Prior observational work has identified a characteristic tropopause-level PV signature, the PV treble clef, to be a sufficient condition for asserting the presence of a warm occluded thermal structure in the underlying troposphere. In the present work, this relationship is exploited in order to investigate the influence of latent heat release (LHR) on the development of occluded thermal structures through comparison of companion full physics and dry numerical simulations carried out using the idealized version of the UW-NMS model. It is shown that inclusion of LHR both accelerates and intensifies the development of the characteristic occluded thermal structure and attendant tropopause-level PV treble clef.

Two potential physical mechanisms through which LHR might influence this development are examined. First, the rearrangement of tropopause-level PV by the flow associated with the diabatically generated lower tropospheric PV is assessed through piecewise PV inversion of the output from the full physics simulation. Second, the effect of direct diabatic dilution of tropopause-level PV by the mid-tropospheric latent heat release in the occluded quadrant is investigated. The analysis offers support for an emerging view that the development of the characteristic occluded thermal structure in mid-latitude cyclones is fundamentally dependent upon latent heat release.