The event described herein was chosen because of the presence of Equator-S in the equatorial magnetosphere during the storm time. The storm main phase started on February 17th and the recovery phase took place on February 18th. The motivation of the study is earlier work that traces particles from one point to another in order to obtain agreement with particle spectra measured in-situ by satellites. The Efield necessary to compute the particle motion is taken from models, and is validated based on the goodness of agreement between traced particle spectra and data. The recovery phase of the storm was selected because the fields (both magnetic and electric) are less variable at such time. In addition to the EQ-S spacecraft, POLAR and FAST observed interesting particle signatures. The signatures are nose dispersions and wedge dispersions. Electrons also showed interesting discrete features in the spectrograms. Figure: overview.pdf describes in detail the: motivation for the work, the upstream conditions and the Dst, kp, indices, and the position of EQ-S, the position of POLAR and FAST, the particle signatures on EQ-S and the particle tracing done by Kistler et al., 1999 as well as my code. Kistler's code traces bounce averaged motion of particles. My code does guiding center tracing. In the appropriate figure from Kistler et al., (shown in the above plot) the Efield used is Volland Stern but is time dependent, based on the kp at the time. The three color figures below show traces from my code with Volland Stern Efield fixed in time for the kp value shown in the panel. Shown also are the results of Ebihara et al. explaining wedge dispersions seen on another event by Viking.
Figure: noEfield.ps shows the result of tracing one particle in zero electric field just to show that the kinetic energy is conserved.
Figure: plotmanyt90.ps shows the result of back-tracing many particles of 90deg. pitch angle in a steady Efield, starting from the EQ-S position. All particles pass from the same point at the nightside because the Efield is symmetric.
Figure: POLAR_OVERVIEW.ps shows an overview of the POLAR satellite data. Particles are from HYDRA, courtesy of J. Scudder and Efield from EFI, courtesy of F. Mozer. Notice the dispersive signature in ions around 10 keV. This is similar to what was seen on EQ-S. Notice the dispersive signatures below 1keV. This is similar to what was seen on other events on Viking (wedge dispersions).
Figure: FAST_IONS.ps shows an overview of the ion signatures observed on FAST.
The dispersed signature of few keV ions is the cusp. Before crossing the cusp, FAST observed similar traces (banded ion structures) as POLAR. Figure: FAST_IONS.ps shows an overview of the electron signatures observed on FAST. Similar banded signatures as on POLAR are observed before the cusp crossing.
Figure: FAST_TMS.ps shows an overview of the ion species information obtained by TEAMS on FAST. The banded ions are both Oxygen and protons.
Figure: FAST_DCfields.ps shows an overview of the DC fields observed on FAST.
More to come later: traces of particles in time-depended field, and particle spectrograms from given Efield model (Volland-Stern).