| name | han-2026-energetic-electrons-hcs-pfss-polarity |
| description | Per-entry paper-skill in wave500_coronal_source_mapping_pfss_045 (HelioSI 501-corpus). See body and metadata.yaml for paper identity and claim boundary. |
han-2026-energetic-electrons-hcs-pfss-polarity
Runtime-neutral paper-skill. Layered: (1) scientific invariants, (2) executable protocol against abstract capabilities, (3) adapter notes (optional examples only), (4) research-generation affordances.
Trigger
Reach for this skill when classifying SEE / SEP events by HCS-sector geometry and you need a PFSS-grounded definition of 'same-side' vs 'opposite-side' relative to the neutral line, cross-checked against strahl PADs and first-order anisotropy.
Layer 1 — Scientific invariant
Paper identity
- Title: Do Solar Energetic Electrons Cross the Heliospheric Current Sheet? A Statistical Study
- First author: C. Han
- Authors: C. Han, R. F. Wimmer-Schweingruber, P. Kühl, L. Berger, Z. Ding, A. Kollhoff, Q. Shi, Z. Xu, M. Qin, M. Wang
- Year: 2026
- arXiv: 2604.19446 (posted 2026-04-21)
- Journal: TODO_verify_with_full_text
- DOI: TODO_verify_with_full_text
Claim (narrow form)
With a 4-test polarity vote (PFSS footpoint sign, in-situ B_R sign, strahl PAD, first-order anisotropy of energetic electrons), 69 SEE events split into 60 same-side / 9 opposite-side; opposite-side events are more isotropic and have both source and observer closer to the HCS, supporting inefficient cross-HCS transport.
Method assumptions
- PFSS is solvable per CR on synoptic Br.
- Spacecraft footpoint can be back-mapped via ballistic + PFSS.
- Strahl PAD is a reliable independent polarity sensor when available.
- First-order anisotropy of energetic electrons resolves arrival hemisphere.
Data assumptions
- Synoptic Br (GONG/HMI/ADAPT) for each event CR.
- Spacecraft B-field (L1/SolO/PSP) for in-situ polarity.
- Strahl PADs from relevant instrument suite.
- SEE flux with anisotropy moments.
Failure modes (skill memory)
- Magnetogram swap flips polarity at the footpoint near the HCS.
- Source-surface height changes source-to-HCS distance — sweep it.
- Strahl dropouts make the strahl test silently unreliable.
- Anisotropy can flip sign across the event window — pin a window.
Figure / numerical targets
- Source-to-HCS distance histogram, same vs opposite (Figure TODO_verify).
- PFSS open-field map with event source markers.
- Isotropy contrast panel between the two classes.
Claim boundary
In scope. The 69-event sample with the 4-test polarity protocol.
Out of scope — do NOT generalize:
- Do NOT cite as a universal cross-HCS transport efficiency.
- Do NOT collapse to a single polarity test (e.g., B-sign only) and quote the same numbers.
Layer 2 — Executable protocol (capability-typed)
Required capabilities (abstract)
| Capability | Purpose | Notes |
|---|
magnetogram.fetch_synoptic_br() | synoptic Br per CR | GONG/HMI |
pfss.solve() | PFSS field on the shell | R_ss≈2.5 |
field.trace_to_photosphere() | observer footpoint | ballistic+PFSS |
magnetogram.locate_neutral_line() | HCS on source surface | |
polarity.evaluate_in_situ() | B_R sign at observer | windowed |
strahl.pad_polarity() | strahl polarity from PAD | instrument |
anisotropy.first_order() | energetic-electron anisotropy | per energy |
ephemeris.observer() | L1/SolO/PSP position | per event |
Procedure
- Assemble event list with onset windows.
- Fetch synoptic Br per event CR; solve PFSS.
- Back-map observer to source surface via ballistic vsw.
- Locate source-surface neutral line.
- Run 4 polarity tests; vote.
- Record source/observer angular distance to HCS.
- Aggregate isotropy diagnostic per class.
Validation target
Reproduce 60/9 split and qualitative HCS-proximity ordering.
Layer 3 — Adapter / runtime notes (optional examples)
- PFSS can bind to sunkit-magex.pfss; ballistic + ephemeris example lives in .library/custom/pfss-tracing/. Not required.
Layer 4 — Research-generation affordances
- Tension with [[jiang-2024-nested-active-regions-hcs-reversal]] — nested ARs stall HCS reversal, so opposite-side events should cluster in stalling phases.
- Cross-product with [[paper-desai-2024-hcs-reconnection-400kev-protons]]: are opposite-side events those with sources embedded in HCS reconnection regions?
- Generative hypothesis: weighting the 4-test vote by strahl coverage quality should reclassify a measurable fraction.
Skill graph → depends_on
- [[pfss-test-problems-solar-stellar-magnetic-fields]] — PFSS solver acceptance test.
- [[paper-desai-2024-hcs-reconnection-400kev-protons]] — sibling HCS-particle skill.
Links
TODOs for full-text verification
- DOI
- journal
- exact event list
- magnetogram product per event