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On the dynamics of the jovian ionosphere and thermosphere.: IV. Ion-neutral coupling |
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| Authors: | George Millward Steve Miller Tom Stallard Alan D Aylward |
| Institution: | a Department of Physics and Astronomy, University College London, Gower Street, London WC1 6BT, UK b Visiting Research Scientist, Institute for Astronomy, Woodlawn Drive, Honolulu, Hawaii HI 96822, USA c Space and Atmospheric Physics Group, Imperial College, London SW7 2AZ, UK |
| Abstract: | We use the fully coupled, three-dimensional, global circulation Jovian Ionospheric Model (JIM) to calculate the coupling between ions in the jovian auroral ovals and the co-existing neutral atmosphere. The model shows that ions subject to drift motion around the auroral oval, as a result of the E×B coupling between a meridional, equatorward electric field and the jovian magnetic field, generate neutral winds in the planetary frame of reference. Unconstrained by the magnetic field, these neutral winds have a greater latitudinal extent than the corresponding ion drifts. Values of the coupling coefficient, k(h), are presented as a function of altitude and cross-auroral electric field strength, for different incoming electron fluxes and energies. The results show that, with ion velocities of several hundred metres per second to over 1 km s−1, k(h) can attain values greater than 0.5 at the ion production peak. This parameter is key to calculating the effective conductivities required to model magnetosphere-ionosphere coupling correctly. The extent to which angular momentum (and therefore energy) is transported vertically in JIM is much more limited than earlier, one-dimensional, studies have predicted. |
| Keywords: | Aurora Ionospheres Jupiter atmosphere Jupiter magnetosphere Modelling |
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