OISO program (Océan Indien Service d'Observation) was labelised INSU Observation Service in July 1997. Since 1997, this Observation Service is supported by three Institutes (INSU, IPEV and IPSL). This program sets up a network coupled oceanic and atmospheric observations on long time to identify and quantify oceanic CO2 sources and sinks variations , to understand air-sea CO2 exchanges from one season to another, from one year to another, to estimate the evolution of these exchanges in response to climatic changes and to identify carbon anthropic in the ocean and its evolution (bonds with the research programs). In addition to detailed study of CO2 oceanic cycle in Indian and southern south-western zone, the data collected at the time during OISO campaigns are usable to force and to validate oceanic models (e.g. IPSL/IM), the atmospheric models reverse and assimilable in the predictive approaches.
The recognition of the responsible processes in CO2 oceanic cycle variations requires a multiannual follow-up and pluridécennal same area. For logistic reasons, choice of a long-term follow-up is fixed on the oceanic zones covered by the ways of Marion-Dufresne rotations in the Indian Ocean, ship chartered by IPEV.

In complement of the logistic ways inter-islands (Island Reunion Crozet- Kerguelen- Amsterdam), observations OISO are extended towards the South for the seasonal and interannual follow-up in southern zone and to revisit sites GEOSECS, KERFIX, INDIGO observed between 1977 and 1995 (which allow a direct measurement of the anthropic penetration of carbon). Observation Service OISO envisages at least two campaigns for a year, one in southern summer, the other in southern winter. In complement of surface measurements uninterrupted (hydrology, biogeochimy) hydrological stations are measured in each area, with taking away to measure hydrological and biogeochemical properties and to understand sub-surface oceanic layers temporal variations.

The southern zone, very little documented and which is far from being correctly represented by oceanic carbon cycle models, including dynamic aspects to which OISO provides interesting observations, for example on the variability of the oceanic layer of mixture. Majority of opposite models based on the atmospheric observations chemical indicate that the Antarctic Ocean is a source of CO2, which is in contradiction with the oceanic observations (including the lookahead of the data of campaigns OISO carried out since 1998). In spite of numerical uncertainties on the assessments Nets of carbon, ocean-atmosphere coupled models predictions indicate that by 2050-2100, Antarctic Ocean response would be particularly sensitive to increase greenhouse due to anthropic activities: notable changes on the thermal structures, oceanic circulation and biological activity would lead to a different distribution of CO2 oceanic sources and sinks which are necessary to observe now, in particular to define initial conditions of good quality. Antarctic Ocean (dynamic, productivity) could played a part to explain climate variations as revealed by the paleoenvironmental data (ice of Vostok and sediment sailors).

 On national level, OISO is associated with programs : PROOF , PNEDC, PATOM, GDR/GEOGAA.

On international level, the area visited is covered by programs organized in collaboration with foreign laboratories in the Atlantic Ocean, Pacifique and south-eastern Indien.
Associated programs : JGOFS , SOLAS, IGBP, CLIVAR.

Atmospheric component OISO is a complement of the observation service RAMCES of 'IPSL.