OpenGGCM Simulation vs THEMIS Observations in an Dayside Event Wenhui Li and Joachim Raeder...
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Transcript of OpenGGCM Simulation vs THEMIS Observations in an Dayside Event Wenhui Li and Joachim Raeder...
OpenGGCM Simulation vs THEMIS Observationsin an Dayside Event
Wenhui Li and Joachim RaederUniversity of New Hampshire
Marit ØierosetUniversity of California, Berkeley
THEMIS 2008 UCLA
THEMIS Observations on 06/03/2007(Øieroset et. al. 2008)
● Northward IMF with strong By
during ~15:25 -- ~17:00 UT
● THEMIS-B in the magnetosheath
● THEMIS-A, C, D and E detect a layer of nearly-stagnant magnetosheath plasma (T ~ 1 keV, N ~ 3-6 cm-3) attached to the magnetopause on closed field lines
● From TH-D to TH-A, magnetospheric ion and electron flux increases
● Thickness of the layer ~ 0.9 RE
● No evidence for Kelvin-Helmholtz waves nor diffusion at the local magnetopause
● Particle distributions suggest double-high latitude reconnection involving the same field lines
OpenGGCM Simulation vs THEMIS Observations
-- Thickness of the cold dense plasma layer
values on the line passing THA at 16:30 UT
~1.3
THEMIS: ~ 1.1 RE along THEMIS trackSimulation: ~ 1.3 RE
CDPL
Open layer
IMF
How the cold dense plasma layer forms?
1. Double high-latitude reconnection captures magnetosheath plasma
Solar Wind
How the cold dense plasma layer forms?
2. New closed flux tubes slowly convect around magnetopause toward nightside -- results in a balance of inflow and outflow at dayside magnetopause and form a cold dense plasma layer
Solar wind
An entry flow pathFrozen-in field lines
Magnetic nulls
(Li et. al. 2005)
Summary
● THEMIS observed cold dense plasma layer in dayside closed field attached to magnetopause
● The multi spacecrafts estimated the thickness of the cold dense plasma layer to be ~0.9 RE
● An OpenGGCM simulation reproduces the THEMIS observations
● Observations and simulation analysis indicate that double high-latitude reconnection causes the formation of this cold dense plasma layer