SURFACE-TEMPERATURE FLUCTUATIONS IN A STOCHASTIC CLIMATE MODEL

This paper considers the geographical distribution of various second moment statistics from a noise-forced energy balance climate model and compares them to the same fields derived from a 40-year data set. The variable considered is the surface temperature field over the Earth. The energy balance model is a standardized one used in several previous studies which emphasized the geographical distribution of the seasonal cycle. It treats two-dimensional geography explicitly by using a different (uniform) heat capacity over ocean than over land. The study compares the (spatially filtered or "smoothed") point variance data with those generated by the model in low-, medium- and high-frequency bands. The study also examines the correlation of surface temperature fluctuations at six representative test points with those of neighboring points. The only adjustable parameter in the study is the strength of the noise forcing. The intercomparisons show that the model produces maps that look remarkably close to those from the data without too much sensitivity to the form of the driving noise.