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Paradox said..TonyAbbott said..
JO NOVA ON THE DESTRUCTION OF OUR HISTORY:
Chris Gillham wonders how the bureau figured out the Marble Bar max was;
* one whole degree too warm on 18 Nov 1923,
* but it was 0.6?C too warm on 19 Nov 1923,
* 0.3?C too warm on 20 Nov 1923,
* 0.2?C too warm on 21 Nov 1923, and
* 0.8?C too warm on 22 Nov 1923?
I have to admit this does get a bit puzzling. I understand the need to cater for changes in the way temperature is recorded. Whether its standardised equipment, the time of day it's read etc.
However when you look at what the homogenisation does to readings like this I can't help but think there is a problem. How can one site be changed differently by up to 0.8 of a degree over 5 consecutive days. Obviously thats totally bogus when looking at individual readings, and I get why people are calling it out. I would understand if the assessment and change uniformly said that site consistantly overread by 0.5 of a degree in that year compared to now because of X reason. But to change so much on a day to day basis, it's obviously not reflecting reality at that site, so how can you just change the raw data like that.
The number one rule of scientific measurement is dont mess with the raw data. Maybe a better way is to keep the individual readings as official but publish the homegenised data as a total adjustment.
I would agree an independant review needs to be taken on how this is done. Not to appease any view in particular, but because enough valid questions have been raised that the whole process needs to be looked at closely, even if the outcome is to say, yes it's all good by an independant expert.
There has already been two independent reviews on the ACORN data set, one in 2011 and one in 2015.
There's an example of why the data is adjusted day-by-day on the BoM site. Basically, a particular day's weather can affect a particular site in different ways; for example if a site is moved then the new site can be affected more on clear calm nights than on windy nights.
BoM data shows that if they did keep the individual readings as official, then the overall Australian temperature is shown to be increasing by substantially more than the currently official ACORN adjusted data shows. So if the BoM stopped adjusting the data, as some "deniers" want, then they would be faced with an even greater average temperature increase than we currently have. If there was a BoM conspiracy then they could just say "the number one rule of scientific measurement is don't mess with the raw data" and leave it at that.
Funnily enough, even Jo Nova's site states that "Among the 60 original stations open in 1910, the very hot days were 0.09C warmer in 1964-2017 than 1910-1963, according to RAW.Surprisingly, the ACORN 1 and ACORN 2 datasets have caused a small increase in the average maximum temperature of 40C+ days in the early 1900s." So even a "denier" site says that the raw data from the original stations show that that there's more extreme heat now and that the BoM adjustments increase the number of very hot days in the early 1900s. If the ACORN data is the result of a conspiracy as some "deniers" claim, why does the raw data show warming and why would the "conspirators" increase the number of very hot days a century ago, when that runs counter to their "conspiracy"?
Oddly enough, some "deniers" are very happy to explain rising temperatures (like the Antarctic record at Esperanza station) as being due to isolated weather events but also claim that extremely hot temps from earlier eras must be relied upon to show evidence of long-term trends. They want to have it both ways.