Radial evolution of power spectra of interplantary Alfvenic turbulence
The radial evolution of the power spectra of the MHD turbulence within the trailing edge of high-speed streams in the solar wind has been investigated with the magnetic field data of HELIOS 1 and 2 for heliocentric distances between 0.3 and 0.9 AU. In the analyzed frequency range 2.8 x 10/sup -4/ 8.3 x 10/sup -2/ Hz the computed spectra have, near the earth, values of the spectral index close to that predicted for an imcompressible hydromagnetic turbulence in a stationary state. Approaching the sun, the spectral slope remains unchanged for frequencies f> or =10/sup -2ts/Hz, whereas at lower frequencies we find a clear evolution toward a less steep falloff with frequency. The radial gradient of the power in Alfvenic fluctuations depends on frequency and it increases upon increasing frequency. For frequencies f> or =10/sup -2/ Hz, however, the radial gradient remains approximately the same. A discussion of possible theoretical implications of the observational features pointed out is given.
- Research Organization:
- Istituto di Fisica dello Spazio Interplanetario, CNR, Frascati, Italy
- OSTI ID:
- 5099173
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 87:A5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
SOLAR WIND
MAGNETOHYDRODYNAMICS
ALFVEN WAVES
FOURIER ANALYSIS
FREQUENCY DEPENDENCE
INTERPLANETARY SPACE
MILLI HZ RANGE
TURBULENT FLOW
FLUID FLOW
FLUID MECHANICS
FREQUENCY RANGE
HYDRODYNAMICS
HYDROMAGNETIC WAVES
HZ RANGE
MECHANICS
SOLAR ACTIVITY
SPACE
640107* - Astrophysics & Cosmology- Planetary Phenomena