Evanescent inertial waves

Abstract

Abstract We investigate evanescent inertial waves, both theoretically and experimentally, in a fluid subject to a background rotation of

$\varOmega$

. We predict that there is a smooth transition from conventional inertial waves to evanescent disturbances at a frequency of

$\varpi = 2\varOmega$

, and that at this cross-over frequency the evanescent disturbances are spatially extensive, having a horizontal extent which is limited only by viscosity, or by the size of the domain. These findings are confirmed by our experiments, which, to the best of our knowledge, represent the first quantitative experimental investigation of evanescent inertial waves.