Looking for Geomagnetic Jerks in the Polar Regions

We study the geomagnetic jerks over the Artic and Antarctic regions using an approach based on the comprehensive geomagnetic field model CM4 and derived secular acceleration maps. We are interested to improve our knowledge on spatial distribution and the time occurrence of geomagnetic jerks over the polar areas where, until now, mainly the lack of a sufficient number of permanent geomagnetic observatories and the strong influence of external origin magnetic fields, have limited conclusive results. To do this, secular acceleration maps of the geomagnetic field, were obtained using synthetic data generated by the comprehensive geomagnetic field model CM4, and jerks were detected as jumps in the secular acceleration values. Our analysis confirms that the occurrence of geomagnetic jerks in the Antarctic continent follows, with an average time lag of about two years, the occurrence of geomagnetic jerks in the Artic region and reveals that the local jerk of 1986 could have a larger spatial extension than so far known. Indeed, evidences of abrupt changes in the secular acceleration maps around this date have been found now both in the Artic region and on the Antarctic continent.