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 (1947,1948). For steady flow past a twodimensional 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 (Queney 1948, Figure 3). For this regime of order-one Rossby number, several new analytical tools for understanding linear topographic waves have been developed: a highly accurate quadrature for computing the Fourier integral, and a steepest descent approximation which resolves the breakdown of Queney’s (1947) analysis aloft of the summit.