Moisture bursts over the tropical Pacific Ocean.

Abstract

'Moisture bursts' are bands of high clouds or middle and high clouds extending poleward and E from deep tropical locations into subtropical and middle latitudes. These events, synoptic in both temporal and spatial scales, are extremely common, particularly over the North Pacific Ocean. We define moisture bursts objectively, in primarily geometric terms, to emphasize both their synoptic scale and their tropical-extratropical interaction. Because moisture burst frequency decreases at times when the ITCZ strengthens, we hypothesize 2 modes in Hadley cell behavior: a strong zonally symmetric mode, and a weaker mode comprised of the statistical ensemble of a large number of transient moisture bursts.-from Authors