South Australia wind hazard re-analysis using data from the Bureau of Meteorology automatic weather stations

[摘要] An electricity blackout in South Australia occurred on 28 September 2016 due to an intense low pressure system that triggered severe thunderstorms, lightning strikes, and consistently heavy rainfall.In May 2017 ElectraNet initiated a new project (Project EC. 14220) intended to assist in understanding the long-term risk to the transmission network of extreme wind events in South Australia.CSIRO worked with JDH Consulting and Weather Solutions to conduct a critical review and analysis of wind gust hazards of various storm types (synoptic and convective such as downbursts, thunderstorms, and tornadoes) with corrections for terrain, topography, wind direction, and effective gust duration (from 3-second to 0.2-second gust speed).This report describes the wind gust hazard analysis based on the daily, half-hourly, and one minute wind gust and wind direction data from 52 automatic weather stations (AWSs) maintained by the Bureau of Meteorology (BoM).The sets of gust speeds generated by synoptic and non-synoptic wind events at AWS stations with record length20 years, and 12 aggregated ‘superstations’, were analysed separately by the generalised Pareto distribution and the generalised extreme-value distribution.Based on the analyses of wind gusts and the associated wind gust directions, we found that non synoptic wind gusts near the coast are mostly produced by thunderstorms and frontal events, whereas extreme winds at inland locations are mostly by downbursts.The transmission lines in Mid North generally run in the north-south direction, which are the most susceptible to the westerly wind gusts.The AWS records show that, in Mid North, over 70 % of non synoptic wind gusts were from the west and northwest directions.In South Australia only three AWS anemometers started operating prior to 1990.As a result, three of the 12 superstations have an equivalent record of around 50 years only.The extent of “sampling errors” on the estimated gust speeds at high return periods may therefore be significant.A study on the confidence intervals at high return periods will provide a measure of the range in which the wind speed possibly lies at a given return period.

[发布日期] 2017-12-01 [发布机构] CSIRO

[学科分类] 地球科学(综合)