Sack Lunch Seminar (SLS)

Langmuir Circulation in the Presence of Lateral Density
Gradients




Comparably little is known about the impact of lateral density
gradients (associated with, e.g., submesoscale fronts) on Langmuir
circulation in the ocean surface mixed layer. Here, 2D
pseudospectral numerical simulations of the laterally stratified
Craik-Leibovich equations are performed to elucidate the effect of
an imposed horizontal density gradient on Langmuir cells. The
simulations show that the downwelling jets between cell pairs become
inclined to the vertical and that, in certain parameter regimes,
narrow cells (with an aspect-ratio less than unity) are preferred.
Linear stability theory is used to corroborate and understand these
effects. For certain initial conditions, the fully nonlinear
simulations also reveal the onset of a secondary instability and a
subsequent energy cascade to fine scales.