The work sheds light on the turbulent processes behind Earth’s magnetic field and hints at links between dynamics in the outer core and deeper layers of the planet.
Earth’s magnetic field arises from moving liquid iron in the outer core around the solid inner core.
A SWARM of dataThe three Swarm satellites, launched in 2013, carry sensitive magnetometers that map Earth’s magnetic field with high precision.
Elisabetta Iorfida, ESA Swarm Mission Scientist, commented that the Pacific reversal challenges the idea of a uniformly westward outer core.
She added that regional changes can arise within a decade, and the findings may help explore interactions among the outer core, inner core, and lower mantle, offering more insight into the core–mantle boundary.
On 2010, a surprising shift occurred deep beneath the Pacific Ocean: the flow of molten iron in Earth’s outer core turned from westward to strong eastward movement. This reversal, still poorly understood, has been studied using satellite observations in combination with ground data. The findings are now detailed in a peer‑reviewed journal.
Researchers analysed data spanning 1997 to 2025, drawing from measurements made by ESA’s Swarm and CryoSat satellites, along with data from Germany’s CHAMP mission and Denmark’s Ørsted mission. The results show that in 2010, a broad region of iron-rich fluid beneath the equatorial Pacific began moving eastward with great intensity, though it had been sluggishly moving westward.
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The observed reversal indicates that the core’s movement can change much more dramatically than once thought. The work sheds light on the turbulent processes behind Earth’s magnetic field and hints at links between dynamics in the outer core and deeper layers of the planet.
Lead author Frederik Dahl Madsen of the University of Edinburgh explained the significance: the large‑scale flow reversal beneath the Pacific raises new questions about the deep interior. He noted that scientists now want to determine whether the reversal is a short‑term fluctuation, part of a repeating pattern, or a new steady state for core circulation. He emphasized that continued monitoring will be essential to track how the flow develops in coming years.
Madsen added that the rise of the strong eastward flow aligns with observed changes in the inner core, as inferred from geodesy and seismology, and the team proposes that these deep‑interior changes may be connected to the Pacific flow shift.
Earth’s magnetic field arises from moving liquid iron in the outer core around the solid inner core. The geodynamo continually changes, but many long‑term flow patterns have appeared stable over decades of data.
A SWARM of data
The three Swarm satellites, launched in 2013, carry sensitive magnetometers that map Earth’s magnetic field with high precision. Their coordinated orbits help separate core signals from crust, oceans, ionosphere, and magnetosphere effects. This capability allowed researchers to reconstruct evolving core–mantle boundary flows and to identify both the Pacific reversal and the 2017 geomagnetic jerk.
Satellite data also revealed wave‑like accelerations and rapidly changing flow structures that might be hidden in noisier datasets. The study suggests the eastward flow may be weakening again after a peak, raising the possibility of a temporary oscillation or a longer natural cycle in core dynamics.
Elisabetta Iorfida, ESA Swarm Mission Scientist, commented that the Pacific reversal challenges the idea of a uniformly westward outer core. She added that regional changes can arise within a decade, and the findings may help explore interactions among the outer core, inner core, and lower mantle, offering more insight into the core–mantle boundary.
This work invites further questions about how Earth’s deepest layers are connected. As the magnetic field evolves, satellite missions continue to provide increasingly detailed views of deep‑Earth processes, suggesting the core may be more variable and complex than previously thought.
