Peculiarities of the Earth magnetic moment change according to the observations at different points of the Earth surface

  1. Institute of Geology and Minerology SB RAS, Russia

   Estimations of local magnetic constant in different regions during one
   epoch and of magnetic moment change rate during magnetic observatory
   operation with long observation series have been carried out. A number of
   interesting regularities have been determined which make us to be more
   attentive to the investigation of global and regional peculiarities in
   spatial-temporal morphology of the Earth magnetic field. Within the
   hypothesis on a single central dipole, it is impossible to explain the
   difference in the observable characteristics of the magnetic field by the
   Earth surface form and relief. Real distances from this surface to the
   center of the Earth differ by not more than 28 km (the top of Chimborazo
   Mountain in Ecuador and the ice surface in the North Pole). But for the
   same value of central dipole magnetic moment the distance difference to it
   from the farthest and the closest points of the Earth surface must exceed
   2200 km. The hypothesis on a single shifted dipole also contradicts with
   magnetic observatory data transformed into local magnetic constant,
   introduced at the beginning of the 20-th century by Bauer L.A. just to
   estimate the Earth magnetic moment change in different regions, and
   forgotten, to our opinion, unfairly by modern magnetologists. ''Average''
   decrease of the Earth magnetic moment with the rate of 5 percent per a
   century is, in reality, composed of its increase in some regions with the
   rates up to 20 percent per a century and decrease in other regions with
   the rates up to 50 percent per a century. For the majority of the magnetic
   observatories, magnetic moment change rate also undergoes considerable in
   amplitude variations with characteristic time of about 60-100 years.