Theory 08/Ocean eddies/Threshold lens
Eddies Need Shear Anisotropy
The claim
Eddy formation requires a threshold in the ratio of horizontal to vertical shear, so strong shear in the wrong direction suppresses eddies.
01Mechanism
Baroclinic growth requires the shear to tilt density surfaces favourably; the ratio determines whether the tilt is unstable.
02Prediction
Formation should track the shear ratio.
03Refutation
Formation tracking shear magnitude would remove the anisotropy.