f-plane two-layer PE baroclinic turbulence
identical to the 'improved' version of the mc2RSW model (DOI: 10.1002/qj.3292) without any moist convection.
run twolayer.py on command line to generate an animation.
needs pyfftw and matplotlib with qt5agg backend for animation.
twolayer_sphere.py is the spherical geometry version (requires shtns).