Oceanic multiple jets are seen to possess spatiotemporal variability imposed by varying
bottom topography resulting in jets that can drift and merge. The dynamics of multiple
jets over a topographic zonal slope is studied in a two-layer quasi-geostrophic model.
The jets tilt from the zonal direction and drift meridionally. In addition to the tilted jets,
other large-scale spatial patterns are observed, which are extracted using the principal
component analysis. The variances of these patterns are strongly influenced by the values
of eddy viscosity and bottom friction parameters. The contribution of the tilted jets to
the full flow field decreases with decreasing friction and viscosity parameters, and purely
zonal large-scale modes, propagating in the meridional direction, populate the flow field.
Linear stability analysis and two-dimensional kinetic-energy spectrum analysis suggest
that the zonal modes gain energy from ambient eddies as well as from the tilted jets
through nonlinear interactions. However, viscous dissipation and bottom friction tend
to suppress the nonlinear interactions, which results in the inhibition of the upscale
energy transfer from eddies to the zonal modes. These simulations suggest that, in the
presence of topography, alternating jet patterns may be sustained through interactions
among various large-scale modes. This is different from the classical zonal jet formation
arguments, in which direct eddy forcing maintains the jets.