Scientists have been keeping close track of the drift of the Earth’s magnetic field for around 400 years now, yet the reason for this westward movement has confounded researchers. However, a new study has suggested a fascinating reason for this drift, and the answer may be found in the Rossby waves that are found in the outer core of the Earth.
Rossby waves, sometimes referred to as planetary waves, lurk in other massive bodies like the sun and the planet Jupiter and flow through rotating liquids. When you consider the fact that rotating liquids are what make up the outer core of the Earth, this would mean that Rossby waves can be found there also, according to Space.
As the University of Cambridge’s O.P. Bardsley notes, these Rossby waves found inside the outer core of the planet are “a bit like turning atmospheric Rossby waves inside out,” with crests that travel in an eastward direction. This is in marked contrast to the Rossby waves that travel westward in the Earth’s atmosphere and oceans.
The geomagnetic field of the Earth is derived from the magnetic iron that is found deep in the core of our planet, and it is this field that keeps us safe from solar radiation. While studying planetary waves, Bardsley researched the magnetic declination that has been occurring on Earth for the past 400 years and described its westward movement in a new study published on May 15.
“The westward drift manifests itself primarily as a series of blobs over the Atlantic near the equator.”
When it comes to the most popular theories for why the Earth’s magnetic field is moving westward, the top one currently is that there is a gyre situated in the outer core of our planet which, while heading in a westward fashion already, is taking the magnetic field of the Earth on a journey west, too. However, O.P. Bardsley explained that there is no actual proof that this gyre even exists, so this theory cannot be proven.
Bardsley believes that it is fully possible that Rossby waves could explain the strange behavior of the Earth’s magnetic field, despite their mainly eastward movement in the Earth’s core.
“It is entirely possible to have a group of waves where the crests themselves are going east but the bulk of the energy is going westward.”
The new study on the possibility of Rossby waves causing the Earth’s magnetic field to drift westward can be read in Proceedings of the Royal Society A.