The magnetic field and electric currents in and around Earth generate complex forces that have immeasurable impact on every day life and protects life on our planet by blocking the majority of harmful solar radiation. The field can be thought of as a huge bubble, protecting us from cosmic radiation and charged particles that bombard Earth in solar winds.
1) Bow shock. 2) Magnetosheath. 3) Magnetopause. 4) Magnetosphere. 5) Northern tail lobe. 6) Southern tail lobe. 7) Plasmasphere.
The magnetic field is thought to be largely generated by an ocean of superheated, swirling liquid iron that makes up Earth’s outer core 3000 km under our feet. Acting like the spinning conductor in a bicycle dynamo, it generates electrical currents and thus the continuously changing electromagnetic field. Other sources of magnetism come from minerals in Earth’s mantle and crust, while the ionosphere, magnetosphere and oceans also play a role.
Convection Currents in the Earth's Mantle.
The geomagnetic field of the past showed areas of weak intensity similar to today's South Atlantic Anomaly over South America and the
southern Atlantic, for example 48,000 years ago. The anomaly of that time did, however, not lead to a geomagnetic field reversal,
about one thousand years later the field recovered to a stable state of field strength.
The strength of the geomagnetic field at Earth's surface during the past: 48,500 and 47,250 years ago and in 2015.
Credit: M. Korte/GFZ
Over the last two centuries, it has lost nearly 10% of its strength, leading some to speculate that a multi-century pole reversal has begun. What's more, scientists have identified a large, localized region of weakness extending from Africa to South America, known as the South Atlantic Anomaly, the field strength in this area has rapidly shrunk over the past 50 years just as the area itself has grown and moved westward.
The red dots in the map show where the Swarm-C satellite lost its GPS connection between launch in November 2013 and March 2015.
These losses in tracking signal were down to equatorial plasma bubbles. The green line denotes the geomagnetic equator.
Credit: NASA blue marble/GFZ Potsdam/ESA Description
Over the past five years a second center of minimum intensity has developed southwest of Africa, which researchers believe indicates the anomaly could split into two separate cells -Sky
These pockets are allowing charged particles from the cosmos to penetrate lower altitudes of the atmosphere - throwing off satellites flying in low-Earth orbit, according to Sky.
Increased occurrence of radiation-induced technical satellite failures of the Swarm satellites (white spots) in the region of the
geomagnetic South Atlantic Anomaly (blue color = reduced field intensity) between April 2014 and June 2017.
Credit: I. Michaelis, GFZ
Scientists are finding that the weakening is causing technical problems for satellites, and seems to be growing in its effects.
According to scientists from the Swarm Data Innovation and Science Cluster (DISC) at the European Space Agency (ESA), measurements from their swarm satellite constellation have shed tremendous light on the second anomaly.
Credit: ESA/ATG Medialab
ESA’s constellation of three Swarm satellites is designed to identify and measure precisely these different magnetic signals. This will lead to new insight into many natural processes, from those occurring deep inside the planet, to weather in space caused by solar activity.
In fact, the anomaly had puzzled ESA researchers as their Swarm satellites would sometimes 'black out' when flying through the affected region. Three years ago, they observed a link between the blackouts and Ionospheric thunderstorms.
"The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously," said Dr. Jurgen Matzka of the German Research Center for Geosciences. "We are very lucky to have the Swarm satellites in orbit to investigate the development of the South Atlantic Anomaly. The challenge now is to understand the processes in Earth's core driving these changes."
If this is the beginning of a pole reversal - which happens roughly every quarter-million years, it would result in multiple north and south magnetic poles all around the globe during the multi-century phenomenon.
"Such events have occurred many times throughout the planet's history," said ESA, adding "we are long overdue by the average rate at which these reversals take place (roughly every 250,000 years)"
Not to Worry!
Not to worry, in theory, as the space agency says that the South Atlantic dip which they're still learning about was "well within what is considered normal levels of fluctuations."
For people on the surface the anomaly is unlikely to cause any alarm, but satellites and other spacecraft flying through the area are experiencing technical malfunctions.
"The mystery of the origin of the South Atlantic Anomaly has yet to be solved," added ESA. -Sky
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