Core–Mantle Interactions

Buffett, B. A.

doi:10.1016/b978-0-444-53802-4.00148-2

Cited by 42 publications

(16 citation statements)

References 135 publications

(162 reference statements)

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“…Changes in aspects of geodynamo behaviour are thought likely to result from secular changes in core cooling modulated by mantle convection over the last several billion years [33][34][35][36][37][38][39] . Indeed the changing nature of the forcing of outer core convection from both above and below implies that it is already a challenge to explain how the geomagnetic field has been continuously sustained over Earth history 40 .…”

Section: Resultsmentioning

confidence: 99%

Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time

Biggin¹,

Bono²,

Meduri³

et al. 2020

Preprint

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A defining characteristic of the recent geomagnetic field is its dominant axial dipole which provides its navigational utility and dictates the shape of the magnetosphere. Going back through time, much less is known about the degree of axial dipole dominance. Here we use a substantial and diverse set of 3D numerical dynamo simulations and recent observation-based field models to derive a power law relationship between the angular dispersion of virtual geomagnetic poles at the equator and the median axial dipole dominance measured at Earth’s surface. Applying this relation to published estimates of equatorial angular dispersion implies that geomagnetic axial dipole dominance averaged over 107-109 years has remained moderately high and stable through large parts of geological time. This provides an observational constraint to future studies of the geodynamo and palaeomagnetosphere. It also provides some reassurance as to the reliability of palaeogeographical reconstructions provided by palaeomagnetism.

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Section: Resultsmentioning

confidence: 99%

Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time

Biggin¹,

Bono²,

Meduri³

et al. 2020

Preprint

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show abstract

“…Such dynamics stand in stark contrast with core flow inversions for present-day SV which suggest low flow magnitudes under the Pacific with only weak upwellings, including in the area under Korea (25). Numerical geodynamo (26)(27)(28)(29) and thermal convection (30,31) simulations show that upwelling (downwelling) structures can be driven by locally low (high) heat flux that renders the local core fluid hot (cold), dynamics ultimately driven by laterally varying thermal structure in the lower mantle. Paleo-and archeomagnetic datasets over the last 3,000 y suggest that patches of reversed radial magnetic field preferentially emerge close to the LLVPs located beneath the Pacific and Africa (32), a behavior that can be explained by expulsion of a toroidal magnetic field, consistent with broad upwelling regions beneath the LLVPs.…”

Section: Resultsmentioning

confidence: 85%

Equatorial auroral records reveal dynamics of the paleo-West Pacific geomagnetic anomaly

Wei

Maffei

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Localized regions of low geomagnetic intensity such as the South Atlantic Anomaly allow energetic particles from the Van Allen radiation belt to precipitate into the atmosphere and have been linked to a signature in the form of red aurora–like airglow visible to the naked eye. Smoothed global geomagnetic models predict a low-intensity West Pacific Anomaly (WPA) during the sixteenth to nineteenth centuries characterized by a simple time dependence. Here, we link the WPA to an independent database of equatorial aurorae recorded in Seoul, South Korea. These records show a complex fluctuating behavior in auroral frequency, whose overall trend from 1500 to 1800 AD is consistent with the locally weak geomagnetic field of the WPA, with a minimum at 1650 AD. We propose that the fluctuations in auroral frequency are caused by corresponding and hitherto unknown fluctuations in the regional magnetic intensity with peaks at 1590 and 1720 AD, a time dependence that has been masked by the smoothing inherent in regularized global geomagnetic models. A physical core flow model demonstrates that such behavior requires localized time-dependent upwelling flows in the Earth’s core, possibly driven by regional lower-mantle anomalies.

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“…О днако н е известно, как эта энергия разделяется ме жду внутримантийной теп логен ер а ц и ей и потоком тепла на границе ядро-мантия. И з к освен н ы х соо б р а ж ен и й (осн овы ваю щ ихся на экстраполяц ии до границы яд ра мантийной адиабаты и оц енки мощ но сти теплового погранслоя) следует, что теп л о в о й п оток ск возь п од ош ву мантии с о ставляет qCMB = 6 16 ТВт, хотя, как отм е чает [Buffett, 2015], невозмож но исключить ни больш ие, ни м еньш ие значения.…”

Section: о в арясова ям хазанunclassified

“…Например, в стандартной и привыч ной нам ситуации из д вух ф аз, н аход я щ ихся в равновесии, твердая ф аза явля ется низкотемпературной, т. е. стабильной, при тем ператур е ниж е тем пературы ф а зового равновесия. Н естандартность внут р ен н его ядра начинается с того, что из-за влиян и я давлен и я твердая ф аза я в ля е т ся вы сокотем п ературн ой , а с ей с м о ло ги ческие данные указываю т на существова ние сло ж н о й в н утрен н ей структуры ядра, вклю чая ан и зотр оп и ю его вн утрен н ей ча сти, н еэкви вален тн ость полуш арий, топ о графию п ов ер хн ости и существование "са м ого в н утр ен н его я д р а " р ади усом 300 -600 км (с м ., наприм ер, недавние о б з о ры [D eguen, 2012;Buffett, 2015;).…”

Section: о в арясова ям хазанunclassified