MODELING THE MONTHLY SEA-SURFACE F(CO2) FIELDS IN THE INDIAN-OCEAN

In order to construct monthly fields of sea surface fugacity of carbon dioxide (f(CO2)) on a large scale in the Indian Ocean, we use a one-d imensional model which takes into account the main physical and biogeo chemical processes controlling f(CO2) variations in the ocean. Physica l and biogeochemical processes are constrained by the monthly variatio ns of sea surface temperature, salinity, chlorophyll concentration, wi nd speed and mixed-layer depth. The model is applied to four locations in the Indian Ocean and it well predicts observed temporal variations in f(CO2) at these locations. Regarding to monthly SCO, observations, the model also well simulates the f(CO2) distribution and its tempora l variations along a track located between 20 degrees and 50 degrees S with a maximal error of +/-10 mu atm. The model is also used to predi ct f(CO2) for 2 degrees x 2 degrees grids over the entire Indian Ocean and simulates seasonal cycles that are consistent with observations. The monthly f(CO2) fields derived from the model are used to estimate a global air-sea CO, flux over the Indian Ocean basin. We estimate a n et sink of 0.5 Gt/yr C for the Indian Ocean (20 degrees N-50 degrees S ), with the main sink located between 20 degrees and 50 degrees S.