AN EXPERIMENTAL INVESTIGATION OF THE SPIN-UP OF A NEUTRALLY STRATIFIED FLUID CORE

The spin-up of a homogeneous fluid in a rotating hemisphere with a solid equatorial plane has been examined experimentally. For the case of small Rossby number, applicable to the Earth, fluid is spun-up by vortex stretching via a small order Ek1/2, where Ek is the Ekman number, vertical velocity induced by Ekman layer pumping. The experimental results compare well with the predictions of the linear theory of Greenspan and Howard (1963). Inertial waves generated by the impulse were observed and their frequency measured.