BAROCLINIC NEUTRALITY AND THE TROPOPAUSE

it is noted that the atmosphere has a baroclinically neutral state tha t permits strong temperature gradients at the ground. In this state, t he concentrated potential vorticity gradient at the ground is separate d from the concentrated potential vorticity gradient at the tropopause by a region where the potential vorticity gradient is zero. The resul ting basic state is analogous to the basic state in the Eady problem. A minimum meridional wavenumber is established by the width of the sub tropical jet, and neutrality is established by moving the tropopause t o a sufficient height so that the total wavenumber corresponds to the short-wave cutoff in the Eady problem. The resulting height is approxi mately the observed tropopause height.