The ring current during sawtooth oscillations: Data-model comparisons for 2 events

M.W. Liemohn, A.J. Ridley, and P.C. Brandt


Data analysis and modeling results of the inner magnetosphere are used to examine the
response of the ring current to sawtooth oscillations. Sawtooth oscillations are
periodic substorm-like events that often occur during the passage of interplanetary
coronal mass ejections (ICMEs). Two storm events will be considered, those on April
18, 2002 and on October 22, 2001. In both events, the sawtooth oscillations occurred
during the midst of an ICME passing by Earth. In situ (LANL MPA and SOPA), remote
sensing (IMAGE HENA), and ground-based (magnetometer) data will be presented, along
with simulation results from a kinetic particle transport model (the RAM code). It is
shown that the ring current exhibits unusual responses to sawtooth oscillations. A
repeated feature is that, following the dipolarizations, SYM-H recovers while the
observed hot ion fluxes intensify. The modeled Dst, however, is affected very little
by these intensifications. Several discrepancies exist between the data and the model
results, and the relative data-model relationship is not consistent between the
events.

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European Geosciences Union General Assembly, Vienna, Austria, 2-7 April 2006