Fronts formed by obliquely reflecting internal waves at a sloping boundary

A characteristic of internal waves reflecting from sloping boundaries is th at they form fronts that travel with the component of the phase speed of th e waves up the boundary. The strength of the fronts is assessed by estimati ng the magnitude of nonlinear terms leading to the asymmetry of density gra dients at the slope when waves travelling in a fluid of uniform buoyancy fr equency are at nonnormal, or oblique, incidence to the slope. Strong nonlin earities, indicating fronts, are found for both supercritical (beta > alpha ) and subcritical (beta < alpha) waves near critical slopes where the incli nation of the boundary to the horizontal, alpha, matches that of the wave g roup velocity beta. They are also found for subcritical waves when beta is near sin(-1)[(sin alpha)/2]. Fronts become weaker as the angle at which the wave approaches the slope, the azimuth or incident angle, increases from z ero (i.e., when waves are nonnormal), but not significantly so until this a ngle exceeds 30 degrees.