Overview

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.

#indian ocean dipole #iod #dmi #sea surface temperature #climate index #seasonal forecasting

Important 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.

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

Splicing this series onto the HadISST-based DMI served by NOAA PSL.

Why: Different SST reconstruction and different climatology, so the join introduces a step change that would be read as a physical signal.

Use instead: One source end to end, this series throughout.

Access & use

Files, endpoints, and worked examples for each distribution.

Data

dmi-monthly

Fixed-width ASCII table, one row per month, columns Year, Month, WTIO, SETIO, DMI.

Format: text/plain

Variables: WTIO, SETIO, DMI

Dimensions: Year × Month

Data dictionary →

Access the dataOpen

https://www.cpc.ncep.noaa.gov/products/international/ocean_monitoring/indian/IODMI/mnth.ersstv6.clim19912020.dmi_current.txt

Data dictionary

What each file holds. A layout describes how the data is stored in a file: its variables, the dimensions they vary over, and any keys.

File layouts

Files	Format	Variables	Dimensions
dmi-monthly	text/plain	WTIO, SETIO, DMI	Year × Month

Variables

Variable	Type	Unit	Description
WTIO	number	degC	Western tropical Indian Ocean SST anomaly, averaged over 50E-70E, 10S-10N.
SETIO	number	degC	South-eastern tropical Indian Ocean SST anomaly, averaged over 90E-110E, 10S-0.
DMI	number	degC	Dipole Mode Index, WTIO minus SETIO. Positive is a positive IOD phase.

Dimensions

Yeartemporal

Calendar year of the anomaly.

Type: integer

Monthtemporal

Calendar month of the anomaly, 1 to 12.

Type: integer

Technical metadata

The full spatial, temporal, and modeling detail behind the summaries elsewhere on this page.

Temporal

Start: 1950-01
End: open (present)
Updates: Monthly

How to cite

Please cite the dataset and any associated peer-reviewed publications.

NOAA Climate Prediction Center (2026) Indian Ocean Dipole Mode Index (DMI). Version 1. NOAA National Weather Service, Climate Prediction Center. https://www.cpc.ncep.noaa.gov/products/international/ocean_monitoring/indian/IODMI/DMI_month.html. Accessed through the CGIAR Climate Action Data Hub, https://cgiar-climate-data-hub.github.io/catalog/enso-driver-dmi_1/.

BibTeX

@misc{enso_driver_dmi_2026,
  title     = {Indian Ocean Dipole Mode Index (DMI)},
  author    = {{NOAA Climate Prediction Center}},
  year      = {2026},
  version   = {1},
  publisher = {NOAA National Weather Service, Climate Prediction Center},
  url       = {https://www.cpc.ncep.noaa.gov/products/international/ocean_monitoring/indian/IODMI/DMI_month.html},
  note      = {Accessed through the CGIAR Climate Action Data Hub, https://cgiar-climate-data-hub.github.io/catalog/enso-driver-dmi_1/}
}

Contacts

Who produced this dataset, and who to reach about it.

Peter StewardMaintainer

Alliance of Bioversity International and CIAT

Point of contact

p.steward@cgiar.org

Brayden YoungbergMaintainer

Alliance of Bioversity International and CIAT

b.youngberg@cgiar.org

NOAA Climate Prediction CenterLicensor

Producer

NOAA CPC Indian Ocean Dipole Mode Index (DMI)