EVALUATION OF THE GEOPHYSICAL FLUID DYNAMIC LABORATORY GENERAL-CIRCULATION MODEL CLIMATE VARIABILITY .1. VARIANCES AND ZONAL TIME-SERIES

This paper statistically analyzes and compares the variability of the observed and simulated (by the Geophysical Fluid Dynamic Laboratory ge neral circulation model(GCM)) northern hemisphere monthly surface air temperatures, averaged within different latitude bands. The objects us ed for the analysis are: seasonal cycle of variances and univariate sp ectral and autocorrelation functions of zonal time series. The estimat es reveal a significant latitudinal trend of all second moments. A com parison shows a statistically significant distinction of the variances of the observed and simulated stochastic systems. In some cases the s hapes of the corresponding univariate spectra and autocorrelation func tions are quite similar, but their numerical values and some features differ markedly, especially for the tropical regions. The approach dev eloped gives reasonable descriptions of the univariate temperature pro cesses, thereby providing an opportunity for solving some of the vital problems of theoretical and practical aspects surrounding validation and diagnosis of GCMs.