MIXING AND AVAILABLE POTENTIAL-ENERGY IN A BOUSSINESQ OCEAN

The commonly used definitions for available potential energy and its s ources in the oceans are based on the quasigeostrophic approximation, so they are not suitable for the study of basin-scale circulation. Acc urate definitions for the available potential energy and its sources a nd sinks can be derived from the classic definition of available poten tial energy. Application of the exact definitions to the ocean reveals the dynamic role of internal mixing and surface thermal forcing. It i s shown that the mechanical energy required for sustaining the basic s tratification by mixing light water downward plays a vitally important role in the balance of potential energy and available potential energ y.