This paper statistically analyzes and compares the variability of the observed and simulated (by the Geophysical Fluid Dynamic Laboratory general circulation model) northern hemisphere monthly surface air temperature latitude-temporal fields. The objects used for the analysis are as follows: multivariate autoregressive and linear regression model parameters, the diffusion equation coefficients, and two-dimensional spatial-temporal spectral and correlation characteristics. The estimates reveal a significant latitudinal trend of all second moments. A comparative study of the estimates demonstrates a significant distinction between the character of the meridional circulations of the observed and simulated systems. The methodology and results presented make it clear that the variability validation problems can be formalized by applying standard statistical techniques of multivariate modeling and multidimensional spectral and correlation analysis to the data averaged spatially and temporally.¿ 1997 American Geophysical Union