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The Particle Acceleration and Transport in the Heliosphere (PATH) numerical code was developed to understand solar energetic particle (SEP) events in the near-Earth environment. We discuss simulation results for the 13 December 2006 SEP event. The PATH code includes modeling a background solar wind through which a CME-driven oblique shock propagates. The code incorporates a mixed population of both flare and shock-accelerated solar wind suprathermal particles. The shock parameters derived from ACE measurements at 1 AU and observational flare characteristics are used as input into the numerical model. We assume that the diffusive shock acceleration mechanism is responsible for particle energization. We model the subsequent transport of particles originated at the flare site and particles escaping from the shock and propagating in the equatorial plane through the interplanetary medium. We derive spectra for protons, oxygen, and iron ions, together with their time-intensity profiles at 1 AU. Our modeling results show reasonable agreement with in situ measurements by ACE, STEREO, GOES, and SAMPEX for this event. We numerically estimate the Fe/O abundance ratio and discuss the physics underlying a mixed SEP event. We point out that the flare population is as important as shock geometry changes during shock propagation for modeling time-intensity profiles and spectra at 1 AU. The combined effects of seed population and shock geometry will be examined in the framework of an extended PATH code in future modeling efforts.

International audience; Whistler-mode chorus has been shown to play a significant role in acceleration of relativistic electrons in the outer Van Allen radiation belt. It can also propagate from its source region and influence large regions of the inner magnetosphere. Distribution of the wave energy density in the space of the wave vector directions is a crucial parameter for modeling of both the wave-particle interactions and wave propagation in the inner magnetosphere. We present a survey of observations of whistler-mode chorus emissions by the Plasma Wave Instrument on the Polar spacecraft in 1996 and 1997 together with a large data set obtained by the STAFF-SA instruments onboard the CLUSTER spacecraft. We show that highly oblique propagation needs to be considered in the radiation belt models.