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The Magnetic North Pole

    Earth's magnetic north pole is where the magnetic field lines are oriented vertically and plunge into the surface of the Earth i.e. where the magnetic inclination is +90 degrees. This is called the magnetic dip pole. The pole varies in position on a yearly basis due to secular variation (or drift in Earth's magnetic field). The British polar explorer Sir James Clark Ross measured the first location of the magnetic north pole on May 31, 1831 (70°5.3'N 96°46.0'W). The now famous Roald Amundsen made the second observation of the north magnetic dip pole in 1904 (70°31'N 96°34'W) during his voyage through the northwest passage. Canadian government scientists have since measured the location of the magnetic north pole beginning in 1947 and continuing through 1994 and 2001. Below is a map showing the 1831 location measured by Ross and the subsequent 1904, 1947, 1994 and 2001 locations. The magnetic north pole has progressively moved offshore over the past few years. The geophysical significance of the North Magnetic dip pole location is actually only of marginal scientific interest or importance, the primary interest has more to do with public outreach.

    The following table is from the Canadian government estimates of where the North Magnetic Pole is moving over the next few years. The observed position is shown for 2001 followed by predicted locations. A recent estimate of the pole location for April 2007 was published by Newitt et al. [2009] using measurements made on the ice.

    Year
    Latitude ( °N)
    Longitude ( °W)
    2001
    81.3
    110.8
    2002
    81.6
    111.6
    2003
    82.0
    112.4
    2004
    82.3
    113.4
    2005
    82.7
    114.4
    2007.3
    83.95
    120.72

     

    There are many other ways to estimate the magnetic north pole position based on the global magnetic field models (i.e. the International Geomagnetic Reference Field (IGRF) models). These computed pole positions are generally quite different than the actual measured dip pole and careful attention to the assumptions made in each calculation is needed. For example, we can compute the Geocentric Axial Dipole north pole using the best-fitting dipole model of Earth's magnetic field, which uses the first three terms (i.e. dipole terms; degree-1) of the spherical harmonic model. This is often called the Centered Dipole (CD) model. The CD northpole is located in northern Greenland. We can compute the best-fitting Eccentric Dipole (ED) north pole, which incorporates the first 8 terms of the spherical harmonic model (i.e. up to degree-2). Alternatively, we can use all 120 of the terms of the spherical harmonic model (up to degree-10) and compute the IGRF Model Dip pole. Below is a figure of the magnetic north pole location based on the computed IGRF Model Dip from 1900 to January 1st 2005. This is called the IGRF Model Dip Magnetic North Pole.

     

    To get more information on the latest location of the Magnetic North Pole check out the following web sites.

  • Tracking the magnetic north pole in Canada by the Geological Survey of Canada
  • Frequently asked questions on geomagnetic fields : NGDC


    The Magnetic South Pole is likewise moving each year. Click here to see the position of the Magnetic South Pole in 1990.


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