D'Andrea, F., S. Tibaldi, M. Blackburn, G. Boer, M. Déqué,
M.R. Dix, B. Dugas, L. Ferranti, T.Iwasaki, A. Kitoh, V. Pope, D. Randall,
E. Roeckner, C. Hall, D. Straus, W. Stern, H van den Dool and D. Williamson,
1996: Northern Hemisphere atmospheric blocking as simulated by 15 atmospheric
general circulation models in the period 1979-1988. World Climate Research
Programme Report WCRP-96, WMO/TD-No. 784, Geneva, 25 pp. Also 1998 Climate
Dynamics, 14, 1979-1988.
As a part of the Atmospheric Model Intercomparison Project (AMIP), the
behavior of 15 General Circulation Models has been analyzed in order to
diagnose and compare the ability of the different models in simulating
mid-latitude atmospheric blocking. In accordance to the established AMIP
procedure, the 10-year model integrations were performed using prescribed,
time evolving monthly mean observed SSTs spanning the period January 1979-December
1988. Atmospheric observational data (ECMWF analysis) over the same period
have been also used to verify the model results. The models involved in
this comparison represent a wide spectrum of model complexity, with different
horizontal and vertical resolution, numerical techniques and physical parameterizations,
and exhibit large difference in blocking behavior. Nevertheless, a few
common features can be found, such as the general tendency to underestimate
both blocking frequency and the average duration of blocks. The relation
between model blocking and systematic errors has also been assessed, although
without resorting to ad-hoc numerical experimentation, it is impossible
to ascribe with certainty particular model deficiencies in representing
blocking to precise parts of the model formulation.