Identification of Flux Ropes through Magnetic Helicity and Partial Variance of Increments
Abstract
Flux ropes, that might abundantly populate the interplanetary space, are very hard to detect, especially from single-spacecraft measurements. These coherent structures manifest features such as magnetic field rotation, pressure balance and so on. They are commonly selected through arbitrary criteria (usually by direct data inspection), by taking into account the typical behaviour of both the magnetic field and kinetic pressure. We provide a complementary approach, based on statistical selection, that relies on the helical nature of these structures. With the support of turbulence simulations, we found that well-defined flux ropes manifest magnetic field twisting, with a clear peak in the large scale magnetic helicity Hm. The boundaries, and hence the extension, of a flux rope, are determined through the Partial Variance of Increments (PVI) technique that is able to identify discontinuities in the magnetic field such as those happening at the boundaries between two interacting flux tubes. These regions might be sites of fast reconnection events. The combined Hm-PVI technique has been tested both on simulations and space data, showing very promising results. Our novel technique is finally applied to Parker Solar Probe mission, showing that these helical, quasi-equilibrium structures strongly characterise the Solar Wind.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSH0510008P
- Keywords:
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- 7509 Corona;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7526 Magnetic reconnection;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7829 Kinetic waves and instabilities;
- SPACE PLASMA PHYSICS;
- 7863 Turbulence;
- SPACE PLASMA PHYSICS