The Bureau of Meteorology (BOM) is at it again.
“On Monday the average maximum daily temperature record for Australia was broken at 40.33°C. The previous record, 40.17°C on 21 December 1972, was held for 40 years. The daily average maximum temperature yesterday (8 January 2013) is a close third at 40.11°C.”
This statement was contained in a press release on Wednesday 9 January 2013, quoting Assistant Director of Climate Information Services, Neil Plummer, and repeated with breathless enthusiasm by the media.
The average maximum daily temperature is a new term, one we haven’t seen before, to my knowledge. However, if BOM can calculate an average annual or monthly temperature, then they probably can calculate an average daily temperature.
This announcement is crying out for a reality check.
Maxima are recorded at 9.00 a.m. on the day following, so Monday’s maxima would not be recorded until Tuesday morning, 8 January. It normally takes a couple of months for data to be “quality assured”, checked for obvious mistakes, and then analysed for climate statements. Yet Monday’s data, recorded on Tuesday, were accepted as correct and analysed one day later, and Tuesday’s data, recorded on Wednesday morning were processed and analysed in much less than 12 hours, and released to a gullible media and public. Why the haste?
Australia’s climate analyses until last year were based on the High Quality (HQ) Network of weather stations, which had enormous problems and has now been superseded by the Australian Climate Observation Reference Network- Surface Air Temperatures (ACORN-SAT, or Acorn) which comprises daily data from 112 sites supposed to be the best available for length of record and quality siting. One can only assume that these Acorn sites were the ones used to calculate the record average maximum daily temperature. It didn’t take long to check daily maxima on Climate Data Online for 7 January from these sites.
Of the 112 sites, 3 have ceased recording and 1 had no data for the 7th January.
The remaining 108 sites had an average daily maximum temperature of:
35.91 degrees Celsius.
That’s 4.42 degrees short of 40.33, and 4.26 short of the record.
Pretty warm, but no cigar.
The median was 35.2C. 34 of 108 sites had maxima of 40.3 or more. 74 had less.
See the dark brown area representing 45C and above? Six (6) Acorn thermometers are in that area, recording 45C or more.
Perhaps BOM used stations other than Acorn? If so, transparency demands they are revealed. A map of their locations would help as they would have to be over represented in hotter parts of the country (in the dark red, grey, and brown areas on the map above).
Further, BOM needs to explain why they were used and not the official Acorn sites. If analysis of Australia wide temperature is to be based on these sites, BOM needs to explain why they went to the trouble and expense of creating Acorn, if they are not going to use it.
Neil Plummer, you have some explaining to do. Half truths, exaggerations, and misrepresentations are not acceptable.