CONTRIBUTIONS OF VARIOUS CLASSES OF CONVECTION TO RAINFALL IN THE ATLANTIC-OCEAN

Whilst the tropics comprise only 50% of the Earth's surface, 75% of th e annual, global rainfall occurs there. Hence, the tropics are the lat ent heat engine for the general circulation of the atmosphere. In this environment, all manner of convective weather systems exist: intense and destructive tropical storms (TS), organized mesoscale convective s ystems (MCCs and CCCs here) and much weaker, short-lived convection (D SL). The relative importance of these differing convective weather sys tems to the hydrologic cycle of the Atlantic Ocean basin is considered here. An automated, satellite-based climatology and classification of these four different classes of convective weather systems is used to define system characteristics and contribution to basin-wide rainfall over an 18 month time period. It is found that short-lived thundersto rms (DSL class) are the largest contributors to the basin-wide rainfal l, however their contribution represents only about half of the total diagnosed rainfall. Organized mesoscale systems contribute the balance . Hence, mesoscale organized weather systems seem to play an important role in the Atlantic Ocean hydrologic cycle. Due to the potentially l arge error bounds on the satellite rainfall climatologies used here, t he results of this study are contrasted with the recent climatology of Cotton et al. (1995), which incorporates some estimates of rainfall c haracteristics for mesoscale systems based on numerical model simulati ons. Comparison of these two climatologies showed good agreement in th e relative magnitudes of rainfall determined for each class of convect ion.