The Effect of Solar-Wind Turbulence on Magnetospheric Activity

Abstract

The solar wind is a highly turbulent medium exhibiting scalings of the fluctuations ranging over several decades of scales from the correlation length down to proton and electron gyroradii, thus suggesting a self-similar nature for these fluctuations. During its journey, the solar wind encounters the region of space surrounding Earth dominated by the geomagnetic field which is called magnetosphere. The latter is exposed to the continuous buffeting of the solar wind which determines its characteristic comet-like shape. The solar wind and the magnetosphere interact continously, thus constituting a coupled system, since perturbations in the interplanetary medium cause geomagnetic disturbances. However, strong variations in the geomagnetic field occur even in absence of large solar perturbations. In this case, a major role is attributed to solar wind turbulence as a driver of geomagnetic activity especially at high latitudes. In this review, we report about the state-of-art related to this topic. Since the solar wind and the magnetosphere are both high Reynolds number plasmas, both follow a scale-invariant dynamics and are in a state far from equilibrium. Moreover, the geomagnetic response, although closely related to the changes of the interplanetary magnetic field condition, is also strongly affected by the intrinsic dynamics of the magnetosphere generated by geomagnetic field variations caused by the internal conditions.

Chaos, complexity, and intermittent turbulence in space plasmas

“…Burlaga (1991) was the first to report the evidence of intermittent turbulence in solar wind by identifying the existence of multifractal structures in the velocity fluctuations associated with recurrent streams at 1 AU and near 6 AU. Solar wind turbulence consisting of Alfvénic fluctuations and convected magnetic coherent structures, such as magnetic flux ropes and current sheets, are the driver of geomagnetic (auroral) activities (D'Amicis, Telloni and Bruno 2020). The extensive literature on interplanetary intermittent turbulence has been reviewed by Bruno and Carbone (2013), Matthaeus et al (2015), and Oughton and Engelbrecht (2021).…”

“…Solar wind intermittent turbulence, consisted of nonlinear Alfvén fluctuations and coherent structures such as magnetic flux ropes and current sheets, is a driver of geomagnetic and auroral activities (D'Amicis et al 2010(D'Amicis et al , 2020. A geomagnetic storm on 2002 February 2 was driven by the long-duration negative B z in the IMFR-3 seen in Fig.…”

<i>Menura</i>: a code for simulating the interaction between a turbulent solar wind and solar system bodies

“…They however realised that the environment close to these obstacles could provide combinations of plasma parameters otherwise not accessible to their measurements in the unaffected solar wind. For a while now, we have seen planetary studies focusing on the effects of solar wind transient effects (such as coronal mass ejection, CME, or co-rotational interaction region, CIR) on planetary plasma environments, on Mars (Ramstad et al, 2017), Mercury (Exner et al, 2018), Venus (Luhmann et al, 2008) and comet 67P/C-G (Edberg et al, 2016;Hajra et al, 2018) to only cite a few, the effect of large-scale fluctuations in the upstream flow on Earth's magnetosphere (Tsurutani and Gonzalez, 1987), and more generally the effect of solar wind turbulence on Earth's magnetosphere and ionosphere (D'Amicis et al, 2020;Guio and Pécseli, 2021). Similarly, plasma physicists have developed comprehensive knowledge of plasma waves and plasma turbulence in the Earth's magnetosheath, presenting relatively high particle densities and electromagnetic field strengths, favourable for space instrumentation, and in a region more easily accessible to space probes than regions of unaffected solar wind (Borovsky and Funsten, 2003;Rakhmanova et al, 2021).…”

Seasonal Variations of Solar Wind Parameters during Solar Cycles 23 and 24

“…The solar wind and the magnetosphere constantly interact, thus constituting a coupled system, because the disturbances of the interplanetary medium cause geomagnetic disturbances [8]. According to [9] [10] coronal mass ejections and co-rotating interaction regions/high-velocity fluxes striking the Earth's magnetic field are the main drivers of geomagnetic activity.…”