Archive for the ‘adjustments’ Category

ACORN-SAT 2: Eucla: The Devil in the detail

February 18, 2019

I’m having a break from looking at Acorn 2 data from Queensland.  I’ve been wondering:  what’s going on?  What’s beneath these changes?  In particular, I was struck by statements in the accompanying Research Paper that

In total, there were 966 adjustments applied in version 2 of the ACORN-SAT dataset, 463 for maximum temperature and 503 for minimum temperature.”

The Bureau is referring to breakpoints in the data where adjustments are applied to all previous years.  In the daily data, there are tens of thousands of adjustments at each station.

For example, in Eucla’s Tmax record, there are 34,145 daily datapoints; 34,144 in Acorn 1; and 33,858 in Acorn 2.  There are  10,190 instances where Acorn 1 makes no change to raw data, and 9,312 in Acorn 2.  Most of the instances of no adjustments are since 1995.  Before then almost every day has been adjusted.

And the devil is in the detail.

The following plots show how adjustments are applied to the range of raw maxima.  First Acorn 1.

Figure 1:  Acorn 1 adjustments as applied to raw maxima at Eucla

Ac1 raw adj

Figure 2:  Acorn 2 adjustments as applied to raw maxima

Ac2 raw adj

Acorn 2 removes the large negative adjustments for temperatures in the high 30s, and the spread is wider for very high temperatures.  So far so good.

Figure 3 shows where many of these adjustments are made.

Figure 3:  Acorn 2 and  raw maxima

Eucla 1913-2017

Between 1930 and 1995 many high temperature spikes are reduced by 5 degrees and more.

For example, here is November 1960.

Figure 4:  Raw, Acorn 1, and Acorn 2 in November 1960

Eucla Nov 1960

The Bureau can truthfully claim that there is a balance between positive and negative adjustments.

However, note how all temperatures over 35C have been reduced by five degrees.  This is common across these years.

Perhaps temperatures on very hot days at Eucla in the 1960s were exaggerated?  Perhaps they were not read accurately?

If this pattern of hot day reductions is generally followed at stations across large regions, e.g. southern Australia, the effect will be that climate analysis based on Acorn 2 will show that past extremes were generally not as high as nowadays.

And that can’t be a bad thing for the meme.

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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.

 

ACORN-SAT 2.0: Western Australia- A State of Confusion

February 14, 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 first 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.

I start with Western Australia, and must thank Chris Gillham for his outstanding work and for allowing me to use data from stations he has used for his annual analysis.

Introduction:

The Bureau of Meteorology has released its latest revision of the Australian temperature record back to 1910.  Previous versions of our historic temperatures included “High Quality”, which I revealed in 2010 to have major flaws, not least being the strong warming bias; and ACORN-SAT 1, released in March 2012, proudly touted as being “World’s Best Practice”, which I (along with others) found to have very many severe problems.  (If you like, check these posts, here, here, here, and here.  There are many others.)

Stung by the public and media criticism which this generated, the Bureau set up a supposedly independent Technical Advisory Forum, which met on one day per year for three years and basically rubber-stamped Acorn.  They did, however, make some recommendations, particularly about transparency.  In the light of this recommendation, this latest release without any publicity at all is perplexing.

Nearly all of Australia’s climate analysis and modelling is based on the previous version, Acorn 1, including monthly, seasonal, and annual means, extremes, and trends.  Sometime in the near future, this will be based on Acorn 2 data.

As this an upgrade to an existing dataset, we might expect there would be a few small tweaks of maybe a few tenths of a degree in some records and any changes to temperature trends would be fairly small.  Perhaps there might be some extra stations in remote areas to improve the density of the sparse network, perhaps some records starting earlier because of newly digitized data, hopefully a sensible fix for the dreadful situation of many daily minimum temperatures being higher than the maximum.

Not so.

No wonder the Bureau has released Acorn 2 so quietly- it is a confusing mess, and completely alters Acorn 1.  Trends are vastly different, some temperatures altered by more than 10 degrees Celsius, and new records established.

The Context – Western Australia

Figure 1 is a map of Australia showing all of the Bureau’s ACORN-SAT climate monitoring stations.  Western Australia occupies the western third of the continent.  Most of it is desert, and there are vast distances between settlements and thermometers.

Figure 1:  Australian ACORN-SAT stations

Acorn map WA

There are 25 Acorn stations in the Western Australian BOM database.  One (Kalumburu 001019) has the latest version data for minima but not for maxima, so complete analysis is not possible.  Differences between Acorn 1 and Acorn 2 are summarized in the following sections.

Trend changes

Trends in maximum temperature have increased by an average of +0.25 degrees Celsius per 100 years (from +1.17C to 1.42C), which is an increase of 21.7% over the trend produced by Acorn 1.  (Click on each graphic to enlarge.)

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

WA Max trend chart

The largest increase in trend is at Wittenoom.

Trends in minimum temperature have increased by an average of nearly +0.22 degrees Celsius per 100 years (from +1.04C to +1.27C), which is an increase of 21.53%.

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

WA Min trend chart

The largest increase  (+1.06C per 100 years- from +0.55C to +1.61C).  The largest decrease in trend was at Halls Creek: -1.31C per 100 years.

Largest temperature differences

In maxima, changes to Acorn 1 daily data were often very large.  Wandering gets the gong for greatest adjustments, ranging from -10.9C to +10.9C applied to individual daily figures, but only on a few days.  Eucla has many large changes made to Acorn 1 data.

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

Diff Tmax Eucla

Minima adjustments ranged from -10.8C at Esperance to +7.8C at Halls Creek for a few adjustments, but at most stations the range was much less, though still substantial changes to Acorn 1.  Here is Perth:

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

Diff Tmin Perth

(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 Carnarvon, whose already homogenized record increased from 48.5C to 51C.  This is now the record for all of Australia, apparently (although I have 87 more stations to check).   Additional large adjustments are the cause:

Figure 6:  Three versions of maxima at Carnarvon 23 January 1953

Carnarvon Max

The previous “record”, held by Albany in the cool south, after much ridicule was reduced from 51.2C to 49.5C.  New records were also established at Bridgetown, Dalwallinu, Eucla, Kalgoorlie, Katanning, Marble Bar, Merredin, Perth, and Port Hedland.

New record low temperatures were established at Bridgetown, Cape Leeuwin, Cunderdin, Dalwallinu, Esperance, Eucla, Forrest, Geraldton, Halls Creek, Kalgoorlie, Learmonth, Marble Bar, Meekatharra, Perth, and Wittenoom.

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

Quality Control: especially minimum temperatures higher than maximum.

In Acorn 1, 16 out of 25 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.

But that is not how he “corrected” the worst Western Australian example in Acorn 1 (minimum 2.1C above maximum) at Kalgoorlie.  Here is a plot of the raw data for 14th to 18th November 1914.

Figure 7:  Kalgoorlie Post Office data for 14-18 November 1914

Kalgoorlie raw

The 16th was a cold rainy day, with only 0.1C separating minimum (15.5C) and maximum (15.6C).  But temperatures in 1914 were read from a Fahrenheit thermometer.  Both 60F and 60.1F convert to 15.6C; 15.5C is 59.9F.  It is likely the temperature ranged from just under 60F to just over 60F.

Acorn 1 adjustments were made with brute force rather than finesse.  The maximum was reduced by 1.3C to 14.3C, and the minimum was raised by 0.9C to 16.4C, resulting in nonsense.

Figure 8:  Kalgoorlie Post Office and Acorn 1 data for 14-18 November 1914

Kalgoorlie Ac1

In Fahrenheit, 57.7F maximum and 61.5F minimum.

The solution in Acorn 2?  Even more brutal adjustments- and not to the mean of the Acorn 1 adjustments (which would have been 15.35C):

Figure 9:  Kalgoorlie Post Office and Acorn 2 data for 14-18 November 1914

Kalgoorlie Ac2

The Acorn 1 minima is decreased (by 3.4C) to 13C, and Acorn 1 maxima decreased by another 1.3C to 13C (or 55.4F), making it 2.6C below the raw temperature as read in 1914.  Now there is no problem with minimum exceeding maximum, but at the cost of raw data tortured beyond recognition.

“Square wave” pattern in adjustments

Bob Fernley-Jones first noticed a peculiar repeating pattern of adjustments to Perth in Acorn 1 monthly data.  I can replicate this in dailies.

Figure 10:  Perth Acorn 1 daily maxima differences 1983-1986

sq wave perth acorn 1

This pattern is still visible in Acorn 2, but is much reduced.  Adjustments are still applied month by month, but they are not as rigid.

Figure 11:  Perth Acorn 2 daily maxima differences 1983-1986

sq wave perth acorn 2

This is how it was changed:

Figure 12:  Perth Acorn 2 minus Acorn 1 daily maxima differences 1983-1986

sq wave perth acorn 2- acorn1

A new square wave- almost a mirror image of Figure 11.  It is good to see that the Bureau has taken notice of criticisms!

Conclusion:

Comparison of Acorn2 versus Acorn 1 data for Western Australia does not encourage confidence in the Bureau’s methods:-

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 WA has been increased by 21.7%, and in minima by 21.5%.

Differences between Acorn 1 and Acorn 2 daily data can be up to nearly 11 degrees Celsius.

New record maximum temperatures have been set.

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

The “square wave” pattern in adjustments in Perth has been largely rectified.  The square wave is now in the difference between Acorn 1 and Acorn 2.

It beggars belief that a dataset that was proudly described as “world’s best practice” just seven years ago has needed to be adjusted by so much.  Has “best practice” changed so much?  How was Acorn 1 so wrong?  How can we be sure that the new version is better, and will itself not be changed again in a few years?

There are now four versions of WA temperature:  Raw; High Quality (no longer available); Acorn 1; and Acorn 2.  All are different.

The record for Western Australia reveals a state, not of excitement, but of confusion.

 

Next: the Northern Territory.

Pretty Patterns

March 13, 2018

Most people like pretty patterns.  They are pleasing to the eye.  But that’s no reason to create them when homogenising data, as the Bureau of Meteorology does when creating its ACORN-SAT datasets for a number of sites.

I am indebted to Bob Fernley-Jones, who noticed this and has been trying without success to point out to the Bureau that they need to address this issue.

For example, the Bureau found problems with maximum data from Darwin, especially before the Post Office and its thermometer were blown to bits by a Japanese bomb in February 1942.  Adjustments were needed as the data source moved from the town to the RAAF base.  Before this, apparently the Stevenson screen had become partially shaded by vegetation.  The problem is that the only other stations available for comparison for identifying and adjusting for discontinuities in the data were hundreds of kilometres away- Port Keats Police Station is 243 km away, Katherine is 270 km away, and Wyndham Port is 446 km away.  Port Keats and Katherine have monthly data from 1938 and 1937 respectively (but with many months of data missing from Katherine), and Wyndham Port has daily data available for the whole 1910-1942 period.  So these three distant sites were used to adjust Darwin’s raw data before 02/02/1941, but only Wyndham Port was used to make adjustments for all data before 01/01/1937 and 01/01/1916.

Here is the result.

Figure 1:  Adjustments to Darwin’s daily maxima 1910 to 1942

Darwin daily adj 1910 1942

Now isn’t that a very pretty and pleasing pattern?  The red line shows the difference between Darwin Acorn Tmax and Darwin raw Tmax, for every day from 01/01/1910 to 31/01/1942, revealing a repeating oscillation in values.  Note that from 2 February 1941 there are no adjustments.

The next plots analyse the three distinct periods by month of the year.

Figure 2:  Daily adjustments to Darwin’s maxima 01/01/1937 to 31/01/1941

Darwin daily adj 1937 to 41 max

Note that these are not mean values:  every single day in each month was adjusted by exactly the same amount as every other day in that month.  Every day in June 1937 was cooled by -0.5 degrees C, and likewise every day in June 1938, 1939, and 1940.  Days in April and December were not adjusted, while the Wet months were warmed and the Dry and Build-up months were cooled.  So much for the Bureau’s explanation that only Winter (-0.47) and Spring (-0.57) were adjusted.

Figure 3:  Daily adjustments to Darwin’s maxima 01/01/1916 to 31/12/1936

Darwin daily adj 1916 to 36 max

Again, every single day in each month has been adjusted by exactly the same amount as every other day in that month.  Days in the Wet were cooled by from -0.2C to -1.2C, while days in the Dry and Build-up months were cooled by -1.2C to -2.2C.  That’s some pretty savage adjusting, and does not vary from the first to the last day of each month.

Figure 4:  Daily adjustments to Darwin’s maxima 01/01/1910 to 31/12/1915

Darwin daily adj 1910 to 15 max

Note again that while the adjustments are not as large as 1916-1936, only February has no adjustment to raw data, and all other months have daily cooling adjustments which are the same from the start to the finish of the month.

Unbelievable.

Time for a clean out.

 

 

 

BEST Adjustments

February 11, 2018

Two years ago I wrote a post about changes in Diurnal Temperature Range (DTR) and whether these were a “Fingerprint of enhanced greenhouse warming”, as claimed by Dr Karl Braganza in an opinion piece at The Conversation in 2011, and in his 2004 paper.

It being time to check more recent data (in 2016 the BEST data finished at December 2015), I went to the BEST site and downloaded the most recent monthly data for maxima and minima, which now extends to July 2017.

I should not have been surprised to find that the two datasets, produced 18 months apart, are different.  The differences are not large enough to be immediately apparent (from 1850 to 2015 the increase in trend per 100 years is only 0.023 degrees Celsius for maxima and 0.007C for minima), but they are none-the-less influential.

Here’s why.

Fig. 1: BEST Tmax 2016 minus 2017 (above zero means the data has been cooled, below zero means it has been warmed.)

BEST max diff

Note the large corrections before 1910, but the overall effect is minor.

Fig. 2:  BEST Tmin 2016 minus 2017

BEST min diff

I have shown the zero value, meaning no adjustment.  Note the large adjustments pre-1910 (but at different times to maxima); apart from two short periods, the whole series is WARMED by about 0.1C; I have marked with arrows the period from the late 1950s to the early 1980s when adjustments were minimal; but note the sudden drop (from January 1983) with recent minima WARMED by about 0.1C.

They have warmed the present and pre-1950, but left the cool 1950 – 1980 period largely alone.   What effect would this have?

Not much if you are looking only at temperature- they certainly can’t be accused of the more usual cooling the past and warming the present.  But if you are looking to find fingerprints of greenhouse warming, this is gold.  One of the fingerprints of enhanced greenhouse warming is greater warming at night than during the day, such that the Diurnal Temperature Range decreases.

The effect is subtle.  There is virtually no change in the long term DTR trend from 1850.

Fig. 3:  Diurnal Temperature Range calculated from BEST 2016:

BEST dtr 1850 2015

Fig. 4:  DTR calculated from BEST 2017:

BEST dtr 1850 2015 2017 version

But there is much uncertainty in data before 1910 as we are told, which is why BOM climate datasets start from 1910.

Fig. 5:  DTR 1910 – 2015 from BEST 2016:

BEST dtr 1910 2015 2016 version

Fig. 6:  DTR 1910 – 2015 from BEST 2017:

BEST dtr 1910 2015 2017 version

Again, virtually no change.  Aha, I hear Global Warming Enthusiasts chortle, gotcha!

The real effect of the adjustments is on the period from 1950, when man-made atmospheric carbon dioxide began increasing rapidly.

Fig. 7:  DTR 1950 – 2015 from BEST 2016:

BEST dtr 1950 2015 2016 version

Note the linear trend value: that equates to less than -0.1C per 100 years- a clear fault with the 2016 BEST data.  But with the new, improved 2017 version, the downward trend in DTR becomes:

Fig. 8:  DTR 1950 – 2015 from BEST 2017:

BEST dtr 1950 2015 2017 version

A three-fold increase in the downward trend in DTR.  This is much better support for the narrative of strong greenhouse warming since 1950.  How convenient.  We just have to wait for the papers and publicity about new evidence for decreasing DTR.

But Global Warming Enthusiasts wouldn’t want us to look at shorter time frames, particularly starting from the dog-leg which still exists from 1983, despite BEST’s warming of the minima data since then by about 0.1C.  This graph includes data to July 2017.

Fig. 9:  DTR 1983 – 2017

BEST dtr 1983 2017 2017 version

That looks like a rather long period of increasing DTR- not good evidence for the meme.  Don’t worry, they’ll explain that by claiming it’s due to “increased cloud and rain” since 1983, and besides, you have to look at the long term trend.

So be prepared for papers and press releases spruiking new confirmation that greenhouse warming is real, as evidenced by strong DTR decrease since 1950.

And all because of almost undetectable changes to the BEST datasets.

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”.
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Wilsons Promontory Lighthouse is on the southernmost tip of the Australian continent, about 170 km from Melbourne. The story of temperature adjustments here illustrates much that is wrong with the Bureau: misinformation, incompetence, lack of transparency, and unscientific behaviour.

Note: Both maxima and minima at Wilsons Promontory are warming. The Minima trend has been cooled, the maxima warmed.  I have no comment on whether the adjustments are justified. I am only interested in the methods used.

ACORN-SAT, (Australian Climate Observation Reference Network- Surface Air Temperatures), was introduced in March 2012, with several revisions mainly to bring the series up to date. It is a daily dataset of minima and maxima, from which monthly and annual means are derived, for 112 sites around Australia. Raw temperature data at these sites were homogenised by a complicated algorithm by comparison with neighbouring sites.

After much criticism, the Bureau has been forced to provide some answers, and agreed to ‘checking’ by a Technical Advisory Forum. The Bureau has provided additional information at the Acorn website, and in September 2014 released a list of the sites with adjustment dates, amounts, and the neighbour sites used for adjustment (see http://www.bom.gov.au/climate/change/acorn-sat/documents/ACORN-SAT-Station-adjustment-summary.pdf). Unfortunately, this additional information has raised more questions than it has unsuccessfully answered.

Problem 1: Missing data
The Bureau says at its FAQ No. 6 at http://www.bom.gov.au/climate/change/acorn-sat/#tabs=FAQs ,
the Bureau provides the public with raw, unadjusted temperature data for each station or site in the national climate database, as well as adjusted temperature data for 112 locations across Australia”, and at No. 8, “Daily digitised data are now available back to 1910 or earlier at 60 of the 112 ACORN-SAT locations, as well as at some non-ACORN-SAT locations.

This is a half-truth, and completely misleading- some would say, dishonest.

The Bureau provides raw data at Climate Data Online at http://www.bom.gov.au/climate/data/, and adjusted data at http://www.bom.gov.au/climate/change/acorn-sat/#tabs=Data-and-networks.

The Bureau has adjusted all Wilsons Promontory maxima before 1/1/1950, and minima before 1/1/1930, and provides daily adjusted temperatures from 1/1/1910.

Unfortunately, there are NO daily raw data for Wilsons Promontory before 1/1/1957.

Where are 47 years of daily temperatures? How is it possible to have adjusted digitised data but no raw digitised data?

Likewise, of the 10 neighbouring sites used for the pre-1950 maxima adjustments, only five have daily raw data before 1957, and for minima, only two (and one is Melbourne- more later). Were the adjustments made with only two comparisons? Otherwise, where are the data for the others?

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

Problem 2: Nonsense temperatures
There are 79 instances when Acorn shows that the minimum temperature, the lowest temperature for the 24 hour period, was higher than the maximum temperature.

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.

More Rutherglen Nonsense

August 15, 2015

Jennifer Marohasy had an interesting post this week on further explanations by the Bureau for their weird adjustments at Rutherglen.  I was particularly interested in this graphic, which is Chart 3 on the Bureau’s station adjustment summary for Rutherglen.  http://www.bom.gov.au/climate/change/acorn-sat/documents/station-adjustment-summary-Rutherglen.pdf

rutherglen comp BOM

The Bureau is comparing Rutherglen’s raw minima with the adjusted data from Wagga Wagga, Deniliquin, and Kerang.  Three questions immediately spring to mind:  1. As Dr Marohasy points out, what is the Bureau doing comparing raw with adjusted data?  Of course they’re going to have different trends!  2.  Why is Kerang shown, when Kerang is NOT included as a neighbour station used to adjust Rutherglen?  And 3.  What difference does this make?

Time for a reality check.

This graph compares like with like: raw minima for Rutherglen and the same neighbours.  Note that only Kerang is warming, and Wagga Wagga is flat, but Deniliquin and Rutherglen are cooling.

rutherglen comp raw

This graph again compares like with like, the same stations but with adjusted data.

 rutherglen comp adjusted

You might think that this shows Rutherglen is now homogenised with the others correctly.  However, when we examine the differences in anomalies from the 1961-1990 means between Rutherglen and the others, we get this:

rutherglen comp differences ADJ

They still got it wrong!  The trend in differences should be close to zero.   Rutherglen’s adjusted record is warming too fast (+0.5C per 100 years) relative to the three neighbours used by the BOM in their explanation.

And note that since 1974, Rutherglen’s minima have been cooling relative to the others.  Perhaps that cooling they corrected for was real after all?

Even if Rutherglen needs to be adjusted; even if these three sites are adjusted correctly; even if Kerang is one of the stations used by the Bureau to adjust Rutherglen- the adjustments at Rutherglen are over cooked.

The “scientists” in charge of the climate change department in the Bureau deserve all the ridicule they get.

More than that- they are not to be trusted with the nation’s climate history.  We don’t trust their data; we don’t trust their methods; we don’t trust their results; and we don’t trust their motives.