  Tropical cyclones cause significant inland hazards, including wind damage and
freshwater flooding, that depend strongly on how storm intensity evolves at and
after landfall. Existing theoretical predictions for the time-dependent and
equilibrium response of storm intensity have been tested over the open ocean
but not yet to be applied to storms after landfall. Recent work examined the
transient response of the tropical cyclone low-level wind field to
instantaneous surface roughening or drying in idealized axisymmetric f-plane
simulations. Here, experiments testing combined surface roughening and drying
with varying magnitudes of each are used to test theoretical predictions for
the intensity response. The transient response to combined surface forcings can
be reproduced by the product of their individual responses, in line with
traditional potential intensity theory. Existing intensification theory is
generalized to weakening and found capable of reproducing the time-dependent
inland intensity decay. The initial (0-10min) rapid decay of near-surface wind
caused by surface roughening is not captured by existing theory but can be
reproduced by a simple frictional spin-down model, where the decay rate is a
function of surface roughness. Finally, the theory is shown to compare well
with the prevailing empirical decay model for real-world storms. Overall,
results indicate the potential for existing theory to predict how tropical
cyclone intensity evolves after landfall.
