Paper#: 44
Poster #: 23
Session Name: Poster Session 2
Room: East Ballroom
Day: Thursday
Time: 10:10 a.m.-Noon
Abstract Title: Concerning the Magnetosphere-Ionosphere Coupling
PresentSurname: Sedykh, P.A., Ponomarev, E.A.
All Authors: P.A. Sedykh, E.A. Ponomarev
Abstract : A necessary condition for the branching of magnetospheric circuit currents is the presence of an angle between the isosurfaces of magnetic and gas pressures. In general the problem is rather complicated because of the need to take into account the influence on the gas pressure distribution exerted by the current that has left for the ionosphere. For the particular case, however, where the convection streamlines run in such a manner that the magnetic field along them can be considered constant, and the pressure relief represents a valley with sharp walls along which field-aligned currents are flowing into (out of) the ionosphere, the problem can be solved analytically. It is shown that the above-mentioned valley is produced when a second maximum appears in the gas pressure distribution because of the nonstationarity of the boundary conditions. The valley lies between these maxima. Since bulk currents in the magnetosphere flow along constant gas pressure lines, they surround this maximum. It can be said that on the earthward slope of the gas pressure hump ( the inner boundary of the plasma sheet ), where (VgradP = Ej) is less than zero ( V - convection velocity, P - gas pressure, E - electric field strength, and j - current density), lies the MHD generator, and on the opposite slope, where (VgradP) is more than zero, lies the MHD compressor. If the electric circuit has no ionospheric load, then the current of the MHD generator feeds the MHD compressor; if, however, such a load appears, then the compressor is fed only by the portion of the current that is not used by the ionosphere. In addition to the above-mentioned current, which circulates between the generator and compressor, there exists also the dawn-dusk external current. On the whole, such a scheme makes it possible not only to reconcile magnetospheric and ionospheric currents but also to explain the appearance of the loading and unloading substorm phases.