Variability of Jupiter's IR H3+ aurorae during Juno approach

Moore, L., O'Donoghue, J. ORCID: https://orcid.org/0000-0002-4218-1191, Melin, H., Stallard, T., Tao, C., Zieger, B., Clarke, J., Vogt, M. F., Bhakyapaibul, T., Opher, M., Tóth, G., Connerney, J. E. P., Levin, S. and Bolton, S. (2017) Variability of Jupiter's IR H3+ aurorae during Juno approach. Geophysical Research Letters, 44 (10). pp. 4513-4522. ISSN 1944-8007 doi: 10.1002/2017GL073156

Abstract/Summary

We present ground-based observations of Jupiter’s H3+ aurorae over four nights in April 2016while the Juno spacecraft was monitoring the upstream interplanetary magnetic field. High-precisionmaps of auroral H3+ densities, temperatures, and radiances reveal significant variabilities in those parameters,with regions of enhanced density and emission accompanied by reduced temperature. Juno magnetometerdata, combined with solar wind propagation models, suggest that a shock may have impacted Jupiter inthe days preceding the observation interval but that the solar wind was quiescent thereafter. Auroral H3+ temperatures reveal a downward temporal trend, consistent with a slowly cooling upper atmosphere, such asmight follow a period of shock recovery. The brightest H3+ emissions are from the end of the period, 23 April.A lack of definitive signatures in the upstream interplanetary magnetic field lends supporting evidence tothe possibility that this brightening event may have been driven by internal magnetospheric processes.