Swarm probes weakening of Earth’s magnetic field

Posted: May 21, 2020 by oldbrew in Electro-magnetism, Geomagnetism, solar system dynamics, Uncertainty
Tags: ,

Credit: NASA


This BBC link includes a video which shows the weakening of the magnetic field over the last 400 years (under ‘Magnetic flip’ sub-heading).
– – –
In an area stretching from Africa to South America, Earth’s magnetic field is gradually weakening, says Phys.org.

This strange behaviour has geophysicists puzzled and is causing technical disturbances in satellites orbiting Earth.

Scientists are using data from ESA’s Swarm constellation to improve our understanding of this area known as the ‘South Atlantic Anomaly.’

Earth’s magnetic field is vital to life on our planet. It is a complex and dynamic force that protects us from cosmic radiation and charged particles from the Sun.

The magnetic field is largely generated by an ocean of superheated, swirling liquid iron that makes up the outer core around 3000 km beneath our feet. Acting as a spinning conductor in a bicycle dynamo, it creates electrical currents, which in turn, generate our continuously changing electromagnetic field.

This field is far from static and varies both in strength and direction. For example, recent studies have shown that the position of the north magnetic pole is changing rapidly.

Over the last 200 years, the magnetic field has lost around 9% of its strength on a global average. A large region of reduced magnetic intensity has developed between Africa and South America and is known as the South Atlantic Anomaly.

From 1970 to 2020, the minimum field strength in this area has dropped from around 24 000 nanoteslas to 22 000, while at the same time the area of the anomaly has grown and moved westward at a pace of around 20 km per year.

Over the past five years, a second centre of minimum intensity has emerged southwest of Africa—indicating that the South Atlantic Anomaly could split up into two separate cells.

Earth’s magnetic field is often visualised as a powerful dipolar bar magnet at the centre of the planet, tilted at around 11° to the axis of rotation. However, the growth of the South Atlantic Anomaly indicates that the processes involved in generating the field are far more complex.

Simple dipolar models are unable to account for the recent development of the second minimum.

Continued here.

Comments
  1. oldbrew says:

    The SAA is linked to the Van Allen radiation belts.

    The South Atlantic Anomaly (SAA) is an area where the Earth’s inner Van Allen radiation belt comes closest to the Earth’s surface, dipping down to an altitude of 200 kilometres (120 mi).

    https://en.wikipedia.org/wiki/South_Atlantic_Anomaly#Position_and_shape

  2. Gamecock says:

    ‘This strange behaviour has geophysicists puzzled and is causing technical disturbances in satellites orbiting Earth.’

    Subs! Who wrote this junk? No conjunct exists. European Space Agency in byline.

    BWTM: ”This strange behaviour has geophysicists puzzled’

    It has been going on for at least 400 years. It cannot be ‘strange.’

    ‘has geophysicists puzzled’

    It’s been going on for 400 years. ‘Has’ is not the right word. Perhaps “continues to puzzle geophysicists” would fix.

    ESA can’t afford competent writers?

  3. ivan says:

    Maybe this is what is causing ‘climate change’ /sark

    Actually I’m surprised they didn’t include a comment about ‘climate change’ in the report – doing so might get them more grant money.

    How does this ‘puzzle’ the researchers if it has been going on for 400 years and how did they measure and record it back in the early 1600’s? Something doesn’t quite add up.

  4. oldbrew says:

    They use seismology to read the history of the magnetic field, apparently.

  5. oldbrew says:

    The solar wind also has its mysteries…

    ‘The acceleration of the fast wind is still not understood and cannot be fully explained by Parker’s theory.’

    https://en.m.wikipedia.org/wiki/Solar_wind

  6. JB says:

    “Simple dipolar models are unable to account for the recent development of the second minimum.”

    So is the “ocean of superheated, swirling liquid iron that makes up the outer core around 3000 km beneath our feet. Acting as a spinning conductor in a bicycle dynamo…” idea.

    Magnetic fields are created with charge flow. They need to start looking outside the earth for the source of that charge.

  7. tom0mason says:

    It is gratifying to see that someone is watching this anomaly.
    “The magnetic field is largely generated by an ocean of superheated, swirling liquid iron that makes up the outer core around 3000 km beneath our feet.” they say …
    My own imaginings on this matter is that there is possibly not one swirling liquid iron bubble beneath our feet but 2 (or maybe 3) ‘bubbles’ of iron, and that this magnetic anomaly indicates where the weakest interface between them is located.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s