Solar wind coherent structures from MHD to sub-ion scales: PSP measurements at 0.17 au
Abstract
We study solar wind coherent structures with Parker Solar Probe measurements during its first perihelion at 0.17 au. Using Morlet wavelet transform, we show that intermittent events from MHD (∼ 105 km) to sub-ion scales (∼ 1 km) coexist.
A bandpass filter is applied in order to investigate separately MHD inertial range, ion scale and sub-ion scale sub-structures. PSP magnetic field and plasma measurements show that the majority of MHD inertial range structures are Alfvénic. For example, we observe an event of ∼ 2×104 km scale that can be interpreted as an Alfvén vortex embedded into a rotational current sheet. However, structures on the MHD range are not always purely Alfvénic. We provide an example of tangential discontinuity with |B| variation and dB/B0=2dV/VA. Furthermore, in the context of possible solar wind heating, we discuss an example of a structure with Tp variation. We underline that coherent structures do exist at ion kinetic and sub-ion scales. They can be associated with with ion-scale Alfven vortices and sub-ion scale compressible vortices. They are usually embedded in larger MHD range structures. Finally, we compare the statistics of 372 structures detected during 5 hours with crossings realized across five type of model structures with various impact parameters. These results generalize what is found on examples. In particular, planar current sheets and vortex filaments are present till the end of the MHD inertial range while compressible vortex-like structures dominate at sub-ion scales scales.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMSH32A..03V