The transmission of barotropic Rossby wave energy through a meridional barr
ier pierced only by narrow gaps is studied with a quasigeostrophic model. T
he incident Rossby wave has the form of either a plane wave or a localized
beam of wave energy. The application of Kelvin's theorem on a contour girdl
ing the separated segments of the barrier demonstrate the necessity for wav
e transmission and helps determine the amplitude of the transmitted wave. W
hen the meridional scale of the incident wave is much larger than the gaps
in the barrier, the transmission becomes independent of the gap width.
The problem of a barrier with two or three gaps is discussed. In the former
case a single bubble of wave energy issues from the region spanned by the
separated barrier segment. When a third gap or slit is allowed, the structu
re of the transmitted wave alters depending on the symmetry of the wave fie
ld and the angle of the incidence of the ray trajectory of the incident wav
e.