The polar onion peeling (POP) method is still under development.
See the discussion here: #30
It doesn't exists in PyAbel!
When you implement it! :)
Code it!
Put it here!
[1] http://dx.doi.org/10.1063/1.3126527
[2] http://www.mathworks.com/matlabcentral/fileexchange/41064-polar-onion-peeling