q 1997 American Meteorological Society On Kelvin Waves in Balance Models

The f-plane linear shallow-water equations support coastal Kelvin waves. These waves propagate along the coast and have zero velocity normal to the coast. It is shown that the balance equations also support coastal Kelvin waves, but these waves differ depending upon the boundary conditions imposed. Three different boundary conditions and resulting Kelvin wave approximations are examined. It is shown that one set of boundary conditions gives balance-model Kelvin waves that are closer to those of the shallow-water equations than the other two boundary conditions. 1