Superposed epoch study of PV5/3 during substorms, pseudobreakups and convection bays

We present a superposed epoch study to examine the entropy parameter PV5/3, for isolated substorms, pseudobreakups and convection bays observed by Geotail in the near-Earth plasma sheet, by using a flux-tube-volume formula with coefficients adjusted to fit magnetic field models for a variety of conditions. It is found that the changes of PV5/3 for these three types of events are distinct: (1) for substorms, PV5/3 increases continuously during the growth phase, decreases after dipolarization, and maintains a low value of similar to 0.08 nPa(R-E/nT)(5/3); (2) for pseudobreakups, PV5/3 changes in a way similar to substorms, but decreases more moderately and then gradually increases; (3) for convection bays, PV5/3 takes a nearly constant value of 0.06 nPa(R-E/nT)(5/3). These results suggest that the characteristics of the processes that violate conservation of PV5/3 play a central role in the temporal and spatial reduction of PV5/3 and thus determine the earthward plasma transport during active times. Citation: Yang, J., F. R. Toffoletto, G. M. Erickson, and R. A. Wolf (2010), Superposed epoch study of PV5/3 during substorms, pseudobreakups and convection bays, Geophys. Res. Lett., 37, L07102, doi:10.1029/2010GL042811.