A three-dimensional ocean general circulation model for mesoscale eddies——Ⅱ Diagnostic analysis

A three-dimensional density field associated with mesoscaie unstable waves generated by the 3-D,primitive-equation model (Wang and Ikeda,1996) is provided to the quasi-geostrophic pressure tendency and ω-equations,and to the (ageostrophic) Q-vector equation.Diagnostic analyses,analogous to the approaches in meteorology:ω-equation and Q-vector method,are for the first time developed to examine the mesoscaie dynamical processes and mechanisms of the unstable waves propagating in the mid-latitude ocean.The weaknesses and strengths of these two diagnostic approaches are evaluated and compared to the model results.The Q-vector method is then recommended to diagnose the vertical motion associated with the mesoscaie dynamics from a hydrographic CTD (conductivity-temperature-depth) array,while the quasi-geostrophic equations produce some small-scale features (errors) in the diagnosed fields.