Detection and Statistics of large-scale Sector Boundary Crossings in the Solar Wind: The SBCross Catalog

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 ($β> 1$, $n_{\mathrm{peak}} > 10\mathrm{\,cm^{-3}}$). 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 ($> 600\mathrm{\,km\,s^{-1}}$) 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.