Wtm. Verkley, A NUMERICAL-METHOD FOR FINDING FORM-PRESERVING FREE SOLUTIONS OF THE BAROTROPIC VORTICITY EQUATION ON A SPHERE, Journal of the atmospheric sciences, 50(11), 1993, pp. 1488-1503
A numerical method is presented that allows one to obtain steady or zo
nally moving (i.e., form-preserving) solutions of the barotropic vorti
city equation on a sphere. The solutions are characterized by nonlinea
r functiOnal relationships between the streakfunction (the streamfunct
ion in a steady or zonally moving frame of reference) and the absolute
vorticity. Three new examples of steady solutions are obtained that r
esemble atmospheric blocking. The examples have approximately the same
global structure but differ in the degree of uniformity of the stream
function and the absolute vorticity in the blocking region. From a num
erical linear stability analysis it is concluded that the example in w
hich the absolute vorticity in this region is the most uniform is to b
e preferred as a description of atmospheric blocking. This conclusion
is consistent with recent observational evidence.