Anderson, J. L., 1995: A simulation of atmospheric blocking with
a forced barotropic model. Journal of the Atmospheric Sciences,
52(15), 2593-2608.
Abstract: Nearly stationary states (NSSs) of the barotropic vorticity
equation (BVE) on the sphere that are closely related to observed atmospheric
blocking patterns have recently been derived. Examining the way such NSSs
affect integrations of the BVE is of interest. Unfortunately, the BVE rapidly
evolves away from the neighborhood of blocking NSSs due to instability
and never again generates suffucient amplitude to return to the vicinity
of the blocking NSSs. However, forced versions of the BVE with both a high
amplitude blocking NSS and more zonal low amplitude NSSs can be constructed.
For certain parameter ranges, extended integrations of these forced BVEs
exhibit two "regimes," one strongly blocked and the other relatively
zonal. Somewhat realistic simulations of low and high frequency variability
and individual blocking event life cycles are also produced by these forced
barotropic models. It is argued here that these regimes are related to
"attractor-like" behavior of the NSSs of the forced BVE. Strong
barotropic short waves apparently provide the push needed to cause a transition
to or from the blocked regime. In the purely barotropic model used here,
there is a rather delicate balance required between the forcing strength
for different spatial scales in order to produce regimelike behavior. However,
the mechanism proposed appears to be a viable candidate for explaining
the observed behavior of blocking events in the atmosphere.