TY - JOUR
T1 - Observations of electromagnetic whistler precursors at supercritical interplanetary shocks
AU - Wilson, L. B.
AU - Koval, A.
AU - Szabo, A.
AU - Breneman, A.
AU - Cattell, C. A.
AU - Goetz, K.
AU - Kellogg, P. J.
AU - Kersten, K.
AU - Kasper, J. C.
AU - Maruca, B. A.
AU - Pulupa, M.
PY - 2012/4/1
Y1 - 2012/4/1
N2 - We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. They have rest frame frequencies fci < f ≪ fce and wave numbers 0.02 ≈ kce 5.0. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves. Although the precursors can have δB/Bo as large as 2, fluxgate magnetometer measurements show relatively laminar shock transitions in three of the four events.
AB - We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. They have rest frame frequencies fci < f ≪ fce and wave numbers 0.02 ≈ kce 5.0. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves. Although the precursors can have δB/Bo as large as 2, fluxgate magnetometer measurements show relatively laminar shock transitions in three of the four events.
UR - http://www.scopus.com/inward/record.url?scp=84861312720&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84861312720&partnerID=8YFLogxK
U2 - 10.1029/2012GL051581
DO - 10.1029/2012GL051581
M3 - Article
AN - SCOPUS:84861312720
SN - 0094-8276
VL - 39
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 8
M1 - L08109
ER -