The Indonesian Throughflow (ITF) is a fundamental component of the heat and freshwater budgets of the Pacific and Indian Oceans, and of the climate system, yet it is poorly observed and simulated in ocean and climate models. In the past, the main throughflow passages have been monitored but over different years and for varied lengths of time, making it impossible to assemble a simultaneous picture of the multiple corridors of the ITF. The INSTANT program, involving researchers from Indonesia, France, the Netherlands, United States and Australia, has now gathered 3 years (December 2003-December 2006) of current, thermohaline stratification and shallow pressure gauge data from an array of moorings that directly measure the ITF from the intake of Pacific water at Makassar Strait and Lifamatola Passage, to the Nusa Tenggara exit channels into the Indian Ocean.
In this project US researchers will pursue, in collaboration with the international team the analysis of this comprehensive ITF data set. The INSTANT in situ data along with coincident satellite data will be used to meet the INSTANT goal of developing a quantitative view of the ITF, its variability and its relationship to remote, regional and local forcing. With the INSTANT data set, we can provide meaningful estimates of the mean ITF and the variability of the associated mass and property fluxes over intra-seasonal, seasonal and inter-annual time scales, all objectives of the INSTANT program. Additionally the INSTANT ITF time series will be used for comparison to output from an array of models to evaluate the skill of these models at simulating aspects of the ITF. The direct measurements of INSTANT will help to mold and ground-truth the required algorithms necessary to convert regional in situ and satellite data into ITF transport proxies as a component of an effective long-term monitoring strategy.
Intellectual Merit: Quantitative knowledge of the behavior of the ITF is of fundamental importance to a wide range of ocean and climate research. The definitive INSTANT ITF data set will allow for quantitative evaluation of model simulation of the ITF and its links with large scale and regional ocean and climate conditions. The INSTANT measurements will serve as the basis of a long-term proxy monitoring system as required to capture the low-frequency ITF variability.
Broader Impacts: As part of the INSTANT educational and outreach component a series of workshops are proposed that will be of benefit to students and post-docs from Indonesia, the USA, and other international partners. Capacity building activities include training visits by Indonesian/East Timor students to SIO and LDEO to work on INSTANT analysis, and support for an Indonesian graduate student at LDEO. Validation of the models with the INSTANT data will benefit a wide range of ocean, climate, and management needs.
This project is a contribution to the US CLIVAR (CLImate VARiability and predictability) Program.
