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Substorm Triggering

Conveners: Larry Kepko (UCLA), Tony Lui (JHU/APL) & Shinobu Machida (Kyoto-U)


It is now widely accepted that a large fraction of substorms are externally triggered by changes in the solar wind conditions. These changes include, for example, northward turnings of the IMF and dynamic pressure pulses. Exactly how triggering occurs and which physical mechanism is responsible is still hotly debated. We have devoted two sessions to this topic, with focus on four broad areas of research:

1. Global MHD simulations

Global MHD simulations allow the substorm community to examine how the magnetosphere responds to external triggers in a way that cannot be accomplished with our current limited suite of in situ measurements. We invite papers that investigate, for example, how altering the duration of southward IMF before a northward turning (i.e., adjusting the time of the trigger) affects the development of the resulting substorm.

2. Triggering mechanism (theory)

This session is devoted to discussing possible physical mechanisms for triggering. An important aspect of substorms is to what extent they are the result of an internal instability as opposed to changes in the solar wind conditions. Theoretical models and simulations which address this topic are welcome.

3. Triggering observations

This broad topic includes statistical studies of solar wind triggers as well as single event studies not included below. Of particular interest are observations of the ionospheric response to triggering, and observations that provide insight into how the trigger propagates through the magnetosphere.

4. Event Studies

All from 1997

Substorm   Onset
 Date:     Time:

Jan 7	     03:30
Jan 7      17:30
Jan 8      14:15
Jan 9      08:15
Jan 10     18:50
Jan 11     10:35
Jan 11     13:50
Jan 12     07:30
Jan 18     02:20
Jan 19     14:30
Jan 21     14:45
Jan 22     05:10
Jan 25     20:18
Jan 26     18:30
Jan 26     22:20
Jan 27     10:15
Jan 27     16:30
Jan 29     19:55
Jan 30     17:10


Above is background material for archival reference only.

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