To achieve a realistic simulation of the location and intensity of ITCZ precipitation has been a challenging task in the atmospheric general circulation modeling research. The false double ITCZ that occurs in many GCMs and the difficulty in simulating monsoon onset—the sudden latitudinal movement of the ITCZ—are well-known examples. In this task a theoretical understanding of the mechanisms responsible for the ITCZ location and intensity would greatly aid the researchers. In this presentation the speaker will review his contributions to this theoretical understanding. The highlights of this presentation include: 1) the mechanisms responsible for the ITCZ location and intensity, 2) the roles of model physics, especially the cumulus convection parameterization, in the these mechanisms, 3) the reasons for the failure of previous ITCZ theories, 4) the origin of systematic errors, such as the false double ITCZ, in the GCM simulation of ITCZ precipitation, and 5) an insight into the identity and the origin of the monsoon and its onset, gained from studying the ITCZ.

A note to the symposium committee

This presentation is a summary of the speaker's papers on the ITCZ and monsoons:

Chao, W. C., M. J. Suarez, J. T. Bacmeister, B. Chen, and L. Takacs, 2006: The Origin of systematic errors in the GCM simulation of ITCZ precipitation over oceans. J. Atmos. Sci. (Submitted)

Chao, W. C., and B. Chen, 2004: Single and double ITCZ in an aqua-planet model with constant SST and solar angle. Climate Dynamics, 22, 447-459.

Chao, W. C., and B. Chen, 2001: Multiple equilibria of the ITCZ and the origin of monsoon onset. Part II: Rotational ITCZ attractors. J. Atmos. Sci., 58, 2820-2831.

Chao, W. C., and B. Chen, 2001: The origin of monsoons. J. Atmos. Sci., 58, 3497-3507.

Chao, W. C., 2000: Multiple equilibria of the ITCZ and the origin of monsoon onset. J. Atmos. Sci., 57, 641-652.