Lunar precursor effects in the Terrestrial magnetosphere and solar wind
description
Transcript of Lunar precursor effects in the Terrestrial magnetosphere and solar wind
ARTEMIS Science Working Team Meeting 9/14-16/2011
LUNAR PRECURSOR EFFECTS IN THE TERRESTRIAL MAGNETOSPHERE AND SOLAR WINDJasper S. HalekasSpace Sciences LaboratoryUniversity of California, Berkeley
The Lunar Space Plasma Environment: Pre-ARTEMIS
Precursor Effects in the Terrestrial Magnetosphere
All Electrons
Upgoing e- (0-15°)
Downgoing e- (165-180°)
EFI FFTSCM FFT
B Wavelets
B Field
fpfce
fci
fpfce
Spin Tone
EFI Background
Free Energy Sources: Reflected Electrons in Magnetosphere
Loss Cone
Beam
Beam + Loss Cone:Produced By CombinedMagnetic & ElectrostaticEffects Near Surface
DownwardElectric Field
Plasma Electrons Follow Magnetic Field Linesand Reflect from E & B
Secondary ElectronsAccelerated Upward
E = - UΔConverging Magnetic Field Lines above Crustal Magnetic Fields
Polarization Properties
Coherent
Parallel-Propagating
Right-Handed
• Wave properties all consistent with parallel-propagating whistlers coming down the magnetic field line towards the Moon
NarrowbandWaves propagating anti-parallel to field
EXB
EB
B0
Instability Conditions
EFI
SCW
Reduced DistributionFunctionWhistler Mode: ω/k, (ωce-ω)/k
Streaming instabilities where df/dv|| positive
Whistlers correlate with edges of loss cone: i.e. df/dvperp positive
Ions in the Mix?• Waves near fci modulate both the electron beam and the whistlers• Possible sources: Electron beam, shadowed ion distributions, bi-ion streaming
FGM Wavelets
Loss Cone Modulated
Electron Beam Modulated
Whistlers ModulatedProton & HeliumCyclotron Frequencies
ICWs?
Precursor Effects in the Solar Wind
IonsUpgoing e- (0-15°)
Downgoing e- (165-180°)
EFI FFT
SCM FFTB Wavelets
B Field
SZA of SurfaceConnection
Fitzenreiter et al., 1990
Solar
Wind
Free Energy Sources: Reflected Electrons in Solar Wind
Generalized obstacle with magnetic fieldgradient and/or electrostatic potential gradient
MagneticField
ConvectionElectric Field
Electron Trajectory
Adiabatic Reflection in dHT Frame Gives you “Ears” in Solar Wind Frame
Whistler Cyclotron Resonance Conditions
EFI
SCW
Reduced DistributionFunction(ωce-ω)/k : ω, k on whistler branch
Ion Observations
P2 Ions
P1 Ions
P1 Reduced Dist. Funct.
P1 Power Spectrum
P1 Propagation
P1 Ellipticity
Parallel-Propagating
RH, LH
Foreshock Ions
Reflected Protons
Free Energy Sources: Reflection From Crustal Magnetic Fields
Reflected Proton FluxesLue et al., 2010
Reflected ProtonsFollow PickupIon Trajectories
Solar
Wind
GyratingProtons
Distribution Near Cycloid “Cusp”
IMF
SW
Pickup Ion Trajectories
Surface Crustal Magnetic Field
ConnectedUnconnected
ReconstructedIon Trajectories
Ion Reflection Source Map
26 Event Periods, June 29 – August 31
Lunar Precursor Effects