Intraseasonal Variability of δ¹⁸O of Precipitation over the Indonesian Maritime Continent Related to the Madden–Julian Oscillation

Abstract

Intraseasonal variability of precipitation over the Indonesian Maritime Continent (IMC) is related mainly to the Madden–Julian oscillation (MJO). The MJO enhances and suppresses precipitation around the IMC according to its phase. This study examined the relationship between the MJO and the stable isotope of the precipitation over the IMC. Observations and simulation data from an isotope circulation model and colored moisture analysis (ICM/CMA) were used. Temporal analyses of the observed and simulated data showed that an active MJO stage, associated with a positive precipitation anomaly over the IMC, was correlated with the depletion of δ¹⁸O_p at all stations. Spatial analysis of the total column precipitable water from the ICM/CMA revealed that during the MJO phase 3-5, water of Indian Ocean origin reached as far as western parts of Borneo and Bali. For other part of the IMC in these phases, vapor was refreshed from the South Maritime Continent Ocean and North Maritime Continent Ocean. Water that originated from the Pacific Ocean traveled westward during MJO phases 3-5, and it retreated eastward during phases 6-8.