{
  "abstract": "At the edge of the Amazon River plume, stirring by the North Brazil Current (NBC) and its eddies creates sharp surface thermohaline gradients on horizontal scales of O (1-100) km. This study provides a comprehensive picture of these gradients and fronts associated with the region's distinctive dynamics. Saildrone observations show that the plume amplifies density gradient variability at all scales from 1-100 km, with frontal sharpness up to 75× stronger inside the plume than outside, with differences reaching 100× at scales below 3 km. Density gradients are partially reinforced or compensated by temperature-salinity variations, with net frontogenesis observed in both regions. To expand in-situ observations, we use a 1 km resolution CROCO (Coastal and Regional Ocean COmmunity model) simulation to assess the spatial distribution of surface fronts and their spatio-temporal variability. We characterize three distinct frontal regimes: (i) broken-up fronts parallel to shore occupy the plume core over the continental shelf, (ii) thin elongated fronts associated with NBC-plume interactions connect nearshore and offshore regions, and (iii) pools of anisotropic fronts driven by the seasonal mixed-layer cycle are present offshore. Salinity dominates density gradients throughout the year north of 15°N, whereas near-shore fronts exhibit seasonal shifts in temperature-salinity dominance linked to the Amazon dis-charge seasonality and NBC strength. Within the plume, freshwater filaments stirred by NBC rings systematically generate density-compensated fronts on their inner edge and reinforced fronts on their outer rim, a pattern with implications for energy cascades and tracer export.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "name": "Dante C Napolitano"
    },
    {
      "name": "Jonathan Gula"
    },
    {
      "name": "Solange Coadou-Chaventon"
    },
    {
      "name": "Sabrina Speich"
    },
    {
      "name": "Cesar B Rocha"
    },
    {
      "name": "James C Mcwilliams"
    },
    {
      "name": "Dongxiao Zhang"
    },
    {
      "name": "Xavier Carton"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7c38nem47sm90.bib",
  "cited_by": 0,
  "doi": "10.5194/os-22-2425-2026",
  "fulltext_url": null,
  "id": "7c38nem47sm90",
  "issns": [
    "1812-0784",
    "1812-0792"
  ],
  "landing_url": "https://hal.science/hal-05739948v1",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.sdu"
    ],
    [
      "hal",
      "1.sdu.ocean"
    ],
    [
      "openalex",
      "1910|Oceanographic and Atmospheric Processes"
    ]
  ],
  "openalex": "W7155217431",
  "pdf_url": "https://hal.science/hal-05739948/document",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-13",
  "publisher": "European Geosciences Union",
  "ris": "https://research.draconitic.com/paper/7c38nem47sm90.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:29Z",
      "native_id": "hal-05739948",
      "source": "hal",
      "url": "https://hal.science/hal-05739948v1"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "hal:1.sdu.ocean",
      "subfield": "oceanography"
    }
  ],
  "title": "Thermohaline gradients and frontal regimes in the northwestern Tropical Atlantic",
  "title_text": "Thermohaline gradients and frontal regimes in the northwestern Tropical Atlantic",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:29Z",
  "url": "https://research.draconitic.com/paper/7c38nem47sm90",
  "venue": "Ocean Science",
  "versions": []
}