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. Copyright 2005 by the American Geophysical Union.