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Uncovering Erosion Effects on the Twist Distribution in Cross-section of Magnetic Clouds

Sanchita Pal - University of Helsinki, Finland; Emilia Kilpua - University of Helsinki, Finland; Jens Po­moell - University of Helsinki, Finland; Simon Good - University of Helsinki, Finland; Daniel Price - University of Helsinki, Finland

Session: Interplanetary CMEs and Solar Particle Events


Magnetic clouds (MCs) are large-scale interplanetary twisted magnetic flux ropes that originate from the Sun. Their interaction with an ambient interplanetary magnetic field may result in erosion. The twist of MCs' magnetic field lines yields information about their formation and geoeffectiveness. We investigate the twist distribution in the cross-section of two MCs, which travel across spacecraft with their cores and leave behind post-eruption arcades as a coronal signature at their solar sources. We observe a monotonous decrease in one of the two MCs' twist profile from the axis to the periphery. In contrast, the twist in the other one initially decreases from its maximum value near the axis, becomes roughly uniform in the central half part, and gradually increases towards the edge. We suggest that a moderate increase in twist values towards the MC boundaries may result from helical field lines that wrap around the flux ropes formed due to low-coronal magnetic reconnection between pre-existing flux ropes and overlying field lines. We compare MCs' magnetic properties within the Sun-Earth domain and find that the MC with a monotonically decreasing twist profile is eroded more than the other, and the erosion peels off the MC's outer layer comprising twisted field lines.

Approaching deadlines:

Registration opens:

16 July 2020

Abstract submission opens:

16 July 2020

European Space Weather Medals:

6 September 2020

Registration deadline:

25 September 2020

Registration deadline: [extended]

10 October 2020

Abstract submission deadline:

4 September 2020