Straus95 Straus, D. M., P. Peng and J. Shukla, 1995: The systematic error and the variability of the mean flow and the transient fluctuations in the COLA GCM extended AMIP integration. Abstracts of the First International AMIP Scientific Conference, Monterey, California, 89.

The mean flow systematic error in the extended AMIP integration (14 years) of the COLA GCM takes the form of wave-train like features emanating from the western tropical Pacific in all seasons. The response of the GCM to warm ENSO SSTs is of the correct form but tends to be weak. A large set of experiments with a wavy-basic state linear model implicates the structure of the GCM diabatic heating patterns in the tropics in both these problems. The variability of seasonal means in the integration and ECMWF analyses is compared, with reasons for the somewhat lower level in the GCM being explored.

The structure of the transients in the GCM integration are examined, including the energetics, time and space-scale dependence, and geographical relationships of the transients to the mean flow gradients. Comparison with ECMWF analyses will emphasize the seasonal dependence of these statistics, and the variability of single season statistics within the run. The role of rapidly growing optimal modes in the analyses and the GCM will be touched upon.