Solar energetic particle events at 1 AU: observations and modeling 
 
Olga P. Verkhoglyadova (1), Gang Li (1,2), Gary P. Zank (1) and Bruce T. 
Tsurutani (3) 
 
(1) Institute of Geophysics and Planetary Physics, University of California, 
Riverside, USA 
(2) SSL, University of California, Berkeley, USA 
(3) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA 
 
We discuss particle acceleration and transport in the heliosphere. These solar 
energetic particles (SEP), when connected to the Earth, enter the magnetosphere 
and high and midlatitude ionosphere. The main observational characteristics of 
SEPs will be briefly reviewed. There are often two components which form a major 
SEP event, one originated from the flare site and another one from solar wind 
particles accelerated at a traveling CME-driven fast forward shock. If a CME and 
a flare are parts of the same process, then interplay between corresponding 
energetic particle components cause variability in observed particle fluxes, 
isotropic contents and spectra. Depending on spacecraft location and magnetic 
connection to either a flare site or a CME-driven shock (or both) we expect to 
observe distinct intensity- time profiles and compositions. By the way of 
example, we present modeling results for the SEP event of December 14, 2006 
using the Particle Acceleration and Transport in the Heliosphere (PATH) 
one-dimensional numerical code developed at University of California at Riverside. 
Time-intensity profiles and spectra of proton and heavy ions are presented and 
compared with in situ measurements by ACE satellite. Impacts from shock accelerated 
SEPs and flare SEPs in the Earth’s ionosphere will be discussed.