Effects of islands on equatorial waves

The effects of islands on equatorially trapped waves induced by the sudden onset of zonal wind are investigated by solving the shallow water equations numerically. The energy propagation associated with an equatorial Kelvin wave is almost unaffected by an island on the equator. The energy transmission ratio is over 0.8 even when the north‐south extent of the island is the same as the Rossby deformation radius. It is also shown that the Maldive Islands in the Indian Ocean and the Gilbert Islands in the Pacific Ocean do not affect the energy flux associated with Kelvin waves significantly. The sea level near the island, however, differs significantly from the sea level associated with an equatorial Kelvin wave in the absence of an island. This result has important implications for the interpretation of sea level measurements at equatorial islands. On the other hand, the energy propagation of equatorial Rossby waves (the lowest mode in the north‐south direction) is greatly affected by an island on the equator. The energy transmission ratio is less than 0.3 when the north‐south extent of the island is the same as the radius of deformation.