The above is my poster for APS DFD 2019 in Seattle. I’ll be taking either my NikonF4 or Fuji Discovery 312 film cameras to the conference and will put my thoughts and pictures together once those are developed.
As posters can be it is light-on-text & light-on-maths, albeit at half resolution for the website. I think I am putting together a functional narrative for the non-local turbulent fluxes and the coherent rolls. What this appears to show is that the coherent structures exist in a state of ‘marginal stability’ (around Ri~0.25). Thus when the eye passes and the winds rapidly switch directions (peaking at ~30 deg per hour) the coherent rolls can’t keep up and decohere. This coincides with the loss of marginal stability in the mixed-layer and the loss of non-local fluxes. Additionally, the time for the nonlocal fluxes to develop seems to be a function of the depth of the mixed-layer and the depth of mixed-layer below the critical Richardson number, as we start getting a similar non-local flux signature slowly after eye-passage. But the growth of that is cut off by the mixed layer hitting then rebounding off the bottom boundary layer.
This all ties in with how the low-aspect ratio mixed-layer rolls interact with the Kelvin-Helmholtz billows at the pycnocline. The storm mixing slightly better than the expectations from Trowbridge (1992) ahead-of-eye, and drops to less efficient mixing after the eye passes and the mixed-layer rolls stop helping transfer kinetic energy down to the pycnocline.