The Bureau of Meteorology's (the Bureau) observations network is extensive. It includes 695 Automatic Weather Stations (AWS) across Australia and collects over 2.5 million temperature readings each day. Data from this network underpins all of the services the Bureau delivers, enabling more than 500,000 public forecasts, and nearly 15,000 weather and ocean warnings to be issued each year.
In July 2017, the Bureau identified problems with the performance of some AWS equipment at very low temperatures which meant that some temperature data was not recorded at two sites; Thredbo Top Station (Thredbo) and Goulburn Airport (Goulburn).
Initial quality assurance investigations undertaken by the Bureau found that the AWS equipment installed at Thredbo in 2007 and at Goulburn in 2003 was not fit for purpose. The type of data acquisition equipment (specifically, a hardware card) fitted in those locations was unable to operate at temperatures below -10.4°C. This occurred on one day at Goulburn and on six days at Thredbo.
When the Bureau became aware of the problem in July, it took immediate action to replace the data acquisition equipment at Thredbo and Goulburn, avoiding any reoccurrence. The Bureau also worked quickly to replace the same equipment at four other sites deemed at risk of experiencing temperatures below -10.4°C. These were in Tuggeranong (ACT), Fingal (Tasmania), Butlers Gorge (Tasmania) and Mt Baw Baw (Victoria).
A panel comprising three external independent technical experts and two senior officers from the Bureau was commissioned to undertake the review. The independent experts are professionals of national and international standing with expertise relevant to the scope of the Terms of Reference.
The panel supported the Bureau's initial diagnosis that outages at temperatures below -10.4°C at Thredbo and at Goulburn were the result of equipment in those locations not being fit for purpose.
The panel confirmed that the ACORN-SAT dataset has not been compromised directly or indirectly by the inability of some Bureau AWS to read temperatures below -10.4°C. The panel found that, across the AWS network, the Bureau’s verification process, quality checks, and processes for finding and acting on equipment failure all achieve their purpose.
The panel found that the Bureau’s data quality control processes work well, flag errors appropriately, and that the Bureau’s practices are of a high standard, and are in line with accepted practice for meteorological services worldwide.
Notwithstanding the soundness of the Bureau's data quality control, there were clearly failures in some of the Bureau's internal processes dating back to the mid- 1990s that allowed equipment that was not fit for purpose to be installed at a small number of locations. Inadequate process, documentation and communication meant that some field officers were unaware of the different capabilities of similar pieces of equipment.
While the Panel considers that the current Bureau AWS network is fit for purpose, it has made a number of recommendations to prevent a reoccurrence of the issues that manifested at Thredbo and Goulburn.