Australian Winter Storms Experiment (AWSE) I: Supercooled Liquid Water and Precipitation-Enhancement Opportunities

Abstract

Some results of the first (1988) Australian Winter Storms Experiment are described. The results shed light on precipitation-enhancement opportunities in winter cyclonic storms interacting with the Great Dividing Range of southeast Australia. The results come from analysis of supercooled liquid water amounts provided by a dual-wavelength microwave radiometer, atmospheric structure from Omegasondes, and precipitation amounts from a large number of tipping-bucket gauges. With these data it is possible to calculate and compare two of the terms in a condensed-phase water budget over a cloud-seeding target area in the Great Dividing Range. The two terms are the horizontal flux of supercooled liquid cloud water entering the budget volume and the vertical precipitation flux at ground level out of the volume. The budget terms have implications for the amount of extra precipitation that may result from seeding. It is found that the amount depends on the frontal or postfrontal stage of activity in the target area and on the wind direction with respect to the mountainous terrain.