Average profile of ion flow and convection electric field in the near‐Earth plasma sheet

Two‐dimensional distribution of ion flow and convection electric field in the near‐Earth plasma sheet (9 < R < 30 R E ) is investigated on the basis of GEOTAIL measurements. Our statistics confirms that the observed ion flow in the plasma sheet is generally earthward, being accompanied by a significant dawn‐to‐dusk component which is distributed asymmetrically about the noon‐midnight meridian. On the other hand, the convection electric field deduced from the V×B term after excluding the effects of ion pressure gradient drift shows much better symmetry about the noon‐midnight meridian. Existence of significant difference between the ion and magnetic flux convection patterns suggests that the frozen‐in condition does not hold in the near‐Earth plasma sheet.