Abstract
Twenty one Precipitation Particle Image Sensors (PPIS) were launched into various clouds at Manus Is., Papua New Guinea (2°S, 147°E) during the Tropical Ocean and Global Atmosphere-Coupled Ocean Atmosphere Response Experiments (TOGA-COARE) international project.
Cloud system development varied with the vertical humidity profiles. These seemed to form in relation to areal convergence and divergence. It is suggested that typhoons are the most effective modifiers of wind field profiles.
Two distinct rain system types were typically observed at Manus Is.: rainbands composing cloud clusters from which intense rainfall fell, and thick, upper layer clouds covering a broad area from which weak but steady rain fell.
The most outstanding result was the finding of a dominant warm rain process in the Manus rainbands. On the other hand, small graupel, including aggregates, fell from thick, upper layer clouds. Subtle differences in precipitation particles from thin anvil clouds and those from stratified typhoon clouds, lead to the conclusion that these thick upper layer clouds are formed by additional lifting of mid-level air. In both cloud types, ice crystal concentration in the equatorial area was minimal in comparison to other tropical regions.
