Updating Australia's high-quality annual temperature dataset

An updated and improved version of the Australian high-quality annual mean temperature dataset of Torok and Nicholls (1996) has been produced. This was achieved by undertaking a thorough post-1993 homogeneity assessment using a number of objective and semi-objective techniques, by matching closed records onto continuing records, and by adding some shorter duration records in data-sparse regions. Each record has been re-assessed for quality on the basis of recent metadata, resulting in many records being rejected from the dataset. In addition, records have been re-examined for possible urban contamination using some new approaches. This update has highlighted the need for accurate and complete station metadata. It has also demonstrated the value of at least two years of overlapping observations for major site changes to ensure the homogeneity of the climate record. A total of 133 good-quality, homogenised records have been produced. A non-urban subset of 99 stations provides reliable calculations of Australia’s annual mean temperature anomalies with observation error variances between 15 and 25 per cent of the total variance and decorrelation length scales greater than the average inter-station separation.