Premium
Simultaneous Polar and Cluster Observations in the Northern and Southern Middle‐Altitude Polar Cusps Around Equinox
Author(s) -
Pitout F.,
Marchaudon A.,
Trattner K. J.,
Berchem J.,
Laakso H.,
Escoubet C. P.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028346
Subject(s) - magnetopause , magnetosheath , polar , physics , atmospheric sciences , altitude (triangle) , asymmetry , cusp (singularity) , equinox , geology , convection , ionosphere , geophysics , astrophysics , magnetosphere , plasma , geometry , astronomy , meteorology , mathematics , quantum mechanics
We present an event of simultaneous observations of the northern and southern middle‐altitude polar cusps by the Polar spacecraft and Cluster fleet that occurred on 23 September 2004. We examine the possible asymmetries in the fields and plasma parameters, although the proximity of the equinox should limit these asymmetries. Ion sensors reveal two dispersions in both cusps, and data analysis leads to the conclusion that those dispersions are due to pulsed reconnection at a single X‐line, which runs along the subsolar magnetopause. While the electromagnetic and particle energy fluxes injected in both cusp are globally very similar, we report significant differences in ion dispersions, width of the low‐latitude boundary layer, and peak convection velocities. We ascribe these differences to the dipole tilt that introduces an asymmetry in the magnetosheath flow at the exterior cusps.