Effect of asymmetric Ekman dissipation on finite-amplitude baroclinic disturbance
Abstract
The finite amplitude dynamics of an unstable baroclinic wave are examined in the presence of unequal Ekman pumping between the upper and lower horizontal boundaries. A total of seven cases, corresponding to different combinations of dissipation strength, are investigated. When the dissipation at both boundaries is negligibly small, the wave enters a perpetual vacillation whose amplitude and period depend on the initial conditions. In a free surface configuration, when the bottom Ekman pumping is strong, the life cycle of the wave amplitude is characterized by a growth stage to a maximum amplitude followed by a decay stage. If the initial amplitude is less than a certain critical value, the equilibrated state becomes totally wave free; otherwise it contains a finite amplitude wave which has lost its vertical phase tilt. When Ekman pumping is weak, a relatively short period damped vacillation develops on the long period growth decay pattern.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- September 1983
- Bibcode:
- 1983PhDT........16C
- Keywords:
-
- Amplitudes;
- Baroclinic Waves;
- Ekman Layer;
- Dissipation;
- Finite Element Method;
- Vacillation;
- Geophysics