The Krakatoa Air-Sea Waves: an Example of Pulse Propagation in Coupled Systems

Abstract

The theory of pulse propagation in an atmosphere coupled to an ocean is applied to the air-sea waves excited by the explosion of the volcano Krakatoa. Numerical results for a realistic atmosphere-ocean system show that the principal air pulse corresponds to the fundamental gravity mode GR_0. A small sea wave is associated with the mode GW_0 with phase velocities close to the √(gh) velocity of the ocean. Free waves with this velocity exist in the atmosphere and transfer energy to the ocean in an efficient manner. These air waves 'jump' over land barriers and re-excite the sea waves. An explosion of 100–150 megatons is required to produce the equivalent of the Krakatoa pressure disturbance.

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