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[Column] A co-occurrence of an El Nino and a positive Indian Ocean Dipole Mode may bring abnormal season

August 23, 2023
Application Laboratory, VAiG, JAMSTEC

As predicted in April (2023/04/13 JAMSTEC News), both an El Nino and a positive Indian Ocean Dipole Mode actually occurred (*1). The combination would be the first in eight years since the 2015 event. The SINTEX-F model predicts that the combination will reach its peak in the boreal autumn (Fig. 1).

Both the El Niño and the positive Indian Ocean Dipole Mode can cause abnormal seasons around the world. In particular, we notice that Indonesia and eastern Australia may experience extremely drier than normal conditions owing to the simultaneous occurrence. It may increase the likelihood of bushfires in the countries in the coming season.

Please see 2023/04/13 JAMSTEC News for more information about an El Niño, an Indian Ocean Dipole Mode, and their predictability.


Fig. 1: Predicted sea surface temperature (SST) anomaly in °C for the 2023 September-November average from August 1, 2023. The base period for the estimation of anomalies is 1991–2020. It shows the mean of 36 ensemble members of the three systems of "F2", "F2-3DVAR", and "F2si" (see details here). We can see a sign of a positive Indian Ocean Dipole: anomalous cooling of SST in the southeastern equatorial Indian Ocean and anomalous warming of SST in the western equatorial Indian Ocean, and a sign of an El Niño: anomalous warming of SST in the central and eastern equatorial Pacific Ocean. The SINTEX-F seasonal forecasts are updated monthly. Please refer to the SINTEX-F homepage and the APL Virtualearth for the latest information.

Please see NOAA websites: El Niño index, Indian Ocean Dipole Mode Index, sea surface temperature, and NASA website: sea level height, etc.