Multi-scale variability of southeast Australian wind resources

Abstract. There is growing need to understand wind variability in various regions through the world, including in relation to wind energy resources. Here we examine wind variability in southeast Australia in relation to the El Niño-Southern Oscillation (ENSO) as a dominant mode of atmospheric and oceanic variability for this region. The analysis covers variability from seasonal to diurnal time scales for both land and maritime regions of relevance to wind energy generation. Wind speeds were obtained from the 12 km grid-length BARRA reanalysis produced for the Australian region, with focus on wind at a typical hub-height of 100 m above the surface. Results show spatiotemporal variations in how ENSO influences wind speeds, including consistency in these variations over the wind speed distribution. For example, ENSO-related variations in mean winds were mostly similar in sign to ENSO-related variations in weak winds, noting uncertainties for strong winds given available data. Diurnal variability in wind speed was larger for summer than winter and for land than ocean regions, with the diurnal cycle maxima typically occurring in the afternoon and evening rather than morning, plausibly associated with sensible heating of air above land following solar radiation. Localised variations in the diurnal cycle were identified around mountains and coastal regions. The results show some indication of ENSO influences on the diurnal variability. These findings are intended to help enhance scientific understanding on wind variability including in relation to ENSO, as well as contribute information towards practical guidance in planning such as for use in energy sector applications.