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The IOD Impacts on the Indian Ocean Carbon Cycle
Author(s) -
Valsala Vinu,
Sreeush M. G.,
Chakraborty Kunal
Publication year - 2020
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2020jc016485
Subject(s) - biogeochemical cycle , indian ocean dipole , oceanography , alkalinity , carbon cycle , upwelling , climatology , environmental science , forcing (mathematics) , dissolved organic carbon , indian ocean , geology , chemistry , ecosystem , biology , ecology , organic chemistry , environmental chemistry
This paper examines the impacts of Indian Ocean Dipole (IOD) Mode on the upper ocean carbon cycle and its variability in the Indian Ocean with available biogeochemical observations and 60 years (1960–2019) of model outputs from a global ocean biogeochemical general circulation model. The upper ocean carbon cycle variability of the Indian Ocean is faithfully reproduced by the model when compared with available observations. The IOD leads to a substantial sea‐to‐air CO 2 flux variability in the southeastern tropical Indian Ocean over a broad region (70–105°E, 0–20°S), with more focus near the coast of Java‐Sumatra due to the prevailing upwelling dynamics and associated westward propagating anomalies. The sea‐to‐air CO 2 fluxes, surface ocean partial pressure of CO 2 (pCO 2 ), the concentration of dissolved inorganic carbon (DIC), and ocean alkalinity (ALK) range as much as ±1.0 mole m −2 year −1 , ±20 μatm, ±35 μmole kg −1 , and ±22 μmole kg −1 within 80–105°E, 0–10°S due to IOD. The DIC and ALK are significant drivers of pCO 2 variability associated with IOD. The roles of temperature (T) and biology are found negligible. A relatively warm T and extremely high freshwater forcing make the southeastern tropical Indian Ocean carbon cycle variability submissive to DIC and ALK evolutions in contrast to the tropical eastern Pacific where changes in DIC and T dominate the pCO 2 interannual variability. For the first time, this study provides a most comprehensive and extended analysis for the region while highlighting significant differences in carbon cycle variability of the eastern tropical Indian Ocean compared to that of the other parts of the global oceans.