676 / 2024-09-18 23:04:49

Impacts of Madden–Julian Oscillation on Indonesian Throughflow in the Makassar Strait in Early 2017

Indonesian Throughflow (ITF),MJO

Session 65 - Oceanic-atmospheric processes over the Indian and western Pacific Oceans

The observed upper 150 m of the Makassar Strait throughflow (MST), a major component of the Indonesian throughflow (ITF), exhibited an unprecedented strong northward flow from January to February of 2017. This robust northward MSTF was associated with two Madden-Julian Oscillation (MJO) events originating in the Indian Ocean and propagating eastward toward the Maritime Continent (MC) during this period. However, these two MJO events had differing impacts on the MST, as one event successfully traversed the MC eastward, while the other was impeded. The immediate local effects of the MJO events, including wind stress and precipitation over the Indonesian region, showed minor influence on the anomalous MST. The first MJO event remotely affected sea level anomalies in the southern Makassar Strait through the propagation of coastal downwelling Kelvin waves along Sumatra, resulting in a northward pressure gradient and transport within the upper layer of the MST. In contrast, the second MJO event was characterized by the propagation of an upwelling Kelvin wave, reducing mixed layer thickness and subsurface layer temperature in southern Indonesian Seas.