Geomagnetic Reversals and excursions: The origin of Earth's magnetic fie...
Δημοσιεύτηκε στις 16 Οκτ 2015
Palaeomagnetic
observations offer important insights into the origin of Earth's
interior, but a detailed reconstruction of the underlying dynamics is
not feasible. A practical alternative is to construct a stochastic model
for the time evolution of the dipole field.
Slow changes in the
field are described by a deterministic (drift) term, whereas short-time
fluctuations are represented by a random (noise) term. Estimates for the
drift and noise terms can be recovered from a time series of variations
in the axial dipole moment over the past 2 million years. The results
are used to predict a number of statistical properties of the
palaeomagnetic field, including the average rates of magnetic reversals
and excursions.
Dr. Buffet will explain how a physical
interpretation of the stochastic models suggests that reversals and
excursions are part of a continuum of time variations in Earth's
magnetic field, arising from convective fluctuations in the core.
Relatively modest changes the amplitude of convective fluctuations can
produce large changes in reversal rates, including the well-known
occurrence of superchrons lasting longer than 10 million years.
observations offer important insights into the origin of Earth's
interior, but a detailed reconstruction of the underlying dynamics is
not feasible. A practical alternative is to construct a stochastic model
for the time evolution of the dipole field.
Slow changes in the
field are described by a deterministic (drift) term, whereas short-time
fluctuations are represented by a random (noise) term. Estimates for the
drift and noise terms can be recovered from a time series of variations
in the axial dipole moment over the past 2 million years. The results
are used to predict a number of statistical properties of the
palaeomagnetic field, including the average rates of magnetic reversals
and excursions.
Dr. Buffet will explain how a physical
interpretation of the stochastic models suggests that reversals and
excursions are part of a continuum of time variations in Earth's
magnetic field, arising from convective fluctuations in the core.
Relatively modest changes the amplitude of convective fluctuations can
produce large changes in reversal rates, including the well-known
occurrence of superchrons lasting longer than 10 million years.
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