Mouse Themis blocking peptide

We present the results of a 2.5-D (2-D in space and 3-D in currents and electromagnetic fields) electromagnetic hybrid simulation run for foreshock wave activity during an interval of a radial interplanetary magnetic field (IMF). The simulation predicts nonlinear waves and foreshock expansion in connection with the development of cavitons and the formation of the foreshock compressional boundary. Fluctuations of the ion velocity V-Y component are associated with wave fronts corresponding to small wave normal angles and oscillate around 0 in the far upstream region. At distances closer to the bow shock, these fluctuations become asymmetric with duskward flow perturbations dominating at dusk and dawnward flow perturbations at dawn. We compare this simulation with THEMIS observations of large-amplitude quasi-monochromatic variations of ion velocity in the foreshock under radial IMF. A case study of simultaneous dual observations of unipolar V-Y fluctuations is followed by a statistical study of similar solar wind deflections in the foreshock. The observations that confirm the simulation predictions indicate that, in addition to ion heating, ultralow-frequency waves participate in the magnetosheath-like plasma flow deflection in the foreshock during periods of small IMF cone angles.

Nishimura et al. (2010) proposed a new plasma intrusion or preonset aurora scenario of substorm triggering. In this scenario, a substorm is triggered by a fast earthward flow generated at the distant neutral line which corresponds to a preonset auroral streamer or arc in the ionosphere propagating from the auroral poleward boundary to the initial auroral brightening site, i.e., "preonset aurora". In the present paper, we revisited three substorm events reported as being triggered by such a mechanism related to preonset auroras, based on THEMIS ground-based all-sky imager data. Unlike previous studies, we examined the arrival timing of the preonset aurora relative to the three steps of auroral onset arc development (initial brightening, enhancement of the wavelike structure, and poleward expansion) to make the role of the preonset aurora in the auroral steps clearer. Our detailed timing analysis found that preonset auroral streamers reached the auroral onset arc but away from the initial brightening site after initial brightening for two events, while no preonset aurora reaching the initial brightening site could be identified for the other event. This result suggests that the processes associated with auroral streamers are unlikely to affect at least initial brightening, even if we consider not only the presence and arrival timing and location of the auroral streamers but also the scale of the corresponding flow and flow vortices. We list a series of open questions for testing the preonset aurora scenario further in future studies.