Department of Mathematics
Courant Institute of Mathematical Sciences
New York University
Mail Address251 Mercer St. New York, NY 10012, U.S.A.
Phones212.998.3307 (voice) 212.995.4121 (fax)
Applied Math II (spring 00)class page
The foundations for our understanding of wave generation by topography were established in studies of Queney (1947, 1948) for steady flow past a two-dimensional ridge. In this seminal work, the downstream radiation pattern was inferred from the dispersion characteristics of linear gravity waves. Queney's streamline figures, obtained by approximating a Fourier integral, are frequently reproduced as the canonical illustration of downstream topographic waves. For the case of constant stratification with f-plane rotation, we find there are significant differences in the near-ridge flow pattern upon comparing the original approximation (Queney 1948, Figure 3) with direct computation of the Fourier integral. Flow corrections in the near-field aloft and downslope regions will be presented in updated figures. These new figures are computed using a high-order numerical integration scheme which is especially designed to resolve the near-inertial singular waves. The implementation of these ideas to computing three-dimensional topographic wave flows will be discussed. Finally, a new analytical approximation suggests that an additional by-product of the topographic wave generation is a weak, near-inertial wave that is produced by backscattering from the downslope surface.