Poster Abstract Title: 
Interaction of a hydrothermal plume with the ambient ocean as measured by acoustic scintillation and an integral model
Authors and their affiliations: 
Guangyu Xu (xupeng66@uga.edu) and Daniela Di Iorio (daniela@uga.edu) University of Georgia, Department of Marine Sciences, Athens, GA, 30602

The vertical velocity and temperature fluctuations of a hydrothermal plume were measured using a self-contained acoustic scintillation system at 20 m above an active hydrothermal edifice (Dante) within the Main Endeavour vent field of the Endeavour segment in Sep 2007. Thirty-six days of data with 1 hr sampling interval were recovered in which tidal oscillating patterns at semi-diurnal frequency were observed for both the plume’s vertical velocity and temperature fluctuations. This tidal variability is shown to be the result of the hydrothermal plume’s interaction with the ambient horizontal cross flows. There is a strong northeasterly residual flow superimposed on the tidal oscillations that enhances the flood current and diminishes the ebb current and this affects the entrainment of ambient waters into the plume. An integral model taking into account the ambient stratification and variations in the horizontal cross-flow is established to show the affects of tidally varying entrainment on the plumes physical properties.


Contributions to Integration and Synthesis: 
The tidal variations observed in the acoustic scintillation measurements reflect the interaction of an integrated hydrothermal plume with its ambient environment. The tidally varying entrainment shown by the integral model is of great importance to the study of the transport of ambient chemicals and biota by a hydrothermal plume.