{
  "abstract": "Infragravity waves generated in the surf zone contribute substantially to nearshore water-level variability, with group-scale variations in wave breaking generating free long waves through breakpoint forcing. Existing interpretations of this mechanism rely largely on an idealised moving-breakpoint picture in which breaking is tied to a local saturation relation, leaving unresolved how the finite extent and evolution of a realistic breaking region control the radiated waves. We first derive a local decomposition of the wave-induced forcing into breakpoint and bound wave forcing, separating the two contributions within the same evolving short-wave field. We then describe the breakpoint-forcing field as a finite, evolving source through its integrated strength, centroid, cross-shore width, and shape. This representation shows that finite source extent produces spatial interference, as phase differences between contributions emitted from different positions attenuate the high-frequency part of the infragravity response and shift this attenuation toward lower frequencies as the source widens. Source migration produces a directional Doppler shift by modifying the arrival times of successive emissions, with shoreward motion compressing arrivals at a shoreward observer and stretching them at a seaward observer. Breaking depth controls both the conversion of this forcing into surface elevation and the celerities governing these propagation-time effects. Controlled numerical experiments across a range of plane-beach slopes reproduce the predicted signatures: broader source footprints strengthen upper-band attenuation on both branches. The diagnosed migration history, with breaking strongest during shoreward motion, partly offsets that attenuation shoreward and reinforces it seaward.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.03300",
  "author_total": 4,
  "authors": [
    {
      "name": "Hedi Midouni"
    },
    {
      "name": "Stephanie Contardo"
    },
    {
      "name": "Jaak Monbaliu"
    },
    {
      "name": "Tomohiro Suzuki"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bpkm4bmnaeg8c.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.03300",
  "fulltext_url": null,
  "id": "bpkm4bmnaeg8c",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.03300",
  "language": null,
  "licence": "CC-BY-NC-ND-4.0",
  "licence_label": "CC BY-NC-ND 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.flu-dyn"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.03300",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bpkm4bmnaeg8c.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:31Z",
      "native_id": "2609.03300",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.03300"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.flu-dyn",
      "subfield": "fluid-dynamics"
    }
  ],
  "title": "Finite-source filtering and Doppler modulation of infragravity waves generated by breakpoint forcing",
  "title_text": "Finite-source filtering and Doppler modulation of infragravity waves generated by breakpoint forcing",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:31Z",
  "url": "https://research.draconitic.com/paper/bpkm4bmnaeg8c",
  "venue": "arXiv",
  "versions": []
}