Posts Tagged ‘Bureau of Meteorology’

ACORN-SAT 2.0: New South Wales- What a mess

April 10, 2019

This is the seventh in a series of posts in which I directly compare the most recent version of Australia’s temperature record, ACORN-SAT 2, with that of the previous version, ACORN-SAT 1.  Daily data are directly downloaded from the Bureau of Meteorology. I do not analyse against raw data (available at Climate Data Online), except for particular examples, as I am interested in how different Acorn 2 is from Acorn 1.  The basis for the new version is in the Research Report.  The Bureau has published a new station catalogue with more detailed information, the adjustment summary for each station, plus lists of comparative stations for adjustments and all comparison stations for each site, with explanations of adjustment terminology.  Well worth a look.

See my previous posts for Western Australia, the Northern TerritoryQueensland,  South Australia, Tasmania, and Victoria for a general introduction.  It is important to highlight this paragraph on the new ACORN-SAT home page:

The purpose of updating datasets like ACORN-SAT is principally to incorporate data that has been recorded since the last analysis was released, as well as historical paper records that have been recently digitised. ACORN-SAT version 2 also incorporates the findings and recommendations of the Technical Advisory Forum, applies the latest scientific research and understanding and, where applicable, introduces new methodologies. The overall aim of the update to ACORN-SAT is to provide improved estimates of historical changes in climate.

As well, in the ACORN-SAT FAQs, the Bureau says:

“… The important question is not which one (version) represents the absolute truth, but whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

Therefore, the Bureau has set their own criterion for whether Acorn 1 and Acorn 2 are at all useful and valuable.  To repeat:

“whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

The Context – New South Wales

Figure 1 is a map of Australia showing all of the Bureau’s ACORN-SAT climate monitoring stations.  New South Wales is the oldest and most populous state with climates varying from semi-desert to montaine.

Figure 1:  Australian ACORN-SAT stations

NSW map all

There are 25 Acorn stations in the NSW BOM database.  Differences between Acorn 1 and Acorn 2 are summarized in the following sections.

Additional data

An extra 27 years of data have been digitised for Canberra, and 45 years for Moree, which has had an enormous effect on annual temperature trends (see below).  Some locations had changes to new sites, with Acorn 1 data merged to Acorn 2 data, including Tibooburra and Wilcannia.

Largest temperature differences

In maxima, changes to Acorn 1 daily data ranged from +8.3 ℃ at Scone in 1996 to -9.6 ℃ at Cabramurra in 1998 applied to individual daily figures.

Remarkably, there were NO changes from Acorn 1 to Acorn 2 at Gunnedah.

Figure 2:  Daily changes in maxima from Acorn 1 to Acorn 2 at Cabramurra

Cabramurra max adj

Minima adjustments ranged from -13.4 ℃ at Wagga Wagga in 1946 to +9.6 ℃ at Scone in 1996 on individual days but with many days adjusted by -2 ℃ or greater.

Figure 3:  Daily changes in minima from Acorn 1 to Acorn 2 at Wagga Wagga:

Wagga min diffs

(Remember, these are adjustments to Acorn 1, which was supposed to be “world’s best practice” seven years ago.  How did the Bureau get it so wrong the first time?  Has world’s best practice changed so much in seven years?)

Record temperatures

New record maxima were established at nine stations, with the highest at Bourke (48.9 ℃) while other stations’ record highs were unchanged or reduced.  There were two notable changes.  Figure 4 shows maxima at Sydney in 1939, where the record was increased by 2.5 ℃ to 47.9 ℃.

Figure 4:  Three versions of maxima at Sydney in 1939

Sydney record max

(The temperature was below 20 ℃ on 16th and 17th.)

Figure 5 shows Port Macquarie, whose record maximum was reduced by -4.1 ℃ from 48.1 ℃ to 44 ℃ in 1944.

Figure 5:  Two versions of maxima at Port Macquarie in 1944

PtMcquarie record max

There is NO daily raw data for any Port Macquarie site from 1921 to 1956 at Climate Data Online, so there is no way of replicating these adjustments.

Such “wildly different results” are beyond rational explanation.

New record low temperatures were established at 15 stations, and a new record low for Acorn stations was set, not at Cabramurra in the Snowy Mountains, but at Inverell in the north: -13 ℃.  Canberra’s minimum was reduced by 2.9 ℃ to -11.5 ℃.

Figure 6:  Three versions of minima at Inverell

Inverell record min

Raw minimum of -10 ℃ is cold enough.  Acorn version 1 had cooled this further by 1.4 ℃, but version 2 cools version 1 by another 1.6 ℃, making it three degrees cooler than the raw figure.  Strange things happen in the past!

Quality Control: especially minimum temperatures higher than maximum.

In Acorn 1, 15 out of the 25 stations had at least one example of minimum higher than maximum- including 12 times at Bourke and Sydney, 15 at Tibooburra, and 212 times at Cabramurra.  The worst example was minimum 2.2 ℃ above maximum in October 1913 at Tibooburra.  Blair Trewin claims he has “fixed” this problem (which he concedes was “physically unrealistic”) by adjusting temperatures in Acorn 2 so that the maximum and minimum are the same, so that DTR for the day is zero.  In his words:

A procedure was therefore adopted under which, if a day had a negative diurnal range in the adjusted data, the maximum and minimum temperatures were each corrected to the mean of the original adjusted maximum and adjusted minimum, creating no change in the daily mean.

That is almost how he “corrected” the worst NSW example in Acorn 1 (minimum 2.2 ℃ above maximum at Tibooburra).  Here is a plot of the raw data and changes made by Acorn 1 and Acorn 2 at Tibooburra in 1913.

Figure 7:  Tibooburra temperatures October-November 1913

Tibooburra DTR 1913

Acorn 1 maxima (orange line) were reduced too far below Raw (brown). Acorn 1 minima (grey) were too far above raw minima (light blue).  Result: garbage. Acorn 2 has changed maxima (dark red) back to 0.1 ℃ below the raw value, and reduced minima (dark blue) from 17 ℃ to 16 ℃.  This is not the “mean of the original adjusted maximum and adjusted minimum”- but at least the DTR is not negative.

The problem was caused by far too large adjustments to both maxima and minima, and was fixed by more arbitrary adjustments.

Not all Acorn 2 adjustments resulted in an increase in warming- in several, the warming trend was reduced.  For example, Figure 8 shows annual temperature trends at Sydney.

Figure 8:  Maxima Trends in Sydney 1910-2017

Sydney max ann trends

The warming rate of +1 ℃ per 100 years in Acorn 1 has been reduced to +0.79 ℃ in Acorn 2.

However, at Coffs Harbour the warming trend in minima was more than doubled, from +1.47 ℃ to +3.17 ℃ per 100 years.

Figure 9:  Minima trends at Coffs Harbour 1952-2017

CoffsHbr min ann trends

Figure 10 shows the effect of including an extra 27 years of data on annual trends at Canberra, with Acorn 1 adjusted downwards from 2011.

Figure 10:  Trends in Canberra minima 1914-2017

Canberra min ann trends

Acorn 1 starts in 1940.  Canberra’s warming trend has been increased from +1.48 ℃ to +2.18 ℃ per 100 years.

Conclusion:

There are no additional stations, but additional digitised data at several stations has a large impact on annual trends.  As well, several Acorn 1 stations closed and their data merged with data from new sites in Acorn 2.

Large differences between Acorn 1 and Acorn 2 daily data of many degrees Celsius are found at several stations.  Interestingly, no changes were made to Version 1 in Gunnedah maxima, and only a few in minima.

New record maxima were established at nine stations, with the remaining stations’ records being reduced or unchanged.  The largest increase was of +2.5 ℃ at Sydney, and the largest decrease was at Port Macquarie where the record high was reduced by -4.1 ℃.

The issue of instances of minima being higher than maxima caused by too vigorous adjustments at 15 stations (including 12 times at Bourke and Sydney, 15 at Tibooburra, and 212 times at Cabramurra) has been “fixed”- only seven years after the problem was pointed out.

Not all Acorn 2 adjustments resulted in an increase in warming- in several, the warming trend was reduced.  However, excessive adjustments have resulted in Coffs Harbour’s Acorn 1 minima trend of +1.47 ℃ per 100 years being more than doubled to +3.17 ℃ in Acorn 2.

The size of the adjustments only seven years after the “world’s best practice” dataset was launched, is incredible, and demands explanation.  The explanation that Acorn Version 2 “applies the latest scientific research and understanding and, where applicable, introduces new methodologies”, is beyond belief, as most datasets so far examined are vastly different from Acorn Version 1.  This is not incremental improvement.

In the ACORN-SAT FAQs, in the answer to:

“Why should the adjustments change, weren’t they correct the first time?”

the Bureau says:

“… The important question is not which one (version) represents the absolute truth, but whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

By their own words they have condemned themselves- “wildly different results” is exactly what has been produced.  Adjustments made in Version 1 were apparently made in error as they have been “corrected” by adjustments in version 2.  Will these adjustments be in error and corrected in version 3?

The Bureau officers responsible for Acorn version 2 appear to be blissfully unaware that they have made adjustments of up to 13.4 ℃ to temperatures in the dataset they proudly claimed to be world’s best practice just seven years ago.

What a mess.

I will next show a summary of Version 2 changes across the whole network, and then look at annual trends at all stations.

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ACORN-SAT 2.0: Victoria- A comedy of errors

April 5, 2019

This is the sixth in a series of posts in which I directly compare the most recent version of Australia’s temperature record, ACORN-SAT 2, with that of the previous version, ACORN-SAT 1.  Daily data are directly downloaded from the Bureau of Meteorology. I do not analyse against raw data (available at Climate Data Online), except for particular examples, as I am interested in how different Acorn 2 is from Acorn 1.  The basis for the new version is in the Research Report.  The Bureau has published a new station catalogue with more detailed information, the adjustment summary for each station, plus lists of comparative stations for adjustments and all comparison stations for each site, with explanations of adjustment terminology.  Well worth a look.

See my previous posts for Western Australia, the Northern TerritoryQueensland,  South Australia, and Tasmania for a general introduction.  It is important to highlight this paragraph on the new ACORN-SAT home page:

The purpose of updating datasets like ACORN-SAT is principally to incorporate data that has been recorded since the last analysis was released, as well as historical paper records that have been recently digitised. ACORN-SAT version 2 also incorporates the findings and recommendations of the Technical Advisory Forum, applies the latest scientific research and understanding and, where applicable, introduces new methodologies. The overall aim of the update to ACORN-SAT is to provide improved estimates of historical changes in climate.

As well, in the ACORN-SAT FAQs, the Bureau says:

“… The important question is not which one (version) represents the absolute truth, but whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

Therefore, the Bureau has set their own criterion for whether Acorn 1 and Acorn 2 are at all useful and valuable.  To repeat:

“whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

The Context – Victoria

Figure 1 is a map of Australia showing all of the Bureau’s ACORN-SAT climate monitoring stations.  Victoria is a small state with climates varying from semi-desert to montaine.

Figure 1:  Australian ACORN-SAT stations

Vic map

There are eleven Acorn stations in the Victorian BOM database.  Differences between Acorn 1 and Acorn 2 are summarized in the following sections.

Additional data

An extra 36 years of data have been digitised for Sale, which has had an enormous effect on annual temperature trends (see below).  Melbourne Regional Office observations ceased on 6 January 2015, but Acorn 2 continues the series with Olympic Park, with an overlap of 19 months.

Largest temperature differences

In maxima, changes to Acorn 1 daily data ranged from +14.6 ℃ at Orbost in 2012 to -4.4 ℃ at Sale in 2013 applied to individual daily figures.

Figure 2:  Daily changes in maxima from Acorn 1 to Acorn 2 at Orbost

Orbost max adj

Minima adjustments ranged from -7.4 ℃ at Orbost to +6.2 ℃ at Rutherglen in 1926 on individual days but with many days adjusted by -2℃ or greater.   Most changes were small but numerous, for example at Rutherglen where the changes to Acorn 1 ranged between -1 ℃ and +2 ℃ for many years.

Figure 3:  Daily changes in minima from Acorn 1 to Acorn 2 at Rutherglen:

Rutherglen min diffs

(Remember, these are adjustments to Acorn 1, which was supposed to be “world’s best practice” seven years ago.  How did the Bureau get it so wrong the first time?  Has world’s best practice changed so much in seven years?)

Record temperatures

New record maxima were established at Cape Otway, Gabo Island, and Mildura, while other stations’ record highs were unchanged or reduced.

Figure 4:  Three versions of maxima at Mildura in 1960

Mildura record max

That eclipses Mildura’s record in raw temperatures of 46.9 ℃.

New record low temperatures were established at Cape Otway, Laverton, Melbourne R.O., Nhill, Rutherglen, and Wilson’s Promontory.  Melbourne’s minima was reduced by 1.1 ℃ to -1.5 ℃.

Figure 5:  Three versions of minima at Melbourne Regional Office

Melbourne record min

Acorn version 1 had warmed the minima by 0.5 ℃, but version 2 cools version 1 by 1.2 ℃, making it 0.7 ℃ cooler than the raw figure.  Strange things happen in the past!

Quality Control: especially minimum temperatures higher than maximum.

In Acorn 1, eight out of the eleven stations had at least one example of minimum higher than maximum- including 48 times at Orbost, 63 at Cape Otway, and 79 times at Wilson’s Promontory.  The worst example was minimum 1.8 ℃ above maximum in February 1946 at Orbost.  Blair Trewin claims he has “fixed” this problem (which he concedes was “physically unrealistic”) by adjusting temperatures in Acorn 2 so that the maximum and minimum are the same, so that DTR for the day is zero.  In his words:

A procedure was therefore adopted under which, if a day had a negative diurnal range in the adjusted data, the maximum and minimum temperatures were each corrected to the mean of the original adjusted maximum and adjusted minimum, creating no change in the daily mean.

That is not how he “corrected” the worst Victoria example in Acorn 1 (minimum 1.8 ℃ above maximum at Orbost).  Here is a plot of the raw data and changes made by Acorn 1 and Acorn 2 at Orbost in 1946.

Figure 6:  Orbost temperatures January – February 1946

Orbost DTR

Acorn 1 maxima (orange line) were reduced below Raw (brown). Acorn 1 minima (grey) were too far above raw minima (light blue).  Result: garbage. Acorn 2 has changed maxima (dark red) back to approximately raw values, and reduced minima (dark blue) markedly.  This is not the “mean of the original adjusted maximum and adjusted minimum”.

The problem was caused by far too large adjustments to both maxima and minima, and was fixed by reducing the minimum, and raising the maximum, on all days to almost the same as the raw figures.

Figure 7 shows the effect Acorn version 2 tinkering adjustments have on annual temperature trends at Nhill.

Figure 7:  Trends in Nhill minima 1944-2017

Nhill min ann trends

Acorn 1 had this series cooling very slightly at -0.13 ℃ per 100 years but Acorn 2 has reversed the Acorn 1 trend to +0.67 ℃ per 100 years.  (This is restored to about 0.13 ℃ above what the “raw” trend showed.)

Figure 8 shows the effect of including an extra 36 years of data on annual trends at Sale.

Figure 8:  Trends in Sale maxima 1910-2017

Sale max ann trends

The arrow shows where Acorn 1 starts in 1946.

Conclusion:

There are no additional stations, but an extra 36 years of data at Sale has a large impact on annual trends.  Melbourne Regional Office is now amalgamated with Olympic Park, despite having only 19 months of overlap.

Large differences between Acorn 1 and Acorn 2 daily data of several degrees Celsius are found at Orbost, Sale, and Rutherglen.

New record maxima were established at Cape Otway, Gabo Island, and Mildura. New record low temperatures were established Cape Otway, Laverton, Melbourne R.O., Nhill, Rutherglen, and Wilson’s Promontory.

The issue of instances of minima being higher than maxima caused by too vigorous adjustments at eight stations (including 48 instances at Orbost, 63 at Cape Otway, and 79 at Wilson’s Promontory) has been “fixed”- only seven years after the problem was pointed out.

Excessive adjustments have resulted in Nhill’s Acorn 1 minima trend of -0.13℃ per 100 years being changed to +0.67 ℃ in Acorn 2.

The size of the adjustments only seven years after the “world’s best practice” dataset was launched, is incredible, and demands explanation.  The explanation that Acorn Version 2 “applies the latest scientific research and understanding and, where applicable, introduces new methodologies”, is beyond belief, as nearly every dataset so far examined is vastly different from Acorn Version 1.  This is not incremental improvement.

In the ACORN-SAT FAQs, in the answer to:

“Why should the adjustments change, weren’t they correct the first time?”

the Bureau says:

“… The important question is not which one (version) represents the absolute truth, but whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

By their own words they have condemned themselves- “wildly different results” is exactly what has been produced.  Adjustments made in Version 1 were apparently made in error as they have been “corrected” by adjustments in version 2.  Will these adjustments be in error and corrected in version 3?

It’s a joke, a continuing comedy of errors.

I have so far looked at 87 of the 112 Acorn stations.  Next up: New South Wales.

ACORN-SAT 2.0: Tasmania- May the Farce be with you

April 1, 2019

This is the fifth in a series of posts in which I directly compare the most recent version of Australia’s temperature record, ACORN-SAT 2, with that of the previous version, ACORN-SAT 1.  Daily data are directly downloaded from the Bureau of Meteorology. I do not analyse against raw data (available at Climate Data Online), except for particular examples, as I am interested in how different Acorn 2 is from Acorn 1.  The basis for the new version is in the Research Report.  The Bureau has published a new station catalogue with more detailed information, the adjustment summary for each station, plus lists of comparative stations for adjustments and all comparison stations for each site, with explanations of adjustment terminology.  Well worth a look.

See my previous posts for Western Australia, the Northern Territory, Queensland, and South Australia for a general introduction.  An important addition to this general introduction is this paragraph on the ACORN-SAT home page:

The purpose of updating datasets like ACORN-SAT is principally to incorporate data that has been recorded since the last analysis was released, as well as historical paper records that have been recently digitised. ACORN-SAT version 2 also incorporates the findings and recommendations of the Technical Advisory Forum, applies the latest scientific research and understanding and, where applicable, introduces new methodologies. The overall aim of the update to ACORN-SAT is to provide improved estimates of historical changes in climate.

The Context – Tasmania

Figure 1 is a map of Australia showing all of the Bureau’s ACORN-SAT climate monitoring stations.  Tasmania is an island state with a cool marine climate.

Figure 1:  Australian ACORN-SAT stations

Tas map

There are seven Acorn stations in the Tasmanian BOM database.  Differences between Acorn 1 and Acorn 2 are summarized in the following sections.

Largest temperature differences

In maxima, changes to Acorn 1 daily data ranged from +5.4 ℃ at Larapuna (Eddystone Point) to -7.3 ℃ in 1946 at Butlers Gorge applied to individual daily figures.

Figure 2:  Daily changes in maxima from Acorn 1 to Acorn 2 at Butlers Gorge

ButlersGorge max adj

Minima adjustments ranged from -9.7 ℃ to +11.3 ℃ at Butlers Gorge on individual days but with many days adjusted by -2℃ or greater.   Most changes were small but numerous, for example at Launceston where the changes to Acorn 1 ranged between -1 ℃ and +2 ℃ for many years.

Figure 3:  Daily changes in minima from Acorn 1 to Acorn 2 at Launceston:

Launceston min diffs

(Remember, these are adjustments to Acorn 1, which was supposed to be “world’s best practice” seven years ago.  How did the Bureau get it so wrong the first time?  Has world’s best practice changed so much in seven years?)

Record temperatures

New record maxima were established at Butlers Gorge, Cape Bruny Lighthouse, Larapuna (Eddystone Point), and Low Head.

Figure 4:  Three versions of maximum at Low Head 3 February 1912

LowHd record max

New record low temperatures were established at all stations except Butlers Gorge.  Low Head’s minima was reduced by 0.7 ℃ to -2.9 ℃.

Figure 5:  Three versions of minima at Low Head July 1944

LowHd record min

Acorn version 1 had warmed the minima by 0.6 ℃, but version 2 cools version 1 by 0.7 ℃, making it 0.1 ℃ cooler than the raw figure.  Strange things happen in the past!

Quality Control: especially minimum temperatures higher than maximum.

In Acorn 1, five out of the seven stations had at least one example of minimum higher than maximum- including 37 times at Butlers Gorge and 39 times at Low Head (again), where the worst example was minimum 2.1 ℃ above maximum in December 1926.  Blair Trewin claims he has “fixed” this problem (which he concedes was “physically unrealistic”) by adjusting temperatures in Acorn 2 so that the maximum and minimum are the same, so that DTR for the day is zero.  In his words:

A procedure was therefore adopted under which, if a day had a negative diurnal range in the adjusted data, the maximum and minimum temperatures were each corrected to the mean of the original adjusted maximum and adjusted minimum, creating no change in the daily mean.

That is not how he “corrected” the worst Tasmanian example in Acorn 1 (minimum 2.1 ℃ above maximum at Low Head).  Here is a plot of the raw data and changes made by Acorn 1 and Acorn 2 at Low Head in December 1926.

Figure 6:  Low Head temperatures December 1926

LowHd DTR

Acorn 1 maxima (orange line) were reduced too far below Raw (brown). Acorn 1 minima (grey) were too far above raw minima (light blue).  Result: garbage. Acorn 2 has changed maxima (dark red) back above raw, and reduced minima (dark blue) almost to the same value as raw, except on the 17th when it has been made the same as the Acorn 2 maximum.  This is not the “mean of the original adjusted maximum and adjusted minimum”.

The problem was caused by far too large adjustments to maxima, and was fixed by arbitrarily making the minimum on the 17th the same as the maximum, unusually higher than other minima adjustments.

Figure 7 shows the effect Acorn tinkering adjustments have on annual temperature trends at Butlers Gorge.

Figure 7:  Trends in Butlers Gorge minima 1944-2017

ButlersGorge min ann trends

Acorn 1 had this series cooling very slightly at -0.12 ℃ per 100 years but Acorn 2 has reversed the Acorn 1 trend to +0.54 ℃ per 100 years.  (This is restored to what the “raw” trend showed, from a messy record with huge data gaps.)

Conclusion:

There are no additional stations, so Tasmania has only seven stations.

There is no more additional digitized data, except for the period 2012 to 2017.

Large differences between Acorn 1 and Acorn 2 daily data of several degrees Celsius are found at Larapuna and Butlers Gorge.

New record maxima were set at Butlers Gorge, Cape Bruny, Larapuna, and Low Head.  New record low temperatures were established at all stations except Butlers Gorge.

The issue of instances of minima being higher than maxima caused by too vigorous adjustments (37 times at Butlers Gorge and 39 times at Low Head has been “fixed” by arbitrary adjustments.

Excessive adjustments have resulted in Butler Gorge’s Acorn 1 minima trend of -0.12℃ per 100 years being changed to +0.54 ℃ in Acorn 2.

The size of the adjustments only seven years after the “world’s best practice” dataset was launched, is incredible, and demands explanation.  The explanation that Acorn Version 2 “applies the latest scientific research and understanding and, where applicable, introduces new methodologies”, is beyond belief, as nearly every dataset so far examined is vastly different from Acorn Version 1.  This not incremental improvement.

In the ACORN-SAT FAQs, in the answer to:

“Why should the adjustments change, weren’t they correct the first time?”

the Bureau spokesman says:

“… The important question is not which one (version) represents the absolute truth, but whether those estimates produce wildly different results, and whether the range of estimates provides a reasonable guide to what has actually occurred.”

By their own words they have condemned themselves- “wildly different results”  is exactly what has been produced.

 

What a farce.

I have so far looked at 76 of the 112 Acorn stations.  Next up: Victoria.

ACORN-SAT 2.0: Queensland: Welcome to Dreamworld

February 28, 2019

This is the third in a series of posts in which I directly compare the most recent version of Australia’s temperature record, ACORN-SAT 2, with that of the previous version, ACORN-SAT 1.  Daily data are directly downloaded from the Bureau of Meteorology. I do not analyse against raw data (available at Climate Data Online), except for particular examples, as I am interested in how different Acorn 2 is from Acorn 1.  The basis for the new version is in the Research Report.

See my previous posts for Western Australia and the Northern Territory for a general introduction.

The Context – Queensland

Figure 1 is a map of Australia showing all of the Bureau’s ACORN-SAT climate monitoring stations.  Queensland is in the north-east from monsoonal tropics to mountain temperate to savannah and desert.

Figure 1:  Australian ACORN-SAT stations

Qld map

There are 26 Acorn stations in the Queensland BOM database.  Differences between Acorn 1 and Acorn 2 are summarized in the following sections.

Largest temperature differences

In maxima, changes to Acorn 1 daily data ranged from +7.2C at Burketown in 2003 to -5.2C at Georgetown on many occasions, applied to individual daily figures.

Figure 2:  Daily changes in maxima from Acorn 1 to Acorn 2 at Georgetown

Georgetown diffs

Minima adjustments ranged from -9.1C at Thargomindah to +6.3C at Charleville, and there were many other large adjustments at other stations as well.  Most changes were small but there were many still substantial changes, for example at Longreach where there were some very large changes to Acorn 1, with large numbers between -4C and +2C.

Figure 3:  Daily changes in minima from Acorn 1 to Acorn 2 at Longreach:

Longreach diffs

(Remember, these are adjustments to Acorn 1, which was supposed to be “world’s best practice” seven years ago.  How did the Bureau get it so wrong the first time?  Has world’s best practice changed so much in seven years?)

Record temperatures

New record maxima were established at 10 stations.  These were +0.8C higher than the previous record in Acorn 1 at Burketown (previous record 44.7C to 45.5C).

Figure 4:  Three versions of maxima at Burketown December 1934

Burketown max 1934

A new record low temperature was established at Palmerville, way up north in tropical Cape Yorke Peninsula, where the ridiculous Acorn 1 temperature of -2.4C was reduced even further to -3.1C.  Unbelievable- the record low at Charters Towers, 500km south, is 1.1C.  The record low at Rockhampton, 1,000 km south, is -1C.

Figure 5:  Three versions of minima at Palmerville June 1913

Palmerville min 1913

New lows were also established at 10 other stations.

Apparently the adjustments made to raw data in Acorn 1 weren’t big enough.

Quality Control: especially minimum temperatures higher than maximum.

In Acorn 1, 15 out of the 26 stations had at least one example of minimum higher than maximum.  Blair Trewin has “fixed” this problem (which he concedes was “physically unrealistic”) by adjusting temperatures in Acorn 2 so that the maximum and minimum are the same, so that DTR for the day is zero.  In his words:

A procedure was therefore adopted under which, if a day had a negative diurnal range in the adjusted data, the maximum and minimum temperatures were each corrected to the mean of the original adjusted maximum and adjusted minimum, creating no change in the daily mean.

That is how he “corrected” the worst Queensland example in Acorn 1 (minimum 2.8C above maximum at tropical Mackay).  Here is a plot of the raw data and changes made by Acorn 1 and Acorn 2 at Mackay from 25 to 31 August 1953.

Figure 6:  Mackay Aerodrome data 25-31 August 1953

Mackay August 1953

Acorn 1 maxima (brown line) were slightly reduced below Raw (bright green) until 27 August but had a major adjustment on the 28th, far below Raw minima (olive) and Acorn 1 minima (blue).  Result: garbage.  Acorn 2 has made minima (purple) less than Acorn 1.  Acorn 2 maxima (red) are slightly less than Acorn 1 except on the 28th when the maximum has been made the same as minimum.

The problem was caused by far too large adjustments.

The problem has been “fixed” by making more arbitrary adjustments, but large adjustments remain.

Amberley:

Amberley came under scrutiny after Acorn 1 because of a major adjustment to minima to account for a discontinuity in the 1980s.  I compare before and after annual data.

Figure 7:  Amberley Minima

Amberley min annual

There is a discontinuity in the raw data, so the negative trend is probably too steep.  However, the adjustments in Acorn 1 were far too great.  Acorn 2 is a slight improvement: the trend is now +2.11C per 100 years instead of +2.62C.

Barcaldine:

Barcaldine’s raw data was not supposed to be adjusted in Acorn 1- at least that was claimed in the Table guidance notes of the Table of Adjustments released in 2014.  However, there were some small one-off adjustments to maxima in Acorn 1: +0.1C in 1962, 1995, and 1996, and -0.1C in 2011. However, both maxima and minima have been strongly adjusted in Acorn 2.  Here is Barcaldine’s Tmax:

Figure 8:  Barcaldine Maxima

Barcaldine max annual

That’s a 52% increase in annual trends!

Conclusion:

There are no additional stations, so the network is still extremely sparse.

There is a very small amount of additional digitized data.

Burketown, Georgetown, Longreach, Normanton, and Richmond all had large differences in maxima between Acorn 1 and Acorn 2 daily data of over five degrees Celsius.  Charters Towers, Longreach, Normanton, Palmerville, and Thargomindah had greater than five degree differences in minima.

New record maximum and minimum temperatures have been set.  Palmerville’s new recod low is especially preposterous.

The issue of instances of minima being higher than maxima caused by too vigorous adjustments has been “fixed” by arbitrary adjustments.

Amberley’s minima adjustments have been reduced.

Barcaldine’s raw data was not adjusted in Acorn 1, but both maxima and minima have been  adjusted in Acorn 2.

The size of the adjustments only seven years after the “world’s best practice” dataset was launched, is incredible, and demands explanation.

You don’t have to go to the Gold Coast to see Dreamworld- it’s in the Acorn 2 adjustments.

I will be concentrating on another project for a few weeks so may not post for a while, but when I do, next will be South Australia.

ACORN 2: Rutherglen-Digging a Deeper Hole

February 26, 2019

Rutherglen is back in the news again, so here’s my two bob’s worth.

Acorn 2 has increased the warming trend in annual minima from +1.71C per 100 years to +1.8C per 100 years:

Figure 1:  Rutherglen annual minima

Rutherglen annuals min

Rutherglen’s lowest minimum has been reduced from -7.9C to -8C.

The “corrections” to Acorn 1 are now from 31 December 2010:

Figure 2: Acorn 2 minus Acorn 1 daily values

Rutherglen Tmin diffs

Who knew thermometers were reading a much as 1.2 degrees too warm in 2010?  (The annual mean differences between Acorn 1 and Acorn 2 for the years before 2011 are from 0.5C to 0.7C).

So, is the new version of Acorn an improvement on the homogenization in Acorn 1 from seven years ago?

As a result of the media interest in Rutherglen, in 2014 the Bureau published this plot, showing Rutherglen’s raw data compared with the homogenized data from Wagga Wagga, Deniliquin, and Kerang.

Figure 3:  BOM justification for adjustments

Rutherglen BOM comparison chart

Comparing raw data from one station with adjusted data from other stations is hardly a valid argument.

Back in 2014, I posited a test for the validity of adjustments.  The aim of homogenizing is to adjust the temperature record to make a “best estimate” of what the temperature should have been.  This is achieved by pairwise comparison between the candidate site and 10 reference sites.

By comparing Rutherglen’s raw and adjusted data with that of each of the stations used in the homogenizing process, we can see how the Rutherglen record compares with its neighbours before and after homogenising.

Subtracting the mean of neighbours’ temperature anomalies from those of Rutherglen, we can tell how well the raw data compare, and how well the adjusted data compare.

Figure 4:  2014 comparison of differences

2014 plot

Back then, it was obvious that Rutherglen minima were cooling at about the same rate as the neighbours, and that the Acorn 1 adjustments were much too great.

Applying exactly the same methodology now, with complete dataset extended to 2017, we see that Rutherglen is cooling very slightly more than neighbours, while Acorn 2 is even more out of touch with the regional reality.

Figure 5:  Rutherglen differences 2019

Rutherglen tmin avg comps

The Acorn 2 adjustments are much too large, and have created an even stronger warming trend.

FAIL.

ACORN-SAT 2.0: The Northern Territory- Alice in Wonderland

February 15, 2019

(UPDATE 17/02/2019:

I have corrected a glitch in trend calculations which are now as shown.  I have deleted all Diurnal Temperature Range plots and discussion as well.)

This is the second in a series of posts in which I directly compare the most recent version of Australia’s temperature record, ACORN-SAT 2, with that of the previous version, ACORN-SAT 1.  Daily data are directly downloaded from the Bureau of Meteorology. I do not analyse against raw data (available at Climate Data Online), except for particular examples, as I am interested in how different Acorn 2 is from Acorn 1.  The basis for the new version is in the Research Report.

See my previous post for Western Australia for a general introduction.

The Context – The Northern Territory

Figure 1 is a map of Australia showing all of the Bureau’s ACORN-SAT climate monitoring stations.  The Northern Territory is right in the Outback, from the monsoonal north to the desert centre. Most of it is savannah or desert, and there are vast distances between settlements and thermometers.

Figure 1:  Australian ACORN-SAT stations

map NT

There are five Acorn stations in the Northern Territory BOM database.  Differences between Acorn 1 and Acorn 2 are summarized in the following sections.

Trend changes

Trends in maximum temperature have changed a lot at individual stations, but on average there has been little change  (+1.29C to +1.27C per 100 years).  (Even though an average of such wildly different stations across such vast territory is meaningless.)

Figure 2:  Maxima trend changes from Acorn 1 to Acorn 2

NT max trend

The “average” change in minima is -33.3%  (+0.55C to +0.37C per 100 years).    This however is mainly due to Rabbit Flat’s short history with much missing data.

Figure 3:  Minima trend changes from Acorn 1 to Acorn 2

NT min trend

Largest temperature differences

In maxima, changes to Acorn 1 daily data were mostly small, except at Alice Springs which had adjustments ranging from -9.2C to +10.1C applied to individual daily figures, but only on a few days.  The +10.1C adjustment was to correct what could only have been a typographical error in Acorn 1, which recorded 26.8C instead of 36.8C on 28 January 1944.  The -9.2C is less easily explained and may be the opposite, Acorn 2 recording 24.1C instead perhaps of 34.1C on 6 March 1943.  Acorn 2 made many other large corrections around these dates, as Figure 4 shows.

Figure 4:  Daily changes in maxima from Acorn 1 to Acorn 2 at Alice Springs

max diff alice

Minima adjustments ranged from -11.5C to +11C also at Alice, and there were many other large adjustments as well.  At the other stations the range was much less, though still substantial changes (-3.6C to +4.6C) to Acorn 1.  Here is Alice Springs again:

Figure 5:  Daily changes in minima from Acorn 1 to Acorn 2 at Alice Springs

min diff alice

(Remember, these are adjustments to Acorn 1, which was supposed to be “world’s best practice” seven years ago.  How did Blair Trewin get it so wrong the first time?  Has world’s best practice changed so much in seven years?)

Record temperatures

A new record maximum was established at Darwin, whose record on 18 October 1982 (unchanged from raw to Acorn 1) increased from 38.9C to 39.5C in Acorn 2.

Figure 6:  Three versions of maxima at Darwin 18 October 1982

Darwin max 1982

A slightly higher record was also set at Victoria River Downs.

A new record low temperature on 21 June 1925 was also established at Alice Springs, where the Acorn 1 temperature of -6.7C was reduced to -9.4C.   (The temperature in the Post Office raw data was -5.6C.)  New lows were established at Darwin and Tennant Creek as well, but on nothing like the same scale.

Apparently the adjustments made to raw data in Acorn 1 weren’t big enough.

Quality Control: especially minimum temperatures higher than maximum.

In Acorn 1, 3 out of the 5 stations had at least one example of minimum higher than maximum.  Blair Trewin claims he has “fixed” this problem (which he concedes was “physically unrealistic”) by adjusting temperatures in Acorn 2 so that the maximum and minimum are the same, so that DTR for the day is zero.  In his words:

A procedure was therefore adopted under which, if a day had a negative diurnal range in the adjusted data, the maximum and minimum temperatures were each corrected to the mean of the original adjusted maximum and adjusted minimum, creating no change in the daily mean.

But that is not how he “corrected” the worst NT examples in Acorn 1 (minimum 4.8C above maximum at Alice Springs, and a 3.9C difference at Tennant Creek).  Here is a plot of the raw data and changes made by Acorn 1 and Acorn 2 at Alice Springs for 11 to 21 June 1932.

Figure 7:  Alice Springs Post Office data for 11-21 June 1932

Alice june 32 min2

Acorn 1 made no change to raw maxima, but was supposed to cool raw minima (the purple line) substantially  (the blue line).  Unfortunately, it is likely that instead of 8.1C, 18.1C was entered, human error resulting in garbage.  Acorn 2 has fixed this, but not by making minima and maxima equal to the Acorn 1 mean (15.7C), and neither is the DTR zero.  Instead there were more arbitrary adjustments.

(At Tennant Creek, to correct negative DTR of -3.9C,  minimum and maximum were both set to 22.9C, which is one degree less than the Acorn 1 mean of 23.9C).

 “Square wave” pattern in adjustments

The peculiar repeating pattern of adjustments to Perth in Acorn 1 also occurs at Darwin, but the pattern is even more bizarre.

Figure 8:  Darwin Acorn 1 daily maxima differences (pre-World War 2)

sq wave Darwin acorn 1

In every month, every day of the month was adjusted in Acorn 1 by exactly the same amount, which is the reason only 1917 is visible- the others are exactly the same.  Blair Trewin has taken notice of the criticism, and adjusted Acorn 2 with a little more intelligence, but the monthly pattern is still visible.  Adjustments are still applied month by month, especially in the Dry months.

Figure 9:  Darwin Acorn 2 daily maxima differences 

sq wave Darwin acorn 2

Conclusion:

There are no additional stations, so the network is still extremely sparse.

There is a very small amount of additional digitized data.

The average trend in maxima for NT has not changed very much, even though there is a large range across individual stations.  There was a reduction in the minima trend of -33.3%, mainly from the large impact of Rabbit Flat’s poor data.

Alice Springs had large differences between Acorn 1 and Acorn 2 daily data of over 11 degrees Celsius.

New record maximum and minimum temperatures have been set.

The issue of instances of minima being higher than maxima caused by too vigorous adjustments or human error has been “fixed” by arbitrary adjustments, and not as described in the research paper.

The bizarre “square wave” pattern in adjustments in Darwin has been largely rectified, at least in the Wet months.

With only five Acorn stations in the Territory, each one has a large impact on the climate record.  Alice Springs, which is said to contribute 7 to 10 percent of the national climate signal, has had extremely large adjustments made to Acorn 1.  VRD and Rabbit Flat, stations with short histories and incomplete data, also have a large impact on the national climate signal.

The size of the adjustments (made by comparison with stations up to 1,300 km away) only seven years after the “world’s best practice” dataset was launched, is incredible, and demands explanation.

Otherwise, it would appear that the temperature record of the Northern Territory, especially at The Alice,but also at other stations, has fallen down a rabbit hole, and appears to be out of a chapter from Alice in Wonderland.

Next: Queensland.

 

How Reliable is the Bureau’s Heatwave Service?

January 24, 2019

The Bureau of Meteorology presents heatwave assessments and forecasts in the interest of public health and safety.  Their heatwave definition is not based on any arbitrary absolute temperature, but uses a straightforward algorithm to calculate “excess heat factors”.  From their FAQs:

“Heatwaves are calculated using the forecast maximum and minimum temperatures over the next three days, comparing this to actual temperatures over the previous thirty days, and then comparing these same three days to the ‘normal’ temperatures expected for that particular location. Using this calculation takes into account people’s ability to adapt to the heat. For example, the same high temperature will be felt differently by residents in Perth compared to those in Hobart, who are not used to the higher range of temperatures experienced in Perth.

This means that in any one location, temperatures that meet the criteria for a heatwave at the end of summer will generally be hotter, than the temperatures that meet the criteria for a heatwave at the beginning of summer.

……

The bulk of heatwaves at each location are of low intensity, with most people expected to have adequate capacity to cope with this level of heat.”

Back in 2015 I showed how this algorithm works perfectly for Melbourne, but fails to detect heatwaves in Marble Bar and instead finds heatwaves at Mawson in the Antarctic.  In light of the long period of very hot weather across most of western Queensland, what does the Heatwave Service show?

Here is their assessment of conditions in Queensland over the last three days….

Fig. 1: Heatwave assessment for 21-23 January 2019

heatwave assessment

Most of inland Queensland has been in a “Low-Intensity Heatwave”, with a couple of small areas near the southern border of “Severe Heatwave”.

And here is their forecast for the next three days..

Fig. 2:  Heatwave forecast for 24-26 January 2019

heatwave forecast

Much the same, with a bit more Severe Heatwave coming.

So what were temperatures really like in the previous three days? Here’s the map for the middle of that period, Tuesday 22nd:

Fig. 3:  Maximum temperatures for 22 January

max 22 jan 1 day

About half the state was above 39 degrees C, a large area was above 42C, and there were smaller areas of above 45C.

And in the past week:

Fig. 4:  Maximum temperatures for 7 days to 23 January

max 22 jan 1 week

Average maxima for roughly the same areas were the same, except there was a larger area averaging over 45C!

This follows December when a large slab of the state averaged from 39C to 42C for the month.

Fig. 5:  Maximum temperatures for December 2018

max 22 jan 1 month

I’m focusing on Birdsville, circled on the map below (and indicated on the maps above.)

Fig. 6:  Queensland forecast towns- Birdsville indicated

qld map

Here are the maxima for Birdsville for January:

Fig. 7:  Birdsville Maxima for January

birdsville jan max

And here’s the forecast for the next 7 days:

Fig. 7:  Birdsville 7 Day Forecast

birdsville forecast

Apart from the 6th, when it was a cool 38.8C, since Christmas Eve the temperature has been above 40C every day, and is forecast to stay above 40C until next Tuesday (and above 45C until Sunday).  Minima have been above 25C on all but three days since Christmas.

And that’s a “Low Intensity” heatwave, with “most people expected to have adequate capacity to cope with this level of heat.”

The Bureau’s unspoken message?  It might be a bit hot, but you’re supposed to be used to it.  Harden up!

Western Queensland residents are pretty tough, but surely a month of such heat deserves a higher level of description than “Low Intensity”- especially for the vulnerable like babies, old people, and visitors.

This is worse than laughable.  The Bureau’s heatwave service is a crock.  As I said in my 2015 post, a methodology that fails to detect heatwaves at Marble Bar (or Birdsville!), and creates them in Antarctica, is worse than useless- it is dangerous.

Case Studies in “World’s Best Practice” 2: Kerang

November 5, 2015

Introduction:  This series of posts is intended to show that despite Greg Hunt’s loyalty, all is not right at the Bureau of Meteorology.

Please refer to my first post, Case Studies in “World’s Best Practice” 1:  Wilsons Promontory, for a complete description of the Bureau’s claims, the problems, data sources, and my methods.

Here are some further examples of “World’s Best Practice”.

********************

Kerang is on the Murray River, about 250 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.  This post took longer than expected because the more I looked, the more problems I found.

Note: Both maxima and minima at Kerang are warming. I have no comment on whether the adjustments are justified.  I am only interested in the methods used.

Problem 1: Missing data

The Bureau’s claim that they provide raw data as well as adjusted data is a half-truth, and completely misleading- some would say, dishonest.

The Bureau has adjusted Kerang maxima at 01/06/1957 and 01/01/1922, and minima at 18/01/2000 and 01/08/1932, and provides daily adjusted temperatures from 1/1/1910.

Unfortunately, there are NO daily raw data for Kerang before 1/1/1962.

Where are 52 years of daily temperatures?  How is it possible to have adjusted digitised data but no raw digitised data for half of the record?

Another issue brought to my attention is that there is an enormous amount of data missing even from Acorn: a large proportion every year before 1960, especially from 1932 to 1949, when 100 to 180 days are missing every year.

null days kerang

This lack of transparency makes it impossible to replicate and analyse the adjustments at Kerang.  If it can’t be replicated, with all data made available, it isn’t science.

Problem 2: Nonsense temperatures

There is only one instance when Acorn shows that the minimum temperature, the lowest temperature for the 24 hour period, was higher than the maximum temperature.

min max kerang

That dot at ‘0.6’ shows that on 2nd February 1950 the coldest temperature was 0.6C hotter than the hottest temperature!  Unfortunately it is impossible to compare with the missing raw data.

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 

Even though UHI makes Melbourne unsuitable for use in climate analysis, the Bureau still uses it to adjust the early data at Kerang!

Problem 4:  Neighbours

One of the neighbours used to adjust Kerang is Broken Hill, 477 km away, and another is Snowtown in South Australia, 565 km away.

Problem 5:  Results of adjustment

Comparison of differences between Kerang and its neighbours, pre- and post adjustment, using annual temperatures.

Firstly, minima, from the 2000 adjustment: Kerang minus neighbours, annual anomalies from 1985-2014.

Kerang comp 2000 min

The adjustment of -0.4C applied to years before 2000 is too great.  The slope of the mean difference from the neighbours is much too steep.

Next, for the 1932 adjustment (annual anomalies from 1917-1946 means):

Kerang comp 1932 min

Again, the adjustment is too great, as they make the differences from neighbours much greater.

The same pattern follows with maxima.  The 1957 adjustment (anomalies from 1944-1973):

Kerang comp 1957 max

And the 1922 adjustment (anomalies from 1910-1938):

Kerang comp 1922 max

In both cases Kerang is cooling compared with neighbours, but the adjustments reverse this and make Kerang compare less well with its neighbours.

Problem 6:  Undocumented adjustments

The Bureau lists only two adjustments to minima at Kerang:  -0.4 on 18/01/2000 and -0.61 on 01/08/1932.  This is not the whole story, as a plot of the actual annualised adjustments shows:

Kerang adjustments min

If the adjustments were as stated, the difference between adjusted and raw temperatures would be indicated by the blue lines.  The actual adjustments are shown by the brown lines.

The queried adjustments are not mentioned in the Bureau’s list here.

Similarly, there are two documented adjustments to maxima: -0.71 on 01/06/1957 and +0.33 on 01/01/1922.  These are visible in the next graph, but note the extra adjustment before 1950, and a series of adjustments from 1948 back to 1925.

Kerang adjustments max

I understand why these are needed: to adjust for the steadily increasing difference between Kerang and neighbours in this period.  But why was this not documented?

Thus we see at Kerang further 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; and undocumented adjustments.

Half-truths, incompetence, lack of transparency, and unscientific practices are evident at many other sites.  A proper investigation into the Bureau is overdue.

Case Studies in “World’s Best Practice” 1: Wilsons Promontory

October 26, 2015

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”.
**********************************************************

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.

min max wils promThat 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.
raw min diffs wils prom

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.
raw min avg diff wils prom

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:
raw v adj min wils prom

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).
raw v adj max wils prom

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.
WilsonPLighthousenSolarPanels notes

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.
wilspromphoto east

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.

More on the absurd ACORN adjustment process

September 29, 2015

This is a Letter to the Editor of The Australian I sent recently, but not published.

Sir

Dr Jennifer Marohasy (Ideology adds heat to the debate on climate change, 29/9)  claims that sites prone to Urban Heat Island effect, such as Melbourne, have been used to adjust the temperature records at sites such as Cape Otway.

This is indeed absurd, but true.  Of the 104 sites used for climate analysis, 22 have been adjusted at least in part by comparison with sites whose artificially raised temperatures make them unsuitable for use in that same climate analysis.

The Bureau of Meteorology lists eight sites which are not used in climate analysis because their records exhibit Urban Heat Island effects: Townsville, Rockhampton, Sydney, Richmond (NSW), Melbourne, Laverton RAAF, Adelaide, and Hobart.

According to the Bureau’s “ACORN-SAT Station adjustment summary”, seven of these sites are still used as comparison sites when adjusting raw temperatures at other locations.  Adelaide is used at Snowtown and Port Lincoln; Townsville at Cairns, Mackay and Charters Towers; Rockhampton at Townsville, Mackay, Bundaberg and Gayndah; Sydney at Williamtown, Bathurst, Richmond, Nowra, and Moruya Heads; Laverton at Orbost, Sale, Wilson’s Promontory, Melbourne and Cape Otway; Melbourne at Orbost, Sale, Wilson’s Promontory, Laverton, Kerang, and Cape Otway; and Hobart at Launceston, Eddystone Point, Cape Bruny, Grove, and Butlers Gorge.

Richmond (NSW) is apparently the only site not used in the adjustment process.

Greg Hunt’s faith in the credibility of the Bureau of Meteorology is touching, but just as absurd.