The Development of a high-quality daily temperature data set for Australia

A set of high-quality daily maximum and minimum data has been developed for Australia for the period from 1957 to the present. This set consists of data from 99 stations throughout Australia, selected according to the quality of their climate record (in terms of site standards, homogeneity and completeness of record) and to provide the best possible spatial coverage of the continent.

Each individual station time series has been examined for inhomogeneities, using the statistical techniques described in Easterling and Peterson (1995) on monthly data and knowledge of available metadata. Adjustments of data to remove inhomogeneities have been carried out at the daily timescale, using a technique of matching percentile points in the frequency distribution in order to take account of inhomogeneities having differing magnitudes under different meteorological conditions. The data were also screened, using processes of spatial intercomparison with neighbouring sites and examination for internal consistency, for errors affecting individual observations. The resultant time series can hence be used for daily analyses of extremes as well as of means.

The data set has been used for a number of applications in the Australian Bureau of Meteorology. These include:

* The development of time series of indices of extreme temperature occurrence, for use in analyses of observed climate change.

* The development of techniques for forecasting of seasonal temperatures over Australia.

* The calculation of spatial averages of temperature for Australia, and regions within it, for use in routine climate analysis and monitoring.

Reference

Easterling, D.R. and Peterson, T.C. 1995. A new method for detecting undocumented discontinuities in climatological time series. Int. J. Climatology, 15. 369-377.