A novel method is proposed to directly evaluate this hypothesis. A modern network of carefully quality-controlled precipitation gauges and satellite (MODIS) observations of cloud top effective radius (re) are used to investigate the link between remotely-sensed cloud microphysical characteristics and surface precipitation. Distributions of precipitation rate for cloudy scenes partitioned by the critical re=14 μm threshold are distinct and precipitation rate is positively correlated with cloud re, so there is a physical link between these parameters.
To provide a meteorological link between potential pollution sources and the Snowy Mountains, a climatology of back trajectories has been compiled using the HYSPLIT model. Trajectories which pass directly through source or nearby control regions are selected, and statistics for both cloud re and precipitation are compared. No significant relationship is found between the pollution sources considered and the Snowy Mountains for either parameter. While convincing examples may be found, the claim that a systematic reduction in precipitation amount has occurred as a result of aerosol pollution is not supported.