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Archeomagnetic Jerks & Abrupt Climate Change

  1. Sep 14, 2009 #1
    http://sciences.blogs.liberation.fr/home/files/Courtillot07EPSL.pdf [Broken]

    I have been looking into puzzling cyclic changes the geomagnetic field which appear to be solar driven as they match the solar magnetic cycle timing. The sun is moved by the large planets about its barycenter. The change in direction of the sun and its acceleration at the time of the change in its direction appear to interrupt the solar tachocline which is the interface between the solar radiative zone and convection zone. The tachocline is the region where sun spots are produced. When the tachocline is disturbed sunspots cannot long build in the tachocline. A sunspot requires a field strength of around 2000 gauss to avoid being torn to pieces as it moves from the bottom of the convection zone (tachocline) to the solar surface.

    The restart of the solar magnetic cycle appears to create massive coronal mass ejection CME which when they strike the earth's ionosphere create very large electrical discharges from the ionosphere to the planet's surface. The timing of perihelion and the earth's axis tilt at the time of the event controls which hemisphere the strike hits.

    I would assume the polarity of the strike remains the same. Depending on the polarity of the earth's magnetic field at the time of the event and the hemisphere the strike occurs in, determines whether the strike will reduce or increase the earth's magnetic field. This explains why the strike does not always have a strong cooling effect on the climate. Prior to the strike the solar magnetic cycle is in a deep minimum which cools the planet. The geomagnetic field resists changes so will initially weaken in the region of the strike before the effect is integrated into the total geomagnetic field constructively or de-constructively.

    The ice sheet insulate the planet and force the strike down to lower latitudes where it has less affect on creating the geomagnetic field. This explains why the geomagnetic field drops in intensity by 70% during the glacial phase of the glacial/interglacial cycle.

    It has been known for sometime that cosmogenic isotopes changes track the abrupt climate changes on the planet.

    Read this paper thinking about the above proposed mechanism.

     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 15, 2009 #2

    Xnn

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    attachment.php?attachmentid=20509&stc=1&d=1252598357.jpg

    Sorry Saul; When I look at historic arctic temperatures over the last 2000 years, there doesn't appear to be much of a solar magnetic cycle to it. Just a slow gradual decline related to the procession of the perihelion up until the late 1800's when industrial CO2 emissions took off.

    http://www.ucar.edu/news/releases/2009/arctic2k.jsp [Broken]
     
    Last edited by a moderator: May 4, 2017
  4. Sep 15, 2009 #3

    The problem is the reconstruction is mixing paleo data with instrumentation data. Depending on the calibration of paleo data it makes the cycle disappear.

    Not the reconstruction is summer temperature. One would expect do to precession the summers would get cooler and the winters would get colder.

    Vostok-ice-core-petit.png


    http://upload.wikimedia.org/wikipedia/commons/c/c2/Vostok-ice-core-petit.png

    There are absolutely abrupt changes in the climatic record.

    For example, the above graph shows all of the past interglacial periods ended abruptly.
     
    Last edited by a moderator: May 4, 2017
  5. Sep 15, 2009 #4
    http://www.pnas.org/content/97/4/1331.full

    Abrupt climate change has in 1990's by examining the Greenland Ice Core.

    Ice-core evidence of abrupt climate changes

    http://www.pnas.org/content/97/4/1331/F1.large.jpg

    F1.large.jpg
     
  6. Sep 16, 2009 #5
    Hi, thanks for the info. Sounds promising
     
  7. Sep 16, 2009 #6
    The problem with paleo proxy reconstruction is that it is always an "affirming the consequent" fallacy. When it rains, the streets are wet. The streets are wet, so it rains. It could be true but it could not be true as well.

    We have just witnessed a tremendous exposure of proxies being misunderstood completely, here, within these threads in the last weeks, without a lot of people noticing.

    It's between this https://www.physicsforums.com/showthread.php?t=333747

    and this: https://www.physicsforums.com/showthread.php?t=335069&page=2

    with this post

    https://www.physicsforums.com/showpost.php?p=2334915&postcount=6

    in which it is shown that the isotope proxy warming started around 15000 years ago


    and this: https://www.physicsforums.com/showthread.php?t=335069&page=2

    in which it is suggested that widespread northern hemisphere warming started 3000-4000 years earlier.

    That's huge.

    I'll elaborate tomorrow.
     
    Last edited: Sep 16, 2009
  8. Sep 19, 2009 #7
    I have been looking for evidence of a periodic solar forcing of the geomagnetic field.

    Attached below is the evidence.

    This paper discusses five volcanoes that erupted during a magnetic field excursion. The five volcanoes are geographically in the same area, but are not linked by the same magna chamber.

    What it appears is the solar magnetic cycle is periodically interrupted. As part of the restart of the solar magnetic field, the sun produces massive coronal mass ejections. The CME create space charge imbalances in the ionosphere which in turn creates an electrical discharge from the ionosphere to the planet's surface.

    The hemisphere where the strike occurs is controlled by the timing of perihelion (closest approach of the sun to earth) and the earth's tilt at the time of event.

    Ice is an insulator. The ice sheets push the strike to lower latitudes. At lower latitudes the strike has less effect on the geomagnetic field, which explains why the geomagnetic field drops in intensity by a factor of 5 to 6 during the glacial part of the glacial/interglacial cycle.

    The strike reinforces the geomagnetic field if the polarity of the magnetic field induced matches the current polarity of the geomagnetic field. If it is opposite to the polarity of the geomagnetic field it will create a magnetic field anomaly in the region of the strike and will eventually reverse the geomagnetic field with subsequent strikes.

    The position of the continents controls the effectiveness of the strike and its effect. This explains why there were periods when the geomagnetic field has cyclically reversing with a period of around 20 kyr and others where the field did not change for millions of years.

    http://www.agu.org/pubs/crossref/2006/2006GL027284.shtml

    Geomagnetic excursion captured by multiple volcanoes in a monogenetic field

     
    Last edited: Sep 19, 2009
  9. Sep 19, 2009 #8
    This is the paper that shows the geomagnetic field drops by a factor of 5. The time constant for a core based change in the geomagnetic field is relatively long 2 to 5 kyrs. There is no explanation for how and why the geomagnetic field would change so rapidly.

    The Archeomagnetic Jerks occur with a periodicity of 600 years. Besides the time constant issue it does not seem possible a core based mechanism could change cyclically every 600 years.

    http://eprints.whiterose.ac.uk/416/1/gubbinsd4.pdf

    Is the geodynamo process intrinsically unstable? K. Zhangand, David Gubbins

     
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