Quote:

A small band of sceptics have long claimed a conspiracy, without evidence, that the bureau deliberately used homogenisation in its centrepiece dataset of 112 weather stations – known as the Australian Climate Observations Reference Network – Surface Air Temperature (Acorn-Sat) – to make the heating of the continent’s climate appear worse. That effort to engage the audit office failed, but the bureau established its own review with a panel of independent international experts. That panel reported that “as the world’s first national-scale homogenised data set of daily temperatures” it had “a high level of confidence in the national temperature trends” from Acorn-Sat. Another independent expert panel reported for three years from 2015 and again backed the bureau’s methods, despite “unsolicited submissions” which they said “do not provide evidence or offer a justification for contesting the overall need for homogenisation and the scientific integrity of the bureau’s climate records.”

https://www.theguardian.com/science/2023/may/07/climate-scientists-first-laughed-at-a-bizarre-campaign-against-the-bom-then-came-the-harassment

So let's have a look at some findings -

" Some such details are provided in Centre for Australian Weather and Climate Research (CAWCR) technical reports (e.g. use of 40 best-correlated sites for adjustments, thresholds for adjustment, and so on); however, the Forum
concluded that it is likely to remain the case that several choices within the adjustment process remain a matter of expert judgment and appropriate disciplinary knowledge."

If it can't be replicated it can't be science. Expert judgment is not replicable.

"Reason for adjustment Maximum temperature Minimum temperature
Statistical                             209                                   244
Site moves (all)                    176                                   170
Screen change or condition   79                                     77
Site condition (without move)   9                                       5
Observation time change         2                                     24
Total                                     450                                    491
Table 7 ACORN-SAT version 2 adjustments by cause. Totals do not add as some adjustments have multiple causes. "

http://www.bom.gov.au/climate/change/acorn-sat/documents/BRR-032.pdf

Statistics can't tell us what the temperature was at a site yesterday, let alone on a day 100 years ago.

"Potshot was the top-secret WWII base that transitioned to RAAF Base Learmonth at the conclusion of WWII. 

    By not adjusting for the highly significant maximum temperature (Tmax) step-change in 2002 detected by BomWatch, ACORN-SAT failed its primary objective which is to “produce a dataset which is more homogeneous for extremes as well as for means”.
    Either Blair Trewin assumed the 12-year overlap would be sufficient to hide the effect of transitioning from the former 230-litre Stevenson screen to the current 60-litre one; or his statistical methods that relied on reference series were incapable of objectively detecting and adjusting changes in the data.
    In either case it is another body-blow to Trewin’s homogenisation approach. Conflating the up-step in Tmax caused by the automatic weather station and 60-litre screen with “the climate” and lack of validation within the ACORN-SAT project generally, unethically undermines the science on which global warming depends.
        Due to their much-reduced size, and lack of internal buffering, 60-litre Stevenson screens are especially sensitive to warm eddies that arise from surfaces, buildings etc. that are not representative of the airmass being monitored.
        Increased numbers of daily observations/year ≥95th day-of-year dataset percentiles relative to those ≤5th day-of-year percentiles, which explains the up-step, is a measurement issue, not a climatological one."
http://www.bomwatch.com.au/bureau-of-meterology/part-5-potshot-and-acorn-sat/