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Thermospheric Control

CHAMP thermospheric density enhancement. Thermospheric Control. Causes of upwelling Large-scale Joule heating Ion upflow Soft electron precipitation Alfv é n waves, small-scale FAC. L ü hr et al. 04. Liu et al. 05. L ü hr et al. 04. 1. 1500. 1600. 1700. 1400. 1800. 1900. 2000.

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Thermospheric Control

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  1. CHAMP thermospheric density enhancement Thermospheric Control • Causes of upwelling • Large-scale Joule heating • Ion upflow • Soft electron precipitation • Alfvén waves, small-scale FAC Lühr et al. 04 Liu et al. 05 Lühr et al. 04 1

  2. 1500 1600 1700 1400 1800 1900 2000 2100 Ionospheric Control Convective transport to the cusp  1010 ions / cm2-s Coster, Erickson, Foster MIT Haystack Observatory 2

  3. 1945 UT 30º Lat 20 Nov 2003 Foster et al. 05 3

  4. Magnetospheric dynamo ( geomagnetically fixed) + Convective plasma surge  Outflow surge Sondrestrom ISR 11 Feb 2002 Semeter et al. 03 4

  5. 5

  6. Observations from low-altitude satellites (FAST) 13 Feb 1997 polar cap Paschmann et al. ‘03 6

  7. Centrifugal (Ponderomotive) Streltsov and Lotko 2008 7

  8. Observations at higher altitude • Intense electromagnetic activity in the “PSBL” • ~ 1-min (Pi 2) oscillations • Oscillations confined mainly to downward current channel • Integrated Poynting flux is upward polar cap plasmasheet down up Evidence for a high-altitude resonator? 19 May 2002 Johansson et al.‘04 8

  9. REFERENCES Moore, T. (1980), Modulation of terrestrial ion escape flux composition (by low-altitude acceleration and charge exchange chemistry), J. Geophys. Res., 85(A5), 2011-2016. Lühr, H., M. Rother, W. Köhler, P. Ritter, and L. Grunwaldt (2004), Thermospheric upwelling in the cusp region: Evidence from CHAMP observations, Geophys. Res. Lett., 31, L06805, doi:10.1029/2003GL019314. Liu, H., H. Lühr, V. Henize, and W. Köhler (2005), Global distribution of the thermospheric total mass density derived from CHAMP, J. Geophys. Res., 110, A04301, doi:10.1029/2004JA010741. Foster, J.C., et al. (2005), Multiradar observations of the polar tongue of ionization, J. Geophys. Res., 110, A09S31, doi:10.1029/2004JA010928. Semeter, J., C. J. Heinselman, J. P. Thayer, R. A. Doe, and H. U. Frey (2003), Ion upflow enhanced by drifting -region plasma structure along the nightside polar cap boundary, Geophys. Res. Lett., 30, 2139, doi:10.1029/2003GL017747. Evans, D., N. Maynard, J. Trøim, T. Jacobsen, and A. Egeland (1977), Auroral Vector Electric Field and Particle Comparisons, 2, Electrodynamics of an Arc, J. Geophys. Res., 82(16), 2235-2249. Lotko, W. (2007), The magnetosphere–ionosphere system from the perspective of plasma circulation J. Atmos. Sol.-Terr. Phys., 69(3), 191-211. Paschmann, G., et al. (2002) Auroral Plasma Physics, Chapter 4 - In Situ Measurements in the Auroral Plasma Space Sci. Rev., 103(1-4), doi:10.1023/A:1023082700768, pps. 93-208. Streltsov, A.V., and W. Lotko (2008), Coupling between density structures, electromagnetic waves and ionospheric feedback in the auroral zone, J. Geophys. Res., 113, A05212, doi:10.1029/2007JA012594. Johansson, T., S. Figueiredo, T. Karlsson, G. Marklund, A. Fazakerley, S. Buchert, P.-A. Lindqvist, and H. Nilsson (2004), Intense high-altitude auroral electric fields - temporal and spatial characteristics Ann. Geophys., 22, 2485-2495.

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