The Seychelles-Chagos Thermocline Ridge (SCTR) is a feature unique to the Indian Ocean – it is a consequence of the meridional asymmetry in the Indian Ocean circulation that arises as a result of geometry of the Indian Ocean and its strong monsoon forcing. The SCTR strongly influences atmospheric convection in both the Indian and Pacific Oceans via initiation of the Madden-Julian Oscillation (MJO) and it is also an important foraging ground for tuna.  Yet, in large part because of its remote location, the current understanding of the physical dynamics of the SCTR remains rudimentary at best, while knowledge of the biogeochemical and ecological dynamics is even less developed.  Moreover, sea level has been falling and the thermocline shoaling in the SCTR region in association with a trend towards rising SSTs in the Indian Ocean since the 1960s.  These trends are likely due to changes in atmospheric circulation in response to anthropogenic greenhouse gas forcing. How future global warming may affect the SCTR and its impacts on patterns of weather variability in the Indian Ocean region and over East Asia, North America, and other parts of the globe, is poorly known if at all. Likewise, how marine biogeochemistry, carbon cycling, ocean acidification, ecosystems and fisheries will change in the SCTR under continued anthropogenic greenhouse gas forcing is highly uncertain.

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This document              describes a science plan and implementation strategy for studying the SCTR that is structured around five themes, each of which presents significant opportunities for profound advances in our ability to understand and predict dynamical variability in the region, its far field impacts, and its effects on biogeochemical processes and ecosystem function in the Indian Ocean.

The five themes are:

1. Ocean-Atmosphere Interactions;

2. Ocean Circulation;

3. Biogeochemical and Carbon Cycles;

4. Climate Variability, Change and Extreme Events; and

5. Ecosystems and Fisheries.

We introduce each theme, followed by a short list of high level scientific questions and an outline of observational and modeling implementation strategies for how to address them.

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