资源环境科技发展态势分析平台

Precipitation falling in the Snowy Mountains region of south-east Australia is a critical resourceproviding water for hydroelectricity, as well as irrigated agriculture and environmental flows throughout the economically important Murray River system. Improved understanding of the drivers of precipitation variability is therefore a key research aim. Focussing on synoptic types responsible for delivering precipitation 10 mm per day, an analysis is presented of the large-scale atmospheric circulation drivers (teleconnections) of seasonal synoptic type frequency using cross-wavelet and boosted regression tree methods. Results demonstrate that relationships are not stationary over the period 1900-2012, and complex interactions between teleconnections and synoptic atmospheric circulation drive precipitation variability. Importantly, we demonstrate that teleconnections do not act in isolation. Relationships with the tropical Pacific Ocean are shown to be key drivers of synoptic types associated not only with the dominant tropical moisture pathways to the Snowy Mountains, but also with extra-tropical sources. Tropical sea surface temperatures are therefore shown to drive synoptic type frequency and facilitate the dominance of synoptic types with tropical moisture sources, most notability since the 1950s.