Multi-spacecraft observations of the heliospheric plasma sheet

The heliospheric plasma sheet (HPS) has been described both as quasi-stationary and transient in nature. In order to better quantify the temporal and spatial scales under which each description is appropriate we have compared observations of the HPS from the two STEREO observatories and Wind. Identification criteria of the HPS included a change in magnetic sector from "towards" to "away" (or vice versa, identified using electron pitch angle distributions), an increase in proton density, and minima in the proton specific entropy argument (T/n^γ−1) and alpha to proton number density ratio. Following the technique of Liu et al. (2010), we have classified each plasma sheet as leading, following, straddling, or absent from the heliospheric current sheet. We find the configuration of the HPS agrees between the three spacecraft when longitudinal separation between observation points is 10 degrees or less (temporal separation of less than 1 day). Preliminary results show that in some cases the HPS is quasi-stationary over longitudinal scales of at least 25 degrees.