Satellite-based monitoring of intraseasonal variations in tropical Pacific and Atlantic convection

An automated Convection Classification, Analysis and Tracking Scheme (CCATS) is used to diagnose spatial and temporal variability of convection in the tropical western Pacific and Atlantic Oceans. Three organized convection classes are differentiated; degree of organization is related to lifetime, symmetry and peak system size. A fourth category of short-lived thunderstorms is also detected. Two cycles of the Madden Julian Oscillation (MJO) are tracked across the Pacific basin. The degree of organization of the convective systems increases as the MJO progresses through the region, preconditioning the environment for tropical cyclogenesis. Satellite-inferred rainfall budgets reveal that tropical western Pacific and Atlantic rainfall is dominated by organized convection. This has potentially important implications for representation of the hydrologic cycle in numerical simulations of the tropics, particularly for models that do not explicitly resolve the mesoscales.