| |
| In this paper the totally barotropic modons the two-layer quasi-geostrophic model with bottom friction and topographic forcing are investigated numerically. It is shown that totally barotropic modons perturbed by the bottom friction behave differently depending on the internal Froude number. When the internal Froude number is small, the upper vortex pair of the modons are almost unaffected by the bottom friction while the lower vortex pair decay in their amplitude and velocity. When the internal Froude number is large, both the upper and lower vortex pairs decay and the lower pair of vortices decay much faster than the upper pair of vortices. It is also shown that the bottom friction parameterized by the classical Ekman pumping has weaker effects on the modons than the bottom friction parameterized by the Ekman pumping in form of surface stress.
Perturbed by the bottom ridge, the modons behave also very differently depending on both the height of the ridge and the internal Froude number. For some range of parameters, the modons are very unstable to topography in the sense that they fission and separate into the upper and lower pairs of vortices traveling in two different wavy trajectories while for other range of parameters the upper pair of vortices can pass through the ridge, but the lower pair of vortices can not, being trapped by the ridge and gradually broken down or the modons are very robust to topographic forcing with their upper and lower pairs of vortices being tightly coupled together and the modons behave as a whole.
|
|
| Keywords:modons, two-layer model, bottom friction, topographic forcing |
|
