The objective of this proposed research is to improve our understanding of certain aspects of the mechanisms responsible for tropical intraseasonal oscillation. The complex dynamic framework will be reduced to a group of tractable models that can be solved separately either by analytic means or by use of quasi- analytic model and numerical computation. The investigation will focus on (1) the couplings between equatorial Kelvin and Rossby waves and among internal vertical modes through moist processes; (2) the roles of boundary layer mass and moisture convergence in the dynamics of the low frequency wave; (3) the consequences of nonlinear versus linear heating representation; (4) the causes of regionally and seasonally northward phase propagation; and (5) the nature of air-sea interaction in the intraseasonal time scale and the impact of this interaction on tropical low frequency variations. This research is important because it seeks to understand the physical mechanisms responsible for a small but significant portion of the observed climate variability in the tropics; variability which may act as a trigger for larger amplitude climate variability.
