A new pathway of tropical cyclone–trough interaction as illustrated by the over‐land re‐intensification of Oswald (2013)

Unlike other documented studies, Oswald's interaction with the two troughs occurred in the mid‐troposphere, not the upper troposphere. Under the high vertical wind shear, the upper TC circulation was greatly weakened.

However, in the middle levels between 400 and 600 hPa, high cyclonic potential vorticity (PV) air, was transported from the troughs to Oswald's mid‐layer circulation, replenishing its outer circulation. With the inner circulation, PV redistribution between the inner core and outer core was observed over the southeastern quadrant. This process enhanced mid‐to‐lower updrafts and boundary‐layer convergence, supporting the downshear reformation of mesovortices.