Idealized simulations of the South Atlantic Convergence Zone

A series of numerical simulations are performed to examine the basic structure of the South Atlantic Convergence Zone (SACZ) which is a subtropical feature located off the coast of southeast Brazil. It possesses a NW-SE tilted structure characterized by enhanced convection during the austral summer season with variability existing on multiple time scales. In order to obtain a clear picture of the time evolution of this convergence band, eigenvector analysis of nondivergent and irrotational model fields is conducted in order to characterize the temporal and spatial structure of circulation tied to SACZ convection. By modulating an idealized diabatic heating source over the Amazon Basin functioning as a time invariant forcing as well as a transient forcing which mimicks the diurnal cycle, the contributions of stationary and propagating wave components can be examined and compared to observational analyses.