The snowy precipitation enhancement research project: a description and preliminary results

A gradual reduction in water from the snow-melt over the past century has motivated Snowy Hydro Ltd. to pursue a wintertime cloud seeding project in the Snowy Mountains of southeastern Australia. The Snowy Precipitation Enhancement Research Project is one of only a few cloud seeding experiments in the last two decades to employ a randomized design, and the first such randomized experiment to incorporate dual-trace chemistry analysis of snowfall as part of the project evaluation. The project design, seeding criteria, ground-seeding network, and measurement infrastructures are described, as are the general components of the statistical evaluation plan. Some initial results from analysis of physical and trace chemical measurements are presented for an extended storm period in 2006 that included five randomized experimental units. The trace chemistry results were found to validate several of the components of the seeding conceptual model, and a unique time series of tracer element concentrations appears to indicate when seeding and tracer materials were released. Progress during the first four seasons of the project is described, as are various findings that could affect the outcome of the project.