Some laboratory experiments on Rossby waves in a rotating annulus

Rossby waves were generated by a slowly oscillating paddle in a rotating annulus of water. The variation with frequency of the real part of the wave number is very satisfactory, but the experiments give only order-of-magnitude agreement between the observed damping with distance from the source and a theoretical estimate which ignores sidewall boundary layers. Behavior of the waves in a closed basin formed by placing a barrier wall across the annulus 60 degrees up-rotation from the wave source agrees qualitatively with theoretical expectation in that at low frequencies the radial motion is concentrated in the region near the reflecting barrier. This effect is a simple generalization of Stommel's original concept of the westward intensification of steady currents and appears to be present in the oceans.