How typical are atypical current sheets?

Abstract

Using multi‐satellite Cluster magnetic field data, we statistically examined how often an atypical, i.e., non‐Harris type, current sheet is formed. We found that a cross‐tail current sheet with an off‐equatorial current density maximum, indicating bifurcation, is frequently formed in thin current sheets with a half thickness of ∼1500 km. The occurrence of off‐equatorial current density maxima is correlated with the occurrence of fast plasma flows, namely if fast plasma flows occur nearby, one is more likely to observe off‐equatorial current density maxima. We also found that many of the center‐peaked current sheets exhibit a feature different from a normal Harris sheet: namely a very intense current concentrated near the equatorial plane, embedded in a broader current sheet with lower current density.