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Ann. Geophys., 25, 847-853, 2007
www.ann-geophys.net/25/847/2007/
© European Geosciences Union 2007
Variability of Jovian ion winds: an upper limit for enhanced Joule heating
M. B. Lystrup1,2, S. Miller1,2, T. Stallard1, C. G. A. Smith1, and A. Aylward1
1Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
2Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement no. NCC 5-538 with the National Aeronautics and Space Administration, Science Mission
Directorate, Planetary Astronomy Program
Abstract. It has been proposed that short-timescale fluctuations about the mean
electric field can significantly increase the upper atmospheric energy inputs
at Jupiter, which may help to explain the high observed thermospheric
temperatures. We present data from the first attempt to detect such
variations in the Jovian ionosphere. Line-of-sight ionospheric velocity
profiles in the Southern Jovian auroral/polar region are shown, derived from
the Doppler shifting of H3+ infrared emission spectra. These data
were recently obtained from the high-resolution CSHELL spectrometer at the
NASA Infrared Telescope Facility. We find that there is no variability within
this data set on timescales of the order of one minute and spatial scales of
640 km, putting upper limits on the timescales of fluctuations that would be
needed to enhance Joule heating.
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