Storm-Time Substorms and Sawtooth Events: Test for Substorm Models

Pulkkinen, T.I., Tanskanen, E.I., Reeves, G.D., Donovan, E., Singer, H.J., 
Slavin, J.A.


A substorm search engine is used to identify substorm onsets that occur during
magnetic storms in the period 2001-2004. Each substorm is analyzed in detail
using several parameters to classify the events. Peak amplitude of the substorm
is defined from the AL-index. Existence and type of energetic particle
injections are determined from the LANL energetic ion and electron data. Tail
magnetic field measurements (GOES, Cluster, Geotail) are used to infer whether a
thin current sheet was formed prior to the substorm onset. Latitudinal
magnetometer chains (CANOPUS, IMAGE) are used to determine whether the main
expansion direction was poleward or equatorward. Possible triggers for the onset
and intensity of the driving electric field are identified from the solar wind
and interplanetary magnetic field measurements (ACE, WIND). The goal of the
study is to statistically examine to what extent the stormtime substorms show
signatures typically associated classical non-storm substorms and to what extent
the activity is characteristic only of storm periods. Furthermore, the goal is
to identify the "sawtooth events" from the data set, and examine whether the
activation characteristics differ from the other stormtime activations.

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Fall Meeting, American Geophysical Union, San Francisco, U.S.A., 
5-9 December 2005