ESS228
Prof. Jin-Yi Yu
Conservation of Potential Vorticity
q Potential Vorticity
     PV = f + z
             f = planetary vorticity = 2Wsinf
            z = relative vorticity = ¶v/¶x- ¶u/¶y
q  f1 + z1 = f2 + z2 
            since f1 > f2  à z1 < z2 
q If z < 0, the vortex decreases rotation when moves toward lower latitudes and increases rotation when moves toward higher latitudes.
Equator
Pole
  H
(z1<0)
f1
f2
  H
(z2> z1)