The approach of an upper-level trough is associated with a local ascent of the isentropic surfaces in the troposphere. The ascent is accompanied by cooling which destabilizes the atmosphere to convection. We attempt to quantify the amount of destabilization as a function of the amplitude and horizontal scale of the trough. The trough is represented by an elongated potential temperature perturbation on the tropopause. The structure of the trough including the isentrope displacement it produces are calculated using the procedure developed by Juckes (1998). The amount of destabilization is characterized by the change in convective available potential energy and convective inhibition brought about by the passage of the trough. The calculations seek to isolate one aspect of the interaction between an upper-level trough and a tropical cyclone.
Reference
Juckes, M., 1998: The structure of idealized upper-tropospheric shear lines. Modified to J. Atmos. Sci.