INFLUENCE OF THE MAKASSAR STRAIT THROUGHFLOW AND WINDS OVER THE SOUTHEASTERN INDIAN OCEAN ON THE SOUTHWESTERN INDIAN OCEAN SST VARIABILITY

Abstract

Seasonal variability of temperature and salinity (T–S) in the southern Makassar Strait influences the baroclinic structure of the Indonesian Throughflow (ITF). Especially, during boreal winter, the intrusion of fresh surface water from the Java Sea into the southern Makassar Strait, which is related to the South China Sea Throughflow, hinders the southward surface flow through the Makassar Strait. Winds over the southeastern Indian Ocean (SEIO), where ITF enters the Indian Ocean, energize the westward-propagating ITF waters. These signals are carried westward by the ITF, influencing the vertical stratification and the sea surface temperatures (SSTs) in the southwestern Indian Ocean (SWIO). The southern Makassar Strait is thus like a valve, which controls the seasonal variability of the T–S properties of the ITF waters; the winds over the SEIO are like a propeller, which supplies energy to the ITF; and the ITF is like a conveyor belt, which connects the SEIO and the SWIO. Hence, the intraseasonal variabilities of SSTs in SWIO are dramatically influenced by the ITF in boreal winter, which is significant since the SSTs in this region have demonstrable regional and global climatic impacts.