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Modeling the propagation of solar energetic particles in corotating compression regions of solar wind

  • Authors: Kocharov, L.; Kovaltsov, G. A.; Torsti, J.; Anttila, A.; Sahla, T.
  • Publication: Journal of Geophysical Research, Volume 108, Issue A11, pp. SSH 1-1, CiteID 1404, DOI 10.1029/2003JA009928, 2003
  • Solar events of 1996 August
  • Theoretical study / Statistical study
  • ADS link
  • Abstract: We present the first modeling of solar energetic particle (SEP) events inside corotating compression regions. We consider gradual compressions in the interplanetary magnetic field brought on by interaction of the solar wind streams of different speed. The compression model is similar to that previously suggested for the acceleration of low-energy particles associated with corotating interaction regions (CIRs). In the framework of focused transport, we perform Monte Carlo simulations of the SEP propagation, adiabatic deceleration and reacceleration. A trap-like structure of the interplanetary magnetic field modifies the SEP intensity-time profiles, energy spectra, and anisotropy. Particle diffusion and adiabatic deceleration are typically reduced. For this reason, at a corotating vantage point the SEP event development after the intensity maximum is slower than would be expected based on the modeling in the standard, Archimedean spiral field. At the noncorotating spacecraft the magnetic tube convection past the observer becomes more important. The numerical model forms a basis on which to interpret SEP observations made by present and future spacecrafts at the longitude-dependent speed of solar wind. In particular, the modeling results are similar to the patterns observed with the ERNE particle telescope on board SOHO in August 1996. In the proton anisotropy data, we find a signature of the magnetic mirror associated with the CIR. A relation is established between the spectra observed at 1 AU and the SEP injection spectrum near the Sun.

Created by mevali. Last Modification: Wednesday 23 of May, 2007 08:37:56 UTC by mevali.