Lateral viscosity (${\nu }_h$)

An effective horizontal transport coefficient for momentum, often representing unresolved eddies in ocean models. A simple constant-coefficient closure adds ${\nu }_h{\nabla }_h^2\mathbf{u}$ to the Cauchy momentum equation and ${\nu }_h{\nabla }_h^2\xi$ to the vorticity equation. Its balance with the beta effect sets the width of a Munk boundary layer.