Changes In The Earth's Magnetosphere

[James Kerman]

The World Magnetic Model will be updated on 30th January 2019 due to magnetic north shifting away from Canada and towards Siberia.  The most current model from 2015 was expected to be accurate until 2020 however researchers are making an unprecedented early change to account for this shift.

Image Credit: World Data Center for Geomagnetism/Kyoto Univ.

Quote

Update, 9 January: The release of the World Magnetic Model has been postponed to 30 January due to the ongoing US government shutdown.

Something strange is going on at the top of the world. Earth’s north magnetic pole has been skittering away from Canada and towards Siberia, driven by liquid iron sloshing within the planet’s core. The magnetic pole is moving so quickly that it has forced the world’s geomagnetism experts into a rare move.

On 15 January, they are set to update the World Magnetic Model, which describes the planet’s magnetic field and underlies all modern navigation, from the systems that steer ships at sea to Google Maps on smartphones.

The most recent version of the model came out in 2015 and was supposed to last until 2020 — but the magnetic field is changing so rapidly that researchers have to fix the model now. “The error is increasing all the time,” says Arnaud Chulliat, a geomagnetist at the University of Colorado Boulder and the National Oceanic and Atmospheric Administration’s (NOAA’s) National Centers for Environmental Information.

The problem lies partly with the moving pole and partly with other shifts deep within the planet. Liquid churning in Earth’s core generates most of the magnetic field, which varies over time as the deep flows change. In 2016, for instance, part of the magnetic field temporarily accelerated deep under northern South America and the eastern Pacific Ocean. Satellites such as the European Space Agency’s Swarm mission tracked the shift.

By early 2018, the World Magnetic Model was in trouble. Researchers from NOAA and the British Geological Survey in Edinburgh had been doing their annual check of how well the model was capturing all the variations in Earth’s magnetic field. They realized that it was so inaccurate that it was about to exceed the acceptable limit for navigational errors.

Wandering pole

“That was an interesting situation we found ourselves in,” says Chulliat. “What’s happening?” The answer is twofold, he reported last month at a meeting of the American Geophysical Union in Washington DC.

First, that 2016 geomagnetic pulse beneath South America came at the worst possible time, just after the 2015 update to the World Magnetic Model. This meant that the magnetic field had lurched just after the latest update, in ways that planners had not anticipated.

Second, the motion of the north magnetic pole made the problem worse. The pole wanders in unpredictable ways that have fascinated explorers and scientists since James Clark Ross first measured it in 1831 in the Canadian Arctic. In the mid-1990s it picked up speed, from around 15 kilometres per year to around 55 kilometres per year. By 2001, it had entered the Arctic Ocean — where, in 2007, a team including Chulliat landed an aeroplane on the sea ice in an attempt to locate the pole.

In 2018, the pole crossed the International Date Line into the Eastern Hemisphere. It is currently making a beeline for Siberia.

The geometry of Earth’s magnetic field magnifies the model’s errors in places where the field is changing quickly, such as the North Pole. “The fact that the pole is going fast makes this region more prone to large errors,” says Chulliat.

To fix the World Magnetic Model, he and his colleagues fed it three years of recent data, which included the 2016 geomagnetic pulse. The new version should remain accurate, he says, until the next regularly scheduled update in 2020.

Core questions

In the meantime, scientists are working to understand why the magnetic field is changing so dramatically. Geomagnetic pulses, like the one that happened in 2016, might be traced back to ‘hydromagnetic’ waves arising from deep in the core¹. And the fast motion of the north magnetic pole could be linked to a high-speed jet of liquid iron beneath Canada².

The jet seems to be smearing out and weakening the magnetic field beneath Canada, Phil Livermore, a geomagnetist at the University of Leeds, UK, said at the American Geophysical Union meeting. And that means that Canada is essentially losing a magnetic tug-of-war with Siberia.

“The location of the north magnetic pole appears to be governed by two large-scale patches of magnetic field, one beneath Canada and one beneath Siberia,” Livermore says. “The Siberian patch is winning the competition.”

Which means that the world’s geomagnetists will have a lot to keep them busy for the foreseeable future.

https://www.nature.com/articles/d41586-019-00007-1

 

[YNM]

Huh...

Maybe somehow it doesn't like to be aligned closely with the rotational pole ?

Also, does the southern magnetic pole lies precisely on the antipodal point ?

[DDE]

Those pesky Russians must not be allowed to seize the magnetic North.

[Green Baron]

Judging from the frequency it gets referenced here, The Core must be be a fascinating movie ... 

 

Seriously, yes, a model update is necessary. And this has quite practical consequences too, like nautical charts. I recall speculations in the late 1900s/early 2000s that a pole flip could be standing before us, but i haven't heard of that since a long time. Maybe the idea was abandoned because too much speculation.

2 hours ago, YNM said:

Also, does the southern magnetic pole lies precisely on the antipodal point ?

In general approximation, it is a dipole. In practice, adjustments are necessary and pole wandering is independent. Which is the case right now. It may happen that locally a compass may not point to one of the "main" poles, non-dipole variations may create a local north or south pole (suggesting a movie "The Quadrupole"  ).

Anyway: a model of earth's magnetic field is only valid for a limited time.

Edited January 14, 2019 by Green Baron

[magnemoe]

2 minutes ago, Green Baron said:

Judging from the frequency it gets referenced here, The Core must be be a fascinating movie ... 

Seriously, yes, a model update is necessary. And this has quite practical consequences too, like nautical charts. I recall some speculating that a pole flip could be standing before us in the late 1900s/early 2000s, but i haven't heard of that since a long time. Maybe the idea was abandoned because too much speculation.

In general approximation, it is a dipole. In practice, adjustments are necessary and pole wandering is independent. Which is the case right now. It may happen that locally a compass may not point to one of the "main" poles, suggesting that local non-dipole variations may "fake" a local north or south pole (suggesting a movie "The Quadrupole"  ).

Anyway: a model of earth's magnetic field is only valid for a limited time.

The pole moved dramatically faster and faster from 1990 up to 2010 who could indicate an switch was incoming but it looks like its started to slow a bit down again. 

[Green Baron]

2 minutes ago, magnemoe said:

The pole moved dramatically faster and faster from 1990 up to 2010 who could indicate an switch was incoming but it looks like its started to slow a bit down again. 

It is probably not like the poles wander around the globe when they switch, that would mean too huge changes in mass movement in the core. There may be short periods with a very weak or even without a magnetic field and/or with high local variations until it builds up again. But nothing is clear, afaik.

[magnemoe]

1 minute ago, Green Baron said:

It is probably not like the poles wander around the globe when they switch, that would mean too huge changes in mass movement in the core. There may be short periods with a very weak or even without a magnetic field and/or with high local variations until it builds up again. But nothing is clear, afaik.

Yes, field become weaker before it flips and build up again its not like its rotate around. 
 

[YNM]

1 hour ago, Green Baron said:

In practice, adjustments are necessary and pole wandering is independent. Which is the case right now.

Yeah, just found that out, I think given the coordinates that now the two magnetic poles are closer than ever - would that explain why the wander has been speeding up ?

And no to have a pole reversal it doesn't have to flip the whole core mass - usually it'll make up new poles somewhere else so the system will be a quadrupole or more. This way the magnetic strength is reduced massively.

[Green Baron]

11 minutes ago, YNM said:

Yeah, just found that out, I think given the coordinates that now the two magnetic poles are closer than ever - would that explain why the wander has been speeding up ?

Well, currents in the core build the magnetic field. But we can't take a look, so we must find a best fitting (and constantly changing) model.

It'll all be easier in the future, when the earth has cooled enough so that all these combobulations have come to a rest. That i can say with some confidence :-)

[YNM]

1 hour ago, Green Baron said:

currents in the core build the magnetic field. But we can't take a look, so we must find a best fitting (and constantly changing) model.

Or maybe we can continue experimenting with one of those molten metal spheres.

1 hour ago, Green Baron said:

when the earth has cooled enough so that all these combobulations have come to a rest. That i can say with some confidence :-)

We'd be doomed by that time.

[magnemoe]

1 hour ago, Green Baron said:

Well, currents in the core build the magnetic field. But we can't take a look, so we must find a best fitting (and constantly changing) model.

It'll all be easier in the future, when the earth has cooled enough so that all these combobulations have come to a rest. That i can say with some confidence :-)

How long will that take? 
An pole flip must create havoc for all animals who use magnetism to navigate. 
However it happens every few million years so it can not be extrication level events. 
Imagining all the birds fly north in autumn. 

[James Kerman]

Further reading has led me to think a possible explanation is the beginnings of something like the Laschamp event.  How effective would 5% of the magnetosphere be at blocking solar and cosmic radiation?

Quote

The Laschamp event was a short reversal of the Earth's magnetic field. It occurred 41,400 (±2,000) years ago during the last ice age and was first recognised in the late 1960s as a geomagnetic reversal recorded in the Laschamp lava flows in the Clermont-Ferrand district of France.^[1] The magnetic excursion has since been demonstrated in geological archives from many parts of the world. The period of reversed magnetic field was approximately 440 years, with the transition from the normal field lasting approximately 250 years. The reversed field was 75% weaker, whereas the strength dropped to only 5% of the current strength during the transition. This reduction in geomagnetic field strength resulted in more cosmic rays reaching the Earth, causing greater production of the cosmogenic isotopes beryllium 10 and carbon 14.^[2] The Laschamp event was the first known geomagnetic excursion and remains the most thoroughly studied among the known geomagnetic excursions.^[3]

https://en.wikipedia.org/wiki/Laschamp_event

I have found some data (from 2009) showing the strength of the magnetosphere over time.

Image Credit: U.S. Geological Survey

[Green Baron]

Yes, that would be the flip mentioned above.

Nobody knows for sure how in detail a polarity flip of the earth's magnetic field occurs. We don't even know how long it takes, maybe 100s of years ? Pretty fast ;-). But there are no remarkable extinctions connected to past flips. So, probably, maybe, it just flips. No refund on old compasses ...

Geomagnetism is used as a method of dating because the phases are preserved in ocean floor when it solidifies. So, from the mid ocean ridges to the continents the polarity is recorded, plus a few ophiolites (ripped off ocean crust during subduction, stacked in between continental crust, example Omani mountains), reaches back a few (not many) hundred million years.

Lave flows can be dated as well this way, which helps for example in East Africa with the dating of early human tools and so. Actually, the Gauss-Matuyama transition was the marker for identifying the earliest human tools for quite some time. But they can do better these days ;-)

Edited January 14, 2019 by Green Baron

[YNM]

31 minutes ago, Green Baron said:

No refund on old compasses ...

I wonder what would we rely on in a reversal or excursion ? Would there be a GPS-based compass of sorts ? GPS has been able to show true north for quite some time.

[Green Baron]

A correction for transforming magnetic course to true course must always be applied. So things will not change on that end, the corrections will just become bigger (could be >180° actually, or a sign flip).

In navigation, one can always use the stars, provided one has an exact chronometer (aka clock). Those who can operate a sextant will be unimpressed. The rest of us will have to check the display every now and then.

 

Edited January 14, 2019 by Green Baron

[magnemoe]

3 hours ago, Green Baron said:

A correction for transforming magnetic course to true course must always be applied. So things will not change on that end, the corrections will just become bigger (could be >180° actually, or a sign flip).

In navigation, one can always use the stars, provided one has an exact chronometer (aka clock). Those who can operate a sextant will be unimpressed. The rest of us will have to check the display every now and then.

Compasses are not very useful for open sea navigation except to know there to aim. 
This is also why it has limited effect on animals as it one of multiple tools, taking left at an railway crossing as the car GPS told me to. 

But yes we would just go GPS and our grandchildren would not understand How you could use compasses and maps then the pole jump around. 
Still it would have hurt if it hit 100 years ago. 

[Green Baron]

16 minutes ago, magnemoe said:

Compasses are not very useful for open sea navigation except to know there to aim.

They are the main navigational instrument at least on manually piloted sailing ships when underway. Especially during night or on the open ocean when there is no other reference the compass is the helmsman's best friend and always in sight. If a gps is on board (mostly the case today), it'll be counter checked several times a day for positioning, but not for steering a course.

It is simple: the compass reacts directly to changes, while the gps needs some time. Steering after the gps leads to a curve like a drunkard's walk (chasing the needle) and therefore chaos when among other traffic. Don't do it ;-)

A gps has its strength together with an autopilot, though a magnetic compass (fluxgate for signal transmission) will back up the automatic rudder.

Edited January 14, 2019 by Green Baron

[YNM]

14 hours ago, Green Baron said:

In navigation, one can always use the stars, provided one has an exact chronometer (aka clock). Those who can operate a sextant will be unimpressed.

I suppose I'll have to learn how our ancestors navigate, then.

Disclaimer : The one linked isn't exactly our direct ancestors, but it's likely that we had known of similar methods, hence the Malagasy and Bajau as well as Orang Laut.

Edited January 15, 2019 by YNM

[DDE]

@YNM, astronavigation now, astronavigation forever.

Edited January 15, 2019 by DDE

[Green Baron]

6 hours ago, YNM said:

I suppose I'll have to learn how our ancestors navigate, then.

You would :-) But it is still modern knowledge and a requirement in many countries. There are a lot of resources around for the interested :-)