A Dynamical Model of the Intertropical Convergence Zone

Abstract A tropical-wave, zonal-flow interaction model is used to test the hypothesis that through the CISK process the “critical-latitude mechanism” (mass convergence in the tropical planetary boundary layer tends to concentrate around the latitude where the Coriolis frequency equals the wave frequency) is responsible for the development of the ITCZ. The wave, zonal-flow interaction model is formulated as a. multi-level numerical model from the ground (sea surface) to the top of the boundary layer, which is set at 5.5 km. The primitive equations aroused for the interior dynamics of the boundary layer. These are coupled with the vorticity equation applied at the top through a CISK parameterization. The model is then integrated in time, using observed wave scales. The results show that for the case of asymmetric mode waves (pressure asymmetric about the equator), an ITCZ consisting of both the mean and perturbation components is developed 1°−3° north of a critical latitude which corresponds to the maximum ...