{
  "abstract": "Paleoclimate archives extend climate knowledge beyond the instrumental era, registering different seasons, variables, time averages, and memory lengths. A longstanding problem is to integrate these heterogeneous sources of information within a unified methodology. Here we present a new data-assimilation framework, Last Millennium Reanalysis 4D-Var (LMR4D-Var), which reconstructs climate trajectories from these heterogeneous datasets while balancing errors in the model, observations, and initial conditions. We compare results using LMR4D-Var to assimilate proxies from PAGES2k, Temp12k, and borehole temperature profiles without treating them as instantaneous equivalents. Instrumental verification shows that LMR4D-Var achieves the highest skill compared with previous reconstructions. Borehole assimilation preserves skill against withheld annually resolved records, increases agreement between reconstructed 300--2000-m ocean heat content and independent estimates, and yields a cooler reconstructed Little Ice Age ocean. Results for Temp12k demonstrate assimilation of decadal-to-millennial records and the potential for Holocene and deeper-time applications with suitable emulators.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.19469",
  "author_total": 5,
  "authors": [
    {
      "name": "Zilu Meng"
    },
    {
      "name": "Gregory J. Hakim"
    },
    {
      "name": "Julien Emile-Geay"
    },
    {
      "name": "Tanaya Gondhalekar"
    },
    {
      "name": "Eric J. Steig"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/es36v7jmcxhe8.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.19469",
  "fulltext_url": null,
  "id": "es36v7jmcxhe8",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.19469",
  "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",
      "nlin.CD"
    ],
    [
      "arxiv",
      "physics.ao-ph"
    ],
    [
      "arxiv",
      "physics.data-an"
    ],
    [
      "openalex",
      "1902|Geology and Paleoclimatology Research"
    ]
  ],
  "openalex": "W7203922340",
  "pdf_url": "https://arxiv.org/pdf/2608.19469",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-09",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/es36v7jmcxhe8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:26Z",
      "native_id": "2608.19469",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.19469"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "arxiv:physics.ao-ph",
      "subfield": "atmospheric"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.data-an",
      "subfield": "computational"
    },
    {
      "field": "physics",
      "origin": "arxiv:nlin.CD",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "Coupled multiscale paleoclimate reconstruction with four-dimensional variational data assimilation",
  "title_text": "Coupled multiscale paleoclimate reconstruction with four-dimensional variational data assimilation",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:26Z",
  "url": "https://research.draconitic.com/paper/es36v7jmcxhe8",
  "venue": "arXiv",
  "versions": []
}