Collaborative Research: Temporal Variability of Vertical Upwelling of a Natural Hydrocarbon Seep and its Connection to the Ocean Surface

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Natural release of methane and oil from hydrocarbon seeps in the ocean floor is poorly understood. This project is a field and modeling study of the properties and behavior of hydrocarbon bubble plumes in the Gulf of Mexico. Observations will be made of hydrocarbon bubble characteristics including size, rise velocity, and dissolution near the source; entrainment of ambient water in the plume phase; and the location of hydrocarbon that reaches the sea surface. The project will also model individual bubble and plume properties. The results have potential broader impacts for understanding natural versus anthropogenic sources of hydrocarbon for predicting ocean climate. The project will also involve training of high school teachers with a focus on building a robotic underwater vehicle for a robotics competition.This project focuses on measuring bubble and turbulent properties of hydrocarbon plumes from natural seeps in the Gulf of Mexico. The techniques to be used include measurements of flow characteristics from high frequency ADCP and of bubble characteristics from Particle Tracking (and Imaging) Velocimetry (PTV and PIV). These observations will be used to estimate bubble size distribution, volume and momentum fluxes, turbulence and entrainment, and vertical upwelling during the initial rise to reveal potential connections with the near-bed turbulence characteristic and hydrographic conditions. Numerical modeling will be used to predict the hydrocarbon trajectory and distribution in the water column and on the surface. Estimates of surface residence time for oil slicks will be made using satellite data and measured surface currents to compare to model predictions of the fate of hydrocarbons at the sea surface. Overall the project will improve understanding of the physical mechanisms that control bubble plumes and entrainment from hydrocarbon seeps and dispersion in the ocean environment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.