Brian Fraser

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Electromagnetic Ion Cyclotron Waves in the
Magnetosphere Wave and Plasma Properties
Brian Fraser Centre for Space Physics,
University of Newcastle , Callaghan, NSW,
Australia With contributions from Jerry
Goldstein, Tom Immel, Paul Lotoaniu, Nigel
Meredith, Mark Moldwin, Howard Singer, Michelle
Thomsen
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Outline

• What is the plasmapause?
• EMIC wave propagation magnetosphere
  ionosphere
• EMIC waves seen in association with plasma plumes
  
• Plasma-Ring Current conditions associated with
  EMIC waves occurring in plasmasphere plume
• Wave plasma Statistics

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1. What is Your Plasmapause? Do all Instruments
see the Same Plasmapause?
OGO-5 H DE-1 H,He,O CRRES e- Cluster e-,
ions
LANL Ions POLAR e-, ions ULF
Waves Ion Mass IMAGE - Plasmasphere/Plume
s He,
Cold plasma measured?
Heavy Ions in the Plasmasphere Ion
Mass Loading
DE-1
DE-1
(Horwitz et al., GRL, 1984) (Fraser et al.,
GRL, 2005)
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2. EMIC Wave Propagation Dispersion in a 3-ion
Cold Plasma
Fraser, 1985
ATS-6
Fraser McPherron 1982
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EMIC Wave Propagation Away from the Equator
(Perraut et al., JGR, 1984)
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Propagation away from a Source Region Within
110 of the Magnetic Equator CRRES Poynting
vector Data
N. Hemisphere
?
?
?
?
S. Hemisphere
Lotoaniu et al., 2005
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Electromagnetic Ion Cyclotron Waves and Plasma
Diagnostics in the Magnetosphere
EMIC Waves Seen as Pc1-2 Waves at High Latitudes
on the Ground
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Bouncing Wave Packets - Ground Observations
Upper Panel A superimposed dynamic spectrum of
Pc1 EMIC waves observed at the near-conjugate
stations of Great Whale River and Byrd. The
solid and dotted arrows represent signals
observed at these two stations respectively. Lower
panel Amplitude records of the wave structure
illustrating the 180? phase shift between
hemispheres (after Saito, 1969).
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CRRES Observations

• EMIC waves at 2-3Hz seen at L4.5-5.5 and
  MLAT27o off the equator (no fine structure)
• Propagated from the equatorial region
• Occurs in the trough region and runs into the
  plasmapause

fHe
Plasmapause
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CRRES Observations

• EMIC event frequency 0.3-1.5Hz at L5.3 and
  MLAT0.5o
• Propagation in the plasmasphere with density
  Ne100cm-3
• Harmonic structure with fundamental below fHe
  and three harmonics above
• Propagation in a density slot where Ne reduces
  from 100cm-3 to 70cm-3 minimum in the duct
• Width of duct is 0.16Re,

(N ½) waves
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Full plasmasphere
EMIC in Plume
EMIC at Plume edge?
Radial Plumes
(Fraser et al., 2005)
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• GOES can only see waves
• with frequencies lt1Hz.
• EMIC waves identified through
• wave analysis.
• Typically similar to IPDP and Pc1-2
• Unstructured pulsations seen in the
• Outer magnetosphere and on the
• Ground at high latitudes
• (Anderson et al 1996 Menk et al 1992)

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23 May 2001 IMAGE FUV-EUV Detached Proton Arc
Plasma Plume
FUV sees arcs 1901-2327UT (T. Immel)
GOES-8 Footprint (T89 Kp3)
EUV plasmasphere (J. Goldstein) GOES EMIC waves
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GOES-8 EMIC Waves 23 May 2001 Note He slot
1.0
Hn
Hz
0
2210
2310UT
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GOES-8 Spectral Analysis 23 May 2001 2210-2310UT
He-Hn
He
Pwr
Pwr
1.0
Coherence
Hn
0
Pwr
Crossphase
LH 0 RH
0
1.0
1.0
0
Frequency (Hz)
Frequency (Hz)
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GOES LANL (MPA) IMAGE (EUV) 23 -24 May 2001
EUV
EUV
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Occurrence of EMIC Waves at CRRES 14 months
1990-1991
Reasonably even distribution with L over Xlt0.25
Normalised wave frequency - ?L
?L 0 is the plasmapause. ?L lt 0 waves in the
plasmasphere ?L gt 0 waves outside the
plasmasphere, in the plasma trough. 
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3. Occurrence of EMIC Waves at CRRES 14 months
1990-1991
More waves occurring outside the Plasmapause
below fHe
Normalised wave frequency - ?L
fHe
?L 0 is the plasmapause. ?L lt 0 waves in the
plasmasphere ?L gt 0 waves outside the
plasmasphere, in the plasma trough. 
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Plasma Cavity- Plasmapause-Plasma Trough

A
B
C
D
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CRRES Orbit 991 9 September 1991
IMF Bz 5nT
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CRRES Orbit 992 9-10 September 1991
IMF Bz 10nT
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6. Ring Current Plasmasphere Interaction for
EMICW
Radial plasmasphere-ring current interaction at
the plasmapause
(Kawamura et al., Mem., NIPR, 1982)
Azimuthal plasmasphere-ring current interaction
with plumes
HENA 10-60keV protons
17 April, 2002
(Goldstein et al., JGR, 2005)
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5. Statistics Plasma Conditions for Plumes
CRRES - Normalised frequency PWE e- density
?
CRRES - Frequency MLT
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Occurrence of EMIC Waves at CRRES 14 months
1990-1991
More waves seen 14-18 MLT and L gt 4
8
4
(Meredith et al., JGR, 2003)
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CRRES Statistics - 1
Normalised frequency - L
Normalised frequency - MLAT
Ellipticity - MLAT
Normalised frequency e- density
RH
LH
Normalised wave frequency - ?L
?L 0 is the plasmapause. ?L lt 0 waves in the
plasmasphere ?L gt 0 waves outside the
plasmasphere, in the plasma trough. 
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CRRES Statistics - 2

• Scatter plot of CRRES EMIC wave event local
  magnetic field magnitude against plasma density.
• Overlaid are contour plots of maximum convective
  growth rate for a pure proton plasma in the NB
  plane generated by Anderson et al. JGR, (1992).

He
Scatter plot of the wave transverse spectral
power density versus ?L Le - Lpp where Le and
Lpp are the L values corresponding to the
position of the wave occurrence and that of the
plasmapause, respectively.
O
Scatter plot of the wave frequency versus local
total magnetic field magnitude.
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Summary

• EMIC waves occur more often in the plasma trough
  than the plasmasphere/plasmapause
• They preferentially occur in association with the
  higher density regions
• The high density regions may be radially
  structured plumes (or a full plasma trough)
• A gradient interface boundary between the ring
  current and the cold/cool plasma may be necessary
  to create instability. This may be
• A radial boundary in the trough produced by
  plumes, or
• An azimuthal boundary provided by the plasmapause
• There may be a threshold density for instability,
  in the range 10-100 cm-3. (Role of plasma ß?)
• NOTE Identification of the plasmapause may
  depend on particle species(e-, H, He, O)

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What Needs to be Done?

• Robust EMIC wave statistics taking into
  consideration Solar Wind IMF conditions, and
  Dst, Kp, AE etc.
• Undertake similar E-field EMIC wave analysis.
  Will see EMIC at low L. Not possible with B field
  due to steep gradient at low L.
• Individual storm event studies for comparison
  with modellers. Do for both RC and RB. (New GOES
  data Available)
• What else does the RB community want from the
  CRRES dataset?
• Important Unresolved Issues
• Are EMIC waves seen during the main phase
• Role of Magnetosonic waves (first few harmonics
  only)
• As yet to be defined