3:00 PM - 3:15 PM
[AOS14-06] Numerical and theoretical results exploring the role of potential vorticity in coastal outflows.
Keywords:potential vorticity, semi-geostrophic equations, coastal currents, Kelvin wave, river plumes
In particular, major qualitative differences occur depending on whether the potential vorticity depth of the river fluid is greater or less than the depth of the buoyant ocean layer. Two mechanisms contribute: flow driven by a nonlinear Kelvin wave, and flow driven by the jump in potential vorticity, the latter of which can drive fluid in either direction. The faster Kelvin wave disturbs oceanic fluid ahead of intruding river water, and causes a redistrubtion of the buoyant ocean layer along the coast. The model allows for the prediction of both the local fluid velocity and the speed of wave propagation in the river fluid and the oceanic Kelvin wave.
The different qualitative behaviours of the outflow can also be investigated using the method of characteristics. There are strong analogues between flows driven by jumps in density and those driven by gradients in potential vorticity. Depending on the values of the model parameters, solutions can feature coastal currents, anticyclonic gyres and plumes that expand offshore, as well as flows separating from the coast.