Crustal concealing of small-scale core-field secular variation

Small-Scale-Field Dynamo.

Dynamic responses of the Earth’s outer core to assimilation of observed geomagnetic secular variation

Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynam...

Drilling Induced Core Fractures and Crustal Stress

Drilling induced core fractures, usually ignored in standard core logging, contain substantial information on the directions of horizontal stresses and the relative magnitudes of the three principal stresses. These fractures have a variety of shapes, variously referred to as petal, petal-centreline, saddle, cup, and scallop. Surprisingly, the morphology of the fractures suggests they are produc...

Compatibility of magnetic imprinting and secular variation

to reach sexual maturity [7] and is thus absent from its natal area for much longer than animals such as salmon and elephant seals [2,3]. Given this long absence, the Kemp’s ridley appears to be particularly susceptible to effects of secular variation if it relies on magnetic imprinting. The modeling results we report here show that the magnetic imprinting hypothesis can account for how the Kem...

Quasi-geostrophic flows responsible for the Secular Variation of the Earth’s magnetic field

A large jet encircling the inner core and carrying a significant part of the core angular momentum and axial vortices of ∼ 700 km diameter mainly clustering around the cylinder tangent to the solid inner core, are inferred from geomagnetic secular variation. These results are presented in the form of maps of axial vorticity in an equatorial section. The study takes advantage of the high precisi...