Introduction: This series of posts is intended to show that despite Greg Hunt’s loyalty, all is not right at the Bureau of Meteorology.
The Bureau describes its methodology for creating the ACORN-SAT temperature reconstruction as “world’s best practice”, as it was described thus by the 2011 International Review Panel. The recent Report of the Technical Advisory Forum accepts this claim, reporting that “the Forum did not prioritise further international comparison of the Bureau’s curation methods in this report. However, the Forum will revisit this issue at its next meeting in 2016.”
In light of this endorsement, here are some examples of “World’s Best Practice”.
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Wilsons Promontory Lighthouse is on the southernmost tip of the Australian continent, about 170 km from Melbourne. The story of temperature adjustments here illustrates much that is wrong with the Bureau: misinformation, incompetence, lack of transparency, and unscientific behaviour.
Note: Both maxima and minima at Wilsons Promontory are warming. The Minima trend has been cooled, the maxima warmed. I have no comment on whether the adjustments are justified. I am only interested in the methods used.
ACORN-SAT, (Australian Climate Observation Reference Network- Surface Air Temperatures), was introduced in March 2012, with several revisions mainly to bring the series up to date. It is a daily dataset of minima and maxima, from which monthly and annual means are derived, for 112 sites around Australia. Raw temperature data at these sites were homogenised by a complicated algorithm by comparison with neighbouring sites.
After much criticism, the Bureau has been forced to provide some answers, and agreed to ‘checking’ by a Technical Advisory Forum. The Bureau has provided additional information at the Acorn website, and in September 2014 released a list of the sites with adjustment dates, amounts, and the neighbour sites used for adjustment (see http://www.bom.gov.au/climate/change/acorn-sat/documents/ACORN-SAT-Station-adjustment-summary.pdf). Unfortunately, this additional information has raised more questions than it has unsuccessfully answered.
Problem 1: Missing data
The Bureau says at its FAQ No. 6 at http://www.bom.gov.au/climate/change/acorn-sat/#tabs=FAQs ,
“the Bureau provides the public with raw, unadjusted temperature data for each station or site in the national climate database, as well as adjusted temperature data for 112 locations across Australia”, and at No. 8, “Daily digitised data are now available back to 1910 or earlier at 60 of the 112 ACORN-SAT locations, as well as at some non-ACORN-SAT locations.”
This is a half-truth, and completely misleading- some would say, dishonest.
The Bureau provides raw data at Climate Data Online at http://www.bom.gov.au/climate/data/, and adjusted data at http://www.bom.gov.au/climate/change/acorn-sat/#tabs=Data-and-networks.
The Bureau has adjusted all Wilsons Promontory maxima before 1/1/1950, and minima before 1/1/1930, and provides daily adjusted temperatures from 1/1/1910.
Unfortunately, there are NO daily raw data for Wilsons Promontory before 1/1/1957.
Where are 47 years of daily temperatures? How is it possible to have adjusted digitised data but no raw digitised data?
Likewise, of the 10 neighbouring sites used for the pre-1950 maxima adjustments, only five have daily raw data before 1957, and for minima, only two (and one is Melbourne- more later). Were the adjustments made with only two comparisons? Otherwise, where are the data for the others?
This lack of transparency makes it impossible to replicate and analyse the adjustments at Wilsons Promontory. If it can’t be replicated, with all data made available, it isn’t science.
Problem 2: Nonsense temperatures
There are 79 instances when Acorn shows that the minimum temperature, the lowest temperature for the 24 hour period, was higher than the maximum temperature.
That dot at ‘1’ shows that on 5th December 1911 the coldest temperature was one degree hotter than the hottest temperature!
All of these occurred before 1950, so it is impossible to compare with the raw data.
The Bureau dismisses this as a minor hiccup of no importance, as an artefact of the adjustment process. The Bureau goes to great pains to explain how carefully the raw data was checked to remove any glaring errors and mistakes. On page 31 of CAWCR Technical Report No. 049, the section “Quality control checks used for the ACORN-SAT data set” describes a test for internal consistency of daily maximum and minimum temperature, which was carried out on the raw data of the ACORN-SAT sites. This test for minima greater than maxima, the first and most important quality control check, obviously was not applied to the adjusted data at all, and these nonsensical values remain years after sceptics made the Bureau aware. Any organisation that can’t perform a basic quality control test on its product is incompetent, as is any Review Panel or Technical Advisory Forum that endorses it.
Problem 3: Artificial warming
Here are the neighbouring sites used.
Maxima: East Sale Airport, Geelong SEC, Laverton RAAF*, Orbost, Queenscliff, Cape Otway Lighthouse, Melbourne Regional Office*, Essendon Airport, Currie, and Ballarat Aerodrome.
Minima: Cape Otway Lighthouse, Kerang, Melbourne Regional Office*, Eddystone Point, Geelong SEC, Bendigo Prison, Swan Hill PO, Cape Bruny Lighthouse, Currie, and Ballarat Aerodrome.
On page 71 of CAWCR Technical Report No. 049 is the statement, “the potential still exists for urbanisation to induce artificial warming trends relative to the surrounding region, and it is therefore necessary to identify such locations to prevent them from unduly influencing assessments of background climate change.”
Included in the eight stations not used in climate analysis because their records exhibit Urban Heat Island effects are Laverton RAAF and Melbourne. Even though UHI makes Melbourne and Laverton unsuitable for use in climate analysis, the Bureau still uses them to adjust the data at Wilsons Promontory!
Problem 4: Neighbours
Cape Bruny Lighthouse is on the far south east coast of Tasmania, and is 509 km south of Wilsons Promontory. Kerang is on the Murray River, 413 km northwest, in a dry inland area, as is Swan Hill, 468 km away. Were there no better correlated sites nearer?
Problem 5: Results of adjustment.
To compare the temperature record at Wilsons Promontory with its neighbours, as we don’t have daily data, we can only use monthly or annual data. A simple but reliable method is to calculate the difference between Wilsons Promontory and each neighbour. This is done for raw and adjusted anomalies from the mean of a common baseline period. If Wilsons Promontory compares well with its neighbours, the differences should be close to zero, and most importantly, in spite of any short fluctuations, there should no trend: Wilsons Promontory should not be warming or cooling relative to its neighbours.
Unfortunately there are no monthly or annual data before 1957 for Eddystone Point or Bendigo Prison, so comparison is further restricted.
Firstly, minima: Wilsons Promontory minus neighbours, annual anomalies from 1916-1945, raw data.
The differences range from +2 degrees to – 2 degrees, so there is plenty of variance, but the bulk of differences are +0.5 to -0.5 degrees. The spaghetti lines can be averaged to show the mean difference.
While there are periods of significant differences (1924-26, 1958-60, and 1974) it is plain that the raw data difference shows zero trend, indicating good comparison between Wilsons Promontory and its neighbours. Now compare the differences following the 1930 adjustment:
The Acorn adjusted record preserves the periods of large differences, but has Wilsons Promontory cooling relative to its neighbours by more than half a degree per 100 years. The adjustment was too large.
Here is the comparison for maxima (anomalies from 1936-1965).
The raw data show Wilsons Promontory cooling a little (-0.13C per 100 years) relative to the neighbours, but Acorn overcorrects, resulting in warming (+0.18C per 100 years) too much compared with the neighbours.
Problem 6: Site quality
On pp. 22-23 of Techniques involved in developing the Australian Climate Observations Reference Network – Surface Air Temperature (ACORN-SAT) dataset (CAWCR Technical Report No. 049) by Blair Trewin, March 2012, we find:-
Standards for instrument exposure and siting in Australia are laid down by Observations Specification 2013.1 (Bureau of Meteorology, 1997). Among the guidelines are:
• Sites should be representative of the mean conditions over the area of interest (e.g., an airport or climatic region), except for sites specifically intended to monitor localised phenomena.
• The instrument enclosure (if there is one) should be level, clearly defined and covered with as much of the natural vegetation of the area that can be kept cut to a height of a few centimetres.
• The distance of any obstruction should be at least four times the height of the obstruction away from the enclosure. (This criterion is primarily directed at elements other than temperature; for temperature the last guideline is more important.)
• The base of the instrument shelter should be 1.1 metres above the ground, with the thermometers approximately 1.2 metres above the ground.
• If no instrument enclosure is provided, the shelter should be installed on level ground covered with either the natural vegetation of the area or unwatered grass, and should be freely exposed to the sun and wind. It should not be shielded by or close to trees, buildings, fences, walls or other obstructions, or extensive areas of concrete, asphalt, rock or other such surfaces – a minimum clearance of five times the width of the hard surface is recommended.
The following photos are from Dayna’s Blog, a fascinating blog about bushwalking in SE Australia. (Interested readers are encouraged to visit https://daynaa2000.wordpress.com/ for some excellent walking tour information and photographs.)
The first view is towards the southwest, towards the direction of the prevailing south-westerly winds.
Note the large areas of concrete under and near the Stevenson Screen; the nearby rock walls, the nearby solar panels almost directly to the south of the screen.
The second photo is in the opposite direction and shows the proximity of a building, another rock wall, and the steep slope of the site.
These photographs make a mockery of the Station Catalogue description, which calls it “a very exposed location”. There are several man made features which surely influence temperatures recorded. Jennifer Marohasy recently asked the Bureau whether the solar panels would reflect onto the screen. The reply was,
“The angle of the panels means that any reflection from the panels is likely to only intersect the instrument shelter for a small part of the day during a limited part of the year. As the instrument shelter is fitted with double-louvered wall panels, it is virtually impossible that a direct beam of light would be able to enter the screen. Further, it is unlikely that the solar panels are influencing the instrument shelter as the shelter is painted to reflect direct and indirect radiation.”
Yet in the Station Catalogue for Alice Springs we find this statement “The site was enclosed by a rock wall about 1 m high and painted white that would have interrupted wind flow and reflected heat.”
They cannot have it both ways. If a 1m high rock wall interrupts wind flow and reflects heat in Alice Springs, then surely rock walls and buildings, large areas of concrete, and solar panels, all on a downward sloping lee side of a hill, will cause artificial warming at Wilsons Promontory.
Wilsons Promontory is a far from ideal site.
Thus we see at Wilsons Promontory misinformation and lack of transparency through failure to supply digitised raw data to allow replication; incompetence through not using basic checks for data integrity, resulting in publication of the “world’s best practice” temperature dataset with minimum temperatures higher than maximum; use of UHI contaminated sites when making adjustments; use of distant neighbours from different climate regimes; over-zealous adjustments resulting in worse comparison with neighbours than before; all at a very poor quality site.
Half-truths, incompetence, lack of transparency, and unscientific practices are evident at many other sites. A proper investigation into the Bureau is overdue.
kenskingdom 