Cause Of Earth’s Magnetic Field Anomalies Identified

According to recent research, irregularities in the cooling process of molten iron in the Earth’s core are responsible for variations in the planet’s magnetic field.

Why do satellite operations and compass readings experience interference that results in inaccurate directions not aligned with true north due to the irregularities in the Earth’s magnetic field?

Earth’s magnetic field loops worldwide and far out into space and is driven by processes deep within the core, where temperatures exceed 5,000°C. Research suggests that how this super-hot core cools is key to understanding the causes of quirks or anomalies in Earth’s magnetic field.

At the center of the Earth is a swirling mass of molten iron that works like a dynamo. The molten iron moves and generates Earth’s global magnetic field. The movement of convective currents facilitates the rotation of this dynamo, which occurs as thermal energy flows from the Earth’s core to the mantle.

Non-uniform cooling

Geophysicists at the University of Leeds have discovered that the cooling process is not uniform across the Earth and that this non-uniformity causes anomalies in the Earth’s magnetic field. Through the use of seismic analysis, it has been determined that there are areas in the mantle beneath Africa and the Pacific that exhibit notably high temperatures. Computer simulations suggest that these hot spots reduce the cooling effect on the core, causing regional or localized changes in magnetic field properties.

To illustrate, in regions where the mantle is warmer, the magnetic field at the core’s surface is expected to be less powerful. This results in a less potent magnetic field that extends into space over the South Atlantic and creates difficulties for satellite orbits.

Dr. Jonathan Mound from the School of Earth and Environment explains that the magnetic field in space serves to redirect the charged particles discharged by the sun. If the magnetic field is weaker, this protective barrier is less effective. Consequently, as satellites travel through this area, these charged particles can cause disruption and interference with their functioning.

The anomaly occurring in the South Atlantic

Scientists have been observing the anomaly in the South Atlantic. However, it is unclear if this is a long-lasting feature or something that happened more recently. The research indicates that variations in the heat flow from the Earth’s core to its mantle are responsible for the observed irregularities in the magnetic field. Where these heat flux differences happen is likely to determine how long they can last.

Mound suggests that the gradual nature of processes within the mantle would imply that temperature irregularities in the lower mantle have likely remained unchanged for millions of years. As a result, it is reasonable to assume that the characteristics of the resulting magnetic field have also been consistent over this extended period.

“However, the hotter outer core is a fluid dynamic region,” says Mound, “so the heat flux and magnetic field properties they cause are likely to fluctuate over shorter timescales, perhaps over hundreds to thousands of years.”

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