Active current sheets near the Earth's bow shock


We present here an investigation of “active current sheets” observed by the AMPTE UK spacecraft near the Earth's bow shock, concentrating on their macroscopic features and geometry. Events selected primarily by flow directions which deviate substantially from the Sun-Earth line show similar characteristics, including their association with an underlying macroscopic current sheet and a hot central region whose flow direction is organized, at least in part, by location relative to the inferred initial intersection point between the current sheet and the bow shock. This region is flanked by “edges” which, according to a Rankine-Hugoniot analysis, are often fast shocks whose orientation is consistent with that expected if a “bulge” on the bow shock convected past the spacecraft. We have found the magnetosheath manifestations of these events which we study in detail. We suggest that these events are the direct result of the disruption and reformation of the bow shock by the passage of an interplanetary current sheet, most probably a tangential discontinuity.

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JGR: Space Physics



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