This is the second episode in the Cobar ACORN-SAT series examining BoM adjustments to the CDO temperature data – here I start to look at adjustments to minimum temperatures. The 1st episode looked at maximum temperatures. A list of ACORN adjustments to Cobar data is here and you can see the first min adjustment listed is 1st Jan 1972 meaning the adjustment factor applies to all data earlier than that. You will see it is labelled as “Statistical” meaning there is no evidence for it in station diaries or admin records but it derives from computer driven comparisons sifting data differences from multiple stations as far away as Parkes and Hillston – see map. In this case of the 4th adjustment the following stations data was used.
Making the chart of Cobar annual minimum temperatures compared to ACORN-SAT my eye was caught by the adjustment starting in 2006 and affecting all earlier years which I have marked with a blue 6. That is unlisted in the ACORN-SAT documentation and is substantial at about -0.4 degrees C. The slight mismatch between Cobar Met Office and ACORN from 2007-2013 is due to rounding differences because I have made my ACORN annuals by averaging a year of daily data which I leave as produced by Excel with multiple decimal places.
The next adjustment to look for is at 1971 where I have the blue 4, which is the 4th adjustment in the ACORN list and is listed at -0.49 degrees C. The increased departure of ACORN cooler than Met Office to about -0.9 is obvious on the chart.
Examining this adjustment in greater detail I have made a chart comparing Cobar MO and ACORN version with nearest neighbours Bourke, Wilcannia and Nyngan. The average difference between the 1971 & 1972 readings for these 3 stations is +0.2 at Cobar MO, +0.4 at Bourke PO, +0.4 at Nyngan, and -0.4 at Wilcannia, an average for the 3 Cobar neighbours of +0.13, not very different from the +0.2 that we know happened at Cobar Met Office. But instead of leaving the higher quality Cobar Met Office readings well alone – what does the BoM decide to do with their adjustment #4? They take off 0.49° making the 1971-1972 difference now 0.7 – greater by 0.3 than any of the neighbours. Presumably the BoM justify this by their computer driven comparisons with sites as distant as Parkes.
If the reasons for an adjustment can not be seen in nearest neighbours then it must be an exercise in fantasy to search for a reason in a cherry picked array of more distant stations which are all of poorer quality than Cobar Met Office.
It is interesting to check the differences in annual minimums between Cobar Met Office and Cobar Airport which are only about 7 or 8 km apart. You might expect them to be very similar and in lockstep – not so from the chart.
Note the BoM never refer to Cobar Airport data in ACORN-SAT – but we are free to check it out.
First there is no evidence here of a step or jump around 2006 – 2007.
While there are such wildly varying and apparently random differences between these two very adjacent sites – what on earth can the BoM learn by comparing Cobar with Parkes – or indeed any other station in their adjustments list.
These are the sort of unsafe foundations that pro-IPCC climate science is based on.
A reader has asked me to look at how ACORN-SAT has adjusted Cobar temperature data. Cobar is an old site with Post Office data from 1881 – then in 1963 the BoM opened the Cobar Met Office on the north side of town. Map from Google Earth with MO marked by “green X”. Detail of Met Office – note housing adjacent. A Met Office is of course purpose built and staffed by BoM professionals. Then in 1994 an Airport station commenced with an AWS.
ACORN-SAT starts with a positive adjustment to the max of 0.41 prior to 1 Jan 1995. Table of ACORN-SAT adjustments for Cobar. I will start by examining the evidence for that first adjustment 1 Jan 1995. This chart shows Cobar district annual max t data from 1963 – the 3 Cobar station plus Bourke PO and Airport – then Wilcannia and Nyngan. All data from the BoM CDO www site. I have marked the year 1995 with a “green 1″ – and the first adjustment to Cobar Met Office is indicated by the “green 2″.
Here is a map of NSW showing all stations used in the various ACORN-SAT adjustments of Cobar. Here is a list of stations used in the first adjustment (1 Jan 1995) – the only one we will discuss at this time.
An important note – BoM ACORN-SAT does NOT use Cobar Airport data, despite the two stations only being about 7km apart and as the chart shows the Airport and MO annual max data are in near lockstep as you would expect.
I am saying this first adjustment is invalid for the following reasons.
 The Airport data for 1994 & 1995 closely agrees with Met Office so this fact must override whatever signals the BoM computes from “data mining” at diverse stations up to a few hundred kms away some in very different climate zones.
 The Cobar Met Office is a purpose built facility staffed by professionals so that data must be considered a more reliable baseline compared to amateur run sites not owned by the BoM.
 If there was a valid reason to adjust Cobar MO data prior to 1 Jan 1995 it is ludicrous to think there would not be a reason revealed in the Met Office admin records.
That is my case that the ACORN-SAT version of Cobar fails at the first hurdle.
There has been much valid criticism of ACORN-SAT in recent months and the entire project must be scrapped.
The BoM was asked to calculate the climate of the Canberra district in the process of deciding on a location for the Australian Federal Capital Territory – Chris Gillham alerted me to this report and he has his own comments on the data in a 1Mb pdf report.
Looking at the temperature data in the Table on page 7 & 8 of the pdf report I decided to check on Goulburn, Cooma and Yass getting data from BoM CDO.
In the case of Goulburn the annual mean temperature was 56.1°F for the 46 years prior to 1910 – this equates to 13.4°C and the station was at an altitude of 702m. Now Goulburn Airport is at an altitude of 640m so the 13.4 in town would equate to 14 at the Airport assuming a standard lapse rate. The Airport in the ten years 2004-2013 averaged 13.1 – so even if we take of 0.2 from the Goulburn Town temperature for possible non-Stevenson screen exposure – we still have Goulburn 105 years ago 0.7 degrees warmer than the last ten years.
In the case of Cooma the annual mean temperature was 54°F for the 44 years prior to 1910 – this equates to 12.2°C and the station at Lambie Street was at an altitude of 812m. Now Cooma Airport is at an altitude of 930m so the 12.2 in town would equate to 11.04 at the Airport. The Airport in the ten years 2004-2013 averaged 11.15 – If we take of 0.2 from the historic Cooma temperature for possible non-Stevenson screen exposure – Cooma 105 years ago might have averaged 10.85 or 0.3 degrees cooler than the last ten years.
Yass is complicated by stations closing in the last ten years with only one month overlap. I have done the calculations and allowing for the site change and altitude differences there is near zero difference between the Yass district pre 1910 and in the last ten years.
Upshot is there seems to be no global warming or significant climate change around Canberra since the 19th Century.
Remember the post two years ago by JoNova – Extreme heat in 1896: Panic stricken people fled the outback on special trains as hundreds die.
Since then of course the BoM has shouted to the rooftops that January 2013 was the “hottest evah”.
This issue has been given some impetus after the speech in parliament by the MP for the Federal seat of Dawson, Mr George Christensen. In his speech – which you can see on YouTube – Mr Christensen made the point that the 1896 heatwave was hotter than anything we have known in recent years.
I thought I would start by posting a series of BoM maximum temperature anomaly maps of 14 Australian hot Januaries from 1932 up to recent years. All maps made at this BoM site which will not go any earlier than 1911. I am working on a map for January 1896 -
“The Conversation” has this recent blog article – FactCheck: was the 1896 heatwave wiped from the record? – which is critical of the speech in parliament by Commonwealth MP for the Federal seat of Dawson, Mr George Christensen. In his speech – which you can see on YouTube – Mr Christensen made the point that the 1896 heatwave was hotter than anything we have known in recent years.
In The Conversation blog under the section headed “Hot history?” the authors mention the long running experiment at Adelaide started by Charles Todd in 1887 where he compared temperatures in a Stevenson screen with an older style Glaisher stand – an experiment which ran on for 61 years to 1947. The blog says – The results of this 61-year experiment show that summer daytime temperatures measured using the Glaisher Stand are, on average, 1C warmer than in the Stevenson Screen. The blog goes on to say – “And this was at a well-maintained station…”. I will show at a later blog post that this 1°C figure is likely to be exaggerated.
The Conversation blog fails to mention that the BoM has a peer reviewed paper which published the results of this experiment.
The 1996 BoM peer reviewed paper – Nicholls, N., R. Tapp, K. Burrows, and D. Richards. Historical thermometer exposures in Australia. Int. J. Climatology, 16, 705-710. – can be downloaded here.
The blog omits a critical quote from page 709 of the 1996 paper which says – “Over the year, the mean temperatures were about 0.2°C warmer in the Glaisher stand, relative to the Stevenson screen.” So in terms of correcting annual mean time series – we need only subtract 0.2°C from questionable pre 1910 readings – I say let the BoM do that.
But let us return to the claim about Adelaide on The Conversation blog – “And this was at a well-maintained station…”.
Following the 1996 BoM paper above – I obtained data from the 1887-1947 Adelaide experiment and published a reply in the International Journal of Climatology detailing my analysis of the 61 years of monthly data.
1997 Hughes, W.S. Comment on, “Historical Thermometer Exposures in Australia.” by N. Nichols et al. International Journal of Climatology, Vol. 17, pp. 197-199. – downloadable here – I produced charts of the seasonal differences – Glaisher minus Stevenson for both maximum and minimum – and it is plain that the 61 years of data is riddled with inhomogeneities producing a dogs breakfast of poorly understood jumps, steps and trends in the differences. This shows that the experiment was far from “well maintained”. Unpublished reports by Swinburne researchers show that records of the 61 year experiment were not well kept.
As reader Ian George has pointed out the BoM in their monthly report for New South Wales say – New South Wales in October 2014: Warmest October on record
Following Ian’s lead I have averaged all the District mean monthly max’s and added them to this map of BoM rain districts – I have shaded orange districts that topped a 4 degree anomaly.
This next map shows the NSW maximum anomaly for October.
As Ian says there are serious differences between the maps – for example – here are many places within the RED +4 degree anomaly contour which did not register a 4 degree anomaly for October according to the district stations listed by the BoM.
Wanaaring, Bourke, Nyngan, Moree, Walgett, Lightning Ridge, Collarenebri, Narrabri, Gunnedah Resource Centre was 4.1 but Gunnedah Airport only 2.3 (UHI in Gunnedah??), Coonabarabran, Inverell, Forbes, Parkes, Deniliquin, Corowa, Tocumwal, Griffith, Lake Cargelligo,
On the other hand I noticed Katoomba had a 4 degree anomaly but is way outside the RED contour.
On balance it looks like Ian is realistic to wonder – “One wonders if the BoM has a flawed shading formula which does not really reflect the actual temperatures.”
This could be a work in progress.
Good to see this new paper – A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand – by C. R. de Freitas & M. O. Dedekind & B. E. Brill.
Also great to see them use the Fig 3 twin diagram ex NASA GISS – that I have been drawing attention to for years as absolutely vital.
Climate Conversation Group has a blog yesterday – Paper adds interesting perspective on NZ temperature trend
The latest article by Ken Stewart – Rutherglen: Spot the Outlier – builds on the momentum started by Dr Jennifer Marohasy who was a key to articles in The Australian on 23-24 August which questioned the BoM ACORN SAT high warming adjusted temperature series. And of course Jo Nova has been active on this issue for a long time.
Top BoM people need to be questioned about ACORN SAT under conditions where there is no escape – then truth might emerge into the light.
The best reference I know to BoM station diaries is the 45 page summary by Simon Torok for his 1996 PhD thesis – “The development of a high quality historical temperature data base for Australia”
This can be downloaded in full in several parts at –
However the Appendix A1 containing the 45 page summary of all station diaries he accessed can be downloaded as an 8MB pdf at – p38/46 Rutherglen station histories – I note their is no entry for Amberley and the entry for Rutherglen is brief.
You get the picture. Western world economic future is being influenced by this stuff.
I saw these diaries in the BoM library at Lonsdale Street, Melbourne in the early 1990’s – a series of maybe foolscap ledgers. I assumed they were put into Commonwealth archives – National Archives of Australia.
If anybody can locate them – please let me know.
Checking Renmark Aero minimums for 7 days 2 August to 8 August 2014 and they average -3.97°C.
Renmark has two stations with daily max & min T available – 24016 Renmark with data from 1957 to 2001 which had no seven day spell in August even breaking zero. Then Renmark Aero 24048 with data from 1995.
The previous coldest 7 day spell I found was -2.2°C in Renmark Aero from 1st to 7th August 1999.
So this August smashed the record somewhat. There must be many more cold minimum records around SE Australia to be hunted out this month.