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arXiv · 2610.28123

Deriving Interplanetary Sector Boundary Crossings using Potential Field Source Surface Modeling

Stephan G. Heinemann·Manuela Temmer·Jens Pomoell·Mathew Owens·Emilia Kilpua·Matti ala-Lahti·Andreas Wagner
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Abstract

The Heliospheric Current Sheet (HCS) and associated interplanetary sector boundaries fundamentally structure the solar wind environment, modulating coronal mass ejection (CME) evolution and solar energetic particle transport. In this study, we evaluate the capability of a static Potential Field Source Surface (PFSS; $R_{ss}=2.5R_\odot$) coronal model to directly map interplanetary sector boundary crossings from the Sun to 1 au without dynamic heliospheric propagation models. We compare ballistically transported HCS crossings derived from GONG-ADAPT and SDO/HMI magnetic maps against sector boundary crossing observations from the SBCross catalog. PFSS modeling reproduces the large-scale interplanetary magnetic field topology well ($J\approx0.50$), achieving hit rates (POD) of 0.64 for GONG-ADAPT and 0.76 for HMI. Carrington synoptic maps outperform flux-transport modeled maps, suggesting that the short-term observational noise from data assimilation degrades topological matching more than map "aging". Predictive skill shows a strong solar cycle dependence, performing significantly better during solar maxima (POD=0.70-0.81) than solar minima (POD=0.56-0.67), attributed to more distinct crossings due to higher HCS inclination angles during maximum. Matched events exhibit travel times close to ballistic estimates of 4.8-4.9 days with an average timing difference centered near zero ($\pm1.1$ days) and 90% of events within $\pm 1.8$ days. The hit rate of HCS structures that interact with CMEs does not degrade (POD = 0.67-0.83), despite propagating $\approx7$ hours faster on average, implying that the CME interaction causes only minor structural changes to the HCS. Larger timing differences (>24 hours) are associated with flatter current sheets. Overall, static PFSS extrapolations offer a computationally inexpensive, effective approach for mapping global sector boundary structure.

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Stephan G. Heinemann, Manuela Temmer, Jens Pomoell, Mathew Owens, Emilia Kilpua, Matti ala-Lahti, Andreas Wagner. 2026-10-20. Deriving Interplanetary Sector Boundary Crossings using Potential Field Source Surface Modeling. https://arxiv.org/abs/2610.28123

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