Formula for a baroclinic adjustment theory of climate

Abstract

Recently, a theory relating baroclinic neutrality and midlatitudes tropopause height has beenproposed. However, GCM results have shown that the dependence of the theory on externalparameters is not consistent with that displayed by these numerical experiments. In the presentpaper we suggest an analytic formula for baroclinic adjustment to the neutrality of Eady wavesthrough tropopause modification. This formula extends considerably the abovementionedtheory by taking into account both a simple representation of the stratosphere and the topography.These modifications alter the tropopause condition for a baroclinically neutral stateand its sensitivity to the external parameters. In particular, the topography introduces a dependenceon the tropospheric vertical wind shear of the neutrality condition. This feature is notpresent in other models that assume a background state with a zero potential vorticity gradientin the troposphere.We show, furthermore, that the modified neutrality condition has sensitivitiesthat may resemble those displayed by GCM simulations, with respect to the parameters definingthe background flow. DOI: 10.1034/j.1600-0870.2002.00296.x