  
Huiyair Chu
Keyword(s):  
Geomagnetic Field ◽  
Hebei Province ◽  
The Past ◽  
Nihewan Basin ◽  
Relative Paleointensity

scholarly journals Persistent westward drift of the geomagnetic field at the core–mantle boundary linked to recurrent high-latitude weak/reverse flux patches

2020 ◽  
Vol 222 (2) ◽  
pp. 1423-1432
Author(s):  
Andreas Nilsson ◽  
Neil Suttie ◽  
Monika Korte ◽  
Richard Holme ◽  
Mimi Hill
Keyword(s):  
Northern Hemisphere ◽  
High Latitude ◽  
Geomagnetic Field ◽  
Outer Core ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core ◽  
The Past ◽  
Convection Rolls ◽  
Westward Drift

SUMMARY Observations of changes in the geomagnetic field provide unique information about processes in the outer core where the field is generated. Recent geomagnetic field reconstructions based on palaeomagnetic data show persistent westward drift at high northern latitudes at the core–mantle boundary (CMB) over the past 4000 yr, as well as intermittent occurrence of high-latitude weak or reverse flux patches. To further investigate these features, we analysed time-longitude plots of a processed version of the geomagnetic field model pfm9k.1a, filtered to remove quasi-stationary features of the field. Our results suggest that westward drift at both high northern and southern latitudes of the CMB have been a persistent feature of the field over the past 9000 yr. In the Northern Hemisphere we detect two distinct signals with drift rates of 0.09° and 0.25° yr−1 and dominant zonal wavenumbers of m = 2 and 1, respectively. Comparisons with other geomagnetic field models support these observations but also highlight the importance of sedimentary data that provide crucial information on high-latitude geomagnetic field variations. The two distinct drift signals detected in the Northern Hemisphere can largely be decomposed into two westward propagating waveforms. We show that constructive interference between these two waveforms accurately predicts both the location and timing of previously observed high-latitude weak/reverse flux patches over the past 3–4 millennia. In addition, we also show that the 1125-yr periodicity signal inferred from the waveform interference correlates positively with variations in the dipole tilt over the same time period. The two identified drift signals may partially be explained by the westward motion of high-latitude convection rolls. However, the dispersion relation might also imply that part of the drift signal could be caused by magnetic Rossby waves riding on the mean background flow.

scholarly journals Variações de intensidade do campo geomagnético em Santa Maria (Brasil) para os últimos 3 mil anos

2018 ◽  
Vol 40 ◽  
pp. 7
Author(s):  
Everton Frigo ◽  
Gelvam Hartmann
Keyword(s):  
Geomagnetic Field ◽  
Climate Changes ◽  
Internal Field ◽  
Outer Core ◽  
The South ◽  
The Past ◽  
Earth Magnetic Field ◽  
Electrically Charged ◽  
Santa Maria ◽  
Magnetic Field Variations

Earth magnetic field variations at secular scales and at hundred quilometers have internal origin at the outer core. The most important feature associated with this internal field is the South Atlantic Magnetic Anomaly (SAMA), which covers the South America and it is characterized by the lowest total field intensity at the surface. Here, we investigate the geomagnetic field variations in Santa Maria (Brazil) over the past 3 ka. Results indicate that the intensities observed in Santa Maria are the lowest of the geomagnetic field over the past 3 ka. The consequences of these field features could be the increase in the electrically charged particles reaching the low Earth atmosphere that may generate problems in the communications systems or climate changes.

scholarly journals IV. On the analytical expressions which give the history of a fluid planet of small viscosity, attended by a single satellite

1880 ◽  
Vol 30 (200-205) ◽  
pp. 255-278 ◽  
Keyword(s):  
Royal Society ◽  
Numerical Treatment ◽  
Secular Changes ◽  
The Past ◽  
Small Viscosity ◽  
The Earth ◽  
History Of ◽  
Analytical Expressions ◽  
Insight Into ◽  
Numerical Quadratures

In a series of papers read from time to time during the past two years before the Royal Society, I have investigated the theory of the tides raised in a rotating viscous Spheroid, or planet, by an attendant satellite, and have also considered the secular changes in the rotation of the planet, and in the revolution of the satellite. Those investigations were intended to be especially applicable to the case of the earth and moon, but the friction of the solar tides was found to be a factor of importance, so that in a large part of those papers it became necessary to conceive the planet as attended by two satellites. The differential equations which gave the secular changes in the system were rendered very complex by the introduction of solar disturbance, and I was unable to integrate them analytically; the equations were accordingly treated by a method of numerical quadratures, in which all the data were taken from the earth, moon, and sun. This numerical treatment did not permit an insight into all the various effects which might result from frictional tides, and an analytical solution, applicable to any planet and satellite, is desirable.

Geomagnetic Field Paleointensity during the Cretaceous Normal Superchron from Marine Magnetic Anomalies

2020 ◽  
Author(s):  
Yuanjie Li ◽  
Qingsong Liu
Keyword(s):  
Geomagnetic Field ◽  
High Strength ◽  
Absolute Intensity ◽  
Outer Core ◽  
Marine Magnetic Anomalies ◽  
Relative Paleointensity ◽  
Polarity Reversals ◽  
Central Atlantic ◽  
Dynamo Process

<p>The knowledge of the geomagnetic field intensity during the Cretaceous Normal Superchron, a long term of forty million years without polarity reversals, may have a large impact on our understanding of the dynamo process occurring in Earth’s outer core. How, it is difficult to get the geomagnetic field behavior during the Cretaceous Normal Superchron resulting from the inadequate sampling or data of variable qualities from igneous rocks and sedimentary. Here we examine 20 magnetic anomaly profiles across the Cretaceous magnetic quiet zone of the Central Atlantic Ocean in the African flank extracted from the EMAG2v3, and calculate a synthetical magnetization profile based on the forward modeling method. We suggest that this profile records the high strength of geomagnetic field at the beginning of ~30 million years and low signal during the late period, which could be correlated with the low-resolution relative paleointensity record from the sediment samples at the Falkland Plateau, and which also could be found the VDMs/VADMs averaged by a 7-Ma sliding window from the absolute intensity records mostly from the MagIC database. Our results support the hypothesis that the distribution of heat flow along the core-mantle boundary is positively correlative to the intensity of the dipole field.</p>

Introductory remarks

1982 ◽  
Vol 306 (1492) ◽  
pp. 9-10 ◽  
Keyword(s):  
Seismic Data ◽  
Geomagnetic Field ◽  
Early History ◽  
The Moon ◽  
The Core ◽  
The Past ◽  
The Earth ◽  
History Of ◽  
The Subject ◽  
Additional Constraints

The suggestion for this Discussion Meeting was put forward more than three years ago. The format of the programme has changed many times since the original version, reflecting in part changing interests in different aspects of the subject. Of the 25 papers to be presented, only 5 discuss the constitution of the core, 13 deal with the geomagnetic field (including the secular variation and reversals) and all but 1 of the remaining 7 on geophysical interpretations are also concerned with the geomagnetic field. This emphasis on geomagnetism reflects the additional constraints that the absence or presence of a magnetic field may put on the constitution of all the planets and the Moon. In contrast to the Earth, the record of the first 10 9 years of planetary history is still at least partly preserved on the Moon, Mercury and Mars (and perhaps on Venus), and a study of this record on these other bodies may yield some information on the early history of the Earth. We have some seismic data for the Moon, but it is only for the Earth that we have a rich store of such data. In this connection, a word of caution is in order. It must not be forgotten that the structure of the Earth as revealed by seismic data is only a snapshot of what it is like today, and in many ways a very imperfect snapshot. There is no science of palaeoseismology, and seismic data tell us nothing about the structure of the Earth in the past nor of its evolution.

6. The Earth’s heat

2018 ◽  
pp. 92-105
Author(s):  
William Lowrie
Keyword(s):  
Heat Transfer ◽  
Geomagnetic Field ◽  
Plate Tectonics ◽  
Internal Heat ◽  
Outer Core ◽  
Radioactive Isotopes ◽  
Convection Heat ◽  
Crustal Rocks ◽  
Geological Processes ◽  
The Earth

The Earth’s internal heat is its greatest source of energy. It powers global geological processes such as plate tectonics and the generation of the geomagnetic field. ‘The Earth’s heat’ explains that the internal heat arises from two sources: the decay of radioactive isotopes in crustal rocks and the mantle, and primordial heat left over from the planet’s fiery formation. The internal heat has to find its way out of the Earth. The three basic forms of heat transfer are radiation, conduction, and convection. Heat is also transferred in compositional and phase transitions. Heat transport by conduction is most important in solid regions of the Earth, while thermal convection occurs in the viscoelastic mantle and molten outer core.

scholarly journals Atmospheric Radiocarbon: Implications for the Geomagnetic Dipole Moment

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 239-248 ◽  
Author(s):  
R S Sternberg ◽  
P E Damon
Keyword(s):  
Dipole Moment ◽  
Secular Variation ◽  
Fluid Motion ◽  
Outer Core ◽  
The Past ◽  
Geochemical Cycle ◽  
Difference Form ◽  
Physical Fields ◽  
Geomagnetic Dipole ◽  
Insight Into

The geomagnetic field is one of the major physical fields of the earth. Because its source is fluid motion in the outer core, it exhibits temporal changes, called secular variation, which are quite rapid compared to most geologic phenomena. The prehistoric secular variation is usually inferred from paleomagnetic data. We will discuss here how changes in the atmospheric 14C content can be used to gain additional insight into the behavior of the dipole moment over the past 8500 years. By rewriting the differential equations representing the 14C geochemical cycle in finite-difference form, we are able to convert the atmospheric 14C activity record into an equivalent radiocarbon dipole moment.

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