AI Insight
Researchers have created the SBCross catalog, a comprehensive database of 1,076 heliospheric sector boundary crossings detected in the solar wind between 1995 and 2026, spanning three solar cycles. Using automated analysis of magnetic field and electron data, they found these structures occur approximately 2.6 times per Carrington rotation, last about 9 hours on average, and extend roughly 7.4 million kilometers in thickness. Importantly, about 15% of these boundaries interact with coronal mass ejections (CMEs), rising to 33% during solar maximum, with CME-associated events showing 54% larger physical sizes and exclusively accounting for all high-velocity boundary crossings above 600 km/s.
Why it matters
This publicly available catalog provides a standardized resource for studying solar wind structures that affect space weather forecasting and our understanding of how solar activity propagates through the heliosphere. The findings about CME interactions with sector boundaries are particularly relevant for predicting geomagnetic storms and their impacts on satellite operations and technological infrastructure.
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⚠️ Preprint – Noch nicht peer-reviewed
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Abstract: Heliospheric sector boundary crossings (SBCs), composed of the Heliospheric Current Sheet (HCS), Heliospheric Plasma Sheet (HPS), and surrounding plasma halo, represent fundamental structures in the solar wind that influence interplanetary dynamics and space weather. We present the textsc{SBCross} catalog, an automated, publicly available database containing 1,076 SBC events derived from in-situ observations spanning more than 30 years (1995–2026), covering Solar Cycles 23 and 24 alongside the rising and maximum phases of Solar Cycle 25. By combining interplanetary magnetic field (IMF) and 255~eV suprathermal electron pitch angle distributions (PAD) data, our algorithm reliably captures large-scale polarity transitions, with $76%$ of detected SBCs exhibiting clear HPS signatures ($beta > 1$, $n_{mathrm{peak}} > 10mathrm{,cm^{-3}}$). Across the catalog, we find an average occurrence rate of $approx 2.6$ events per Carrington rotation, a median event duration of $approx 9.0$,hours, and a median physical thickness of $approx 7.4 times 10^6$,km. Furthermore, approximately $approx 15%$ of detected SBCs interact with interplanetary coronal mass ejections (CMEs) on average, with this proportion rising up to $33%$ during solar maximum. These CME-associated events exhibit systematically longer durations (median of $10.0$,hours), $54%$ larger physical thicknesses, and higher average solar wind velocities. Notably, all high-velocity SBC events ($> 600mathrm{,km,s^{-1}}$) are exclusively driven by CME interactions, demonstrating local plasma pile-up and structural entanglement resulting from fast CMEs overtaking the ambient slow background. The textsc{SBCross} catalog serves as an updated successor to the classic SBC list by L. Svalgaard, delivering a standardized, open-access resource for the heliophysics community to systematically investigate sector boundary transitions.