The BoM has just this month added a downloadable table of ACORN adjustments to their www site. Giles was established as a purpose built meteorological station in 1956 – I read where its origins relate to Defence – Woomera rocket range. The site has never moved yet the BoM found a statistical reason to add warming to Giles minimum data with a -0.48° adjustment prior to 1 Jan 1998.
The BoM list 10 stations used to compare with Giles to arrive at their warming adjustment on 1/1/1998
1/1/1998 Statistical adjustment
Warburton Airfield 13011 – W
Watarrka 15652 – Wat
Carnegie 13015 – C
Uluru Rangers 15660 – U
Kulgera 15603 – K
Telfer Aero 13030 – T
Yulara Airport 15635 – Y
Marla Police Station 16085 – MPS
Coober Pedy Airport 16090 – CP
Curtin Springs 15511 – CS
This map shows the above 10 stations as well as other stations used to justify time of obs adjustments in 1964 and 1978 which I am not addressing specifically here – some stations are in more than one list. Abbreviations for the sites are after the BoM station number.
1978 Time of Obs adjustment
Warburton Airfield 13011 – W
Ayers Rock 15527 – hidden on map by Uluru Rangers
Telfer Aero 13030 – T
Ernabella 16013 – E
Newman 7151 – N
Curtin Springs 15511 – CS
Sand Hill 5064 – SH
1964 Time of Obs adjustment
Maralinga 18114 – Ma
Mundiwindi 7062 – M
Cook 18110 – Co
In the 1/1/1998 Statistical adjustment list – at least two stations are so low quality with huge gaps that I am amazed the BoM would use them to make changes to data from the purpose built – 24/7 professionally staffed Giles Met Office.
Warburton Airfield – comments on graphic from the Climate Data Online BoM site – just type in station numbers –
Uluru Rangers – once again so gap ridden it is staggering the BoM would use such low quality data to alter thousands of readings from the purpose built – 24/7 professionally staffed Giles Met Office.
There is more – most of these comparison stations are so far from Giles that there is no validity in the comparisons – some like Telfer and Newman are in a different climate zone. In 1991 when the BoM critiqued a paper of mine they said that Charleville and Cunnamulla were not neighbours and that “Regional differences in climate would present a major uncertainty in some of the conclusions drawn from the comparisons.” Readers can see from the map how far Charleville is from Cunnamulla – far closer than most of the BoM comparisons with Giles. BoM hypocrisy level is high.
Have you noticed how, in the Adjustments section showing the Aust mean temp graph, that all the AWAP temps prior to 1970 have been adjusted down and after 1990, the ACORN data has been adjusted upwards relative to AWAP.
Cooled the past, warmed the present.
www.bom.gov.au/climate/change/acorn-sat/#tabs=Adjustments
Well spotted, Warwick!
The table of adjustments reg.bom.gov.au/climate/change/acorn-sat/documents/ACORN-SAT-Station-adjustment-summary.pdf is a good start. But to really judge whether the adjustments are reliable, we would need to see not just what they are, but how they were arrived at. The BoM gives a general description of methods, with some examples at cawcr.gov.au/publications/technicalreports/CTR_049.pdf, but there is no way of following each step of calculation through for each station to see what impact it has.
In the present case, for example, what weight exactly was given to the lousy data from Uluru Rangers and the super-lousy data from Warburton Airfield? Fancy imposing an adjustment to Giles data before 1998 on the basis of Warburton, which is missing data for 1988-97!
The Bureau need to publish the whole ACORN model so people can see exactly what they have done, and how sensitive the results would be to other choices being made.
OK that may be a big job. But one thing I would like to know in the meantime is what difference ACORN made. The BoM says on the top of the adjustments page: “It is important to emphasise that both the much larger, raw (unadjusted) data set (known as AWAP) and the smaller (homogenised) ACORN-SAT data set show that Australia has been getting warmer since 1910 and that the two data sets indicate a very similar amount of warming overall.” But what I would want to know first is, how much difference did the ACORN adjustments make to the ACORN stations alone?
The ACORN stations were selected as supposedly being the most reliable to start with. That may well have been right as far as the quality of the records were concerned, but why include Sydney, Melbourne, Brisbane Airport, Adelaide, Canberra, Hobart, Darwin etc. if you are after underlying climate signals excluding urban warming? And then, if the ACORN stations were the best, there were obvious risks in adjusting them based on records that were judged inferior.
Many other issues here, may comment further.
Seems that publicity in the “Australian” has caused Simon Birmingham (Parliamentary secretary in charge of BOM) to act. BOM are required to now have in place a oversight committee, with outside independent members, for ACORN by the end of this year. Maybe just maybe there will not be adjustments such as the move adjustment for Gayndah 1993 when there was no move.
Maybe the Roman action with failed battles should be carried out with BOM -ie sack the general, then randomly get rid of one in ten of the rest of the soldiers (that is the origin of the word decimate). The threat of a another decimation should focus the minds of the remainder to do the right thing.