A Model Analysis of Potential Vorticity on Isopycnal Surfaces for the Global Ocean

• Main Author: Marble, Douglas C.
• Other Authors: NAVAL POSTGRADUATE SCHOOL MONTEREY CA
• Format: Text
• Language: English
• Published: 1993
• Subjects: Physical and Dynamic Oceanography; *OCEAN CURRENTS; *VORTICES; *THERMOCLINES; *OCEAN BASINS; MATHEMATICAL MODELS; OUTPUT; OCEAN SURFACE; LAYERS; CONVECTION; COORDINATES; CIRCULATION; CORIOLIS EFFECT; OCEANOGRAPHY; INDIAN OCEAN; GRADIENTS; CHARTS; BOUNDARIES; EDDIES(FLUID MECHANICS); VENTILATION; MODELS; DENSITY; GLOBAL; *OCEAN CIRCULATION; VORTICITY; Antarctic; Indian; Pacific; The Antarctic; Antarc*
• Online Access: http://www.dtic.mil/docs/citations/ADA275047; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA275047

Charts of potential vorticity (q) within four different density layers, calculated from an eddy resolving global ocean general circulation model, are presented for the Atlantic, Pacific, and Indian Ocean Basins. Potential Vorticity is evaluated as q = (f/p)*(delta sigma/delta z), a formulation that is valid for large, slow scales and allows it to be readily calculated from model output. Here, f is Coriolis, p in situ density, sigma the potential density referred to the sea surface, and z the vertical coordinate. The model is shown to represent oceanic density structure with reasonable accuracy. The most significant departure from observations are the steep density gradients on the northern boundary of the Antarctic Circumpolar Current. This may be due to model convective adjustment parameterizations and the extent of the smoothing in the cataloged data, which may be greater in the southern oceans due to relatively scarce observations. Model derived values of potential vorticity correspond well with those calculated from observations. In the middle and lower layers, the three basins tend toward homogenization, representing unventilated layers. Gyres of q in the upper layers of the northern Atlantic and Pacific Oceans, with their northern boundaries anchored in the outcrop region, illustrate the ventilation of these layers. Oceanography, Numerical modeling, Potential vorticity.