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Impacts of El Niño/La Niña and Indian Ocean Dipole events on the Global Climate

Sea surface temperature (SST) variability in the tropics can significantly impact on the global climate through atmospheric circulation. El Niño/La Niña events, which are identified by SST fluctuations from the central to the eastern equatorial Pacific (NINO.3), are widely-known examples of this. In addition, SST variability in the western tropical Pacific (NINO.WEST) and the tropical Indian Ocean (IOBW) may also have significantly affect climate conditions around the world (see the figure/table below for information on NINO.3, NINO.WEST and IOBW). Indian Ocean Dipole (IOD) events also significantly impact climate conditions in Southeast Asia, East Asia and in/around the Indian Ocean. The results of statistical surveying relating to climate conditions and ENSO/IOD provided here.

	Area	Longitude/Longitude
NINO.3	Eastern equatorial Pacific	5°N–5°S, 150°W–90°W
NINO.WEST	Western tropical Pacific	15°N–EQ, 130°E–150°E
IOBW	Tropicl Indian Ocean	20°N–20°S, 40°E–100°E
IOD	Difference between WIN (western Indian Ocean) and EIN (eastern Indian Ocean)	WIN: 10°S–10°N, 50°E–70°E EIN: 10°S–EQ, 90°E–110°E

Schematic Charts for ENSO

Schematic charts indicate typical anomaly patterns of surface temperature and precipitation for each season (boreal spring, summer, autumn and winter) as seen in past warmer/cooler SST events in the area of NINO.3 (corresponding to El Niño/La Niña events), NINO.WEST and IOBW. The figures below are examples for El Niño and La Niña impacts in boreal winter (from December through February). These results are based on observation and Japanese Reanalysis for Three Quaters of a Century (JRA-3Q) data from 1948 through 2021 (a period of 74 years).

Impacts of El Niño in boreal winter (Click the figure to jump to schematics for El Niño impacts.)	Impacts of La Niña in boreal winter (Click the figure to jump to schematics for La Niña impacts.)

More schematic charts are available on the pages shown below.
Previous temperature and precipitation anomalies:

• El Niño events
• La Niña events
• Warmer SST events in the western tropical Pacific (NINO.WEST)
• Cooler SST events in the western tropical Pacific (NINO.WEST)
• Warmer SST events in the tropical Indian Ocean (IOBW)
• Cooler SST events in the tropical Indian Ocean (IOBW)

Detailed Charts for ENSO and IOD

The "Detailed Charts" page shows anomaly patterns of three-month-mean temperature and precipitation fields centered on each calendar month for previous warmer/cooler SST events in NINO.3, NINO.WEST and IOBW and positive/negative IOD events with 5° x 5°-grid representation, from which the schematic charts described above were derived.

Data and Analysis Method

Data and analysis method details are provided on the "Data and Analysis Method" page.