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MHD mode decomposition in the inner-heliosphere from the Parker Solar Probe
- Publication Year :
- 2019
- Publisher :
- HAL CCSD, 2019.
-
Abstract
- We use measurements from the Parker Solar Probe in the inner heliosphere to decompose low frequency fluctuations in fields and plasmas into their constituent MHD modes. The decomposition is performed in frequency space in the spacecraft frame over a range extending from mHz up to that corresponding to the advection of the average bulk ion gyro-radii over the spacecraft. The decomposition reveals the outward propagation of a broad spectrum of shear Alfven waves along the background magnetic field with reversals in propagation in the plasma frame through 'switchback' intervals of reversed radial magnetic field. This morphology suggests propagation from a source closer to the sun along 'corrugated' field-lines that provide alternating radial orientations as the magnetic field is advected with the flow over the spacecraft. Locations of shear mode intensification are correlated with enhanced slow mode oscillations propagating along the magnetic field with the shear mode and over roughly the same frequency range. Curiously, during intervals of depressed magnetic field strength a significant fraction of the observed spectral energy density is comprised of fast mode waves propagating mostly inward in the plasma frame.
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.od.......166..7e0705279cf8d2a53f8c656130011c34