WHISPER new observation - Narrow band observation - Harmonic form
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• WHISPER new observation - Narrow band observation - Harmonic form - Northern and in the southern hemisphere - Regular plasmasphere ; « Christmas Tree » nfce waves in the plasmasphere region : A new observation using WHISPER/CLUSTER instrument F. El-Lemdani Mazouz (1,2), P. M. E. Décréau (1), J. L. Rauch (1), J. G. Trotignon (1), X Vallières (1), S. Kougblenou (1), P. Canu (2), F. Darrouzet (3). (1) LPC2E, ( France), (2) LPP ( France), (3)IASB-BIRA, (BELGIUM). Email: [email protected] Abstract:Whisper instrument on board CLUSTER spacecraft allows the detection of a new class of wave observation in the plasmasphere region. We present here, spectral and statistical properties of these observations observed at nfce, at frequencies higher than the local plasma frequency. We start via an event study to present spectral properties of these observations, frequency and intensity behaviour are determined. High values of the modulation index, and intensity dependence on the B field orientation indicates a linear polarization on the spin plan. We present also a statistical study, on the nfce events, using a data set covering the three years 2002-2004. Strong MLT dependence of these emissions is shown. The correlation between these observations and a particular form of the plasmasphere so called “Christmas tree form” is pointed out. Finally the study of the variation of the Ae index indicates an augmentation of this index one day before the events, indicating a correlation between injection of energetic particles and the observation of nfce emissions. A New class of wave observation: nfce emissions Orientation / Magnetic Field Statistical properties Modulation index 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0% 20% 40% 60% 80% 100% nfce observations ALL perigee pass t t- 24 t t- 24 700<A e 300<A e<700 100<A e<300 A e<100 • Particule injection • High values of the Ae index 24 hours before the obser 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% non M M fp kHz occurrence 30 40 50 60 70 80 90 • High values of fp • Typical values of the « Christmas Tree form » → Method of the maxima of intensity: - Exactly situated at nfce - Successive observation on each band - 3 harmonics in the NH : M7,M6,M5 Predicted by Farrel (2001) • Modulation about 90% Linear polarisation observed in the spin plane Conclusion • WHISPER instrument allows the detection of a new class of wave phenomena at nfce, predicted by a maser synchrotron theory (Farrel, 2001). • nfce observation: rare phenomena strongly confined to premidnight sector • Statistical and events study shown the relationship between this observation and the plasmasphere “Christmas- tree” form. • MLT localization and AE index variation shown the correlation between nfce observation and particle • Strongly confined to the premidni • 3 years of data: 2002- 2004 : 30 events (C3 observation) ~8 % Variation of Θ (angle between electric and magnetif field) Frequency (kHz) 80 60 40 20 2 dB above 10 -7 V rms Hz -1/2 60 50 30 20 10 0 0 40 22:14 4.13 31.05 23.63 20:50 4.60 -23.50 22.94 21:11 4.36 -11.12 23.09 21:32 4.43 2.38 23.25 21:53 4.11 15.62 23.42 UT R(Re) LAT SM (°) MLT C4 20040317 5 fce M7 M6 M5 Position of the satellites at 21h10 SM coordina tes Time frequency dependence Z GSE Receptive antenna Spin plan X GSE Y GSE sun B E B θ 20040317 • Maximum of intensity for the higher harmonic M7 (3.10 -4 V rms .Hz -1/2 ) • Maximum of intensity in the perpendicular direction /B 00 03 06 09 12 15 18 21 Midnight Dawn Noon Dusk Plasmapause 2 3 4 5 6 L(RE) e- Injection particules e+ Particules injection e+ nfce Occurrence of nfce observation Equatorial L-MLT projection on Sm coordinates Equatorial values of the plasma frequency Variations of the AE index in the 24 hours preceding an observation
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nfce waves in the plasmasphere region : A new observation using WHISPER/CLUSTER instrument - PowerPoint PPT Presentation
Transcript of WHISPER new observation - Narrow band observation - Harmonic form
• WHISPER new observation
- Narrow band observation
- Harmonic form
- Northern and in the southern hemisphere
- Regular plasmasphere ; « Christmas Tree »
nfce waves in the plasmasphere region : A new observation using WHISPER/CLUSTER instrument
F. El-Lemdani Mazouz (1,2), P. M. E. Décréau (1), J. L. Rauch (1), J. G. Trotignon (1), X Vallières (1), S. Kougblenou (1), P. Canu (2), F. Darrouzet (3). (1) LPC2E, ( France), (2) LPP ( France), (3)IASB-BIRA, (BELGIUM).
Email: [email protected]
Abstract:Whisper instrument on board CLUSTER spacecraft allows the detection of a new class of wave observation in the plasmasphere region. We present here, spectral and statistical properties of these observations observed at nfce, at frequencies higher than the local plasma frequency. We start via an event study to present spectral properties of these observations, frequency and intensity behaviour are determined. High values of the modulation index, and intensity dependence on the B field orientation indicates a linear polarization on the spin plan.We present also a statistical study, on the nfce events, using a data set covering the three years 2002-2004.Strong MLT dependence of these emissions is shown. The correlation between these observations and a particular form of the plasmasphere so called “Christmas tree form” is pointed out. Finally the study of the variation of the Ae index indicates an augmentation of this index one day before the events, indicating a correlation between injection of energetic particles and the observation of nfce emissions.
A New class of wave observation: nfce emissions
Orientation / Magnetic Field Statistical properties
Modulation index
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0%
20%
40%
60%
80%
100%
nfce observations
ALL perigee pass
tt-24
tt-24
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
700<Ae
300<Ae<700
100<Ae<300
Ae<100
• Particule injection
• High values of the Ae index 24 hours before the observation
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
non M M
fp kHz
oc
curr
en
ce
30
40
50
60
70
80
90
• High values of fp
• Typical values of the
« Christmas Tree form »
→ Method of the maxima of intensity:
- Exactly situated at nfce
- Successive observation on each band
- 3 harmonics in the NH : M7,M6,M5
Predicted by Farrel (2001)
• Modulation about 90% Linear polarisation observed in the spin plane
Conclusion
• WHISPER instrument allows the detection of a new class of wave phenomena at nfce, predicted by a maser synchrotron theory (Farrel, 2001).
• nfce observation: rare phenomena strongly confined to premidnight sector
• Statistical and events study shown the relationship between this observation and the plasmasphere “Christmas-tree” form.
• MLT localization and AE index variation shown the correlation between nfce observation and particle injection.
• Mode observation in the perpendicular direction / magnetic field
• Strongly confined to the premidnight sector
• 3 years of data: 2002-2004 :
30 events (C3 observation) ~8 %
Variation of Θ
(angle between electric and magnetif field)
Fre
qu
ency
(kH
z)
80
60
40
20
2
dB
ab
ove
10-7
Vrm
sH
z-1/2
60
50
30
20
10
00
40
22:14
4.13
31.05
23.63
20:50
4.60
-23.50
22.94
21:11
4.36
-11.12
23.09
21:32
4.43
2.38
23.25
21:53
4.11
15.62
23.42
UT
R(Re)
LATSM(°)
MLT
C4 20040317
5 fce
M7
M6
M5
Position of the satellites at 21h10
SM coordinates
Time frequency dependence
Z GSE
Receptive antenna
Spin planXGSE
YGSE
sun
B
E
B
θ
20040317
• Maximum of intensity for the higher harmonic M7 (3.10-4 Vrms.Hz-1/2 )
• Maximum of intensity in the perpendicular direction /B
00
03
06
09
12
15
18
21
Midnight
Dawn
Noon
Dusk
Plasmapause
2 3 4 5 6 L(RE)
e-
Injection particules
e+
Particules injection
e+
nfce
Occurrence of nfce observation
Equatorial L-MLT projection on
Sm coordinates
Equatorial values of the plasma frequency
Variations of the AE index in the 24 hours preceding an observation
