Revisiting Queney's Flow over a Mesoscale Ridge

The most familiar illustrations of downstream topographic waves are the streamline plots from the original linear wave studies of Queney. For steady flow past a two-dimensional ridge, Queney's downstream radiation patterns were obtained through approximations of the Fourier integral which describes the dispersion of linear gravity waves. In the case of constant stratification with rotation, a high-accuracy numerical quadrature of the Fourier integral reveals significant departures in the near-ridge streamfunction pattern from the original depictions. This numerical accuracy is achieved by a specialized quadrature scheme for computing the singular Fourier integrals encountered in this regime of order-one Rossby number. In addition, a steepest descent approximation is presented which resolves the breakdown of Queney's analysis above of the summit and quantifies the unusually weak decay of wave amplitude with height.