Unveiling the Mystery: NASA Detects 7,000-Kilometer Gravity Anomaly Over the Atlantic Linked to a Surprising ‘Geomagnetic Jerk’

Researchers from NASA and the German Aerospace Center (DLR) recently uncovered a strange gravity anomaly over the Atlantic Ocean using data from the Gravity Recovery and Climate Experiment (GRACE). This discovery might be linked to a phenomenon called “geomagnetic jerk,” observed globally.

The Earth’s geomagnetic field, which stretches from its core into space, has its quirks. One of them is these geomagnetic jerks—sudden shifts in the magnetic field recorded at various observatories. A 2009 study noted several jerks in the past century, with the latest ones occurring in 1991, 1999, and 2003. In 2007, an abrupt change, a “jerk signal,” caught researchers’ interest.

So, what exactly is this gravity anomaly? GRACE consists of two satellites that measure changes in distance between them as they orbit Earth. When one satellite flies over a denser area (think of a mountain or a massive water body), it speeds up; when it passes over lighter areas, it slows down. This data helps create a gravitational map of the Earth.

Gravity anomalies occur when the measured gravity differs from expected values based on the Earth’s mass distribution. The Puerto Rico Trench has the largest negative anomaly on Earth at -380 milliGal, and another in the Indian Ocean shows the lowest gravity compared to expectations.

Led by geophysicist Charlotte Gaugne Gouranton from Paris Cité University, researchers analyzed GRACE data and spotted a significant anomaly over the Atlantic, reaching its peak between 2006 and 2008. This anomaly, about 7,000 kilometers long, showed a sharp contrast between areas of strong and weak gravity. Initial attempts to explain it through water shifts fell short.

The researchers now believe that interactions at the core-mantle boundary (CMB) might be behind this anomaly. There, immense heat and pressure might change the mineral bridgmanite, the most abundant on Earth, impacting its density. They propose that the rapid shifts in mass at great depths contribute to this gravity anomaly.

This could also explain the geomagnetic jerks seen across different observatories. Understanding how this new data influences core dynamics and the geomagnetic field remains a crucial step in their ongoing research. This study is important as it sheds light on processes beneath the Earth’s surface that we have yet to fully comprehend.

For detailed insights, you can find the original study in the journal Geophysical Research Letters here.

Source link