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Rings: Semicoherent oceanic features
1Center for Meteorology and Physical Oceanography, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
Chaos (Woodbury, N.Y.)
|June 1, 1994
Summary
Simple models of ocean and atmospheric eddies are often flawed. This study shows that nonlinear geophysical eddies lose energy by radiating Rossby waves, leading to their gradual decay.
Area of Science:
- Geophysical Fluid Dynamics
- Nonlinear Dynamics
- Oceanography and Atmospheric Science
Background:
- Solitary wave and isolated eddy models are commonly used to explain persistent nonlinear features in geophysical systems.
- These simplified models often rely on oversimplified dynamics or inappropriate constraints for real-world eddies.
- A detailed physical examination reveals limitations in current isolated eddy models.
Purpose of the Study:
- To investigate the detailed physics governing the longevity and evolution of nonlinear geophysical eddies.
- To demonstrate the role of wave radiation in the decay of such eddies.
- To present a more complete model for understanding geophysical eddy dynamics.
Main Methods:
- Development and analysis of a more complete dynamical model for geophysical eddies.
- Investigation of the interaction between eddies and their surrounding fluid environment.
- Focus on Rossby wave radiation, particularly in the barotropic mode.
Main Results:
- Nonlinear geophysical eddies, such as rings, interact with their environment through Rossby wave radiation.
- This radiation primarily occurs in the barotropic mode.
- The generated waves cause a slow decay of the eddy as energy is transferred to the wave field.
Conclusions:
- Isolated eddy models require refinement to account for wave radiation effects.
- Rossby wave radiation is a key mechanism for the energy loss and decay of geophysical eddies.
- A comprehensive understanding of eddy dynamics necessitates considering their interaction with the broader fluid system via wave propagation.