Coastally trapped waves in the atmosphere

It is suggested that the ‘coastal lows’ observed off southern Africa are similar in structure to ‘coastally trapped waves’ in the ocean. Inversion conditions typical of the area prevent escape of energy upwards and Coriolis effects keep energy trapped against the high escarpment which borders the continent. Coastal disturbances are produced because low‐level flow in the synoptic‐scale systems cannot cross the barrier provided by the escarpment. Nonlinear effects cause lows to be more prominent than highs. A simple nonlinear forced Kelvin wave model is found to reproduce many of the features observed.