Propagation of electron and proton shock-induced aurora and the role of the interplanetary magnetic field and solar wind
Meurant, M.[Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium); AB(Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium); AC(Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium); AD(Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium); AE(Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium]
Gérard, Jean-Claude[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
[en] Shock-induced aurora observed with satellite-borne ultraviolet imagers shows distinct characteristics from the more common and extensively studied aurora generated during magnetospheric substorms. It is initiated in the noon sector immediately following dynamic pressure pulses associated with the arrival of enhanced solar wind plasma at the front of the magnetosphere. The auroral brightening rapidly propagates toward the dawn and dusk sectors and may eventually trigger the development of an auroral substorm on the nightside. The FUV imaging system on board the IMAGE satellite has the ability to discriminate between proton and electron precipitation. This feature has been used to study the morphology and dynamics of the electron and proton precipitation following pulse-induced magnetospheric perturbations. A different dynamic is observed for aurora caused by electron and proton precipitation, as well as the important role played by the north-south component of the interplanetary magnetic field. The propagation from the noon to the night sector mainly occurs through the afternoon region for proton precipitation and the morning sector for electron aurora, as expected from azimuthal drift of newly injected plasma. The asymmetry of the precipitation distribution around the noon-midnight axis is more pronounced during negative B[SUB]z[/SUB] periods, when activity is the most important. The magnitude of both the interplanetary magnetic field and the solar wind speed appears well correlated with the precipitated power, by contrast with the solar wind density and the magnitude of the dynamic pressure, which appear to play a minor role. It is suggested that adiabatic compression and plasma waves play an important role on the locations of electron and proton precipitation in the dayside.