Collisions of oceanic mesoscale eddies with seamounts often result in major modifications of their structure, having significant impacts to the re-distribution of water properties and mixing rates. We investigated the interaction between a self-propagating barotropic cyclonic eddy with an obstacle and determined the conditions for an eddy to bifurcate into two eddies. A series of idealized laboratory experiments were carried out in a glass tank mounted concentrically on a 1 m diameter rotating turntable. As in a previous study, after a self-propagating cyclonic eddy came into contact with the obstacle, fluid peeled off the outer edge of the eddy and a so-called ”streamer” went around the cylinder in a counterclockwise direction. Under certain conditions, this fluid formed a new cyclonic eddy in the wake of the cylinder, causing bifurcation of the original eddy into two eddies. In the present study we performed three sets of idealized laboratory experiments with the aim of investigating the importance of the slope of the side walls of the obstacle, the influence of the obstacle horizontal cross sectional area and the importance of the height of the obstacle. The present results suggest that bifurcation occurs only when the obstacle height is more than 0.85 % of the eddy height and that steep sloping walls do not influence the bifurcation mechanism. In addition, experiments performed using an obstacle with an elliptical horizontal cross section revealed that the length which the ”streamer” has to travel around the obstacle (and not the dimension of the obstacle in the direction orthogonal to the flow) is the relevant parameter governing the occurrence of bifurcation. Observations of a ”Meddy” bifurcating after collision with the Irving Seamount in the Canary Basin show similar behavior suggesting that these idealized laboratory experiments could be used to infer the result of eddy collisions with seamounts of varying geometry in the ocean
Cenedese, C., Adduce, C. (2003). Laboratory experiments on eddy collisions with seamounts of varying geometry. In European Geophysical Society - American Geophysical Union - European Union Geosciences Join Assembly.
Laboratory experiments on eddy collisions with seamounts of varying geometry
ADDUCE, Claudia
2003-01-01
Abstract
Collisions of oceanic mesoscale eddies with seamounts often result in major modifications of their structure, having significant impacts to the re-distribution of water properties and mixing rates. We investigated the interaction between a self-propagating barotropic cyclonic eddy with an obstacle and determined the conditions for an eddy to bifurcate into two eddies. A series of idealized laboratory experiments were carried out in a glass tank mounted concentrically on a 1 m diameter rotating turntable. As in a previous study, after a self-propagating cyclonic eddy came into contact with the obstacle, fluid peeled off the outer edge of the eddy and a so-called ”streamer” went around the cylinder in a counterclockwise direction. Under certain conditions, this fluid formed a new cyclonic eddy in the wake of the cylinder, causing bifurcation of the original eddy into two eddies. In the present study we performed three sets of idealized laboratory experiments with the aim of investigating the importance of the slope of the side walls of the obstacle, the influence of the obstacle horizontal cross sectional area and the importance of the height of the obstacle. The present results suggest that bifurcation occurs only when the obstacle height is more than 0.85 % of the eddy height and that steep sloping walls do not influence the bifurcation mechanism. In addition, experiments performed using an obstacle with an elliptical horizontal cross section revealed that the length which the ”streamer” has to travel around the obstacle (and not the dimension of the obstacle in the direction orthogonal to the flow) is the relevant parameter governing the occurrence of bifurcation. Observations of a ”Meddy” bifurcating after collision with the Irving Seamount in the Canary Basin show similar behavior suggesting that these idealized laboratory experiments could be used to infer the result of eddy collisions with seamounts of varying geometry in the oceanI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
