IMF B_y dependence of region 1 Birkeland currents near noon

Abstract

We have conducted a statistical study of large‐scale Birkeland currents, hot plasma, and the By component of the interplanetary magnetic field. Forty‐eight Viking orbits from July 19, 1986, to September 2, 1986, were used in the study during a time period when the 3‐RE geocentric apogee was located near the dayside high‐latitude region usually associated with the polar cusp. We first compared the location of magnetosheathlike electrons to the region 1 and “traditional cusp” Birkeland current systems near noon. It was found that the region 1 Birkeland current system was colocated with the region of most intense magnetosheathlike electron flux. We therefore infer that the “traditional cusp” current system, located poleward of the region 1 system, is associated with field lines that extend to the plasma mantle in the outer magnetosphere. Using this same data base a statistical study between the By component of the IMF and the flow direction of the region 1 Birkeland current system as a function of magnetic local time was performed. We determined that the flow direction of the region 1 current system near noon depends on the By component of IMF. The meridian that separates the dawnside and duskside region 1 Birkeland currents shifted to magnetic local times before noon when By was less than 0 nT, and to the afternoon when By was greater than 0 nT. The extent of the shift away from noon was dependent on the magnitude of the IMF By component.

A numerical model of the ionospheric signatures of time-varying magneticreconnection: I. ionospheric convection

“…The same was true of the models of the corresponding patterns of ionospheric (Friis-Christensen et al, 1985) and field-aligned (Iijima et al, 1978;Erlandson et al, 1988) currents.…”

Ionospheric conductivity dependence of dayside region-0, 1, and 2 field-aligned current systems: statistical study with DMSP-F7

“…Their (R0, R1) current pair can be regarded as (R0, v-R1) in our terminology, because the intensities of R0 and v-R1 are the same; in their events the (c-R1, R2) pair was presumably nonexistent. Some papers suggested that there is no R2 in the midday sector (Iijima and Potemra, 1978;Erlandson et al, 1988) and it is interesting to note that the midday R1 may be constructed by v-R1 only.…”

Overview of Solar Wind–Magnetosphere–Ionosphere–Atmosphere Coupling and the Generation of Magnetospheric Currents

“…The polarity of the R0 current depends on the B Y component of the IMF, being upwards (downwards) in the northern hemisphere for B Y > 0 (B Y < 0) and opposite in the southern hemisphere (Wilhjelm et al 1978;Erlandson et al 1988;Papitashvili et al 2002;. This current system is associated with east-west flows in the dayside polar cap caused by magnetic tension forces on newlyreconnected field lines.…”