Cutting-Edge Results from Formation Flying Observations Cutting-Edge Results from Formation Flying Observations near Earth’s magnetopause Hiroshi Hasegawa 長長長 長 ( ) ISAS/JAXA Meeting on “Opportunity for Collaboration on ERG and SCOPE Missions & Community Input” (16-17 March 2009)
29
Embed
Cutting-Edge Results from Formation Flying Observations Cutting-Edge Results from Formation Flying Observations near Earth’s magnetopause Hiroshi Hasegawa.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Cutting-Edge Results from Formation Flying Observations
Cutting-Edge Results from Formation Flying Observations
near Earth’s magnetopause
Hiroshi Hasegawa (長谷川 洋)
ISAS/JAXA
Meeting on “Opportunity for Collaboration on ERG and SCOPE Missions & Community Input” (16-17 March 2009)
We hope to reach a complete understanding of fundamental physical processes (reconnection, shock, & turbulence) in the Plasma Universe.
• How does it start?
• How does it evolve?
• What feedbacks/consequences does it bring about?
In the future SCOPE era
As data analysts or theorists,
We should prepare well enough for the future missions,
by learning from “currently” available data from on-going multi-satellite missions.
We should not just wait
>10 satellites in near-Earth space
Geotail
Cluster (4 sc)
THEMIS (5 sc)
KAGUYA, & SW monitor
Most of the data are publicly available.
• How does it start?
• How does it evolve?
• What feedbacks/consequences does it bring about?
As a demonstration,
Here we address the Kelvin-Helmholtz instability (KHI) that can be excited at the magnetopause (it = KHI).
What we can do with available data
Shocked solar wind
Magnetopause KHI
Hasegawa et al., 2004; Nakamura et al., 2004
Kelvin-Helmholtz vortices may play a role in transport of solar wind into the magnetosphere, in other words, anomalous transport of collision-less plasma.
• How does it start?
• How does it evolve?
• What feedbacks/consequences does it bring about?
What we can do with available data
C1 electron
C1 ion
density
Cluster event on 20 Nov 2001 (19 LT)(Hasegawa et al., 2004; Chaston et al., 2007; Foullon et al., 2008)
temperature
velocity
magnetic field
TotalPvv
)(
Total-P perturbation in the vortex
streamline
Force balance
Total-P perturbation in the vortex
• Dominant-mode period ~200 s (Wavelength ~6 Re)• Power also at ~400 s: Beginning of vortex pairing?
• Spatial initial value problem• Assumptions: MHD, d/dt =0, 2D, & B along invariant axis z.
Dominant-mode wavelength ~6 Re
Vortex structurefrom Grad-Shafranov-like reconstruction of
streamlines (Sonnerup et al., 2006; Hasegawa et al., 2007)
C1
C3
• Two vortices within one dominant-mode wavelength.
Breakup of a parent MHD-scale vortex (cascade)?
The KHI seen by Cluster was fully in a nonlinear phase, characterized by merging/breakup (inverse-cascade/cascade) of the vortices.
• How does it start?
• How does it evolve?
• What feedbacks/consequences does it bring about?
The observed KHI wavelength (~6 Re) is much longer than predicted by theory.
Why???
What we can do with available data
Simultaneous observations of the magnetopause at different longitudes