HR: 15:25h
AN: SH33B-08    [Abstracts]
TI: Anisotropy of solar wind fluctuations: fast wind vs slow wind.
AU: Dasso, S
EM: sdasso@iafe.uba.ar
AF: Instituto de Astronomia y Fisica del Espacio. Universidad de Buenos Aires., CC 67 Suc. 28, Buenos Aires, BUE 1428 Argentina
AU: * Milano, L J
EM: lmilano@bartol.udel.edu
AF: Bartol Research Institute. University of Delaware., 217 Sharp Lab, Newark, DE 19716 United States
AU: Matthaeus, W H
EM: yswhm@bartol.udel.edu
AF: Bartol Research Institute. University of Delaware., 217 Sharp Lab, Newark, DE 19716 United States
AU: Smith, C W
EM: Charles.Smith@unh.edu
AF: Institute for Earth, Oceans and Space. University of New Hampshire., 207 Morse Hall, Durham, NH 03824 United States
AB: The fluctuations in the solar wind are often modeled in terms of two distinct populations: (a) a 'wave-like' population with quasi-parallel wavenumbers and (b) a quasi-two dimensional 'turbulent-like' fluctuations with perpendicular wavenumbers. Here the qualification "quasi-parallel" or "quasi-2D" means that nearby wavevectors are grouped together in an idealzed way, for simplicity. The relative abundance of these two populations is important in gaining insight on the dynamics of waves or turbulence in the solar wind, and also in understanding the transport of energetic particle populations, as turbulence geometry has a major impact on scattering. It has been established in the literature that turbulence is, generally speaking, more developed in the slow solar wind, with power spectra closer to the kolmogorov value at 1AU, while the fast solar wind is more "Alfvenic", typically with higher values of the cross helicity. It seems natural therefore to investigate the anisotropy structure of solar wind fluctuations as a function of wind speed. We present here our preliminary results in this regard, obtained from magnetic and plasma data from the ACE specraft, at 1AU, essentially in the ecliptic plane. We also discuss possible implications for the modeling the evolution of waves and turbulence in the solar wind.
DE: 7509 Corona
DE: 7524 Magnetic fields
DE: 7839 Nonlinear phenomena
DE: 7863 Turbulence
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting