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Mission DEMETER Quelques résultats sur l’ionosphère

Mission DEMETER Quelques résultats sur l’ionosphère J.J. Berthelier, T. Onishi, X. Wang*, E. Seran (LATMOS), M. Malingre (LPP) * Maintenant à OCA Atelier Pôle Système Solaire IPSL, Avril 2013. DEMETER. Plan 1- DEMETER: objectifs et charge utile scientifiques

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Mission DEMETER Quelques résultats sur l’ionosphère

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  1. Mission DEMETER Quelques résultats sur l’ionosphère J.J. Berthelier, T. Onishi, X. Wang*, E. Seran (LATMOS), M. Malingre (LPP) * Maintenant à OCA Atelier Pôle Système Solaire IPSL, Avril 2013

  2. DEMETER Plan 1- DEMETER: objectifs et charge utile scientifiques 2- Recherche d’effets pré-sismiques 3- Perturbations induites par les émetteurs VLF 4- Effets d’une éclipse dans l’ionosphère supérieure 5- Perturbations ionosphériques associées aux ondes de gravité 6- Instabilités de l’ionosphère équatoriale

  3. DEMETER Mission et Objectifs Scientifiques • - Premier µ-satellite de la famille MYRIADES du CNES • Lancement depuis Baïkonour le 29 juin 2004 • par lanceur Dniepr (ex SS19) • - Arrêt des opérations 9 décembre 2010 • Plus de 6 ans de bons et loyaux services • Objectifs scientifiques de la mission • 1- Recherche d’effets ionosphériques pré-sismiques • 2- Perturbations ionosphériques induites • par les activités humaines • 3- Physique de l’ionosphère et météorologie spatiale

  4. DEMETER • Orbit • - Circular at 715 km (later 650 km) , 98° inclination, • Quasi helio-synchronous • nodes ascending ~ 22.30 LT, descending ~ 10.30 LT • - 3 axis stabilized, X nadir, - Z aligned with orbital velocity

  5. DEMETER Orbites et zones de mode Burst

  6. DEMETER Recherche d’effets pré-sismiques dans l’ionosphère Analyse statistiques des ondes VLF Distribution statistique Sans activité sismique M>5, d ≤40 km M ≥ 4.8, d ≤40 km M>5, d ≤40 km

  7. DEMETER Perturbations ionosphériques associées aux émetteurs VLF

  8. DEMETER Effets des émetteurs VLF sur les ceintures de radiation

  9. DEMETER Eclipse 29 Mars 2006 Effets dans l’ionosphère supérieure

  10. DEMETER Eclipse 29 Mars 2006 Effets dans l’ionosphère supérieure Observations DEMETER Modélisation SAMI2

  11. DEMETER MSTID et ondes de gravité

  12. Data comparison at the same conjugate points of different altitudes (300km and 660km)

  13. DEMETERPropagation des perturbations dans l’ionosphère supérieure Ionosphère non collisionnelle DEMETER 660km ≤ 400 km Ionosphère collisionnelle F-peak 300km

  14. DEMETERModélisation ionosphérique SAMI2 Difference Normal SAMI2 Simulation SAMI2 Simulation with MSTID The difference of 2 results illustrates a propagation of MSTID perturbation along B-field. Propagation reaches to the other hemisphere.

  15. DEMETER Comparaison Observations Simulations Phase differences of observedparameters and theirorders correspond wellbetween the observation and a simulation.

  16. SAMI2: Plasma Propagation Ion Acoustic wave in SAMI2 for each ion species Propagation speed matches to that of the ion acousticwave of the major ion species (H+) at high altitudes

  17. The Magnetic Storm of November 7 to 10, 2004 Orbits with plasma depletions

  18. Nigh-time Orbit 1903 Equatorial Plasma depletion and Plasma waves Electrostatic Turbulence at boundaries Continuous ELF EM emissions Burst of LH turbulence Triggered by whistlers

  19. DEMETER orbit F-layer plasma velocity in depletion

  20. LH Emissions Solitary Structures

  21. Lower Hybrid Emissions 1- Bursts of electrostatic LH turbulence triggered by strong whistlers, High intensity, 104 µV2/m2.Hz at ωLH Relaxation time ~ 10s 2- Evolve as solitary, monochromatic LH structures Large amplitude (~10 mV/m) wave packets, duration ~ 20 ms, Most often detected in localized density holes (ΔNi/Ni ~ -10% to -15%) Interpretation LH turbulence: scattering of whistler waves by pre-existing irregularities (e.g. Bell and Ngo, 1990) LHSS as eigenmodes of cylindrical magnetic field aligned depletions (e.g. Schuck et al., 1998)

  22. LH emissions and ion heating

  23. Super-thermal ion tails

  24. Ion Heating • 1- Super-thermal ions detected in deep plasma depletions • - simultaneous with LH turbulence and solitary structures • - heavy ions O+, NO+ • 2- No heating of the core ion distribution • stays at constant moderate temperature ~ 1200°K • 3- Development of a super-thermal ion tail • typical: Nhot/Ncold~1-5%, Thot ~ 1 to 3 eV (~ 10 to 30 Tcold) • Interpretation • Heating by LH solitary waves • Mechanism? resonant interaction unlikely since VLH >>Vthi

  25. EQUATORIAL PLASMA BUBBLES AND IONOSPHERIC OBSERVATIONS BY DEMETER. Summary of main observations 1- Deep plasma depletions (similar to SIBB, Kil et al., 2003) - consequence of the previous rise of the bottomside F-layer - downward plasma motion and bifurcation 2- ELF EM waves - Magnetospheric Line Radiations - trapped/ducted in deep and large depletions 3- LH turbulence and LHSS - LH turbulence due to scattering of high amplitude whistlers by irregularities - LHSS as eigenmode of magnetic-field aligned small scale irregularities 4- Ion Tail Heating - Interaction with LHSS, but mechanism TBD.

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