Magnetopause moving at extreme velocity Knut Stanley Jacobsen, University of Oslo

1. 1 Magnetopause moving at extreme velocity Knut Stanley Jacobsen, University of Oslo

2. 2 Magnetopause moving at a speed of 800 km/s

3. 3 The velocity is perpendicular to the magnetic field

4. 4 Ground signatures were observed DRBY H DRBY D DRBY Z PINE H PINE D PINE Z

5. 5 THD V ACE B THB B Density V_x V_y V_z Temp. Ppla+ Pmag Ppla+ Pmag+ Pram Hot Flow Anomaly

6. 6 The magnetosheath first hits D, then E, then A TH <-B <-B <-A <-D <-E

7. 7 The order of magnetosheath encounters indicate something moving tailward GSM position at 14:05 -0.43 -30.45 4.20 2.16 -11.45 1.67 1.19 -11.57 1.55 -0.28 -14.10 1.93 Separation of D and A in XY-plane ~= 3.6 R_E To close this distance in ~60 secs requires a speed of ~380 km/s

8. 8 Example of similar event: 2007-09-04 - No esa data for Themis B and E, and no high-resolution data for Themis A. - Magnetopause velocity exceeds 600 km/s

9. 9 Example of similar event: 2007-08-28 - All spacecraft have high-resolution data. - They are located inside the magnetopause at different distances. - Magnetopause velocity exceeds 600 km/s