{
  "cdh_schema_version": "v0.5.0",
  "extensions": [
    "https://cgiar-climate-data-hub.github.io/cdh-metadata-standard/v0.5.0/extensions/cdh/schema.json"
  ],
  "id": "enso-driver-roni",
  "title": "NOAA CPC Relative Oceanic Nino Index (RONI)",
  "version": "1",
  "description": "The Nino 3.4 sea-surface-temperature anomaly expressed relative to the tropical-mean SST anomaly, published monthly by the NOAA Climate Prediction Center as overlapping three-month windows.\n",
  "resource_type": "dataset",
  "license": "CC0-1.0",
  "keywords": [
    "enso",
    "roni",
    "sea surface temperature",
    "climate index",
    "seasonal forecasting"
  ],
  "note": "CPC REVISES PAST VALUES, so a refetch changes history - pin and record the fetch date with any analysis. RONI differs from the Nino 3.4 anomaly by up to 0.567 degC on a time-trending gap (about +0.20 degC in 1981-1995 falling to about -0.30 degC in 2015-2025), so mixing RONI and Nino 3.4 in one analogue-season comparison biases matches toward older years. Values are three-month means labelled by their centre month.\n",
  "access": "public",
  "contact": [
    {
      "organization": "NOAA Climate Prediction Center",
      "url": "https://www.cpc.ncep.noaa.gov/",
      "roles": [
        "licensor",
        "producer"
      ]
    },
    {
      "name": "Peter Steward",
      "organization": "Alliance of Bioversity International and CIAT",
      "email": "p.steward@cgiar.org",
      "roles": [
        "point-of-contact",
        "maintainer"
      ]
    },
    {
      "name": "Brayden Youngberg",
      "organization": "Alliance of Bioversity International and CIAT",
      "email": "b.youngberg@cgiar.org",
      "roles": [
        "maintainer"
      ]
    }
  ],
  "citation": {
    "title": "Relative Oceanic Nino Index (RONI)",
    "authors": [
      {
        "organization": "NOAA Climate Prediction Center"
      }
    ],
    "date": "2026",
    "publisher": "NOAA National Weather Service, Climate Prediction Center",
    "url": "https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/"
  },
  "created": "2026-09-18",
  "updated": "2026-10-14",
  "temporal": {
    "start_date": "1950-01",
    "end_date": null,
    "update_frequency": "monthly"
  },
  "structures": [
    {
      "name": "roni-table",
      "dimensions": [
        {
          "name": "SEAS",
          "type": "season",
          "description": "Overlapping three-month window named by the initials of its months (DJF = Dec-Feb ... NDJ = Nov-Jan), labelled by its centre month.\n",
          "data_type": "string",
          "values": [
            "DJF",
            "JFM",
            "FMA",
            "MAM",
            "AMJ",
            "MJJ",
            "JJA",
            "JAS",
            "ASO",
            "SON",
            "OND",
            "NDJ"
          ]
        },
        {
          "name": "YR",
          "type": "temporal",
          "description": "Calendar year of the window's centre month.",
          "data_type": "integer",
          "step": "P1Y"
        }
      ],
      "variables": [
        {
          "name": "ANOM",
          "description": "Relative Oceanic Nino Index: the Nino 3.4 SST anomaly minus the tropical-mean (20S-20N) SST anomaly, averaged over the three-month window.\n",
          "data_type": "number",
          "unit": "degC"
        }
      ]
    }
  ],
  "data": [
    {
      "name": "roni-ascii",
      "description": "Fixed-width ASCII table, one row per overlapping three-month window.",
      "locations": [
        {
          "url": "https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt",
          "title": "HTTPS"
        }
      ],
      "media_type": "text/plain"
    }
  ],
  "additional_links": [
    {
      "title": "Indian Ocean Dipole Mode Index (DMI)",
      "rel": "related",
      "id": "enso-driver-dmi",
      "description": "Sister IOD driver from the same ERSSTv6 reconstruction and 1991-2020 climatology."
    }
  ],
  "cdh": {
    "domain": [
      "climate"
    ],
    "usage": {
      "intended_uses": [
        "classifying seasons by ENSO phase (El Nino, La Nina, neutral)",
        "selecting analogue years for seasonal outlooks and impact analysis",
        "ENSO driver for rainfall, drought and crop anomaly studies"
      ],
      "not_recommended_for": [
        {
          "use": "Mixing RONI with the raw Nino 3.4 anomaly in one time series or distance metric.",
          "reason": "The two differ by up to 0.567 degC and the gap trends over time, so a mixed series biases analogue matching toward older years.\n",
          "use_instead": "One index end to end, RONI throughout."
        }
      ]
    }
  }
}