{
  "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-dmi",
  "title": "NOAA CPC Indian Ocean Dipole Mode Index (DMI)",
  "version": "1",
  "description": "Monthly Indian Ocean Dipole Mode Index published by the NOAA Climate Prediction Center: the sea-surface-temperature anomaly of the western tropical Indian Ocean (50E-70E, 10S-10N) minus that of the south-eastern tropical Indian Ocean (90E-110E, 10S-0), computed from ERSSTv6 against a 1991-2020 climatology. Both poles are published alongside the index.\n",
  "resource_type": "dataset",
  "license": "CC0-1.0",
  "keywords": [
    "indian ocean dipole",
    "iod",
    "dmi",
    "sea surface temperature",
    "climate index",
    "seasonal forecasting"
  ],
  "note": "This is CPC's own DMI from ERSSTv6 against a 1991-2020 climatology, not the widely cited NOAA PSL series computed from HadISST (which carries a non-commercial licence). The two differ in reconstruction and base period, so values are not interchangeable and the series must not be spliced. CPC publishes both poles (WTIO, SETIO) alongside the index.\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": "Indian Ocean Dipole Mode Index (DMI)",
    "authors": [
      {
        "organization": "NOAA Climate Prediction Center"
      }
    ],
    "date": "2026",
    "publisher": "NOAA National Weather Service, Climate Prediction Center",
    "url": "https://www.cpc.ncep.noaa.gov/products/international/ocean_monitoring/indian/IODMI/DMI_month.html"
  },
  "created": "2026-09-18",
  "updated": "2026-10-14",
  "temporal": {
    "start_date": "1950-01",
    "end_date": null,
    "update_frequency": "monthly"
  },
  "structures": [
    {
      "name": "dmi-table",
      "dimensions": [
        {
          "name": "Year",
          "type": "temporal",
          "description": "Calendar year of the anomaly.",
          "data_type": "integer",
          "step": "P1Y"
        },
        {
          "name": "Month",
          "type": "temporal",
          "description": "Calendar month of the anomaly, 1 to 12.",
          "data_type": "integer",
          "step": "P1M"
        }
      ],
      "variables": [
        {
          "name": "WTIO",
          "description": "Western tropical Indian Ocean SST anomaly, averaged over 50E-70E, 10S-10N.",
          "data_type": "number",
          "unit": "degC"
        },
        {
          "name": "SETIO",
          "description": "South-eastern tropical Indian Ocean SST anomaly, averaged over 90E-110E, 10S-0.",
          "data_type": "number",
          "unit": "degC"
        },
        {
          "name": "DMI",
          "description": "Dipole Mode Index, WTIO minus SETIO. Positive is a positive IOD phase.",
          "data_type": "number",
          "unit": "degC"
        }
      ]
    }
  ],
  "data": [
    {
      "name": "dmi-monthly",
      "description": "Fixed-width ASCII table, one row per month, columns Year, Month, WTIO, SETIO, DMI.",
      "locations": [
        {
          "url": "https://www.cpc.ncep.noaa.gov/products/international/ocean_monitoring/indian/IODMI/mnth.ersstv6.clim19912020.dmi_current.txt",
          "title": "HTTPS"
        }
      ],
      "media_type": "text/plain"
    }
  ],
  "additional_links": [
    {
      "title": "Relative Oceanic Nino Index (RONI)",
      "rel": "related",
      "id": "enso-driver-roni",
      "description": "Sister ENSO driver from the same ERSSTv6 reconstruction and 1991-2020 climatology."
    }
  ],
  "cdh": {
    "domain": [
      "climate"
    ],
    "usage": {
      "intended_uses": [
        "classifying seasons by Indian Ocean Dipole phase (positive, negative, neutral)",
        "selecting analogue years for seasonal outlooks and impact analysis, paired with an ENSO index",
        "IOD driver for East African rainfall, drought and crop anomaly studies"
      ],
      "not_recommended_for": [
        {
          "use": "Splicing this series onto the HadISST-based DMI served by NOAA PSL.",
          "reason": "Different SST reconstruction and different climatology, so the join introduces a step change that would be read as a physical signal.\n",
          "use_instead": "One source end to end, this series throughout."
        }
      ]
    }
  }
}