REPW-07 Brian Fraser Centre for Space Physics, University of Newcastle, Callaghan, NSW, Australia With contributions from: Jerry Goldstein, Tom Immel, Paul Loto’aniu, Nigel Meredith, Mark Moldwin, Howard Singer, Michelle Thomsen Electromagnetic Ion Cyclotron Waves in the Magnetosphere: Wave and Plasma Properties

REPW-07 Outline 1.What is the plasmapause? 2.EMIC wave propagation – magnetosphere & ionosphere 3.EMIC waves seen in association with plasma plumes 4.Plasma-Ring Current conditions associated with EMIC waves occurring in plasmasphere & plume 5.Wave & plasma Statistics

REPW-07 Heavy Ions in the Plasmasphere Ion Mass Loading (Horwitz et al., GRL, 1984)(Fraser et al., GRL, 2005) 1. What is Your Plasmapause? Do all Instruments see the Same Plasmapause? OGO-5H + DE-1H +,He +,O + CRRESe - Cluster e -, ions LANL Ions POLAR e -, ions ULF Waves Ion Mass IMAGE - Plasmasphere/Plumes He +, “Cold” plasma measured? DE-1

REPW EMIC Wave Propagation: Dispersion in a 3-ion Cold Plasma ATS-6 Fraser & McPherron 1982 Fraser, 1985

REPW-07 EMIC Wave Propagation Away from the Equator (Perraut et al., JGR, 1984)

REPW-07 Propagation away from a Source Region Within ±11 0 of the Magnetic Equator CRRES Poynting vector Data N. Hemisphere S. Hemisphere     Loto’aniu et al., 2005

REPW-07 Electromagnetic Ion Cyclotron Waves and Plasma Diagnostics in the Magnetosphere EMIC Waves Seen as Pc1-2 Waves at High Latitudes on the Ground

REPW-07 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). Bouncing Wave Packets - Ground Observations

REPW-07 Plasmapause ·EMIC waves at 2-3Hz seen at L= and MLAT=27 o off the equator (no fine structure) ·Propagated from the equatorial region ·Occurs in the trough region and runs into the plasmapause CRRES Observations f He+

REPW-07 BHBH Ellipticity Azimuth ·EMIC event frequency Hz at L=5.3 and MLAT=0.5 o ·Propagation in the plasmasphere with density N e =100cm -3 ·Harmonic structure with fundamental below f He + and three harmonics above ·Propagation in a density slot where N e reduces from 100cm -3 to ~70cm -3 minimum in the duct ·Width of duct is ~0.16Re, CRRES Observations (N + ½) waves

REPW-07 Maps from: Spasojevic et al. (2003) G8 G10 18:20-20:00UT G8 21:00-24:00UT G10 21:35-22:20UT G8 3. EMIC Waves and Radial Plasma Structures (Fraser et al., 2005) Full plasmasphere Radial Plumes EMIC in Plume EMIC at Plume edge?

REPW-07 9 June June UT 1822UT 1317LT 1215LT G10 G8 21:3022:30UT 16:3017:30LT Hn Frequency EMIC Waves appearing in Plumes GOES can only see waves with frequencies <1Hz. 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)

REPW May 2001 IMAGE FUV-EUV Detached Proton Arc; Plasma Plume GOES-8 Footprint (T89 Kp=3) FUV sees arcs UT (T. Immel) EUV plasmasphere (J. Goldstein) GOES EMIC waves

REPW-07 GOES-8 EMIC Waves 23 May 2001 Note He + slot UT Hz Hn

REPW-07 He Hn He-Hn Coherence Crossphase Pwr LH 0 RH Frequency (Hz) GOES-8 Spectral Analysis: 23 May UT

REPW-07 EUV GOES – LANL (MPA) – IMAGE (EUV) May 2001

REPW Ring Current – Plasmapause Interaction for EMICW (Kawamura et al., Mem., NIPR, 1982) (Goldstein et al., JGR, 2005) Plasmasphere-ring current interaction at the plasmapause L = April, 2002 (Summers et al., JGR, 1998)

REPW-07 Normalised wave frequency -  L  L = 0 is the plasmapause.  L < 0 waves in the plasmasphere  L > 0 waves outside the plasmasphere, in the plasma trough. Occurrence of EMIC Waves at CRRES : 14 months Reasonably even distribution with L over X<0.25

REPW-07 Normalised wave frequency -  L  L = 0 is the plasmapause.  L < 0 waves in the plasmasphere  L > 0 waves outside the plasmasphere, in the plasma trough. 3. Occurrence of EMIC Waves at CRRES: 14 months f He+ More waves occurring outside the Plasmapause below f He+

REPW-07 AB C D Plasma “Cavity”- Plasmapause-Plasma Trough

REPW-07 L= Plasmasphere-Plasmapause-Plasma Plumes Geostationary orbit (GOES, LANL) GTO orbit (CRRES) A B C D

REPW Plasmaspheric Plumes and EMIC Waves Following a Storm CRRES 9 September, 1991 EMIC (Density from Moldwin et al., 2003) Orbits separated by ~10hr Orbits at same MLT’s SSC occurred at end of orbit 990 Orbits in recovery phase Plume evolution and EMIC wave association EMIC at steep gradients/edges?

REPW-07 CRRES Orbit 9919 September 1991 IMF B z ~ –5nT

REPW-07 CRRES Orbit September 1991 IMF B z ~ –10nT

REPW Ring Current – Plasmasphere Interaction for EMICW (Kawamura et al., Mem., NIPR, 1982) Azimuthal plasmasphere-ring current interaction with plumes (Goldstein et al., JGR, 2005) Radial plasmasphere-ring current interaction at the plasmapause 17 April, 2002 HENA 10-60keV protons

REPW-07 L= EMIC Waves and Plasma Gradients Radial Gradient Azimuthal Gradient Convection Corotation

REPW-07 CRRES - Normalised frequency – PWE e- density CRRES - Frequency – MLT 5. Statistics: Plasma Conditions for Plumes 

REPW-07 Occurrence of EMIC Waves at CRRES: 14 months (Meredith et al., JGR, 2003) 4 8 More waves seen MLT and L > 4

REPW-07 CRRES Statistics - 1 Normalised frequency - L Normalised frequency - MLAT Normalised frequency – e - density Normalised wave frequency -  L Ellipticity - MLAT  L = 0 is the plasmapause.  L < 0 waves in the plasmasphere  L > 0 waves outside the plasmasphere, in the plasma trough. RH LH

REPW-07 Scatter plot of the wave transverse spectral power density versus ΔL = Le − Lpp where Le and Lpp are the L values corresponding to the position of the wave occurrence and that of the plasmapause, respectively. Scatter plot of the wave frequency versus local total magnetic field magnitude. O+O+ He + 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 N–B plane generated by Anderson et al. JGR, (1992).

REPW-07 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 cm -3. (Role of plasma ß?) NOTE: Identification of the plasmapause may depend on particle species(e -, H +, He +, O + )

REPW-07 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…………