Localized sudden changes in the geomagnetic secular variation.

Four centuries of geomagnetic secular variation from historical records

We present a new model of the magnetic ­ eld at the core{mantle boundary for the interval 1590{1990. The model, called gufm1, is based on a massive new compilation of historical observations of the magnetic ­ eld. The greater part of the new dataset originates from unpublished observations taken by mariners engaged in merchant and naval shipping. Considerable attention is given to both correcti...

Long-Term Seafloor Electromagnetic Observation in the Northwest Pacific May Detect the Vector Geomagnetic Secular Variation

Sea Floor ElectroMagnetic Stations (SFEMSs) are now operating at two deep seafloor sites called the 'WPB' and the 'NWP' in the West Philippine Basin and the Northwest Pacific Basin, respectively. One of the main objectives of the SFEMSs is to detect the geomagnetic secular variations on the deep seafloor where long-term geomagnetic observations have not so far been achieved. SFEMSs can measure ...

Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk

Observatory monthly means provide an excellent opportunity to study the temporal changes of the magnetic field at a given location. Unfortunately, the uneven distribution of the present observatory network makes it difficult to determine the global field change pattern. Recently, we have developed an approach to extract satellite monthly means at a regular network of “virtual observatories” at ...

Changes in cosmic ray cut-o rigidities due to secular variations of the geomagnetic ®eld

An analytical expression is derived for the cuto€ rigidity of cosmic rays arriving at a point in an arbitrary direction, when the main geomagnetic ®eld is approximated by that of an eccentric dipole. This expression is used to determine changes in geomagnetic cuto€s due to secular variation of the geomagnetic ®eld since 1835. E€ects of westward drift of the quadrupole ®eld and decrease in the e...

Fractal Analysis for Geomagnetic Secular Variations