Abstract
This chapter describes the Indian Ocean Observing System (IndOOS) and highlights the scientific advances it has enabled since its inception in the mid-2000s. IndOOS is a long-term sustained multi-national effort that consists of in situ observing system components designed to complement a constellation of earth-observing satellites. A central goal of IndOOS is to advance the description, understanding, and prediction of the Indian Ocean’s role in weather and climate. The in situ components are basin-scale in scope with regional elements that provide essential oceanic and atmospheric data on key phenomena. The original emphasis of IndOOS was on large-scale physical oceanography, marine meteorology, and ocean–atmosphere interactions. Recently, priority has been given to the systematic inclusion of biogeochemical measurements to better understand changes in marine ecosystems and fisheries, as well as to the development of boundary current observations that can better constrain the basin-wide heat budget. The challenges in sustaining IndOOS and the opportunities for expanding it to address societal needs are also discussed.