The lifecycle of the North Atlantic storm track

We present a two-dimensional model to describe the relationship between transient eddies and their growth rate. This model is justified using Nakamura and Zhu's (2010) framework. The structure of our model is that of a damped oscillator. With an addition of a stochastic forcing, we show that this model is very close to the observed relationship between various eddy quantities and the associated baroclinicity. In both the model and the reanalysis data eddy variables occur in spike like fluctuations, while the growth rate increases more steadily during the time of low eddy values. Our model can provide an insight into the frequency of the eddy spike events as well as their amplitude. We further show how our model can be justified from the Lorenz-84 model that was obtained by van Veen (2001) by truncating the 2-layer quasi-geostrophic model to three degrees of freedom. We believe this confirms that our model can provide valuable information about several key processes of the real system, as well as offering a new perspective into the study of theoretical baroclinic lifecycles. These results are also supported by our study of local energetics.