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Ionospheric Feedback Effects on the Quasi-stationary Coupling Between Llbl and Postnoon/Evening Discrete Auroral Arcs : Volume 26, Issue 4 (13/05/2008)

By Echim, M. M.

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Book Id: WPLBN0003972129
Format Type: PDF Article :
File Size: Pages 16
Reproduction Date: 2015

Title: Ionospheric Feedback Effects on the Quasi-stationary Coupling Between Llbl and Postnoon/Evening Discrete Auroral Arcs : Volume 26, Issue 4 (13/05/2008)  
Author: Echim, M. M.
Volume: Vol. 26, Issue 4
Language: English
Subject: Science, Annales, Geophysicae
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Historic
Publication Date:
2008
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

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Roth, M., Keyser, J. D., & Echim, M. M. (2008). Ionospheric Feedback Effects on the Quasi-stationary Coupling Between Llbl and Postnoon/Evening Discrete Auroral Arcs : Volume 26, Issue 4 (13/05/2008). Retrieved from http://worldebookfair.com/


Description
Description: BIRA-IASB, Avenue Circulaire 3, 1180 Bruxelles, Belgium. We discuss a model for the quasi-stationary coupling between magnetospheric sheared flows in the dusk sector and discrete auroral arcs, previously analyzed for the case of a uniform height-integrated Pedersen conductivity (ΣP). Here we introduce an ionospheric feedback as the variation of ΣP with the energy flux of precipitating magnetospheric electrons (Εem). One key-component of the model is the kinetic description of the interface between the duskward LLBL and the plasma sheet that gives the profile of Φm, the magnetospheric electrostatic potential. The velocity shear in the dusk LLBL plays the role of a generator for the auroral circuit closing through Pedersen currents in the auroral ionosphere. The field-aligned current density, j||, and the energy flux of precipitating electrons are given by analytic functions of the field-aligned potential drop, ΔΦ, derived from standard kinetic models of the adiabatic motion of particles. The ionospheric electrostatic potential, Φi (and implicitely ΔΦ) is determined from the current continuity equation in the ionosphere. We obtain values of ΔΦ of the order of kilovolt and of j|| of the order of tens of μA/m2 in thin regions of the order of several kilometers at 200 km altitude. The spatial scale is significantly smaller and the peak values of ΔΦ, j|| and Εem are higher than in the case of a uniform ΣP. Effects on the postnoon/evening auroral arc electrodynamics due to variations of dusk LLBL and solar wind dynamic and kinetic pressure are discussed. In thin regions (of the order of kilometer) embedding the maximum of ΔΦ we evidence a non-linear regime of the current-voltage relationship. The model predicts also that visible arcs form when the velocity shear in LLBL is above a threshold value depending on the generator and ionospheric plasma properties. Brighter arcs are obtained for increased velocity shear in the LLBL; their spatial scale remains virtually unmodified. The field-aligned potential drop tends to decrease with increasing LLBL density. For higher values of the LLBL electron temperature the model gives negative field-aligned potential drops in regions adjacent to upward field-aligned currents.

Summary
Ionospheric feedback effects on the quasi-stationary coupling between LLBL and postnoon/evening discrete auroral arcs

Excerpt
Atkinson, G.: Auroral arcs: result of the interaction of a dynamic magnetosphere with the ionosphere, J. Geophys. Res., 75, 4746–4755, 1970.; Bythrow, P., Heelis, R., Hanson, W., Power, R. A., and Hoffman, R. A.: Observational evidence for a boundary layer source of dayside region 1 field-aligned current, J. Geophys. Res., 86, 5577, 1981.; Chiu, Y T. and Cornwall, J M.: Electrostatic model of a quiet auroral arc, J. Geophys. Res., 85, 543–556, 1980.; Chiu, Y T. and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the magnetospheric-ionospheric auroral region, J. Geophys. Res., 83, 629–642, 1978.; De Keyser, J., Roth, M., and Lemaire, J.: The magnetospheric driver of subauroral ion drifts, Geophys. Res. Lett., 25, 1625–1628, \doi10.1029/98GL01135, 1998.; Drakou, E., Sonnerup, B., and Lotko, W.: Self-consistent steady state model of the low-altitude boundary layer, J. Geophys. Res., 99, 2351–2364, 1994.; Cran-McGreehin, A. and Wright, A.: Current-voltage relationship in downward field-aligned current region, J. Geophys. Res., 110, A10S10, doi:10.1029/2004JA010870, 2005.; Echim, M., Roth, M., and De~Keyser, J.: Sheared magnetospheric plasma flows and discrete auroral arcs: a quasi-static coupling model, Ann. Geophys., 25, 317–330, 2007.; Lundin, R. and Evans, D.: Boundary layer plasmas as a source for high-latitude, early afternoon, auroral arcs, Planet. Space Sci., 33, 1389–1406, 1985.; Evans, D.: The characteristics of a persistent auroral arc at the high latitude in the 1400 MLT sector, in: The Polar Cusp, edited by: Holtet, J. and Egeland, A., pp. 99–109, D. Reidel, 1985.; Fridman, M. and Lemaire, J.: Relationship between auroral electron fluxes and field-aligned electric potential differences, J. Geophys. Res., 85, 664–670, 1980.; Hardy, D., Gussenhoven, M., and Brautigam, D.: A statistical model of auroral ion precipitation, J. Geophys. Res., 94, 370–392, 1989.; Harel, M., Wolf, R., Reiff, P., and Hillis, H.: Study of plasma flow near the Earth's plasmapause, Tech. Rep. AFGL-TR-77-286, U.S. Air Force Geophys. Lab, 1977.; Hasegawa, A.: Particle acceleration by MHD surface wave and formation of aurora, J. Geophys. Res., 81, 5083–5090, 1976.; Iijima, T. and Potemra, T.: Amplitude distribution of field-aligned currents at northern high latitudes observed by Triad, J. Geophys. Res., 81, 2165–2174, 1976.; Knight, L.: Parallel electric fields, Planet. Space Sci., 21, 741–750, 1973.; Kozlovsky, A. and Kangas, J.: Characteristics of the postnoon auroras inferred from EISCAT radar measurements, J. Geophys. Res., 106, 1817–1834, 2001.; Lemaire, J.: Impulsive penetration of filamentary plasma elements into the magnetosphere of the Earth and Jupiter, Planet. Space Sci., 25, 887–890, 1977.; Lemaire, J. and Roth, M.: Penetration of solar wind plasma elements into the magnetosphere, J. Atmos. Terr. Phys., 40, 331–335, 1978.; Lemaire, J. and Scherer, M.: Plasma sheet particle precipitation: A kinetic model, Planet. Space Sci., 21, 281–289, 1973.; Lotko, W., Sonnerup, B. U. O., and Lysak, R. L.: Nonsteady boundary layer flow including ionospheric drag and parallel electric fields, J. Geophys. Res., 92, 8635–8648, 1987.; Lummerzheim, D. and Lilensten, J.: Electron transport and energy degradation in the ionosphere: evaluation of the numerical solution, comparison with laboratory experiments and auroral observations, Ann. Geophys., 12, 1039–1051, 1994.; Lundin, R. and Sandahl, I.: Some characteristics of the parallel electric field acceleration of electrons over discrete auroral arcs as observed from two rocket flights, Tech. Rep. SP-135, European Space Agency, 1978.; Lundin, R., Yamauchi, M., Woch, J., and Marklund, G.: Boundary layer polarization and voltage in the 14 MLT region, J. Geophys. Res., 100, 7587&ndash

 

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