THE WAVE IMPEDANCE OF A LOCALIZED BOTTOM HETEROGENEITY IN A STRATIFIED SHEAR-FLOW WITH THE CRITICAL LAYER

The wave impedance of a localized obstacle at the bottom of a stratifi ed shear flow is found; the flow under consideration is characterized by the Richardson number above 0.25, and it has a critical layer for l ee waves, where the phase velocity of these latter coincides with the flow velocity. It is shown that, with medium gradient Richardson numbe rs and large and medium Froude numbers, the wave impedance in a flow w ith the critical layer increases several times as compared with a flow constant along the vertical, provided the ambient velocity is the sam e.