1. Multi-spacecraft analysis of the geomagnetic tail: The source of intense and explosive aurora Miho Saito Solar-terrestrial environmental laboratory, Nagoya University 8 March, 2013 GCOE conference CREDIT:NASA/STEREO

2. Geomagnetic tail

3. Aurora from space At the initiation of substorm To Sun

4. Saito, M., 11th ICS, Sep 2012 Is a substorm a manifestation of energy storage and release in the tail ?: 1. Aurora Model of auroral development [Akasofu, 1964] From auroral observations, the answer is not obvious.

5. Is a substorm a manifestation of energy storage and release in the tail ?: 2. Magnetic energy YES. When we know HOW the energy is loaded, we may know how it is released, Yan Song ICS11

6. [Saito et al., 2010 JGR] In-situ observation of tail and drawback of single spacecraft measurements

7. 7 Five-spacecraft view of tail THEMIS orbits during 6-7 UT To Sun

8. Thinning at 11 Re in the pre-midnight (THEMIS) 8 Magnetic field (SM) ~20min

9. Textbook view of energy storage in the tail [McPherron et al., 1973; McPherron, Introduction to Space Physics] 9

10. 10 Five spacecraft obtain both spatial structure and its temporal changes.  P T ~0  n~0,  P<0 P T =P i +P e +P b PiPi NiNi Thinning (~20 min) P T =P i +P e +P b The defect of in-situ measurements removed!

11. Multi-spacecraft obs. show new types of energy storage process in the geomagnetic tail Incompressible change

12. Multi-spacecraft obs. improved in-situ diagnosis of the geomagnetic tail – The findings are also useful for forecasting the space weather We showed, for the first time, the incompressible nature before the intense and explosive aurora Conclusions Tail Energy flow Aurora Solar Wind

13. Compressibility matters Is it also the case for space? (Future study) A paint-cans-and-rifle experiment in “For the love of physics” by Walter Lewin rifle paint can liquid + air -> can deformed liquid filled -> explosion Result of the shock