The extratropical tropopause inversion layer: Global observations with GPS data, and a radiative forcing mechanism

The GPS data are organized according to the height of the thermal tropopause in each profile, and a temperature inversion layer above the tropopause (with an average magnitude of 3--5 K) is found to be a ubiquitous, climatological feature.

The GPS data show that the inversion layer is present for all seasons in both hemispheres, spanning the subtropics to the pole, and there is not strong longitudinal structure. Dependence of the inversion layer on upper-troposphere vorticity is studied; while anticyclones exhibit a substantially stronger inversion than cyclones (as expected from balanced dynamics), the inversion is evident for all circulation types. Radiative transfer calculations indicate that strong gradients in both ozone and water vapor near the tropopause contribute to the inversion.