In the presence of a strong magnetic field (such as the geomagnetic field) the plasma tends to flow along the magnetic-field lines; therefore, in most ionospheric flow calculations the use of the gyrotropic approximation is justified. Here, it is shown that the gyrotropic 20-moment approximation is equivalent to the gyrotropic 16-moment approximation. Consideration is then given to return-current-generated polar wind transients. Ionospheric return currents generate significant downward heavy ion flows in the topside ionosphere with peak values well exceeding 10 to the 8th/sq cm sec. When the return current ceases, the polar ionosphere rapidly returns to its previous equilibrium state. During the recovery phase of the return-current event, an upward-propagating heavy-ion transient is formed, which is mainly characterized by a relatively short O(+) upwelling event. The H(+) escape flux remains a relatively constant (within 10-20 percent) during field-aligned-current events.


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    Title :

    Time-dependent polar wind modeling


    Contributors:

    Published in:

    Publication date :

    1988-01-01



    Type of media :

    Miscellaneous


    Type of material :

    No indication


    Language :

    English


    Keywords :


    Time-dependent polar wind modeling

    Gombosi, T.I. / Nagy, A.F. | Elsevier | 1989





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