Stationary wave amplitude in a stratified wavespeed
= Stationary wave amplitude in a stratified wavespeed
{title2=$A=\mu/(c\sqrt\ell)$}
For an individual monochromatic component in $c=c(Y)$, conserved $\omega,k$ give $\ell=\sqrt{\omega^2/c^2-k^2}$. With amplitude independent of $X,T$, <wave-action transport for a variable-speed wave> conserves $c^2\ell A^2$ on a positive-$\ell$ branch, hence $A=\mu/(c\sqrt\ell)$. The divergence at $\ell=0$ signals failure of the outer <WKB approximation>.