Solar Wind Interaction With Jupiter's Magnetosphere: A Statistical Study of Galileo In Situ Data and Modeled Upstream Solar Wind Conditions

Abstract

Jupiter's magnetosphere is often said to be rotationally driven, with strong centrifugal stresses due to large spatial scales and a rapid planetary rotation period. While the solar wind is therefore expected to have a relatively small influence on Jupiter's magnetosphere and aurora, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the ultraviolet auroral position and brightness. We report on the results of a comprehensive, quantitative study of the influence of the solar wind dynamic pressure on magnetospheric data sets measured by the Galileo mission (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003). Using model predictions of the solar wind conditions near Jupiter calculated by propagating measurements made near the Earth, we have established how predicted changes in the solar wind affect the magnitude and direction of the magnetic field in the magnetosphere, the hectometric auroral radio emissions, and energetic particles in Jupiter's magnetosphere. We find that increases in the solar wind dynamic pressure are statistically associated with magnetospheric compression events but that tail reconnection and plasmoid release is most likely driven internally by the Vasyliunas cycle. We find no link between solar wind conditions and the occurrence of quasiperiodic modulations in the magnetosphere. Overall, we conclude that activity in Jupiter's magnetosphere is both internally and solar wind driven. Finally, we examine the effects of solar wind-induced magnetospheric compressions on Jupiter's auroral brightness and mapping, finding that a solar wind compression could shift the auroral mapping of a given point in the magnetosphere by~3°on average.

A Jovian Magnetodisc Model for the Juno Era

“…al., 1986;Desch & Barrow, 1984;Galopeau & Boudjada, 2005;Hess et al, 2012;Ladreiter & Leblanc, 1989;Louarn et al, 2001;Prangé et al, 1993;Terasawa et al, 1978). However, Jupiter's magnetosphere is driven both by internal processes and solar wind ram pressure variations (Vogt et al, 2019).…”

“…The record in Figure 6 is far from continuous, with just a few days sampled every 53 days or so, and the record of auroral observations is even less so; nevertheless, there is a growing body of work linking variations in solar wind ram pressure to variations in auroral intensities (Baron et al, 1996; Clarke et al, 2009; Connerney Satoh, & Baron, 1996; Gurnett et al, 2002; Kita et al, 2019; Murakami et al, 2016; Nichols et al, 2017; Tao et al, 2016) and radio emissions (Barrow et al, 1986; Desch & Barrow, 1984; Galopeau & Boudjada, 2005; Hess et al, 2012; Ladreiter & Leblanc, 1989; Louarn et al, 2001; Prangé et al, 1993; Terasawa et al, 1978). However, Jupiter's magnetosphere is driven both by internal processes and solar wind ram pressure variations (Vogt et al, 2019).…”

Are Dawn Storms Jupiter's Auroral Substorms?

“…Reconnection on the dayside magnetopause, while it does exist at Jupiter (Ebert et al., 2017), cannot open a significant amount of flux (Desroche et al., 2012; Masters, 2017), leading to a very different type of magnetospheric topology where the amount of flux open to the solar wind is very limited and intertwined with closed flux tubes connected to the distant magnetotail (Zhang et al., 2020). By comparing the occurrence of magnetotail reconnection and plasmoid release to predictions of the solar wind input (Vogt et al., 2019), showed that these large scale reconfigurations of the magnetotail were mostly independent from solar wind compression.…”

“…The stretching of the field lines provides favorable conditions for reconnection to occur. At Earth, such reconnection closes the magnetic field lines open to the solar wind in the magnetotail, while at Jupiter, reconnection is internally driven (Ge et al., 2010; Kronberg et al., 2005; Vogt et al., 2019; Woch et al., 2002) and is expected to take place on closed field lines. In the middle magnetosphere, various plasma instabilities may occur, such as ballooning instability (Hameiri et al., 1991; Kalmoni et al., 2018; Oberhagemann & Mann, 2020), cross‐field current instability (Lui et al., 1991), shear flow ballooning (Viñas & Madden, 1986) or shear flow‐interchange instability (Derr et al., 2020).…”

Six Pieces of Evidence Against the Corotation Enforcement Theory to Explain the Main Aurora at Jupiter

“…Furthermore, Vogt et al. (2019) noted that the dawn‐dusk discrepancy on the bend‐back angle is even larger during solar wind compressions, which should lead to a brightening of the dawn arc of the MEs but a dimming of the dusk arc if the corotation enforcement current were driving the main auroral emissions. Again, this is contrary to the observations, as the MEs brighten at all local times during compressions of the magnetopause (Yao et al., 2020).…”