HR: 10:20h
AN: SH32B-01 INVITED    [Abstracts]
TI: Anisotropies and Helicities in the Solar Wind Inertial and Dissipation Ranges at 1 AU
AU: * Smith, C W
EM: Charles.Smith@unh.edu
AF: University of New Hampshre, Department of Physics and Astronomy, Space Science Center, Morse Hall, University of New Hampshire, Durham, NH 03824, United States
AU: Vasquez, B J
EM: Bernie.Vasquez@unh.edu
AF: University of New Hampshre, Department of Physics and Astronomy, Space Science Center, Morse Hall, University of New Hampshire, Durham, NH 03824, United States
AU: Leamon, R J
EM: leamon@grace.nascom.nasa.gov
AF: ADNET Systems, Inc., ADNET Systems, Inc., NASA/Goddard Space Flight Center, Code 671.1, Greenbel, MD 20771, United States
AU: Hamilton, K
EM: kmz4@cisunix.unh.edu
AF: UC/Riverside, Department of Physics and Astronomy, UC/Riverside, Riverside, CA 92521, United States
AB: We have constructed a data base of ACE observations at 1 AU based on 960 intervals spanning the broadest possible range of solar wind conditions including magnetic clouds. Using spectral analysis of high resolution magnetic field data we compare inertial range characteristics with properties in the measured dissipation range. We find that previous conclusions by Leamon et al. [1998a,b,c] are upheld: average wave vectors are more field-aligned in the dissipation range than in the inertial range, magnetic fluctuations are less transverse to the mean field in the dissipation range, and cyclotron damping plays an important, but not exclusive role in the formation of the dissipation range. However, field-aligned wave vectors play a larger role in the formation of the dissipation range than was previously found. In the process we examine characteristics of the inertial range that are relevant to the manner in which the dissipation range is created. We find significant contrast between these inertial range results and the conclusions of Dasso et al. [2005] who examine larger scale fluctuations within the inertial range. Dasso et al. found a dominance of field-aligned wave vectors in the high-speed wind and a dominance of 2D wave vectors in low-speed winds. We find that the orientation of the wave vectors for the smallest scales within the inertial range are not organized by wind speed and that on average all samples show the same distribution of energy between perpendicular and field-aligned wave vectors. We conclude that this is due to the time required to evolve the spectrum toward a 2D state where the smaller inertial range scales examined here evolve more quickly than the larger scales of earlier analysis. Likewise, we find no such organization by to wind speed within the dissipation range.
DE: 2134 Interplanetary magnetic fields
DE: 2149 MHD waves and turbulence (2752, 6050, 7836)
DE: 2159 Plasma waves and turbulence
DE: 2164 Solar wind plasma
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting