Wednesday, September 03, 2014
BOM gives specious reason for revising temperature data
Supposition trumps the facts!
The removal of a longstanding temperature record at Bourke of 125 degrees Fahrenheit (51.7C) set in 1909 was the result of a critical 1997 paper that revised a string of records and brought Australia’s hottest recorded temperature into the second half of the 20th century.
Until the paper by Blair Trewin, who is now a leading climate scientist at the Bureau of Meteorology, Australia’s hottest recorded temperature was 53.1C at Cloncurry on January 16, 1889.
But after revision, the record has been accepted as the 50.7C recorded at Oodnadatta, South Australia, on January 2, 1960.
The Cloncurry record was erased because the temperature was taken with old technology and “the thermometers were probably overexposed to direct sunlight or radiant energy”.
At Bourke, however, the temperature record was taken with a near-new Stevenson screen and clearly documented in the official record and monthly audit.
Nonetheless the Bourke temperature was discarded from the record as an “observational error” because it was logged on a Sunday, a day that temperature records were generally not taken.
The deletion of the Bourke record has helped to fan a vigorous debate about the quality of the bureau’s historical temperature data.
Discussing the adjustment in the 1997 paper, Mr Trewin said a Stevenson screen was installed at Bourke in August 1908. “The original manuscript record for Bourke shows temperatures of 125F (51.7C) observed on both 2 and 3 January.
“The observation on January 2 has been corrected on the manuscript to 112F (44.4C), which is consistent with the temperatures over the region,” the Trewin paper said.
“However, 3 January was a Sunday, and no other observations were made on this day.
“It is therefore likely that the observation is actually the maximum temperature for the 48 hours to 0900, 4 January, and therefore it would be affected by the same error which was corrected in the case of the 2 January observation.”
He said “no other station in NSW or southern Queensland is known to have exceeded 47.2C on this day”.
However, Jennifer Marohasy, who has questioned the bureau about changes to the historic temperature record, said the nearest station, Brewarrina, had recorded 123F (50.6C) on the same day (January 3, 1909).
Dr Marohasy has a doctorate in biology and is openly sceptical of the consensus position on anthropogenic climate change.
The Brewarrina temperature record is widely reported in historic newspaper articles but the bureau’s online temperature record for Brewarrina does not start until January 1, 1911.
“In fact 125 is clearly written into the Bourke ledger for Sunday 3rd January in the pen that was being used at that time,’’ she said. “The entry is also underlined.”
“At the time all records were audited and a summary written at the end of the month.
“This summary clearly states that the maximum temperature on 3 January 1909 was 125F.”
Posted by John J. Ray (M.A.; Ph.D.).