Relationships Between the Subtropical Jet and Hadley Cell

The subtropical jet, often referred to as the "thermally-driven jet," is thought to co-exist with the edge of the Hadley cell. However, recent analysis of output from the Climate Model Intercomparison Project phase 5 (CMIP5) reveals that the location of the subtropical jet is poorly correlated with the latitude at which the mean meridional circulation crosses zero, a common metric used to define the poleward edge of the Hadley cell. Here, we further examine the relationships between the subtropical jet and Hadley cell, focusing on both the location and the strength of the jet. Interannual variability and forced responses are examined, as well as the dynamical balances controlling the behavior of the jet and Hadley cell. Preliminary analysis shows a moderate interannual correlation between latitude of Hadley cell edge and strength of the subtropical jet, such that a weaker jet is associated with a more poleward Hadley cell edge. This pattern contrasts that of a response to a quadrupling of CO₂ where a poleward shift of the Hadley cell edge corresponds to with a stronger jet.