Ocean carbon cycling in the Indian Ocean: 1. Spatiotemporal variability of inorganic carbon and air‐sea CO₂ gas exchange

The spatiotemporal variability of upper ocean inorganic carbon parameters and air‐sea CO 2 exchange in the Indian Ocean was examined using inorganic carbon data collected as part of the World Ocean Circulation Experiment (WOCE) cruises in 1995. Multiple linear regression methods were used to interpolate and extrapolate the temporally and geographically limited inorganic carbon data set to the entire Indian Ocean basin using other climatological hydrographic and biogeochemical data. The spatiotemporal distributions of total carbon dioxide (TCO 2 ), alkalinity, and seawater p CO 2 were evaluated for the Indian Ocean and regions of interest including the Arabian Sea, Bay of Bengal, and 10°N–35°S zones. The Indian Ocean was a net source of CO 2 to the atmosphere, and a net sea‐to‐air CO 2 flux of +237 ± 132 Tg C yr −1 (+0.24 Pg C yr −1 ) was estimated. Regionally, the Arabian Sea, Bay of Bengal, and 10°N–10°S zones were perennial sources of CO 2 to the atmosphere. In the 10°S–35°S zone, the CO 2 sink or source status of the surface ocean shifts seasonally, although the region is a net oceanic sink of atmospheric CO 2 .