The Enigma of Saturn's North-Polar Hexagon

It has been suggested that the north-polar hexagon found on Saturn is an unusual Rossby wave. If this is to be the case, one must not only explain how a Rossby wave can be hexagonal in shape, albeit with curved corners, but also why it is hexagonal rather than in the form of some other polygon. It is possible that a spectrum of Rossby waves with different amplitudes resulting from the velocity profile of the hexagonal jet could contribute to its shape.