Suppression of CO2 efflux by gas bubbles under a hurricane

Junhong Liang, Louisiana State University, Baton Rouge, United States, Eric A D'Asaro, Applied Physics Lab, Univ of Washington, Seattle, United States, Craig L McNeil, University of Washington, Applied Physics Laboratory, Seattle, United States, Yalin Fan, US Naval Research Laboratory, Stennis Space Center, United States, Ramsey R Harcourt, Applied Physics Laboratory, University of Washington, Seattle, United States, Bo Yang, University of Virginia, Department of Environmental Sciences, Charlottesville, VA, United States, Steven R Emerson, University of Washington Seattle Campus, Seattle, WA, United States and Peter P Sullivan, National Center for Atmospheric Research, Mesoscale Microscale Meteorology, Boulder, CO, United States
Abstract:
The role of gas bubbles on the air-sea transfer of soluble gas CO2 under a hurricane (Hurricane Frances 2004) is studied using a coupled modeling framework that simulates ocean surface boundary layer turbulence, gas bubbles and dissolved gases simultaneously. The model is initialized with observed water-column conditions and is driven by realistic meteorological conditions. The simulated CO2 efflux with an explicit bubble effect is about 11% of that estimated using a gas flux parameterization commonly used in other hurricane CO2 efflux studies. In the subtropical surface ocean where gases are slightly supersaturated, gases can still dissolve from bubbles to the ocean due to hydrostatic pressure and surface tension exerted on bubbles. The dissolution in supersaturated water is not accounted for in commonly used gas flux parameterizations, leading to the significant overestimate of CO2 efflux under hurricanes. The results highlight the significance of bubbles under high wind even for soluble gases such as CO2, and the need to consider bubble effects in global carbon budgets.
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