Initialization of unstable coupled systems by breeding ensembles

Experiments with breeding, which is a process that mimics ensemble data assimilation were carried out for possible isolation of the slow coupled instabilities in the background flow. The bred perturbations were defined as the difference between the two nonlinear runs at the end of the month and are rescaled and added to the new analysis. It was found during the experimentation there was a spurt of growth preceding the two El Nino and La Nina episodes. The results suggests that breeding with long rescaling intervals can be used to capture the slowly evolving ENSO component of a coupled model.