From CANOPUS to NORSTAR and THEMIS Science

1. From CANOPUS to NORSTAR and THEMIS Science Igor Voronkov, Eric Donovan, and Brian Jackel Department of Physics and Astronomy, University of Calgary

2. CANOPUS MSPs, ASI, MAGs; • GOES 7, GOES 8, GOES 9, GOES 10; • Geotail, Polar, WIND, IMP 8, INTERBAL, etc. • NRCan MAGS.

3. CANOPUS Substorm Event Database Revisited 1. An equator-most (breakup, pre-onset, etc.) arc differs in its nature from other discrete arcs, such as growth phase, poleward boundary, FLR, quite time stationary, etc. arcs. 2. A breakup arc intensifies as a result of magnetic field line stretching at the near-Earth plasma sheet (NEPS). 3. Rare but suggestive examples show marginally stable system of the arc-NEPS system. 4. A breakup results from additional stretching of the NEPS magnetic field lines. This can be brought by: 4.1 Fast internal stretching of the NEPS; 4.2 Convection reversal (e.g., due to the IMF northward turning); 4.3 Energy input from the more distant plasma sheet (e.g., BBFs); 4.4 Self-consistent stretching of the entire central plasma sheet: NENL and near-Earth breakup together.

4. Bold Assertions An equator-most arc is a marginally stable structure which can be produced in the local min-B region at the near-Earth edge of the PS. The latter is required by equilibrium of the stretched magnetic field topology. Breakup is a process triggered by fast additional energy input to the min-B region, which allows overcoming the threshold of min-B quasi-linear instability. It can be triggered in a variety of ways: fast additional stretching of the NEPS, convection reversal, bursty flow, etc. By itself (“alone”), this process can be responsible for “pseudo-breakups” and local substorms. Full onset is an interaction of the NEPS breakup and more distant PS disruption (or “NENL”). It requires both stretched NEPS and narrow more distant PS. The process can be initiated both ways.

5. The auroral arcs could be generated in different plasma sheet domains by a variety of mechanisms (in that case we have to develop better arc/process categorization), and/or they simply connect the different regions (propagating from one to another region) as typical for the auroral streamers. V.A. Sergeev, ICS-6.