Rotational and divergent geopotential components

It has been traditional in meteorology to divide the velocity field up into rotational and divergent components, but not the geopotential field. The difference between the observed and computed geopotential is the quantity we refer to as the divergent, or in some cases, ageostrophic, geopotential. The momentum equations equivalent to the linear balance set of equations are given. The linear balance equation is intergrated to give a diagnostic relation between the rotational wind components and the gradient of the rotational geopotential plus an extra term which involves the gradient of the planetary vorticity advection potential (PVAP). The rotational and divergent geopotential fields and the PVAP have been computed from climatological mean January and July conditions. In addition for January, the tendencies due to the Coriolis force associated with the ageostrophic velocity are given and are shown to be related to the acceleration of jets in entrance regions and deceleration in exit regions of in excess of 30m s^-1/day for the Northern Hemisphere. -from Authors