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Event Plumes :

The initial rise of a hydrothermal plume from a line segment source--results from a three-dimensional numerical model (Abstract)

Problem Description:
Observations have shown that magmatic events at the sea floor can suddenly and quickly release large quantities of heat to the ocean. The resulting mega- or events plumes are large, rotating inclusion of water hundreds of meters thick, tens of kilometers in diameters, centered hundreds of meters above the sea floor. Their presence is detectable by their temperature, particle, and trace metal signatures. The initial rise and development of megaplumes have been studied using several variants of the numerical model Hot_Cross. Since crustal fracturing and heat release during the event is typically along a linear segment, the study addresses the circulation and plume development from a line segment source.

model images, click for large size

a) Side view of a model megaplume's thermal anomalies midway along the plume's line-source length. Line contours are vertical velocity isopleths in m/s.
b) Plan view of the plume 100 m above the sea floor. Inflow velocities are presented by vectors. The single contour represents the 0.05 m/s horizontal speed isopleth. Twisting of plume and vectors is caused by the Earth's rotation.

click for larger view

FLI Animation (0.33 mb)
mov Animation (0.28 mb)



Related Papers:

Lavelle, J.W. (1997): Buoyancy-driven plumes in rotating, stratified cross flows: Plume dependence on rotation, turbulent mixing, and cross-flow strength. Journal of Geophysical Research, 102(C2), 3405-3420.

Lavelle, J.W., and D.C. Smith IV (1996): Effects of rotation on convective plumes from line segment sources. Journal of Physical Oceanography, 26(6), 863-872.

Lavelle, J.W., and E.T. Baker (1994): A numerical study of local convection in the benthic ocean induced by episodic hydrothermal discharges. Journal of Geophysical Research, 99(C8), 16,065-16,080.

Baker, E.T., J.W. Lavelle, R.A. Feely, G.J. Massoth, S.L. Walker, and J.E. Lupton (1989): Episodic venting of hydrothermal fluids from the Juan de Fuca Ridge. Journal of Geophysical Research, 94(B7), 9237-9250.
  Modeling focuses: Chronic focused-source | Event Plumes | Axial Valley transport | Ridge Flow | Geochemical Transport | Hydrographic-Tracer Relationships