A simple axisymmetric model of magnetosphere-ionosphere coupling currents in Jupiter’s polar ionosphereстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 29 мая 2015 г.
Аннотация:We propose a simple illustrative axisymmetric model of the plasma flow and currents
in Jupiter’s polar ionosphere which are due both to internal magnetospheric plasma
processes and the solar wind interaction. The plasma flow in the model is specified using a
combination of observations, previous modeling, and theory, and the ionospheric and
field-aligned currents are then calculated. With increasing latitude, the model represents
conditions in the inner, middle, and outer magnetosphere on closed field lines and on open
field lines mapping to the tail lobes. The model allows us to address three important
topics, concerned with the closure of the upward field-aligned currents flowing in the
middle magnetosphere region, the energy transfers from planetary rotation to polar upper
atmosphere heating and to the magnetosphere, and the relative significance of auroral
processes associated with the boundary of open field lines (and hence with the solar wind
interaction) and with the middle magnetosphere. It is shown in particular that the energy
transfers to the polar upper atmosphere and magnetosphere are of order hundreds ofTWeach
and that discrete auroral precipitation is expected both at the boundary of open field lines and
in the middle magnetosphere, though being dominated by the latter. While the initial
calculations assume for simplicity a constant ionospheric conductance, we also present a
development of the model in which the conductance is self-consistently increased in
regions of upward field-aligned current by the precipitation of accelerated electrons. It
is shown that this feedback acts to spread the upward current in the region
equatorward of the open field line boundary, thus reducing the energy flux and total
power of precipitating auroral electrons in this region. At the same time it concentrates
the upward current in the equatorward part of the middle magnetosphere, thereby
increasing the energy flux and total power of precipitating electrons in this region.