Presented at the 2014 Aquarius/SAC-D Science Team MeetingThe proposed research is a pioneering work to determine the freshwater flux from the Bay of Bengal, the South China Sea, and the Eastern Indian Ocean (BBSCSEIO) and its impacts on the Indonesian Throughflow (ITF), using in situ observations and satellite data, especially the Aquarius/SAC-D satellite ocean salinity data. We will collaborate with numerical model scientists to validate the modeled results with our analysis results derived from in situ and remotely sensed data. We hypothesize that freshwater flux from BBSCSEIO play an important role in controlling the vertical stratification and mixing of the ITF in the Makassar Strait and all ITF exit passages into the Indian Ocean. We can make an analogy as if the ITF is a cup of coffee, then the freshwater flux from BBSCSEIO is creamer. Although it is much weaker than the main ITF through the Makassar Strait, it is a dominant factor to adjust the taste & color (stratification and mixing) of the ITF. The ongoing in situ observations in the Karimata Strait will capture freshwater flux from the Bay of Bengal and the South China Sea. Meanwhile, moorings in the Sunda Strait, the Lombok Strait and an array of the Indian Ocean RAMA and Java Upwelling moorings will capture that from the Eastern Indian Ocean (south and west of Java/Sumatra). All the observations will be used to validate and calibrate the satellite ocean salinity data. Because in situ observation is not sustainable due to logistical challenge and high costs, satellite Aquarius/SAC-D data and the follows up mission will be used as a proxy of the heat flux and freshwater flux from the BBSCSEIO. Given the importance of ITF in the global ocean circulation and climate as well as water cycle, it is necessary and important to determine the heat flux and freshwater flux from the BBSCSEIO.