{
  "abstract": "A spacecraft crossing the aurora cannot tell whether structures in the field-aligned currents are short-lived or merely small. However, by tracking clusters of coherent radar echoes from aurorae and Fourier-transforming motion-shifted echo pairs across radar snapshots, we can calculate the dynamic structure factor of the point-clouds, thereby quantifying the auroral electric field's spatial power and its persistence from 5 to 40 km, in regions where the radar look-direction is perpendicular to the geomagnetic field. This follows from the fact that coherent E-region radar echoes appear only where the ionospheric electric field exceeds the Farley-Buneman instability threshold, and so a point-target imaging radar naturally samples the field's excursion set; the field's spatiotemporal correlations are discernible from that point process. We find that the echo pattern moves with its cluster: large-scale structures persist for tens of seconds, but scales under 10 km renew within seconds, and conjunctions with Swarm satellite pairs replicate the same scale dependence in field-aligned currents. Coherent radar can thus quantify multi-scale variability in the auroral electric field on Alfvénic timescales.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2606.26854",
  "author_total": 4,
  "authors": [
    {
      "name": "Magnus F Ivarsen"
    },
    {
      "name": "Kaili Song"
    },
    {
      "name": "Jean-Pierre St-Maurice"
    },
    {
      "name": "Glenn C Hussey"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7447qcbb7210k.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.26854",
  "fulltext_url": null,
  "id": "7447qcbb7210k",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.26854",
  "language": null,
  "licence": "CC-BY-SA-4.0",
  "licence_label": "CC BY-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "arxiv",
      "physics.geo-ph"
    ],
    [
      "arxiv",
      "physics.space-ph"
    ],
    [
      "openalex",
      "3103|Ionosphere and magnetosphere dynamics"
    ]
  ],
  "openalex": "W7166134753",
  "pdf_url": "https://arxiv.org/pdf/2606.26854",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7447qcbb7210k.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:22Z",
      "native_id": "2606.26854",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.26854"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:physics.space-ph",
      "subfield": "stellar"
    },
    {
      "field": "earth",
      "origin": "arxiv:physics.geo-ph",
      "subfield": "geophysics"
    }
  ],
  "title": "Excursion-set structure factor of the auroral electric field",
  "title_text": "Excursion-set structure factor of the auroral electric field",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:44Z",
  "url": "https://research.draconitic.com/paper/7447qcbb7210k",
  "venue": "arXiv",
  "versions": []
}