The equations describing the two-dimensional vortices first described by Chaplygin in 1899 and 1903 are shown to have solutions of higher order that differ from a simple dipole. It is also shown that for these higher-order vortices a very small asymmetry dramatically changes the topology of the stream function. These vortices could be important for understanding the phenomenon of atmospheric blocking.
This explains how to introduce a PolarStreamPlot into Mathematica. It was used for the streamline plots in this paper.