INVESTIGADORES
BERTUCCI Cesar
congresos y reuniones científicas
Título:
The ULF wave foreshock boundary: Cluster observations
Autor/es:
ANDRES, N.; MEZIANE, K.; MAZELLE, C. X.; ; BERTUCCI, C.;; GOMEZ, D. O.
Reunión:
Congreso; American Geophysical Union, Fall Meeting 2013; 2013
Resumen:
In the upstream region of the bow shock, the interaction of
backstreaming ions with the incoming solar wind gives rise to a number
of plasma instabilities from which ultra-low frequency (ULF) waves can
grow. Due to the finite growth rate, it is expected that the region of
ULF wave activity is spatially localized in the ion foreshock.
Observational evidence of the ULF wave foreshock boundary has
accumulated over the last three decades. Among other things, it has been
shown that the geometrical characteristics of the boundary are very
sensitive to the interplanetary magnetic field (IMF) cone angle. In the
present work, we aimed at revisiting the properties of the ULF wave
foreshock boundary. For this purpose, we use the first three years of
magnetic field data from the flux gate magnetometer (FGM), and the
plasma densities and velocities from the hot ion analyzer (HIA)
low-geometry factor side on board RUMBA (SC 1). We use a specific and
accurate criterion for the determination of boundary crossings, and a
3-D structure bow shock model to reconstruct the foreshock geometry. In
particular, our criterion is used to qualitatively measure the
differences between the magnetic field in the wave and no-wave zones,
taking into account possible rotations of the IMF. A new identification
of the ULF wave foreshock boundary is presented and it is compared with
previous results reported in the literature as well as with theoretical
predictions.