Zonal and eddy forms of the available potential energy equations in pressure coordinates

Abstract

An approximation to the zonal and eddy forms of the available potential energy equations is developed from the exact equations in pressure coordinates. These equations preserve the form and symmetry of the exact equations to a large extent and reduce without approximation to the exact equations when the fields are purely zonal. The expressions for zonal and eddy available potential energy are applied to long-term atmospheric circulation statistics for the globe for the December–February season. The values of AZ and AE thus calculated differ somewhat from those obtained using Lorenz's approximate equations.