FULL ARTICLE HERE:
"CONCLUSION (not edited)
There appears to be no valid reason to lower Darwin, Australia maximums by 0.67C for all years prior to 1980 all the way back to the start of the record in 1910. The reason given is “statistical” and is based on the 4 reference stations.
There is no statistical reason given that could explain this in the Trewin 2018 peer reviewed paper quoted by Acorn-Sat as their reference. The result of this adjustment is a significant increase in Darwin’s century scale warming trend.
Unless someone can come up with a valid explanation, I would say that this adjustment was the result of either some sort of error or alternately was the result of politically motivated support for the global warming narrative.
DETAILS: (carefully selected quotes only)
ACORN-SAT routinely adjusts measured historical temperatures to correct for various equipment changes, site, and vegetation changes etc. Some of these changes are legitimate and some are not.
A reduction in historical temperatures enhances any century scale warming. In the case of Darwin, historical temperatures have been lowered significantly causing Darwin’s warming rate over the last century to be nearly one full degree higher per century than it would have been if raw temperatures as measured were used.
I am interested here in two of the adjustments made by the Australian Bureau of Meteorology (BOM) to raw data for inclusion in the ACORN-SAT 2.2 Darwin maximum temperature reconstruction.
They are:
The cooling of recorded and unadjusted historical temperatures prior to 1/1/37 due to the station change from the Darwin Post Office (DPO) (#014016) to Darwin Airport (DAP) (#014015) in 1942.
This adjustment also included an estimate for any temperature change across the in-continuity from 1/1/37 to 1942. All temperatures prior to 1/1/37 were reduced by 1.02C based on only one reference station, Wyndham Port (WP) (#001005).
The BOM reduced all maximum temperatures prior to 1/1/80 (including further reducing the maximum temperatures prior to 1/1/37) for statistical reasons based on the reference stations, Cape Don (#14008), Jabiru Airport (#14198), Oenpelli (#14042) and Katherine Council (#14902). All maximum temperatures from 1/1/80 back to the beginning of the reconstruction in 1910 were reduced by 0.67C.
... The first thing to notice is that Wyndham port maximums warm by about 2.0C from 1925 through to 1955 while Darwin Post Office maximums are level from 1925 to 1936.
Darwin Airport maximums are also level from 1942 to 1945 and only rise by about 0.4C from 1942 to 1955. This should immediately make us suspicious about using Wyndham Port as the only comparison station to adjust the Darwin temperatures for the station move, cyclone and Post Office bombing between 1/1/37 and 1942.
... By using this homogenization algorithm, they have transferred the anomalous warming in the Wyndham Port maximum record to the Darwin record. I will show here why Wyndham Port (WP) should not have been used as a comparison station for Darwin.
... Darwin is in a unique position in that it is the only station in Australia to have only one comparison station. The Wyndham Port inhomogeneity was, consequently, not picked up and was allowed to contaminate the Darwin record.
... On the evidence from the maximum data, Wyndham Port (WP) should not be used as a reference station for either Darwin Post Office (DPO) or Darwin Airport (DAP) as it clearly has strong warming from 1925 to 1955 that is not apparent in either Darwin record.
Another reason why Wyndham Port should not be considered as a reference station for Darwin is that its minimum temperatures from 1942 to 1950 are strongly negatively correlated with the Darwin Airport ...
Darwin Airport minimums rise strongly from 1942 to 1950 while Wyndham Port minimums fall by nearly 2.0C during this same period. The temperature drivers in the two places appear to be unrelated for this period.
Wyndham Port should have been disqualified as a reference station ... Wyndham Port was used as a reference station for Darwin despite it having a large and obvious increase in temperature from 1925 to 1955 that does not appear in either Darwin record. This has occurred because the homogenisation algorithm used by Acorn-Sat is faulty as discussed above.
It is quite possible that this situation is common in the Acorn-Sat homogenised series in Australia and other similarly homogenised series around the world.
2. THE ADJUSTMENT TO MAXIMUM DARWIN TEMPERATURES
PRIOR TO 1/1/80
Acorn-Sat reduced all Darwin maximum temperatures prior to 1/1/80 (including further reducing the maximum temperatures prior to 1/1/37) for statistical reasons based on the comparison stations, Cape Don (#14008), Jabiru Airport (#14198), Oenpelli (#14042) and Katherine Council (#14902) All maximum temperatures from 1/1/80 back to the beginning of the reconstruction in 1910 were reduced by 0.67C.
I am at a loss to know what possible statistical changes could reduce every maximum temperature from 1/1/80 back to the start of the record in 1910 by 0.67C. This is significant and not explained as far as I can see. What possible reason could Acorn-Sat have for changing a perfectly good data set by such a large amount many years after the original data was recorded."