SH51B-01
April, 21, 2002 event: integrated analysis of the coronal mass ejection and the solar energetic particle acceleration
We present the results of simulations for coronal mass ejection and solar energetic proton acceleration for the event of April, 21, 2002. Mostly we focus on the detailed comparison between the LASCO images, on one hand, and predicted white light images from numerical simulations, on the other hand, to investigate the temporal evolution of the magnetic free energy release in the course of the coronal mass ejection. This study allows us to achieve a better agreement between the observations and the simulation results for the proton acceleration by the shock wave at an earlier stage of the CME evolution.
SH51B-02
Temperature Anisotropy Modified Solutions for Interplanetary Shock Parameters: Validation and Statistics From WIND
For shock parameter determination, we consider the iterative nonlinear least squares fitting technique of Szabo [1994] which was improved by taking temperature anisotropy into account. The range of validity of the modified technique is tested by analyzing synthetic shocks with different properties. In order to estimate the influence of temperature anisotropy on the determined shock parameters, we have made an extensive statistical analysis of interplanetary shocks observed by the Wind spacecraft and compared anisotropic solutions with those made under assumption of temperature isotropy. The more accurately determined shock parameters may serve to better understand particle acceleration processes at shocks.
SH51B-03
Wind observations of Fast Fermi acceleration at curved interplanetary shocks
Interplanetary shocks can accelerate electrons by a Fast Fermi mechanism, as evinced by reflected upstream beams similar to those observed at planetary bow shocks. We present Wind observations of loss cone electron distributions characteristic of Fast Fermi acceleration, and estimate the cross shock potential from the width of the loss cone. We also present evidence for and discuss the implications of mesoscale (several RE) curvature on interplanetary shock fronts, which creates `bays' where particles may be multiply reflected.
SH51B-04
Solar Particle Source Energy spectrum: Stochastic acceleration vs Neutral Current Sheet acceleration vs Shock Wave acceleration
It has been shown in a series of works that some solar particle events (SPE) are composed of two different relativistic populations, a Prompt Component (PC) and a Delayed Component (DC), each one with different energy spectrum behavior. The source spectra of the DC tend to be an inverse power law at the steady state situation, whereas the spectra of the PC are considerable deviated from such a power law. Here we attempt to reproduce the observational spectra of the PC and the DC on terms of different scenarios: (i) DC acceleration from magnetic merging in a Magnetic Neutral Current Sheet (MNCS). (ii) Stochastic acceleration of an injected population pre-accelerated in a MNCS. (iii) Stochastic acceleration with monoenergetic injection. (iv) Stochastic acceleration with monoenergetic injection, while undergoing adiabatic deceleration. We contrast our results with those assuming Shock Wave Acceleration. Results are illustrated for the case of the September 29, 1989, July 14, 2000, October 28, 2003 and January 20, 2005 Ground Level Events (GLE`s).
SH51B-05
Simulation study of EM radiation from Langmuir/z waves in warm magnetized plasmas
Linear mode conversion (LMC) of Langmuir waves to radiation near the plasma frequency at density gradients is relevant to solar and interplanetary radio bursts, planetary foreshocks, and perhaps pulsar radio emissions. We study LMC in warm magnetized plasmas using numerical electron fluid simulations as functions of the angles between the density gradient, ambient magnetic field (B0), and wavevector. The dependences of the mode conversion efficiency on B0, spatial scales of density gradients, incidence angle θ of the Langmuir wave, relative to the density gradient, and the angle α between density gradient and B0 are presented. The mode conversion window narrows as B0 increases and the conversion efficiency increases as α increases. We show strong evidence that LMC produces extraordinary (x) mode as well as ordinary (o) mode radiation from Langmuir waves. Equal amounts of o- and x-mode radiation are produced in the unmagnetized limit at least when ¥á is small. Possible applications of LMC to the solar radio bursts in the solar wind and corona, and to planetary continuum radiation are also explored and it is suggested that LMC can explain linear and/or elliptical polarizations of type II and III solar radio bursts.