HR: 16:45h
AN: U42B-04 INVITED     [PDF]
TI: Geomagnetic Variations and Their Possible Effects on System Earth
AU: * Glassmeier, K
EM: kh.glassmeier@tu-bs.de
AF: Institute for Geophysics, Technical University of Braunschweig, Mendelssohnstrasse 3, Braunschweig, 38106 Germany
AU: * Glassmeier, K
EM: kh.glassmeier@tu-bs.de
AF: MPI for Aeronomy, Max-Planck-Strasse 2, Katlenburg-Lindau, 37191 Germany
AB: The Earth magnetic field exhibits a variety of temporal variations with time scales ranging from a few seconds up to millions of years. The most pronounced variation is certainly a polarity transition during which the geomagnetic field strength decays down to about 10-20 % of its current value. A question of immediate interest is whether and in which way System Earth reacts on such a dramatic event. First the magnetosphere changes its size and shape. Due to the decreasing geomagnetic field the magnetopause is located much closer to the surface of the Earth. If the field exhibits strong quadrupole components magnetic reconnection can happen in the northern dayside magnetosphere with the southern hemisphere featuring a closed magnetosphere. Also the magnetotail structure changes drastically. Energetic particle entry occurs not only in dipolar cap regions but over much enlarged areas. As the ionospheric conductivity depends on the geomagnetic field strength first estimates furthermore indicate that externally driven geomagnetic variations are stronger during times of a polarity transition. The weaker field also makes the middle atmosphere much more sensitive to energetic particle events and large natural ozone holes are very likely during polarity transitions as first model calculations indicate.
DE: 1512 Environmental magnetism
DE: 1522 Paleomagnetic secular variation
DE: 1535 Reversals (process, timescale, magnetostratigraphy)
DE: 2708 Current systems (2409)
DE: 2740 Magnetospheric configuration and dynamics
SC: U
MN: 2003 Fall Meeting