Hi Graham,
This is indeed a very interesting animation.
Before I was trying to use epitrochoid and hypertochoid to picture such differential vortical events of varying angular velocities, but this induced drift animation you posted can simply illustrate better.
Particularly it is for analyzing
Ice Age events that has displayed cyclical positive and negative buffs in shorter periods and periodically Earth spiked into Ice Ages that have non-linear periods. Galactic center of Milky Way and Sun is in differential rotation interacting at different angular velocities similar to the induced drift animation but in oppoiste phase; i.e. Galactic center is rotating in cw direction with enormous angular momentum and Sun is rotating in ccw with relatively weak angular momentum.
The link for citation use of this picture did not work for me, please provide the URL.
Thanks.