Relationship between Low Clouds and the Inter-Tropical Convergence Zone

The global and time mean intertropical convergence zone (ITCZ) is located a few degrees north of the equator because of strong sea surface temperature and pressure gradients due in part to horizontally extensive stratocumulus clouds in southern hemisphere eastern ocean basins. These stratocumulus clouds act like a blanket, preventing incoming solar radiation from making it to the surface, and they are associated with a vertically thin trade wind inversion (TWI) layer. Despite recent progress in describing the global and time mean ITCZ through an energy balance framework, nearly all modern Earth system models continue to produce an overly strong southern hemisphere ITCZ over the east Pacific Ocean. Our research group is developing new understanding of the TWI layer’s relationship with low clouds, lower tropospheric buoyancy, and large-scale dynamics, and how each component works together to produce conditions favorable for the southeast Pacific ITCZ using both observations and Earth system models.