The poleward extent of the midlatitude storm tracks and Hadley circulation in an idealized GCM

Simulations from an idealized, dry GCM are analyzed to investigate how the location of the midlatitude storm tracks varies over a large range of insolation gradients, planetary radii, and rotation rates. Over a wide range of meridional insolation gradients and extratropical stability values, both the location of the midlatitude storm tracks and the edge of the Hadley circulation move poleward in tandem, maintaining a constant spatial separation for much of the parameter range. We find that the supercriticality (Sc), a measure of ratio of the meridional temperature gradient to the bulk stability, assumes a constant value of Sc ~ 0.7 at the edge of the Hadley circulation for most parameter choices, which suggests that the Hadley cell extent may be controlled by the subtropical stability. We repeat this analysis for simulations from an idealized moist model and using reanalysis data. The idealized model provides an excellent framework to test these relationships over a wide range of climate regimes