Relative vorticity from a variable-depth transport streamfunction
= Relative vorticity from a variable-depth transport streamfunction
{title2=$\zeta=\nabla\cdot(H^{-1}\nabla\psi)$}
The <ocean transport streamfunction> convention $Hu=-\psi_y$, $Hv=\psi_x$ gives <relative vorticity> $\zeta=H^{-1}\nabla^2\psi-H^{-2}\nabla H\cdot\nabla\psi$. This identity is exact for variable positive depth and does not assume that depth variations are small.