14.5
Linear long wave eigenmodes in eddy resolving basins
PAPER WITHDRAWN
Matthew S. Spydell, SIO/Univ. Of California, La Jolla, CA; and P. Cessi
The role of low-frequency quasigeostrophic basin modes is examined in a time-dependent eddy resolving numerical model. A three-layer quasigeostrophic formulation is considered as this is the minimum model where long first baroclinic mode wave speeds are consistent with observations [Dewar 1998]. Baroclinic eigenmodes are calculated about a mean double gyre circulation for different forcing magnitudes assuming negligible relative vorticity. These eigenmodes have low frequencies and small decay rates independent of the size of dissipation. These low-frequency eigenmodes only exist when mass is conserved in each of the three layers. In time-dependent steadily forced eddy resolving experiments, a subset of these inertialess eigenmodes is resonantly excited by boundary pressure fluctuations caused by instabilities in the western boundary current region. These eigenmodes appear as long baroclinic waves in the eastern portion of the basin.
Session 14, Oceanic Eddies
Thursday, 12 June 2003, 10:45 AM-1:15 PM
Previous paper