Analysis and interpretation of tropical intraseasonal variability

The warm pool of the tropical western Pacific (TWP) serves as the "boiler box" of global circulation as it underlies near continual deep convection at the divergent focus of large-scale atmospheric circulations. A principal aim of the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE; Webster and Lukas, 1992) was therefore to understand the processes which influence these warm sea surface temperatures (SST).; This work begins with an investigation of the surface energy balance anomalies which regulate the TWP during their warmest episodes. Such episodes are shown to demonstrate a lifecycle on intraseasonal time scales. Evaporative and solar flux anomalies dominate the integrated heat deficit and surplus of the oceanic mixed layer during the onset and retreat of warm events, often to near equal extent. Quantitative estimates of all flux anomalies are given. Moreover, the anomalies are shown to be strongly influenced by intraseasonal variability of the Austral-Asian monsoon system.; Cooling of the warm pool is often associated with enhanced surface westerly winds. The most intense wind events are termed westerly wind bursts (WWBs). The bursts are found to be associated with robust variations in the ocean and atmosphere. Variations at the onset of bursts include latent destabilization of the atmosphere followed by an increase in convection and surface westerly winds. Surface radiative flux anomalies cool the surface. Strongly influenced by surface wind speed, turbulent fluxes increase during WWBs. Despite the moistening influence of evaporative fluxes however, the atmosphere above the warm pool dries and becomes increasingly stable during the bursts. A conceptual model is developed which describes dynamic and moist interactions at the onset, peak, and decay of seven major westerly wind events from 1985 to 1992.; Attention is then broadened to the larger Austral-Asian monsoon systems. As moisture is the atmospheric constituent most responsible for establishing the lateral heating gradients which drive the monsoons, a diagnostic investigation emphasizing the monsoons' hydrologic cycles is carried out. The monsoons are shown to depend heavily on interhemispheric transports of moisture in the mean. Intraseasonal transients in the monsoons, termed "active phases", follow latent destabilization of their most convective regions. Intraseasonal hydrologic-dynamic anomalies on a large-scale are shown to be responsible for the destabilization and large-scale interactions are described.