Physics
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufmsm32b..08m&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #SM32B-08
Physics
[2407] Ionosphere / Auroral Ionosphere, [2736] Magnetospheric Physics / Magnetosphere/Ionosphere Interactions, [2772] Magnetospheric Physics / Plasma Waves And Instabilities, [2794] Magnetospheric Physics / Instruments And Techniques
Scientific paper
Known meso-scale processes include the polar wind and plasmaspheric plumes, consisting mainly of light ions, and generic auroral ionospheric heating processes, which add heavy ion outflows including O+ and atmospheric molecular ions to the light ion outflows. Known micro-scale processes include Alfvén waves propagating into the ionosphere from turbulent magnetospheric boundary layers, current-driven instabilities leading to lower hybrid waves in the auroral acceleration region near 1 Re altitude, and convection and shear driven instabilities along auroral flux tubes, including pick-up ion ring beam relaxation in the topside, and Joule-frictional heating in the F region. Much of the latter is sunk into the neutral gas, leading to observable upwelling features above the auroras. Plasma outflows are observed to be dominated by superthermal (eV to 10's eV) ions that are transversely heated and whose flux rises in a power law relationship to the incident DC and AC Poynting (EM) fluxes and the density of precipitating hot electrons. These facts are thought consistent with lifting of ions by the ambipolar electric field, enhanced by superthermal electron precipitation, combined with heating and-or ponderomotive forcing of the ions by broadband cyclotron frequency range waves. The ambipolar electric field is reasonably well understood, but the source of ion resonant waves is indeterminate and their amplitudes cannot be derived from macroscopic disturbance conditions such as MHD field, current, and plasma conditions. The Outstanding Question in all this is "what are the mechanisms by which solar wind energy flux is dissipated in ionospheric plasmas to produce enhanced outflow?" To answer this question, a new mission is needed to provide a comprehensive picture of ionospheric mass ejection, including: i) detailed observations of the 3D energy-angle distribution of transversely accelerated ions and electrons down to thermal energies of ~0.1 eV; ii) control of plasma sensor potential at the plasma potential; iv) observation of BBELF wavelengths as well as frequencies for mode identification; v) observations of auroral neutral gas upwelling that go beyond recent accelerometer missions. Such a mission should deliver simultaneous conjugate diagnostics from the F region (250-300 km), from the exobase region (500-1300 km), and from the auroral acceleration region (4000-6000 km). Ionospheric observations could be provided by incoherent scatter radar.
Khazanov George V.
Moore Thomas Earle
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