Due to the consistency of the formation of rainbands, the Island of Hawaii is an excellent natural laboratory for the study of the interactions of the larger scale flow with mountainous terrain. An experiment held during the Summer of 1985 and subsequent numerical modelling studies have led to a new theory on the formation mechanisms of the rainbands off the east coast of the Big Island. The earliest work indicated that rainband formation was caused chiefly by the interactions between sea/land breeze, mountain/valley breeze and the trade winds. The more recent research, however, indicates that under strong trade wind conditions, the island scale flow may be more complex and involves the dynamical interactions between the strong trades and orography. As part of a larger experiment, the Principal Investigators propose to collect data to test this new hypothesis. In addition to furthering our understanding of the physics of these rainbands, the simplicity of the physics associated with this process should allow an unique opportunity to verify and test a mesoscale numerical model which will have value beyond this experiment.
