Synoptic Variability and the Seasonal Cycle Amplitude of CO2

Observations show that the seasonal cycle amplitude of CO2 increases with latitude, and that the seasonal cycle amplitude has been increasing over the last century. Here, we use a simplified model with an idealized tracer to explore the potential role of the midlatitude circulation in driving this seasonal cycle behavior. We find that the seasonal cycle amplitude of the tracer increases with latitude, as seen in the observations. We also explore the impact of the mean storm track position and the emission latitude on the tracer seasonal cycle.