Magnetics Business & Technology - September/October 2019 - 19

RESEARCH & DEVELOPMENT

navigation systems, for example. Adding to the difficulty of accurate forecasting, ground-based magnetic observatories are built
on land, information about these jerks has been incomplete as
the ocean, of course, covers 70% of Earth's surface. But thanks
to ESA's trio of Swarm satellites, which measure variations in
Earth's magnetic field from space, scientists can now study the
global structure of geomagnetic jerks.

magnetic jerks. "While our findings make fascinating science, there are some real-world benefits of
understanding how our magnetic field changes.
"Many modern electronic devices such as smart
phones, rely on our knowledge of the magnetic
field for orientation information. Being able to
better forecast field changes will help with such
systems."

Dr. Chris Finlay

In a paper published recently in Nature Geosciences scientists
from the Paris Institute of Earth Physics and the Technical
University of Denmark describe how they created
a computer model for geomagnetic jerks, and
they have offered an explanation as to why they
happen. Our magnetic field is generated mainly
by the churning of fluid within Earth's core. Researchers know of two types of movement that
cause different variations in the magnetic field:
those resulting from slow convection movement, which can be measured on the scale of a
century, and those resulting from rapid hydromagnetic waves, which can be detected over a
few years.

For more information, visit: http://www.esa.int

M A G N E T I Z I N G
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T E C H N O L O G Y

M E A S U R I N G

A U T O M A T I O N

Graph tracking geometric jerks

Now, the researchers have been able to
document the series of events that lead to jerks
which, in the simulation, arise from hydromagnetic waves emitted within the core. As molten
matter rises up to reach the outer surface of the
Earth's core, it produces powerful waves along
the magnetic field lines near the core. The team
explained that this results in sharp changes in
the flow of liquid beneath the magnetic field.
The jerks originate in rising blobs of metal that
form in the planet's core 25 years before the
corresponding jerk takes place. These current
findings are part of a longer-term project in
which scientists hope to predict the evolution of
the geomagnetic field over the coming decades.
Chris Finlay, professor of geomagnetism at
DTU Space, said, "Swarm has made a real
contribution to our research, allowing us to make
detailed comparisons, in both space and time,
with physical theories on the origin of these
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organized by UK Magnetics Society:
MMA'19 - Magnetic Materials and Applications
September 18-19, 2019 - Milan, Italy
th

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Magnetics Business & Technology - September/October 2019

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