Plasma flow during the brightening of proton aurora in the cusp

Abstract

[1] On the basis of simultaneous observations from the Super Dual Auroral Radar Network (SuperDARN), the far ultraviolet instrument on the IMAGE spacecraft, and a magnetometer installed on the east coast of Greenland, we present the characteristics of plasma flow during a westward moving proton aurora in the cusp, observed on 28 July 2000. Data with a time resolution of 12 and 25 s from SuperDARN at Þykkvibaer, Iceland, show that the flow having a poleward component, which was accompanied by a quick equatorward expansion of the flow region, occurred in the early stages (approximately 1.5 min) of the brightening. Data from the magnetometer from a ground station on the Greenland east coast, which is located a few hundred kilometers west of the radar's field of view, show perturbations that are consistent with equatorward flow overhead, coincident with the expansion. The presence of flow vectors in opposite directions suggests that vortical flow was present during the proton aurora. Evidence supporting the suggested flow pattern has been found in an event recorded by the Greenland west coast magnetometer chain and in a cusp pass of the DE 2 spacecraft in the literature. We attribute the moving proton aurora to the traveling bulge at the polar cap boundary, which is the footprint of a flux transfer event, and imply that the preexisting vortical flow may be intensified when it becomes inflow to the bulge.

Three-dimensional imaging of the plasma parameters of a moving cusp aurora

“…The overall flow pattern is not symmetric with respect to the boundary between the two field-aligned current regions. This asymmetry is not included in the twin-vortex flow pattern that was originally proposed by Southwood (1985;1987), but rather similar to the picture proposed by Taguchi et al (2010) in that the return flow associated with downward field-aligned current is clearer than that with upward field-aligned current.…”

Investigating the particle precipitation of a moving cusp aurora using simultaneous observations from the ground and space

“…During the interval shown in Figure 8f,g,h,i,j,k, the auroral structure was moving eastward, but prior to that (Figure 8d,e), the auroral structure had been moving poleward, roughly along the 1100 MLT meridian. A recent study based on simultaneous observations from the Super Dual Auroral Radar Network (SuperDARN), a farultraviolet instrument on the IMAGE spacecraft, and a ground magnetometer also reported similar flow features for the cusp proton aurora event (Taguchi et al 2010).…”

Double bursts inside a poleward‐moving auroral form in the cusp

“…The extent of the PMAF in the direction of movement (Figure 2) spans more than 700 km. This scale size is twice that of the mesoscale plasma injection region in the cusp (MPIC), i.e., 300–400 km [ Suzuki et al , 2008; Taguchi et al , 2009, 2010], which has been estimated from the analysis of data obtained through remote sensing techniques that allow a spacecraft to perform observations of precipitating ions [e.g., Frey et al , 2002]. Therefore, the high time resolution data obtained through the ground‐based remote sensing technique (the all‐sky imager) has uncovered the extremely elongated shape of the PMAF, which has not been apparent based on spacecraft data obtained with a time resolution of 2 min.…”