Archive for April, 2019

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.