Anthropogenic CO 2 Inventory of the Indian Ocean

• Published in: Global Biogeochemical Cycles
• Main Authors: Sabine, C. L., Key, R. M., Goyet, C., Johnson, K. M., Millero, F. J., Sarmiento, J., Wallace, Douglas W.R., Winn, C. D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 1999
• Subjects: Southern Ocean
• Online Access: https://oceanrep.geomar.de/id/eprint/3140/; https://oceanrep.geomar.de/id/eprint/3140/1/Sabine_et_al-1999-Global_Biogeochemical_Cycles.pdf; https://doi.org/10.1029/1998GB900022

This study presents basin-wide anthropogenic CO2 inventory estimates for the Indian Ocean based on measurements from the World Ocean Circulation Experiment/Joint Global Ocean Flux Study global survey. These estimates employed slightly modified ΔC* and time series techniques originally proposed by Gruber et al. [1996] and Wallace [1995], respectively. Together, the two methods yield the total oceanic anthropogenic CO2 and the carbon increase over the past 2 decades. The highest concentrations and the deepest penetrations of anthropogenic carbon are associated with the Subtropical Convergence at around 30° to 40°S. With both techniques, the lowest anthropogenic CO2 column inventories are observed south of 50°S. The total anthropogenic CO2 inventory north of 35°S was 13.6±2 Pg C in 1995. The inventory increase since GEOSECS (Geochemical Ocean Sections Program) was 4.1±1 Pg C for the same area. Approximately 6.7±1 Pg C are stored in the Indian sector of the Southern Ocean, giving a total Indian Ocean inventory of 20.3 ±3 Pg C for 1995. These estimates are compared to anthropogenic CO2 inventories estimated by the Princeton ocean biogeochemistry model. The model predicts an Indian Ocean sink north of 35°S that is only 0.61–0.68 times the results presented here; while the Southern Ocean sink is nearly 2.6 times higher than the measurement-based estimate. These results clearly identify areas in the models that need further examination and provide a good baseline for future studies of the anthropogenic inventory.