Ionosphere and ground‐based response to field‐aligned currents near the magnetospheric cusp regions

Abstract

A special campaign was conducted at the Sondre Stromfjord incoherent scatter radar facility in October 1985 to study hydromagnetic and atmospheric gravity wave phenomena near the cusp regions of the magnetosphere. During a day when the convection reversal boundary was measured just to the north of the radar, a field‐aligned current filament of inferred amplitude ∼2 × 105 A was measured at the boundary. Both ion and electron heating appeared to accompany the current filament. Magnetic field data acquired in the southern conjugate hemisphere are used to conclude that the current filament was probably on closed field lines. The current filament may be evidence of the magnetosphere boundary layer on closed field lines, perhaps produced by the injection of magnetosheath plasmoids onto the field lines by a flux transfer‐type reconnection process.

Transient production of F-region irregularities associated with TCV passage

“…The standard deviation of 1σ is plotted with a gray horizontal line for the reference of amplitude fluctuations. The bottom three panels show the three components of fluxgate magnetometer data from the South Pole Station, and the conjugate data from Iqaluit are also plotted with dotted lines to show that similar vortices passed in both hemispheres, in terms of "magnetic impulse events" (Lanzerotti et al, 1986(Lanzerotti et al, , 1987. It is noticed that Pc1-2 activity is enhanced during the TCV passage in the intervals of 13:10-13:18 UT in Fig.…”

Superposed epoch analysis applied to large-amplitude travelling convection vortices

“…Goertz et al, 1985;Lanzerotti et al, 1986Lanzerotti et al, , 1987. The motivation for these studies came from theoretical works predicting the ground signature of FTEs (Saunders et al, 1984;Southwood, 1987;Lee, 1986).…”

Electric Field and Current Coupling at High Latitudes

“…It is seen that the response to the changes in the IMP does not take place simultaneously over GRCCNWALD et al (1990) (1985) interpreted a set of electric field measurements from the STARE coherent scatter radar as evidence of an ionospheric signature of a flux transfer event. LANZEROTTI et al (1986LANZEROTTI et al ( , 1987 used single-station magnetometer measurements from the northern and southern cusp to support the idea of the existence of a localized Hall current system consistent with the proposed model by SAUNDERS (1984) and LEE (1986) of a poleward moving Hall current loop.…”

“…An important confirmation of this is the observed conjugacy of the events seen in the northern and southern hemisphere. LANZEROTTI et al (1987) show that for most events the vertical magnetic perturbations associated with the events correspond to field-aligned currents directed in the same direction relative to the local ionosphere. This is consistent with a source on closed magnetic field-lines as opposed to the predictions from flux transfer events on open field-lines.…”