Lagged teleconnections between two types of ENSO and Southeast Asian autumn rainfall anomalies

Abstract

Abstract The lagged teleconnections of the two types of El Niño–Southern Oscillation (ENSO) on Southeast Asian autumn rainfall (SEAAR) anomalies for lagged time varying from 12 to zero months are investigated for the period 1979 to 2019 using Singular Value Decomposition (SVD) and composite analyses. It shows that the first two SVD coupled modes always exhibit the patterns of the two types of ENSO for all lagged times. First, the canonical El Niño (EN) from preceding autumn induces significantly wetter SEAAR, due to the transition from EN to La Niña (LN) in the following year. Thereafter, disparities between ENSO and ENSO Modoki teleconnections on SEAAR are most pronounced for the 6-month lag, in which an El Niño Modoki (EM)/La Niña Modoki (LM) occurring in the preceding spring is a strong indication of a much drier/wetter SEAAR. Subsequently, for 3-month and zero lag, both EN and EM (LN and LM) bring drier (wetter) SEAAR. However, EM leads to drier (wetter) conditions in the north (south). Regarding LN and LM, LM causes significantly less rainfall in the Philippines, northern Indochina, and Sumatra. The differences in SEAAR anomalies under ENSO and ENSO Modoki conditions are linked to a more northward (southward) Walker circulation in EM compared to EN (LM compared to LN). Different evolution patterns, i.e., transition from EM to LM occurs less frequently than EN to LN, particularly with preceding autumn and spring ENSO events, contribute to the distinct lagged teleconnections between the two ENSO types. It also results in longer teleconnection persistence of LM and LN compared to EM and EN.