ON KELVIN WAVES IN BALANCE MODELS

The S-plane linear shallow-water equations support coastal Kelvin wave s. These waves propagate along the coast and have zero velocity normal to the coast. It is shown that the balance equations also support coa stal 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 b oundary conditions gives balance-model Kelvin waves that are closer to those of the shallow-water equations than the other two boundary cond itions.