It is not disputed that Blair Trewin under the supervision of David Jones (both working at the Australian Bureau of Meteorology) remodel all the historical temperature data generating trends and statistics that look quite different from the actual measurements.
The remodelled series are then passed on to university and CSIRO climate scientists who base much of their climate research on these ‘second-hand’ statistics.
So, when Michael Mann and David Karoly tell you it’s getting hotter and hotter, this is their interpretation of Blair Trewin’s statistics, not their interpretation of the actual data.
When I say there needs to be more scrutiny of what Blair does to the actual measurements, I’m simply making a request.
As Andrew Bolt explains in his column yesterday harshly entitled ‘On the deceit of Paul Barry’:
Marohasy does not say the Bureau is “part of a huge conspiracy”. What she does say is undeniably true: the Bureau has repeatedly adjusted its data, with the result that the past looks cooler and therefore the warming greater.
The only dispute is over whether the Bureau has done this correctly, to make the data more accurate. It says yes, Marohasy says no.
What evidence does Barry offer that she’s wrong? None. No interest. All he has is mockery and an appeal to his mob.
Thanks Andrew, for explaining the situation so succinctly.
It is the case that none of the adjusting is denied by Blair at the Bureau.
To help Paul Barry and others explore what Blair has actually done, my colleague Jaco Vlok has created a table with an interactive drop-down menu for each of the 112 weather stations with remodelled data.
The adjusting is laid-out, and explained here:
Go and have a play!
For example, if you click on the link, and scroll down (the 112 stations are listed alphabetically) all the way to Wagga, and then across to TMax you will find a chart that shows the raw data, and then the Blair Trewin reconstructions for this weather station that is used to calculate national averages and global warming.
First Blair created ACORN V1, that was back in 2011.
ACORN V2 is the data reworked to further increase the rate of warming.
Thanks Jaco. Thanks Andrew.
Now, Paul … go and have a look, and play. It is not a conspiracy, nor is it rocket science. But understanding can take time, especially when it is not what you might expect Bureau employees to be doing to the historical temperature data.
The feature image shows Jaco Vlok (far left) backing me up in a dispute about the value of remodelling historical temperature data.
Ian George says
Recently it was reported that Canberra had its highest minimum of 26.7C on record.
I looked up Acton and found that on January 14th, 1939 the minimum was 27.2C.
This followed an eight day heatwave of +38C (4 days over 40C).
On checking ACORNV2, the temp for that day was reduced to 25.3C. In fact all the min temps for that period were reduced by at least 1.5C. The max temps for that period were all reduced by 0.6C.
Honestly, how can they do that and still maintain any basis of credibility?
Geoff Walker says
Behind every academic or govt. employee ‘cooking ‘ data lies a grant gouger trying to feather their own nest. Agree? It’s everywhere now: universities; CSIRO; and most public agencies. Go Jennifer! You’ve got them worried!
Mike Thurn says
It’s a sad indictment on Governments worldwide who deliberately aid and abet by caving in to the Climate Industrial Complex.
And how does one expect our own slightly right of centre Government take on an entrenched bureaucracy intent on supporting its own ‘left of left’ political/environmental pursuits, whilst blocking anything and anyone in Government who resists.
In the absence of a strong leader stepping up to the plate soon, l can only suggest that time is fast running out for us Australian’s to turn the tide. We are confronted by emboldened self-serving bureaucrats that see no wrong in others massaging figures and narratives in order to suit their ends.
Trump is attempting to unwind the damage caused by an unhinged bureaucracy. The might of the Democrats along with what supportive bureaucracy is left, will stop at nothing in their pursuit of Trump. Love him or dislike him we should hope he wins in November, otherwise we are stuffed.
Keep at it Jennifer. Where there is a will there is a way. If there is anything l can do that might be of assistance, please let me know.
Tony Howard says
What a sheer bloody disgrace. As a former Technical Assistant in the ’70’s CSIRO it was one of n my regular duties to record the weather data at 9 am.
Do these new age “scientists ” presume that my readings were inaccurate.
How dare you?
Alan Tomlin says
I presume the non-compliant Australian weather stations recently documented by Ken’s Kingdom (https://kenskingdom.wordpress.com/2020/01/ scroll down to see the listing) would be excluded from your interactive adjusting table? Just asking…..
Ian Thomson says
Keep it up Jen. Well said Mike Thurn.
Do the BOM describe the adjustment process /specific reasons/formula’s used for the adjustments anywhere so this can be reviewed. Would be interested to work through it.
Bob Fernley-Jones says
Another BoM cheat is that some ACORN stations are more equal than others when it comes to national and regional averaging; under a system of area weighting factors which have changed over time.
Alice Springs is famously located in the hot centre and currently has a factor value of 0.033. In comparison for instance, Mount Gambier near the coast has less impact on national averaging at a trivial 0.0027. (In total, the 112 stations add to a value of 1).
In the early years, there were only 57 ACORN stations and Alice Springs had a higher value of 0.88. However, as more stations were progressively added, individual values fell and they included an increasing proportion of sites that are typically hotter (than for example, even Alice Springs). A notable example is Giles in WA that was opened in 1957. It has a current value of 0.061 or almost double the factor for Alice Springs but it is also typically significantly hotter…
These temperature series only go back to ca. 1910, where the BOM like to start their records, even though many stations have uninterrupted measurements extending back into the 1800s.
This truncation neatly avoids the searing temperatures (and associated human death toll) of the Federation Drought period (1896-1903), where measured temperatures were higher than measured temperatures today.
This neat trick of hiding the Federation Drought produces an incomplete picture of Australia’s recent temperature history.
The problem for the BOM is those long-lived, uninterrupted temperature series especially from rural locations are inconsistent with the ACORN-Sat adjustments which have cooled past temperatures.
Richard Bennett says
SUE THEM FOR ALTERING THE DATA WITHOUT ANY PUBLIC ANNOUNCEMENT STATING THAT THE DATA HAS BEEN ALTRERED TO JUSTIFY GOVERNMENT CLIMATE POLICIES.
Hi Jennifer, I have read your posts for many years, keep up the good work.
Don’t forget that Kenskingdom has done a survey of the BoM sites and discovered only 42 of the 111 Acorn sites actually comply with the BoM specifications for weather station sites. Here – https://kenskingdom.wordpress.com/2020/01/16/australias-wacky-weather-stations-final-summary/ it could be handy if you linked the site conditions also!
no excuse to change Woomera data nothing has changed there for years and yet they did it, thats all the evidence you need to they are crooks
Aynsley Kellow says
A key question for me is why the Australian data before 1910 are not fit for purpose, yet they are included global datasets like HadCRUT.
Bill Hankin says
Jen, I know you are on the side of the angels here but I am going to make criticisms of this post
1: Many of us know that Trewin & Blair have fiddled and farted around with the historical data But lots of ordinary folk do not know. They trust the BOM – a lot, Implicitly in fact !
Breaking that trust demands explaining things simply & directly.
This post is not simple & direct..It is complex for 112 BOM
stations, and even I had trouble following what you were explaining what you were stating and asking me to do.
In fact I gave up.
2 : You do not mention at all that Ken Stewart ( with a bit of help from me ) showed that lots of the ACORN stations are located in faulty non compliant places.. And so give inaccurate observations anyway…
You make some good points, and Ken Stewart has done some good work showing problems with placement of some of these same 112 weather stations. This generates problems with the actual measurements additional to the calibration issues, which I have also previously detailed including in my letter to the Chief Scientist.
This post is about the changes after the measurements have been taken, so it is another issue.
There are issues with placement (as Ken and you have detailed), there are issues with calibration, and then on-top of all of this they homogenise.
Blair has homogenised all of the stations used to calculate the average temperature for Australia: he has remodelled all 112 ACORN-SAT stations.
The Bureau NEVER shows the raw data with the remodelled ACORN-SAT data. The first time this has been done for all 112 sites is here: https://jennifermarohasy.com/acorn-sat-v1-vs-v2/
Jaco and I have scrapped their data sets, converted daily values to annual and present them in a graphical form … so, you and Paul Barry, have some idea of the extent and magnitude of all the fiddling.
I am hearing that you would now like each of the charts explained, and so I will get to this next. Should I begin with Adelaide, because they are listed alphabetically? There is a pressing need to get data digitised for Mildura, and I could explain this as I explain the charts?
What if I do a blog post each month outlining what each chart means, and providing background information? So, there will be 112 x 2 posts with one each month?
Bill Hankin says
Solution : Do one station at a time
a great question. The BOM raise a number of issues why they cant include data from before ca. 1910, most of which are to do with data quality – such as recording issues, site moves, different enclosures like Stevenson Screens, etc etc
The result is that it conveniently stops the BOM from attempting a “best estimate” temperature series, even from long-lived, continuous rural stations that have a minimum of (or no) interference.
The BOM dare not construct a temperature series back to, say 1885 based on a selection of these “platinum stations” for fear of what it might show: measured temperatures in the Federation Drought were higher than today, and the homogenisation process used in the construction of Acorn-SAT1 and Acorn-Sat2 temperature series is invalid – the magnitude of the adjustment is greater than the global warming signal it is meant to show.
BOM reports that this is the hottest summer on record, yet real experiences tell us the opposite. BOM is corrupted by big corporate interests just like the rest of our Govt.
The Bureau changes and tampers with daily highs and lows everyday at every station. Struggle to see how they can record daily highs of up to 1.2C higher than the temperatures posted every 0.5hr, with lows adjusted only 0.1C lower than the lowest low posted. Definitely appears to be a bias to making it hotter. This is done every day and at every station.
Bill Hankin says
Hi Jen, thanks for your reply.
1: If Paul Barry is on your case, we know you are right ! He’s a light weight propaganda pusher !
2: Thanks you for taking up the idea of one station at a time. By all means lets start with Adelaide. If you need any local site photos tell me and I’ll go take some.
We just need to be clear which station in Adelaide as they have moved them about and started new ones..
3: As you point out there are multiple layers of ‘failure’ in the BOM’s weather station network . But in my experience showing how the location of individual BOM weather stations is wrong, is the easiest way of starting to help ordinary folk understand from the ground up, so to speak, where the BOM has ‘bombed’ out.
So, I will start with Adelaide and if you can get me some photographs, and provide more background that would be great for both West Terrace and also Kent Town.
Thank you! Jen
Chris Gillham says
Bear in mind that all the RAW v ACORN 1 v ACORN 2 comparison charts are at http://www.waclimate.net/acorn2/index.html, as well as 224 min and max Excel downloads containing the dailies, calculated monthlies and annuals for each dataset. Repetitive checking over the past year has found the calculations accurate.
They even provide the average temperature each day of the week yearly since 1910, and the annual calculations are correctly coded to omit years in which there were months without the required minimum 15 days of observation.
It’s also worth checking http://www.waclimate.net/very-hot-days.html to see how the RAW data shows a decrease in Australia’s very hot 40C+ days since 1910, while ACORN shows an increase, and ditto with hot 35C days at http://www.waclimate.net/hot-days-60.html.
For a case study, http://www.waclimate.net/very-hot-days-marble-bar.html shows how ACORN area averaged algorithm adjustments to daily temps have robbed Marble Bar of its world record heatwave in 1923/24.
All charts and data, which have been available for the past 12 months, can be downloaded and published wherever without attribution.
Bill Hankin says
I know the location of them both. So I think I can get some photos tomorrow.
There is also one at the Adelaide Airport. But getting access through security was an issue when Ken was interested in this station
Frank Mulcahy says
This is more than interesting ( re the historic temperatures). I just checked the Tasmanian stations as this is where I live. Cape Bruny has been an incredibly important manned station as it is a lighthouse that automated some time ago. Being a BOM location it would have been read at least twice a day, 9 am and 3 pm. It was important for visual ocean observations. Anyway, Cape Bruny is one of those stations with robust, uninterrupted weather readings.
Similar for Butlers Gorge in the highlands, that would be a station with Stevenson screen and class A pan read probably 9 am every day.
Launceston is a tragedy, the site of the weather station was moved from the city to the airport so the data loses relevance. This then makes you wonder about historic city stations and how increasing acres of asphalt and masonary must change the climate (microclimate) which can be misleading.
‘The Bureau changes and tampers with daily highs and lows everyday at every station. ‘
Notice that myself. Casino recorded its top temp on 5th Feb at 12:10pm of 25.8C on the 10 min scale but recorded 26.7C in the same minute on the ‘Latest Weather Observations for New South Wales’ High temp data. Of course, the 26.7C is the official temp. O.9C in one minute – nearly all the warming since 1910.
It also loses data. On Thursday, 6th Feb Casino recorded 90.2mm up to 9:00am Friday. The data was shown on the NSW Observation site. Sometime Friday the data simply disappeared and Casino now a blank space for that day on the DWO.
Bill in Oz says
Hi Jen, photos of Kent Town BOM sent by e-mail !
Brian Johnston says
You are very courageous
I appreciate your work and sincerity
john byatt says
my goodness https://tamino.wordpress.com/2020/02/12/cult-of-stupidity-naming-names/?fbclid=IwAR3VJaNXgJnSdPDpFcztsfgNL-X6OKExt46vlhRbURv2aCaTzgr7OlQIyGA
John Brookes says
But, given that BoM are quite open about how and why they adjust data, and given that it is obvious the data needs adjusting to form an accurate record, what is the problem?
Wagga Wagga is an obvious case. The full period of 1910 – now can only be covered by combining temperature records from 2 sites. They are different sites, so won’t read the same temperature. But they are close enough to each other that they will have the same trends, and the trends are what we are interested in. You can see where the data from the 2 sites have an overlapping period that the older one consistenly reads ~1 degree higher than the newer one. Now you could move the older records temperatures down, or the newer records temperatures up, or you could move one down a little and the other up a little – it really doesn’t matter, but you have to do it.
And once you’ve made that adjustment, you can calculate a trend from 1910 to the present. Until you’ve done that, you simply can’t generate a trend from 1910 to now.
So I’m not sure what you are complaining about. A complete temperature record for a single station from 1910 to now is a rarity. The only way to get enough data to do a good job is by combining data from the records of stations that are sufficiently close to each other that they show the same trends. BoM has done this, and explained why. What more do you want?
Chris Gillham says
This is in response to Frank Mulcahy and his interest in Tasmania’s Cape Bruny, as I looked at the site’s data about a year ago.
Blair Trewin writes in the ACORN 2 technical report re the influence of AWS response times …
“Figure 8 shows two examples of this. Alice Springs is the most extreme example; the November 2011 probe replacement there resulted in an increase in mean one-minute temperature fluctuations of approximately 0.16 °C at 1500 and 0.03 °C at 0600. Assuming that the increased variation is distributed symmetrically about the one-minute mean and that the change of probe did not introduce any inhomogeneities into the one-minute mean, this equates to an upward shift of about 0.08 °C for maximum temperature and a downward shift of 0.01-0.02 °C in minimum temperature. In less arid climates the effect is smaller (e.g., for Sydney, around +0.03 °C for maxima and –0.01 °C for minima).”
ACORN catalogue re Cape Bruny : “The site appears to have been close to its current location before a move in April 1939. It also moved on 13 November 1961, and 45 m east in March 1969. An automatic weather station (094198) has been operating since 1997 at Cape Bruny. This is expected eventually to supersede the current site. It is about 50 m west of the current site, close to the 1961–1969 location of the manual site, but is in a more exposed location on top of the ridge. This exposure has clearly reduced rainfall readings but impacts on temperature are less clear.”
i.e. Cape Bruny provides a fairly unique comparison of AWS vs manual Stevenson screens just 50 metres apart over 20 years of observation.
94010 1998-2017 average max 15.57C
94198 AWS 1998-2017 (50 metres west) average max 16.02C
94010 1998-2017 average min 9.47C
94198 AWS 1998-2017 (50 metres west) average min 9.28C
94010 has an elevation of 55 metres and 94198 has an elevation of 60 metres, so there’s a five metre upward slope west of 94010 over 50 metres. With the sun setting to the west, the higher slope should only start to cast shadow on the lower screen very late in the afternoon, a few hours after the daily maximum has been recorded.
94010 has had an average rainfall of 879.0mm since 1998 and 94198 has had an average annual rainfall of 763.5mm since 1998.
Trewin explains the marked difference in rainfall just 50 metres apart (http://media.bom.gov.au/social/blog/1047/to-bourke-and-beyond-one-scientists-epic-journey-to-112-weather-stations/)…
“One example is at Cape Bruny in Tasmania, where we have two sites 50 m apart, one on the top of a hill and one just off to the side in a more sheltered location. Visiting there on a windy, showery, day made me appreciate how much more exposed the hilltop site is, and it turns out the hilltop site measures 17 per cent less rain than the more sheltered one, because some of the rain blows over the top of the gauge.”
The 94198 AWS averages 0.45C warmer max per annum.
94010 is cooler than the AWS each month by …
Either the AWS response time is more of an influence during warmer weather, as effectively acknowledged by the bureau, or something else about the stations’ environment is reducing the difference as the months get cooler (and the days get shorter).
Note from the ACORN catalogue re the position of 94198 … it is about 50 m west of the current site, close to the 1961–1969 location of the manual site …
In the eight available annual observations during 1961-1969, the Cape Bruny 94010 manual site average maximum was 14.88C. When shifted east to its current site, the eight years of 1970-1977 had an annual average maximum of 15.30C (even though average annual rainfall was 950.6mm in 1961-69 and 1,098.2mm in 1970-77).
So the manual screen was 0.42C cooler when in the western location where the current AWS is now recording 0.45C warmer.
The higher 94198 location should also be more exposed to cooler westerly, easterly and southerly winds off the ocean – powerful enough to blow 17% of rainfall over the gauges, according to Trewin. This suggests the 94198 AWS location isn’t a warmer environment and the warmer readings are more likely to be due to instrumental influences. (However, there may be some temp rounding influence as x.0F/C rounding averaged 84.13% in 1961-69 and 46.60% in 1970-77.)
Also and oddly, the 94198 annual mean 3pm wind speed is 25.7kmh and the 94010 annual mean 3pm wind speed is 27.8kmh – meaning the manual site has slightly stronger afternoon winds than does the AWS on a higher elevation. Most Cape Bruny winds are westerlies and southerlies (http://www.bom.gov.au/clim_data/cdio/tables/pdf/windrose/IDCJCM0021.094010.3pm.pdf).
Cape Bruny is the most southerly of all ACORN stations and, as a result, one of the coldest near sea level. The rainfall shows it’s not arid. 94010 is surrounded by grass and 94198 by what looks like low scrub (heath to 0.5m, as described above), but presumably well exposed to avoid vegetation shade.
Maximum temperatures are normally recorded mid afternoon when shading isn’t an issue. Stevensons are not supposed to be located on watered grass but it’s unlikely the grass changes colour due to seasonal drying as there is very little difference in Cape Bruny’s rainfall between the 12 months, and all months are rainy enough to maintain the green (driest Feb with average 56.12mm, wettest July with average 95.1mm, meaning in the driest month the location still gets an average 2mm of rainfall every day. This should also maintain the greenery and albedo of the surrounding heath and 3m shrubs just east of the AWS.)
Trewin’s A2 report explanation of AWS response times reads like an effort to minimise this artificial warming by confining it only to a small number of hot, arid locations and thus not sufficiently influential to adjust the national dataset.
Plenty of individual stations show sharp maximum temperature increases post AWS installation with some levelling thereafter, and the rapid warming consistently looks more pronounced than Trewin’s insignificant description.
Ken Stewart considers Cape Bruny non-compliant with site standards …https://kenskingdom.wordpress.com/2019/12/05/the-wacky-world-of-weather-stations-no-283-cape-bruny-tas/
Cape Bruny poses questions not only about the AWS response time warming at the site itself but the response warming at all Australian sites, hot, cold, arid or wet, and is an example that can be used to highlight the AWS influence.
The sites get moved I have looked into Alice Springs (use to live there) one site which goes back to 1878 to 1953 was moved at least once during this period from the telegraph station to the post office in town. Then relocated to the airport but at least they have over lap in the data but not from the initial relocation.
There is also the issue of using electronic thermometers vs mercury thermometers the electronic ones have almost no thermal inertia where as the mercury have quite a lot. What this would mean is the electronic ones will show a higher temp spike depending on how much time they allow for averaging in there recording. I don’t think the long term temp data is good enough to tell whether there is a warming trend or not.
Thank you so much for your efforts.
Don’t try to merge data in a non professional way. Separate stations are separate stations..
If we look at the Wagga Wagga AMO station alone, it is obvious that raw untampered data has the highest trend from 1942 til now (adjustments are warming the past).
Hence, I believe that Big Coal has infiltrated BoM, and deceivingly tries to downplay the consequences of global Warming..
We are watching how history is twisted into Holy Scripture to serve the goal of putting those who did the twisting into power. Fight on.
Jeff Ollerton says
Perhaps you’d care to comment on this? If you have the courage to allow it through moderation that is:
Ron READ says
Dr. Jennifer: You are commended for your commitment and effort in reconstructing temperatures more accurately so as to reflect a trend which if I understand correctly shows that Australia is not experiencing exothermic conditions but rather the antithesis?
As a novice Climate Researcher what puzzles me the most are the inferences by so many from within and from outside the “science” community that the planet is experiencing AGW. How can this be categorically deemed to be science when (and again my understanding) that science requires “scientific method” under extreme laboratory accuracy to prove an observed hypothesis. Where and when were such laboratory experiments conducted to determine the earths climate over the past few centuries?
Haphazard world-wide temperature and precipitation readings with casual repeatibility might only show trends and didn’t Dr. Raymond Wheeler do this over a century ago?
Right now, I am reading all the “climate gate” documents as well as the testimony given by Dr. Michael Mann to the House Science Committee in the US Congress!
In summary, even if I wanted to believe AGW, it would be extremely difficult given the dubious information delivered by the East Anglia CRU (who coalesced with Mann to deny appropriate scientific “peer review”) to the IPCC.
Your comments are appreciated.
John Brookes says
I am surprised by the loyalty of your followers.
TONY SMITH says
Hi Jen, thank you for taking the time to generate this invaluable site, Ihave been an avid reader and have passed on your articles to countless numbers of friends and colleagues, who have now become your readers as well. I would request, as has Bill Hankin, that a simplified explanation of the data sets be given, as Bill states – “This post is not simple & direct..It is complex for 112 BOM stations, and even I had trouble following what you were explaining what you were stating and asking me to do.” – I do hope you will take time to somehow get the info to me in a more ‘readable’ form. Yours Tony
I have a comment about the Tamino defence of BoM temps fiddling (more a basic question really) –
how come the instrumental records by thermometers prior to 1910 in Australia (and 1950 in Canada) are not regarded as reliable enough by “the authorities” to determine the state of climate(s) in those relatively recent times, but the tree-ring proxy temps that formed the basis of the MBH “hockey stick” are held as gospel for the state of climate(s) back in the days of yore?
John Brookes, your credulity and world-class rationalizations are much more impressive.
It is not at all clear why wholesale downward adjustments of past temperature records are undertaken.
And the rationalizations you offer are at best circular and post hoc.
Bill Hankin says
@John Brookes, our loyalty is based on a keen appreciation of the science researched and presented here by Jennifer Marohassy.
It would seem by contrast that you are unable to understand and appreciate her research and science.
Frankly that is your problem. Not Jennifer’s nor our’s.
Perhaps you can wander back off into the unscientific backwoods you came from now ?
For the trollster Brookes:
Dr Alan Longhurst has a published article of some import. Perhaps Brookes could exactly address the points that Longhurst makes. Paul Barry most certainly will not.