Convection in Tropical Oceans - Global Atmospheres Coupled Ocean - Atmosphere Response Experiment: Horizontal scale, morphology, and rainfall production.

摘要

Shipboard radar data collected during the recent Tropical Oceans - Global Atmospheres Coupled Ocean - Atmosphere Response Experiment (TOGA COARE) provided an unprecedented view of convection in the western Pacific warm pool, a region of global climatological significance. Previous studies have shown that the vertical transport of heat and momentum by convection differs with the scale and organization of precipitating systems. The relative importance of these transports by mesoscale convective systems (MCS) versus smaller groups of convective clouds over the tropical oceans is not well understood. The goal of this study is to understand the variability of warm pool rainfall production in terms of the horizontal scale and morphology of convective systems. This variability is examined in the context of the kinematic and thermodynamic state of the environment. Furthermore, high frequency convective variability (1-5 days) is studied in detail.; It is found that although most of the rainfall is associated with MCS scale systems, unorganized isolated convection was most common and produces a significant fraction of the total rainfall. Although MCS scale heating dominated the COARE mean, distinct sub-MCS scale events heating occurred more frequently. Environmental moisture profiles distinguished between modes of convective organization more clearly than wind profiles. Furthermore, the weak diurnal variation of rainfall was found to result from the superposition of stronger, distinct diurnal rainfall variability associated with each mode of organization. These results are important to the refinement of convective parameterizations in global climate models.