IOPW Aurora amd Magnetosphere sub-Discipline

                          Update Oct 2018

   Over the past year there has been a high level of activity in the 
study of mainly Jupiter's, and to a lesser extent Saturn's, aurora and 
magnetospheres.  At Jupiter the continuation of the JUNO mission, 
covering high latitude and low altitude regions never before measured, 
has provided a wealth of new data with surprising results.  At Saturn 
the final / proximal orbits of Cassini covered regions of the inner 
magnetosphere and at high latitudes that have never before been
measured in situ, and work on these data continues.  This work was 
reported at the July 2018 Magnetospheres of the Outer Planets 
conference, held in Boulder CO (lasp.colorado.edu/home/mop/mop2018/).  
The next MOP meeting will be in summer 2019 in Sendai Japan.  The higher 
than usual frequency of these meetings reflects the rapidly changing 
results from mission at both Jupiter (Juno) and Saturn (Cassini data).

   One science highlight from the combined observations of Jupiter's 
aurora and magnetosphere is particularly interesting.  It has been
widely assumed that Jupiter's bright aurora are associated with strong
field-aligned currents.  However, comparing HST and JUNO images of the
aurora with in situ data on the particle populations and energies 
along the corresponding flux tubes, it have become clear that there are
many cases where bright aurora are NOT associated with either strong
currents or particle acceleration along the flux tubes.  There is work
in progress to try to explain these cased with some combination of
downwards currents and/or horizontal ionospheric currents.  

   Considerable effort and telescope time at a wide range of earth-based
facilities has been devoted to coordinated studies of both planets.  For 
Jupiter there is a large HST program for Jupiter led by Denis Grodent 
during the main orbits of JUNO, and these observations are concentrating 
on the close passes of JUNO over the polar regions.  For Saturn there 
has been a multi-year program for Saturn’s aurora, led by Laurent Lamy 
and Sarah Badman.  Multiple ground-based facilities have been used for 
IR observations of H3+ emissions from Jupiter’s aurora and ionosphere, 
led by Tom Stallard, Luke Moore, James O’Donoghue, and others.  This 
work is for the most part in progress, and there is a very active 
comparison of the data sets with the measurements from JUNO and Cassini. 
In addition, scientists on the Hisaki /Exceed mission have been getting
excellent data on the plasma torus and overall auroral activity at Jupiter,
which is being analyzed on its own for statistics and time variations 
and correlations, and also compared with data from HST and JUNO.  

New Publications: 

“An Isolated, Bright Cusp Aurora at Saturn”, J. Kinrade et al., J. Geophys. Res., 122, 6121-6138, doi:10.1002/2016JA023792 (2017).  

“Long-term Variability of Jupiter's Magnetodisk and Implications for the Aurora”, M. Vogt, E. Bunce, J. Nichols, J.T. Clarke, and W. Kurth, J. Geophys. Res., 122, doi:10.1002/2017JA024066 (2017).  

“Evidence for Auroral Emissions from Callisto’s Footprint in HST UV Images”, D. Bhattacharyya, J.T. Clarke, J. Montgomery, B. Bonfond, J.-C. Gerard, and D. Grodent, J. Geophys. Res., 123, doi:10.1002/2017JA024791 (2018).  

“Hubble Space Telescope Observations of Variations in Ganymede's Oxygen Atmosphere and Aurora”, P. Molyneux, and 9 co-authors incl. J.T. Clarke, J. Geophys. Res., 123, doi:10.1029/2018JA025243 (2018). 

“Jupiter’s Aurora Observed with HST during JUNO Orbits 3 to 7”, D. Grodent and 16 co-authors incl. J.T. Clarke, J. Geophys. Res., 123, doi:10.1002/2018JA025046 (2018). 

"Analysis of IR-bright regions of Jupiter in JIRAM-Juno data: Methods and validation of algorithms", D. Grassi, et al., JQSRT, Vol. 202, p. 200-209 (2017).

"Identification of Jupiter's magnetic equator through H3+ ionospheric emission", T. Stallard, et al., Nature Astronomy, 2, 773-777 (2018). 

"Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter", A. Mura, et al., Science, 361, pp. 774-777 (2018). 

"Concurrent ultraviolet and infrared observations of the north Jovian aurora during Juno's first perijove", Icarus, 312, 145-156, (2018).