Swarm tracks Earth’s turbulent magnetic field 

Posted: May 12, 2016 by oldbrew in Geomagnetism, research
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Earth's magnetosphere [image credit: SPL / BBC]

Earth’s magnetosphere [image credit: SPL / BBC]


The BBC report by Jonathan Amos includes two ‘blink-and-you-miss-it’ videos that offer a global view of the magnetic patterns. The three-year east-west oscillation sounds interesting.

Europe’s Swarm mission is providing an unprecedented view of Earth’s turbulent magnetic field, scientists say. The three-satellite constellation is now routinely mapping its convulsions, allowing researchers to probe the mechanisms that drive the “invisible shield” in remarkable new detail.

Movies released this week by the Swarm team show how the field strengthens and weakens over time.
They also illustrate the speed at which those changes occur.

“I’m interested in using Swarm data to see what’s happening down in the planet’s molten outer core, where fluid motions are generating this field,” said Chris Finlay from the Technical University of Denmark.
“For me, this is real Earth exploration, because we know so very little about what is going on in that place,” he told BBC News.

The planet’s magnetic field is a complex, multi-component problem. As well as that dominant signal generated 3,000km beneath our feet in the swirling convection of liquid iron, there are other contributions pulling on the needle of every compass. These include the magnetism retained in rocks, and even a very subtle effect derived from the movement of salt water ocean currents. The Swarm satellites’ task is to try to tease apart these various factors, to get a clearer picture of the field’s most significant behaviours.

The magnetic “bubble” that protects us from space radiation is known to be in a long-term weakening phase, perhaps heralding one of the periodic flips where north becomes south and south becomes north. This hasn’t happened for 780,000 years. Whether we’re actually heading for another reversal now, scientists will only be able to gauge by studying the type of data coming from Swarm.

In the movies showcased here at the Living Planet Symposium in Prague, the satellites’ information is critical to the end of the animated sequences, which cover the past 15 years. One of the videos tracks changes in intensity in the magnetic field. Red is strong; blue is weak. [See the linked BBC report for videos].

The very dark blue region over the South Atlantic is the famous anomaly where the field’s weakness allows radiation belts around the Earth to bite down into the atmosphere. It’s over this zone where orbiting spacecraft suffer most of their electronic upsets. The movie reveals the anomaly to be widening, with its centre moving westwards, over Brazil, Uruguay, Paraguay and Argentina.

“Look also at the patch over North America which is decreasing in intensity; whereas over Asia, it’s been getting stronger. We haven’t really noticed this much before. We see it happening really quite quickly in the last few years,” explained Dr Finlay.
“And it’s that change in the topology which is also the reason the magnetic north pole is drifting away from the Americas as well. This is a decadal trend and Swarm is allowing us to track it in great detail.”

The second movie describes the rate of change in Earth’s magnetic field. Regions where changes are slowing are depicted in blue, while red highlights those locations where the changes are speeding up. An eye-catching feature is the oscillation west of Africa.

“We can now make these maps down at the outer edge of the dynamo, on the core-mantle boundary, and there we see a lot more of the small-scale details of the field change,” said Dr Finlay.
“We can use those changes at the core surface to map the flow within the core. And, for example, this positive-negative-positive oscillation – we’re seeing changes in the liquid motion within the core. There’s an oscillation in the flow in the east-west direction, which is going back and forth on a timescale of about three years.”

Source: Swarm tracks Earth’s turbulent magnetic field – BBC News

Comments
  1. craigm350 says:

    Reblogged this on CraigM350 and commented:
    blink-and-you-miss-it indeed!

  2. ren says:

    10 May 2016
    With more than two years of measurements by ESA’s Swarm satellite trio, changes in the strength of Earth’s magnetic field are being mapped in detail.

    Launched at the end of 2013, Swarm is measuring and untangling the different magnetic signals from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere – an undertaking that will take several years to complete.
    http://www.esa.int/Our_Activities/Observing_the_Earth/Swarm/Earth_s_magnetic_heartbeat

  3. “The magnetic ‘bubble’ … is … in a long-term weakening phase, perhaps heralding one of the periodic flips where north becomes south and south becomes north. This hasn’t happened for 780,000 years.”

    Not for “780,000 years”, but just now, when they want publicity for their “new understanding”. Sure. You bet.

    Today’s scientists think the public is as incompetent to estimate simple probabilities (for their empty speculations being true) as they have become. They are no better than evangelists shouting “These are the End Times!” “Repent … oh, and believe us without question, too”.

    Sorry, but it’s hype, all the way down. And somebody needs to say it, loud enough for everyone to get it, and for scientists to stop it. They are trying to dumb down the public, just as they have dumbed themselves down to this sorry state.

  4. ren says:

    Annual rate of change of declination for 2015.0 to 2020.0 from the World Magnetic Model (WMM2015). Red –easterly change, blue – westerly change, green – zero change. Contour interval is 2’/year (1/30th of a degree), white star is location of a magnetic pole and projection is Mercator

  5. TLMango says:

    The motion of the sun gives us axial precession and obliquity.
    Axial precession and obliquity are just two of the motions that
    influence the earth’s dynamo. Periodic weakening of the earth’s
    magnetic field is what gives us regular cooling cycles. When we
    fully understand how the magnetic field facilitates the release of
    heat, then we will have finally made the connection between the
    sun’s motion and the cooling cycles.

    See my graph of the 144 year Bretagnon wave oscillating on the
    Hallstatt cycle at:
    Weathercycles.wordpress.com

  6. oldbrew says:

    ‘Space mission first to observe key interaction between magnetic fields of Earth and sun’
    http://phys.org/news/2016-05-space-mission-key-interaction-magnetic.html

    More claims about ‘magnetic field lines’ and magnetic reconnection.

    Given the fact that magnetism is invisible, what are they really observing?
    Do ‘magnetic field lines’ exist in three dimensional reality?

  7. Paul Vaughan says:

    These are the quotes I’m flagging:

    “[…] using Swarm data to see what’s happening down in the planet’s molten outer core, where fluid motions are generating this field […] For me, this is real Earth exploration, because we know so very little about what is going on in that place […] There’s an oscillation in the flow in the east-west direction, which is going back and forth on a timescale of about three years.”

    I’m not looking at this as a climate driver but rather as an indicator of Earth’s changing shape (to which climate is very sensitive).

    However, they’ll need multidecadal & centennial observation to make this really interesting. Yet, there may be some useful clues in a few years of data.

  8. ren says:

    The magnetic field protects against ionizing radiation. Current changes (during low solar activity) are favorable to Europe – the field strengthens and unfavorable to America – the field is weakening.
    http://geomag.bgs.ac.uk/research/modelling/IGRF.html
    Visible is the large increase in the Indian Ocean, where the ionization is weakest.

    This is evident also in the area of ozone and has an impact on the polar vortex.

  9. Oldmank says:

    Quoting from above: ” This hasn’t happened for 780,000 years”.

    How do they know that? From remanent magnetism locked in the rock?

    Orientation of certain places with respect to sunrise on horizon changed repeatedly during the Holocene. In other places ?????, but I would not take the case of a steady earth for granted. Far from it.

  10. oldbrew says:

    ‘There’s an oscillation in the flow in the east-west direction, which is going back and forth on a timescale of about three years.’ – Dr Finlay

    ‘It is well known that the lunar nodes precess westward around the ecliptic, completing a revolution in 18.6 years. Lunar perigee moves eastward, completing a revolution in 8.85 years. Because of these opposite motions, a node meets a perigee in exactly 6 years.’
    http://syrte.obspm.fr/jsr/journees2014/pdf/Sidorenkov.pdf

    2 x 3 years = 6 years. Possible connection?

    See also: De Rop’s long-term lunar cycle
    https://tallbloke.wordpress.com/2016/01/05/de-rops-long-term-lunar-cycle/

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