TY - JOUR T1 - Available Potential Energy in Density Coordinates A1 - Colin De Verdiere,Alain A1 - Huck,Thierry A1 - Pogossian,Souren A1 - Ollitrault,Michel AD - Univ Bretagne Occidentale, Lab Oceanog Phys & Spatiale, Brest, France. AD - AD - UR - https://archimer.ifremer.fr/doc/00464/57521/ DO - 10.1175/JPO-D-17-0272.1 KW - Energy transport KW - Ocean circulation KW - Ocean dynamics KW - Isopycnal coordinates N2 - The vertically integrated potential energy of an incompressible stratified fluid formulated in density coordinates can be simply written as a weighted vertical sum of the squares of the vertical displacements of density surfaces, a general expression valid for arbitrary displacements. The sum of this form of potential energy and kinetic energy is then a conserved quantity for the multilayer shallow water model. The formulation in density coordinates is a natural one to find the Lorenz reference state of available potential energy (APE).We describe the method to compute the APE of an ocean state and provide two applications. The first is the classical double-gyre, wind-driven circulation simulated by a shallow water model at high resolution.We show that the eddy kinetic and eddy potential energies are localized in regions of large gradients of mean APE. These large gradients surround an APE minimum found between the two gyres. The second is the timemean World Ocean Circulation reconstructed from hydrography (World Ocean Atlas) and reference velocities at 1000 db from the Argo float program to obtain an absolute circulation. The total available potential energy exceeds the total mean kinetic energy of the World Ocean by three orders of magnitude, pointing out the very small Burger number of the circulation. The Gulf Stream, the Kuroshio, the Agulhas retroflection, and the confluence regions are four examples that confirm the shallow water model results that large gradients of mean available potential energy can be used as predictors for the presence of high eddy kinetic energy (obtained here from satellite altimetry). Y1 - 2018/08 PB - Amer Meteorological Soc JF - Journal Of Physical Oceanography SN - 0022-3670 VL - 48 IS - 8 SP - 1867 EP - 1883 ID - 57521 ER -