The Bureau of Meteorology has ordered a full review of temperature recording equipment and procedures after the peak weather agency was caught tampering with cold winter temperature logs in at least two locations.
The bureau has admitted that a problem with recording very low temperatures is more widespread than Goulburn and the Snowy Mountains but rejected it has attempted to manipulate temperature records.
The bureau’s chief executive, Andrew Johnson, has called for an urgent review and the immediate replacement of recording equipment at a number of undisclosed sites. The action was outlined in a letter to federal Environment Minister Josh Frydenberg and follows weeks of turmoil over why data showing minus 10.4C readings at Goulburn and Thredbo went missing.
Bush meteorologist Lance Pidgeon blew the whistle on the missing data after watching the minus 10.4C Goulburn recording from July 2 disappear from the bureau’s website. “The temperature dropped to minus 10.4, stayed there for some time and then it changed to minus 10 and then it disappeared,” Mr Pidgeon said.
He relayed his concerns to scientist Jennifer Marohasy, who has queried the bureau’s treatment of historical temperature data. After questions were asked, the bureau restored the original recording of minus 10.4C to its website. A bureau spokeswoman said the low recording had been checked for “quality assurance” before being posted.
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The bureau said limits were set on how low temperatures could go at some stations before a manual check was needed to confirm them. “The bureau’s quality control system, designed to filter out spurious low or high values was set at minus 10 minimum for Goulburn which is why the record automatically adjusted,” a bureau spokeswoman said.
“The error was picked up yesterday internally and quality control processes are being reviewed for those stations where temperatures below minus 10 are possible.”
Dr Johnson told Mr Frydenberg the failure to record temperatures of minus 10.4C at Goulburn on July 2 was due to equipment being “not fit for purpose”.
A similar failure had deleted a reading of minus 10.4 at Thredbo Top on July 16 even though temperatures at that station had been recorded as low as minus 14.7 in the past. That temperature was still blank on the bureau’s website yesterday.
Dr Johnson said failure to record the very low temperatures had “been interpreted by a member of the community in such a way as to imply the bureau sought to manipulate the data record”.
“I categorically reject this implication,” he said.
The bureau’s handling of temperature data and the homogenisation of records to form a national average has been controversial.
It has said warmer minimum temperatures were one reason for the upward trend in average temperatures due to climate change.
In a letter to Mr Frydenberg, Dr Johnson said: “Preliminary analysis had indicated the ACORN-SAT national temperature record had not been affected by the issues experienced at Goulburn and Thredbo Top Station.” But, he added, electronic hardware “not only at Goulburn and Thredbo Top Station, but also a small number of other automatic weather stations in cold climate locations, are not fit for purpose”.
“I have taken steps to ensure that the hardware at these locations is replaced immediately,” he said. “To ensure that I have assurance on these matters, I have actioned an internal review of our AWS network and associated data quality control processes for temperature observations.
“The review will be conducted by a member of the bureau’s senior leadership team and will involve independent external expertise where appropriate.
“I expect the review to be conducted in a matter of weeks and I will report back to you as soon as it is completed.”
Dr Marohasy said Dr Johnson’s claims of equipment failure were easily disproven by the screen shots that showed the very low temperatures before being “quality assured” out.
She said claims the omission of the very low temperatures did not affect the national temperature record were also easily disproven.
“While Goulburn station is not a listed ACORN-SAT station, it is used to homogenise Canberra and Canberra is an ACORN-SAT station,” Dr Marohasy said.
The bureau did not respond to questions about how widely the quality control system had been applied and at what upper temperature the cut-off had been set.
Dr Marohasy has evidence of the initial minus 10.4C recording at Thredbo before it was deleted for quality assurance.
“This either reflects an extraordinary incompetence, or a determination to prevent evidence of low temperatures,” Dr Marohasy said.