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, D. Straus, W. F. 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 (Results from an AMIP Diagnostic Subproject), WCRP-96. WMO/TD-No. 784, WMO, 25 pp., figures, and appendix.

Abstract: 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 midlatitude 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 models 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 differences 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 relate with certainty particular model deficiencies in representing blocking to precise parts of the model formulation.