This project encompasses a number of important topics relating to the dynamics and predictability of the atmosphere. Dr. Robinson will employ a suite of models, ranging from simple to complex general circulation models, to examine the following: (1) what determines the temporal and spatial scales of the low frequency variability in atmospheric models and in the atmosphere, (2) the relative contributions of the tropics and midlatitudes to low frequency variability, (3) the extent of dependence of atmospheric predictability on the initial large-scale flow pattern, (4) the relationship between US summer climate (and rainfall) to the interannual variability of sea surface temperatures, particularly in the tropics. This research builds on his prior studies in which he demonstrated the strong coupling between synoptic scale eddies and low frequency variability of the atmosphere, namely that the synoptic eddies serve as the principal energy sources for low frequency phenomena. This has important implications for the predictability of atmospheric flows.