6–10 Jul 2026
University of the Western Cape
Africa/Johannesburg timezone
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Linking Coronal Structures to L1 Solar Wind Disturbances over Three Solar Minima

8 Jul 2026, 12:00
20m
Lecture Hall C3 (University of the Western Cape)

Lecture Hall C3

University of the Western Cape

Oral Presentation Track D - Astrophysics & Space Science Astrophysics & Space Science

Speaker

Thembalethu Zulu

Description

Periodic solar wind streams observed at the Lagrange point L1 provide critical insight into coronal hole structures during solar minima. This study characterises and identifies the coronal sources of periodic solar wind streams measured at L1 during the last three solar minima between cycles 22–23, 23–24, and 24–25. In situ solar wind speed and heliospheric magnetic field data from the Advanced Composition Explorer (ACE) spacecraft, with a one-hour cadence, are analysed. Fourier analysis is employed to detect and characterise periodicities in the solar wind. Magnetic connectivity between the L1 point and the solar coronal hole is established using two approaches: the Parker heliospheric magnetic field (HMF) model combined with potential field source surface (PFSS) extrapolation, and the Fisk HMF model. The Parker HMF model traces magnetic field lines from L1 to the source surface, while PFSS extrapolation traces them from the source surface back to their coronal hole origins. The Fisk HMF model provides direct coronal hole mapping. Carrington synoptic maps provide global context by displaying magnetic field-line footpoints corresponding to solar wind disturbances observed at L1, while heavy ions charge state ratios serve as plasma diagnostics linking solar wind streams to their coronal hole source regions.

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Author

Co-author

Dr Ruhann Steyn (Supervisor)

Presentation materials