Results will be reviewed for the linearized disturbance impulse
response of non-uniform boundary layers. Two distinct forms
of boundary layer non-uniformity have been studied. First,
we consider the global behaviour of impulsively excited disturbances
in temporally steady rotating-disc boundary layers,
where there is a spatial inhomogeneity which stems from the
radially increasing circumferential velocity. We then consider
the oscillatory Stokes layer that is driven by the time-periodic
in-plane motion of a bounding flat plate. This provides a second
type of boundary layer non-uniformity, which allows us to
address the effects of base-flow unsteadiness upon the global
development of disturbances.