Generation of equatorial Kelvin, Yanai and short Rossby waves near a western boundary.

When a coastal disturbance propagating toward the equator on a western boundary reaches the equator, equatorial Kelvin and Yanai waves are generated and transport energy eastward along the equator. If the frequency of the coastal disturbance is in the band between the lowest possible equatorial gravity wave frequency and the highest possible equatorial Rossby wave frequency, the rest of the response is boundary trapped near the equator and the western boundary. If the frequency of the coastal disturbance is below the maximum frequency for the first possible Rossby wave mode with real wave number, but above the maximum frequency for the second Rossby mode, the only equatorial disturbances that will be generated are a Kelvin wave, a Yanai wave, and a short equatorial Rossby wave. This Rossby wave has westward phase velocity and eastward group velocity. We investigate this process numerically for a variety of boundary coastline orientations.