HR: 14:55h
AN: SH13B-06    [Abstracts]
TI: New Insights into The Structure of the Turbulent Interplanetary Magnetic Field
AU: * Matthaeus, W H
EM: whm@udel.edu
AF: Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 United States
AU: Giacalone, J
EM: giacalon@lpl.arizona.edu
AF: Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 United States
AU: Jokipii, J R
EM: jokipii@lpl.arizona.edu
AF: Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 United States
AB: We present new insights into the structure of the turbulent interplanetary magnetic field. Various authors [1,2] have studied field line random walk associated with interplanetary fields consisting of smooth mean fields and fluctuations. One possible way to generate fluctuations [3,4] is at a source surface near the solar surface, by random transverse plasma motions (such as supergranulation at the solar photosphere or perhaps reconnection), together with a uniform radial outflow at a specified solar wind speed. In this approach, the structure of the magnetic field fluctuations is controlled by the temporal and spatial dependence of the footpoint velocity field. These combine to regulate the spatial structure observed in the interplanetary field. Further dynamical processing is ignored in this view, which is therefore most appropriate for large scale fluctuations. Comparison of this picture with observations from the magnetometer on the Ulysses spacecraft has shown good agreement. A quite different approach to modeling the spatial structure of interplanetary fluctuations is embodied in the so-called two component model, This was introduced [5,6,7] as a useful simplified parameterization of interplanetary fluctuations, and, since it is associated with no specific generation mechanism, this approach is consistent with either solar-surface or in situ generation of turbulence. This also shows good agreement with observations. Here, we show that these two apparently different ways of modeling turbulent fields can be closely related. In particular, we show that by properly choosing the temporal and spatial dependence of the transverse velocity field at the solar source surface, we can generate the two component model (as well as many other possible models). The consequences of this insight for our understanding of turbulence and energetic-particle transport are discussed. [1] Jokipii and Parker, Phys. Rev. Lett, 21, 44, 1968 [2] Matthaeus et al, Phys. Rev Lett. 75, 2136, 1995 [3] Jokipii and Kota Geophys. Res. Lett., 16, 1, 1989 [4] Giacalone and Jokipii, Astrophys. J. 616, 573, 2004 [5] Matthaeus, Goldstein and Roberts, JGR, 95, 20673, 1990 [6] Tu and Marsch, 98, 1257, 1993 [7] Bieber etal, Atrophys. J., 420, 294, 1994
DE: 2134 Interplanetary magnetic fields
DE: 2139 Interplanetary shocks
DE: 7524 Magnetic fields
DE: 7863 Turbulence (4490)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005