Why Does Extreme Precipitation Occur in Borneo During Both El Niño and La Niña Winters?

Abstract

AbstractExtreme precipitation over the Maritime Continent (MC) is not only vital for local livelihoods, but also influences atmospheric circulation in tropical and extra‐tropical regions. The warm (cold) phase of El Niño‐Southern Oscillation usually leads to dry (wet) condition around the MC in boreal winter. This study unravels that extreme precipitation occurs in Borneo during both El Niño and La Niña winters. Extreme precipitation in Borneo is associated with tripole and dipole anomalous vertical motion pattern, respectively, over the MC‐tropical Pacific in El Niño and La Niña years. A parallel analysis reveals that weak precipitation in Borneo in El Niño and La Niña years occurs with dipole and tripole anomalous vertical motion pattern, respectively, over the MC‐tropical Pacific. The amplitude of the equatorial central‐eastern Pacific sea surface temperature (SST) anomalies may be a factor in the change of anomalous vertical motion pattern over the MC‐tropical Pacific. Further analysis identifies a tendency of extreme precipitation in late December to early−mid January and weak precipitation in February in Borneo. This suggests a critical role of seasonal change in the eastern equatorial Pacific SST in the occurrence of extreme precipitation in Borneo.