A Preliminary Study On The Temporal Variation Rule Of The Indonesian Throughflow System

Indonesian Through Flow (ITF), a flow from the Pacific Ocean to the Indian Ocean through the Indonesia sea area, forms one of the most significant means of heat-exchange and water-exchange in the global oceanic system. ITF plays an important role in the circumfluence of global thermocline and exerts great influence on transferring water volume as well as keeping a balance between heat absorption and expense of the Pacific and Indian Ocean. Research shows that ITF transfers lots of heat to the Indian Ocean, thus influences the interaction between the Pacific and the Indian Ocean, as well as the global climate change at large. ITF also exerts potential effects on ENSO and Indian monsoon.Based on SODA documents, the paper analyzes the variations of principal oceanic factors, such as temperature, flux and salinity. Two maximum temperatures appear in two half-annual information, namely, from February to April and from August to November, both with temperature dropping afterwards. More than 60% volume of ITF flows through Selat Makassar, which serves as a main transferring channel for the ITF. ITF' s volume and heat transferring depend mainly on the surface layer due to its comparatively higher temperature and faster flowing speed. ITF' s volume transferring varies distinctively in different seasons, with minimum 2-3sv in January and maximum 10-11sv in July according to the agelong monthly average statistics draw from SODA. Such is resulted from the latitude-oriented wind of the South Pacific and Indian Ocean and coincides well with the correspondent pressure gradient. The seasonal variation of ITF is that it transfers more volume in summer than in winter in the northern hemisphere. The annual variation of ITF is that it transfers less water volume during El Nino period, with the temperature reducing and salinity rising. But during La Nina period, exactly the opposite of the former, ITF transfers more water volume whi ]e experiencing temperature rising and salinity reducing. The annual variation of ITF has a certain relation to El Nino, but not identical with ENSO, and carries some other information. The seasonal and annual variations of ITF have great correlations with the large-scale pressure gradient between the Pacific and Indian Ocean. However, ITF experiences less volume transferring, less depth in thermocline, lower temperature in surfacelayer and higher salinity during ENSO period. These all result from the reduction of salty hot water, the reinforcement of updraft flow, the drop in the amount of precipitation, etc. The decadal variation of ITF is that the decadal signal lies in the change of latitude-oriented wind stress in the Equator-Pacific region.