Physical forcing of Air-Sea Carbon Flux in the Bay of Bengal from the Bay of Bengal Ocean Acidification Mooring (15oN, 90oE)

The Bay of Bengal Ocean Acidification (BOBOA) moored buoy site was established at 15°N, 90°E on 23 November 2013. It is providing the first continuous measurements of surface water and air CO₂ concentrations and pH along with physical measurements (which include near surface temperature and salinity, wind speed, precipitation, current speed, etc.) in the northern Indian Ocean. The Bay of Bengal is of interest because it is subject to strong ocean-atmosphere interactions. The air-sea flux of CO₂ is likely to be influenced by severe tropical storms and by large intraseasonal, seasonal and interannual variations in wind, surface heat and fresh water fluxes. Yet there are relatively few discrete carbon flux and pH measurements to quantify these impacts in the region. The BOBOA time series reveals strong seasonal variations in air-sea CO₂ flux with outgassing of CO₂ to the atmosphere occurring predominantly during the spring intermonsoon and early southwest monsoon time periods (April through June) and ingassing occurring predominantly during the northeast monsoon (November-February). Seasonal changes in pH and its variability are also observed. However, significant interannual, intraseasonal and high frequency variability is also apparent in both time series measurements. The influence of physical forcing on this variability is examined using the physical measurements from the mooring.