Archive for the ‘temperature’ Category

“Pause” Update

July 9, 2015

With the release of June data, showing the marked impact of a moderately strong El Nino, using UAH v. 6.0 data I have calculated the longest period back that the length of the pause in tropospheric temperature has been less than +0.01 degrees Celsius per 100 years:

Globally:

uah pause globe 0615

North Polar:

uah pause npol 0615

Northern Hemisphere:

uah pause nh 0615

Tropics:

uah pause tropics 0615

Southern Hemisphere:

uah pause sh 0615

South Polar:

uah pause spol 0615

Australia:

uah pause oz 0615

USA:

uah pause usa 0615

The El Nino will affect the length of the pause in some regions, but not all.  The pause continues!

The effect of two adjustments on the climate record

June 24, 2015

The warming bias in Australia’s ACORN-SAT maximum dataset is largely due to just two adjustments.

Last week’s Report of the Technical Advisory Forum’s review of the ACORN-SAT temperature reconstruction produced some rather bland, motherhood type statements.  However, hidden in the public service speak was a distinct message for the Bureau of Meteorology: lift your game.  Two of the areas I have been interested in are (a) whether individual adjustments are justified, and (b) the effect of these adjustments on national and regional temperature trends.  In this post I look at adjustments at just two sites, which are responsible for the single largest increase in national trend.

On page 17 of the Report we find the following graphic:

Fig. 1: Scatterplot of difference between AWAP and Acorn annual mean temperature anomalies.

scatterplot awap acorn mean diff

This is a clear statement of how much Acorn adjustments have cooled past temperatures, as AWAP is regarded as being only “partially homogenised”, and close to raw temperatures.   There is a considerable difference- more than 0.2 degrees- between the two interpretations of temperatures 100 years ago.

Mean temperature is the average of maximum and minimum.  In this post I shall look at just maximum temperatures, from 1911 to 2013.  The following graph is a plot of the difference between monthly Acorn and AWAP maximum anomalies, which I think is much more informative:

Fig. 2:

scatterplot awap acorn max months

Note there is a trend of +0.22 degrees / 100 years in the differences, indicating a predominance of cooling of earlier data; there is a very large range in the first 50 years, from about -0.7C to +0.3C, and one outlier at +0.4C, reducing to a much narrower band in the 1960s before increasing in the last 20 years; and the bulk of differences are negative before 1970.

Now let’s look at what has been happening in the past 35 years- in fact, in the satellite era:

Fig. 3: Monthly differences between AWAP and Acorn before and after December 1978

scatterplot awap acorn max phases

The trend in differences for the first 67 years is 0.33C / 100 years, but there is a very small tendency for Acorn to be cooler than AWAP recently- and the range of differences has been increasing.

That’s an interesting find, but I want to examine in more detail the effect of the adjustments which cause those differences.  Here are annual maxima in AWAP compared with Acorn.

Fig. 4: Annual mean of monthly maximum anomalies: AWAP and Acorn

graph awap acorn max

Again we see that Acorn has increased the warming trend from +0.59C to +0.81C per 100 years, an increase of +0.22C, or 37.3%.

However, the difference appears more marked before the mid 1950s.  The next graph shows the trends from 1911 to 1955 compared with the trends from 1956 to 2013.

Fig. 5: Comparison of trends in maxima before and after the middle of the 20th Century.

graph awap acorn phases

Note: while the trends of AWAP and Acorn are very similar (+1.32 to 1.4C per 100 years) since the 1950s- which the Bureau never tires of proclaiming- before then the plot tells a different story.  Acorn reduces the cooling trend by 0.44C per 100 years, a reduction of 86%.

How was this achieved?

On page 44 of the technical paper CTR-050 we find this explanation:

Returning now to maximum temperature, the differences between the AWAP and ACORN analyses show a marked drop in the early 1930s, with a sudden decrease of about 0.15 °C. This is most likely attributable to substantial negative adjustments between 1929 and 1932 in the ACORN-SAT dataset, indicating substantial discontinuities (expressed as artificial cooling) at a number of individual locations with a large influence on national analyses, because of the sparsity of data in their regions in that period. These discontinuities are mostly related to site moves that are associated with concatenated records for single locations. These include Alice Springs, Kalgoorlie and Meekatharra. Alice Springs, where the adjustment is associated with a site move in late 1931 or early 1932 from the Telegraph Station to a climatologically cooler site in the town, has a notably large “footprint”; at that time there were only two other locations within 600 kilometres (Tennant Creek and Charlotte Waters) which were observing temperatures, while the nearest neighbours to the west (Marble Bar and Wiluna) were more than 1200 kilometres away.

This large change between AWAP and Acorn is shown in the next graph.

Fig. 6: 12 month mean difference in monthly maxima anomalies

graph awap acorn diff 1930 drop

As I explained in my post in September 2014, Acorn sites are homogenised by an algorithm which references up to 10 neighbouring sites.  A test for the validity of the adjustments is to compare the Acorn site’s raw and adjusted data with those of its neighbours, by finding the differences between them.  Ideally, a perfect station with perfect neighbours will show zero differences: the average of their differences will be a straight line at zero.  Importantly, even if the differences fluctuate, there should be zero trend.  Any trend indicates past temperatures appear to be either relatively too warm or too cool at the station being studied.  My aim is to check whether or not individual adjustments make the adjusted Acorn dataset compare with neighbours more closely.   If so, the trend in differences should be close to zero.

I have tested the three sites named above.  I use differences in anomalies calculated from the mean of maxima for the 30 year period centred on 1931, or for the period of overlap if the records are shorter.  The neighbours are those listed by the Bureau on their Adjustments page.

Fig. 7:  Meekatharra differences from neighbours (averaged)

Meek acorn v neighbours avg

Note that the Acorn adjustment (-0.77C at 1/1/1929- the adjustment of +0.54C at 1/1/1934 does not show up in the national signal) is indeed valid: the resultant trend in differences is close to zero, indicating good comparison with neighbours.  However, since Meekatharra’s record starts only in 1927, two years of the Meekatharra adjustment cannot have had a large influence on the national trend as claimed.

Fig. 8:  Kalgoorlie differences from neighbours

Kalg acorn v neighbours avg

Kalgoorlie’s steep cooling compared with neighbours (from 170 km to 546 km away) has been reversed by the Acorn adjustment (-0.62C at 1/1/1930- the adjustment of -0.54C at 1/12/1936 does not show up in the national signal), so that Kalgoorlie now is warming too much (+1.02C / 100 years more than the neighbours).  Kalgoorlie’s adjustment is too great, affecting all previous years.

I now turn to Alice Springs, which ‘has a notably large “footprint”’.  Too right it does- its impact on the national climate signal is 7% to 10%, according to the 2011 Review Panel, p. 12.

Fig. 9:  Alice Springs differences from neighbours

Alice acorn v neighbours avg

Alice Springs, cooling slightly compared with neighbours, has been adjusted (-0.57C at 1/1/1932) so that the Acorn reconstruction is warming (+0.66C / 100 years) relative to its neighbours.  The adjustment is much too large.

And exactly where are these neighbours?

Tennant Creek (450 km away), Boulia (620 km), Old Halls Creek (880 km), Tibooburra (1030 km), Bourke (1390 km), and Cobar (1460 km)!

The site with the largest impact on Australia’s climate signal has been “homogenised” with neighbours from 450 km to 1460 km away- except the adjustment was too great, resulting in the reconstruction warming too much (+0.66C / 100 years) relative to these neighbours.  The same applies at Kalgoorlie.  Meekatharra’s record only starts in 1927 so its effect can be discounted.  These are the only remote Acorn sites that had large adjustments at this time.  All other remote Acorn sites open at this time either have similar trends in raw and Acorn or had no adjustments in this period.

The 37.3% increase in the trend of Australian maxima anomalies in the “world’s best practice” ACORN-SAT dataset compared with the “raw” AWAP dataset is largely due to just two adjustments- at Kalgoorlie and Alice Springs- and these adjustments are based on comparison with distant neighbours and are demonstrably too great.

If it wasn’t so serious it would be laughable.

Open Letter to Bob Baldwin

June 15, 2015

Dear Mr Baldwin

What does it take to get action following a formal complaint?

I draw your immediate personal attention to this matter.

It is now fully 11 weeks since I submitted four simple questions to Dr Vertessy’s office (Reference REF2015-089-17) , nine weeks since my follow up request with a copy to you, and four weeks since I made a formal complaint to you.  Sam Hussey-Smith of your office emailed me on Tuesday 19th May, saying he would “seek to get a response as soon as possible”.

Still nothing.

I may be a mere insignificant individual with a minor query, but surely I deserve to be treated with a little respect, and surely the Bureau of Meteorology, the Environment Department, and the office of its Parliamentary Secretary, all need to demonstrate transparency and public accountability.

Perhaps Dr Vertessy hopes I will get sick of waiting and will lose interest, saving him the embarrassment of an apology and a probable retraction.   He should not underestimate my determination.  The longer he delays, the more it looks as if he has something to hide.

I seek your urgent personal intervention to ensure an immediate response.

Yours sincerely

Ken Stewart

 

Here is my formal complaint, sent 4 weeks ago (18 May).

Dear Mr Baldwin

Formal Complaint re: Dr Bob Vertessy, Director and C.E.O. of the Bureau of Meteorology

It is seven weeks since I submitted four questions to Dr Bob Vertessy, Director and C.E.O. of the Bureau of Meteorology, through the Bureau’s feedback channels, and two full weeks since I followed this up with a complaint with a copy to your office.  The Bureau acknowledged receipt (ReferenceREF2015-089-17) and an officer of the Bureau has confirmed that my queries were indeed passed on to the Director’s office.  However, there has been no other response at all, either from the Bureau or from your own office.

Seven weeks, Mr Baldwin, seven weeks!  This is beyond simple negligence.  It is now in the realm of conscious breach of the Bureau’s own Service Charter for the Community proudly displayed athttp://www.bom.gov.au/inside/services_policy/serchart.shtml .

Dr Vertessy demonstrably fails to meet several elements of his own Charter, in that:

  • I have not been treated with respect and courtesy;
  • The Director has not been clear and helpful in his dealings with me, and has given no reason for delay;
  •  My enquiries, which it appears the Director cannot answer, have not been referred to an appropriate source;
  • The Director has not dealt with my enquiries and subsequent complaints quickly and effectively;
  • The Charter claims the Bureau will “Reply to your letters, faxes and e-mails within two weeks – on more complex issues, our initial reply will give you an estimate of the time a full response will take, and the cost, if any.”  While lower level officers reply courteously well within this time (usually within hours or at most days), it seems the CEO is above this requirement.

It seems the Bureau has a long way to go in its aim to “Develop a more streamlined system of handling your enquiries and feedback on our services”.

I therefore request that you act to obtain for me an immediate reply to my queries from Dr Vertessy.  I also expect his apology and an explanation for not meeting “acceptable standards of quality, timeliness or accuracy”.

Until then, Dr Vertessy’s lack of response speaks volumes about his own credibility as a scientist, a communicator, and the Bureau head, as well as the credibility and accountability of the Bureau of Meteorology as a whole.

Yours sincerely

 

 

 

Ken Stewart

Call that a Pause?

May 13, 2015

The length of the “pause”, “hiatus”, slowdown”, or “plateau”, whatever you wish to call it, is of great interest to sceptics and mainstream climate scientists alike, although Global Warming Enthusiasts such as John Cook try to pretend it doesn’t exist and/or is not important.

In this post I am showing the length of time during which the linear trend of temperatures is less than +0.01C per 100 years- i.e. zero or negative.  I use the UAH version 6 data to April 2015 which has been recently released, for various regions of the globe.  University of Alabama (Huntsville) data are derived from satellite radiosonde data for the lower troposphere.  These represent how the bulk of the atmosphere is behaving.

I am well aware of the criticism that commencing the trend calculation near the 1997-1998 El Nino may distort the trend, so these calculations merely show how far in the past we can go to find a zero or negative trend.  (In a future post I intend to exclude the big lump of data around this period for an alternative look at trends.)  In several of these plots there is very little discernible bulge around 1997-1998 at all, so I consider the trends are valid.

Firstly, how long is the pause globally?

Fig. 1:  Global data with zero trend (less than +0.01C/100 years) (Click to enlarge)

uah pause apr 15 globe

This includes the 1997-98 El Nino which may distort the trend calculation.  However, see several plots below which don’t show this effect.

Fig. 2:   North Polar (60 degrees North to 90 degrees North)

uah pause apr 15 npol

Despite claims to the contrary, during this admittedly short period the Arctic has not been warming.

Fig. 3:  Northern Hemisphere (Equator to 90 Degrees North)

uah pause apr 15 NH

Only slightly shorter than for the whole globe. Trend= +0.007C/100 years.

Fig. 4:  Southern Hemisphere (Equator to 90 degrees South)

uah pause apr 15 SH

This includes three years before the 1997-98 El Nino.  The trend is +0.006C/100 years.

Fig. 5: Tropics (20 degrees North to 20 degrees South)

uah pause apr 15 Tropics

The tropics include the Tropical Pacific where ENSO events are identified, and the pause extends well before the super El Nino.

Now you’ve heard that Antarctic sea ice is expanding to new records, but of course this is due to, variously, stronger katabatic winds and/or melt water filling the gaps and freezing over- all due to global warming naturally.  But you may have a suspicion that the Antarctic region is not actually warming as much as global warming enthusiasts would have you believe.  Has there been a pause in Antarctica?

Fig. 6:  South Polar region (below 60 degrees South)

uah pause apr 15 spol

Now that’s a Pause!

I also checked pause length for Australia and the USA.

Fig. 7: Australia

uah pause apr 15 aus

There does not appear to be an unusually large spike during 1997-98.

What about our North American cousins?

Fig. 8: Contiguous USA

uah pause apr 15 usa48

The effects of the 1997-98 El Nino do not have a large influence here either.

Note to Global Warming Enthusiasts: The Pause is real!  Build a bridge and get over it!

Beef Week, PETA, and Dr Vertessy

May 11, 2015

Last week was Beef Australia 2015 in Rockhampton.  The bus trip and the day I attended were thoroughly enjoyable, very professionally run, and a credit to the organisers and the beef industry generally.  The way the beef industry adapts to changing conditions through technology is fascinating.

One incident is worth repeating.  A chap was wandering around Beef Week wearing a cap with PETA embroidered on it.  Naturally people were pretty suspicious of him until they read the words printed in tiny script- “People Eating Tasty Animals.”  I’d like a cap like that.

I was pleased to find the Bureau of Meteorology stall, and met the local observers as well as Jess Carey of the Brisbane office, who instantly remembered my queries to Dr Vertessy about his claims on ABC Radio.  A thoroughly nice fellow.  He assured me he had forwarded on my queries within minutes, but had no idea of the reason for the delay in replying.

Speaking of which, today is six weeks since I sent my query to the Bureau, and still no reply.

Dr Vertessy’s lack of response speaks volumes about his credibility as a scientist, a communicator, and the Bureau head, not to mention the evidence for his claims.

The longer the delay, the more sceptical I am of anything the Bureau says about climate.

Still No Reply From Bureau Boss

April 28, 2015

On Monday 30 March I asked Dr Vertessy five questions about his claims on ABC Radio the day before.  So far, not a word in reply.

This afternoon I sent a reminder email to Jess Carey of the Brisbane BOM office, who had passed on my queries on Tuesday 31 March to the Director’s office.

Good afternoon Jess

As it is now four weeks since you passed my queries to the Director’s office and there has been no response, I can only assume that
(a)  this has been inadvertently overlooked and a reminder memo from you will prompt an immediate, apologetic, and informative reply,
or
(b)  no reply will be forthcoming, as an honest reply is not possible without embarrassing the Director.
I will expect a reply by 5.00 p.m. Thursday 30/04/2015.
Yours sincerely (and I do not imagine the delay is at all your personal responsibility)
Ken Stewart

Are We Getting More Heatwaves? Part 2

April 22, 2015

It is now over three weeks (15 business days) since I questioned Dr Vertessy on his claims in his ABC Radio interview, but still no reply.

To test Dr Vertessy’s claim that we are seeing “of the order of five times the number of very serious heatwaves” as in the middle of last century, I have continued to use the following metric:

“Three days or more in a row in summer (December- February) where the maximum temperature is in the top 5% of temperatures for that day at that location, with daily benchmarks calculated using daily maxima for each month from 1961 to 1990.”

I have also used as an absolute metric of very hot days the Bureau’s own definition, days above 40 degrees Celsius.  I have used ACORN-SAT maxima to 31 December 2014 downloaded directly from the Bureau’s Acorn site, and daily maxima from 1 January to 28 February this year for each site, downloaded from Climate Data Online.  I have calculated decadal running counts of the number of days meeting the criterion to show how hot weather has changed over time.

In this post I have looked at rural locations to the north and west of Melbourne, including far western New South Wales and northern Victoria.  Where there is a continuous ‘raw’ record, I compared with raw data.

Once again, results are mixed, but I also came up against the major difficulty in analysing Australian temperatures- missing data.

I’ll first show a group of locations that appear to support Dr Vertessy’s claim.- Deniliquin, Nhill, and Kerang.

Fig. 1: Decadal count of heatwave days in Deniliquin

Decadal cnt 95 3d heatwaves summer Deniliquin3

Fig. 2: Decadal count of very hot days in Deniliquin

Decadal cnt 40 Deniliquin

Fig. 3: Decadal count of heatwave days in Nhill

Decadal cnt 95 3d heatwaves summer Nhill

 Fig. 4: Decadal count of very hot days in Nhill

Decadal cnt 40 Nhill

Fig. 5: Decadal count of heatwave days in Kerang

Decadal cnt 95 3d heatwaves summer Kerang

 Fig. 6: Decadal count of very hot days in Kerang

Decadal cnt 40 Kerang

Deniliquin, Nhill, and Kerang all appear to show the present decadal count of both heatwave days in summer and very hot days to be very much greater than- 4 to 5 times greater than- that of the count to the mid 1950s.  But next consider Tibooburra.

Fig. 7: Decadal count of heatwave days in Tibooburra

Decadal cnt 95 3d heatwaves summer Tibooburra

Acorn shows the recent peak, and the number of heatwave days in the decade to 1915 is about the same as the 1920s and 1940s- early 1950s.  The raw record shows the current count is about the same or even less than in the 1950s.

Fig. 8: Decadal count of >40C days in Tibooburra

Decadal cnt 40 Tibooburra

This shows a distinct rise to 2007, with a small decline since, but still above anything previous.  However, consider the following.

Fig. 9:  Decadal percentage of available data at Tibooburra

Decadal percent obs Tibooburra

With up to a third of data missing in Acorn, the heatwave and very hot day counts are too low for more than two decades.   The apparent dip in the decadal counts can be attributed to missing data.

This problem is as bad or worse at Nhill and Kerang.

Fig. 10:  Decadal percentage of available data at Nhill

Decadal percent obs Nhill

Fig. 11:  Decadal percentage of available data at Kerang

Decadal percent obs Kerang

A fair comparison is not possible.  Only Deniliquin can conclusively confirm Dr Vertessy’s claim.

I now turn to Bourke, Cobar, Walgett, Mildura, and Rutherglen.

Fig. 12: Decadal count of heatwave days in Bourke

Decadal cnt 95 3d heatwaves summer Bourke

 Fig. 13: Decadal count of very hot days in Bourke

Decadal cnt 40 Bourke

Bourke has five to ten more heatwave days than in the 1950s, not five times more.  (The peak 10 years ago got to twice as many.)  The effect of adjustments can be clearly seen, but even Acorn shows the number of very hot days (>40C) is less than the 1920s.

Fig. 14: Decadal count of heatwave days in Cobar

Decadal cnt 95 3d heatwaves summer Cobar

Fig. 15: Decadal count of very hot days in Cobar

Decadal cnt 40 Cobar

Cobar has recently had twice as many heatwave days as the 1950s, but less than the early 1930s, and the recent very hot day peak is less than the 1940s.

Fig. 16: Decadal count of heatwave days in Walgett

Decadal cnt 95 3d heatwaves summer Walgett

Fig. 17: Decadal count of very hot days in Walgett

Decadal cnt 40 Walgett

Walgett has many fewer heatwave and very hot days than the 1940s.  To 2015, the decadal count of heatwave days is half that of the mid 1950s.

Fig. 18: Decadal count of heatwave days in Mildura

Decadal cnt 95 3d heatwaves summer Mildura

Fig. 19: Decadal count of very hot days in Mildura

Decadal cnt 40 Mildura

The recent/ current peak in decadal counts of very hot/ heatwave days is about twice that of the mid 1950s, but not markedly higher than the 1940s and late 1960s.

Rutherglen is interesting.  Here is an example of how one extreme season can affect the record, with a large step up in the 1938-39 summer, but Acorn adjustments have increased the decadal count in the 1940s even more.

Fig. 20: Decadal count of heatwave days in Rutherglen

Decadal cnt 95 3d heatwaves summer Rutherglen

Fig. 21: Decadal count of very hot days in Rutherglen

Decadal cnt 40 Rutherglen

Acorn does not always cool the past.  In Rutherglen adjustments have increased the number of very hot days in the record from 1939 to the late 1940s, garbling the climate record.  Unfortunately for the Bureau, this shows heatwave days in the decade to 2015 a bit more than twice the number to 1955, but less than the 1940s.

And who knows how many heatwave days were between 1959 and 1965:

Fig. 22:  Decadal percentage of available data at Rutherglen

Decadal percent obs Rutherglen v raw

Rutherglen has November 1959 to December 1965 missing, which makes comparison with the mid 20th century period somewhat difficult.

Conclusion:

So, are rural sites getting about five times more very serious heatwaves now compared with the middle of last century?  At six of nine rural sites in western NSW and northern Victoria, No.  Only Deniliquin definitely supports Dr Vertessy’s claim.  While some sites (Nhill and Kerang) appear to support the claim, fair comparisons are not possible because up to a third of data is missing from crucial years.  None of the other sites support his claim (although no doubt careful selection of comparison periods will allow global warming enthusiasts to agree with him).  Most show similar or higher frequency of heatwave days than now, before the 1950s.

We are not getting more heatwaves.

Are We Getting More Heatwaves?

April 14, 2015

As it is now two weeks (nine business days) since I questioned Dr Vertessy on his claims in his ABC Radio interview, it appears an answer is still to be given, so I shall post what I have found so far.

Dr Vertessy claimed that we are seeing “of the order of five times the number of very serious heatwaves” as in the middle of last century.  Not knowing Dr Vertessy’s definition of a “very serious heatwave”, I have used the following metric:

“Three days or more in a row in summer (December- February) where the maximum temperature is in the top 5% of temperatures for that day at that location, with daily benchmarks calculated using daily maxima for each month from 1961 to 1990.”

I have also used as an absolute metric of very hot days the Bureau’s own definition, days above 40 degrees Celsius.  I have used ACORN-SAT maxima to 31 December 2014 downloaded directly from the Bureau’s Acorn site, and daily maxima from 1 January to 28 February this year for each site, downloaded from Climate Data Online.

Note that this does not consider other serious factors such as humidity or night time minima.

I have initially looked at all state capitals, and will later look at other locations.

I have calculated decadal running counts of the number of days meeting the criterion to show how hot weather has changed over time.

So what did I find to be the answer to “Are we getting five times more heatwaves than we did 60 years ago”?  Mostly no, but it depends where you look.

Fig. 1: Decadal count of heatwave days in Adelaide

Decadal cnt 95 3d heatwaves summer Adelaide

Yes, but the peak may be past.

Fig. 2: Decadal count of >40C days in Adelaide

Decadal cnt 40 Adelaide

This shows a distinct recent rise.

Fig. 3: Decadal count of heatwave days in Brisbane

Decadal cnt 95 3d heatwaves summer Brisbane

A peak 10 years ago, dropping to zero heatwaves in the decade to 2015.

Fig. 4: Decadal count of >40C days in Brisbane

Decadal cnt 40 Brisbane

One day, 22 February 2004.

Fig. 5: Decadal count of heatwave days in Darwin

Decadal cnt 95 3d heatwaves Darwin

As Darwin doesn’t have “summers”, the count was of all days.  Note the 1930s and 1970s.  Darwin is not seeing more heatwaves.  Darwin has never had a day over 40C.

Fig. 6: Decadal count of heatwave days in Hobart

Decadal cnt 95 3d heatwaves summer Hobart

Hobart has had no heatwave days in the past decade, compared with five in the 1950s.

Fig. 7: Decadal count of >40C days in Hobart

Decadal cnt 40 Hobart

Hobart has fewer extremely hot days than in the past.

Fig. 8: Decadal count of heatwave days in Melbourne

Decadal cnt 95 3d heatwaves summer Melbourne

Melbourne has fewer heatwave days than the middle of last century.

Fig. 9: Decadal count of >40C days in Melbourne

Decadal cnt 40 Melbourne

Melbourne has more very hot days than it did in the 1950s, but less than the 1940s.

Fig. 10: Decadal count of heatwave days in Perth

Decadal cnt 95 3d heatwaves summer Perth

Perth has had 10 heatwave days in the past decade.  In the decade to 1955 it had 6- but in the 1960s it had three times the current number.

Fig. 11: Decadal count of >40C days in Perth

Decadal cnt 40 Perth

The recent peak was one more than in the 1960s.  The warming since the 1970s is clearly visible.

Fig. 12: Decadal count of heatwave days in Sydney

Decadal cnt 95 3d heatwaves summer Sydney

Four days in the last 10 years, compared with zero in the 1940s and 1950s- but less than the 1960s.

Fig. 13: Decadal count of >40C days in Sydney

Decadal cnt 40 Sydney

The current peak of seven days in the past 10 years of very hot days is about the same as the 1940s and 1960s, but much less than the 1980s.

Technically, Dr Vertessy is correct in his claim of “of the order of five (four to six?) times the number of very serious heatwaves” as in the middle of last century, at Adelaide, Darwin, and Sydney, but not at Brisbane, Melbourne, Hobart, or Perth.  However, Sydney had far more in the 1960s, and Darwin had as many in the 1970s and far more in the 1930s.  Adelaide alone shows a clear picture of many more heatwave days in the past 10 years.

In several of the records it is possible to see cycles of 15 – 20 years duration.  While there is an argument that heatwaves and extremely hot days are weather events, not climatic, resulting from blocking highs or the lateness of sea breezes, these apparent cycles indicate a climatic influence.  What would cause blocking highs to be more persistent, or sea breezes to be consistently later, for 10 years or more?  Atmospheric circulation patterns, including the location of the sub-tropical ridge, would appear to be the major influence.

The longer term analysis from 1910 shows a more complete picture than since the 1950s.  Wouldn’t it be good to use “carefully curated” Acorn maxima from before 1910.

In a future post I will look at other locations, as a continent’s climate extremes can’t be usefully analysed with only seven sites.  As well, this analysis has used ACORN-SAT data only.   What will the raw data show?  Therefore I will also compare results for Acorn and raw.   Bourke might prove interesting.

Meanwhile, I am waiting patiently for Dr Vertessy’s response.  Apart from Adelaide, the state capitals certainly don’t support his claim.

The Bureau Boss on Temperature Trends, Heatwaves, and Climate Change

March 31, 2015

On Sunday profile on ABC Radio on Sunday 29 March, the Director and CEO of the Bureau of Meteorology was interviewed.  The whole interview is here:

http://www.abc.net.au/radio/programitem/peyl3MNdrQ?play=true

For a scientist who claims to be only interested in science and not in advocacy, he certainly sounds like a fervent Global Warming Enthusiast.

Here is the feedback I sent to the Bureau.

“[THESE QUESTIONS ARE DIRECTED TO DR. BOB VERTESSY, WHO WAS INTERVIEWED ON ABC RADIO ON SUNDAY]

Dear Dr Vertessy

I was interested to listen to your interview on Sunday Profile on ABC Radio yesterday, 29 March 2015. I was particularly interested in your comments regarding public criticism of the Bureau’s adjustments to temperature data, and on the increasing frequency in heatwaves.

Several times you stated that the adjustments “make no difference at all” to temperature trends, that the raw temperature data “tell exactly the same story”, and that we see “the same result (in temperature trends) for the whole continent” as for raw data.

You also stated that heatwaves are becoming “one of our most serious natural disasters”.  They are “a bit of a silent killer- it’s the number one cause of death.”  You also said, “We are probably seeing of the order of five times as many very serious heatwaves today as we did in the middle of last century.”

I have some questions.

Q.1: Can you please supply me with a reference to your data that show that the number one cause of death is heatwave?  I was sure it was cardio-pulmonary disease usually associated with very cold weather, with mortality rates much higher in winter than summer.  Perhaps you meant heatwaves are the number one cause of death when compared with other natural disasters, which is debatable.  This was not at all clear and must surely have misled some listeners.

Q.2:  Can you please supply me with a reference to your data that show five times as many very serious heatwaves today compared with the middle of last century?  Could you also please tell me your criteria for a very serious heatwave.

For the next question I refer you to Table 1 on page 14 of On the sensitivity of Australian temperature trends and variability to analysis methods and observation networks  (CAWCR Technical Report No. 050), R.J.B. Fawcett, B.C. Trewin, K. Braganza, R.J Smalley, B. Jovanovic and D.A. Jones , March 2012 (hereafter CTR-050).  This shows that quadratic change in mean annual temperatures from 1911 to 2010 in adjusted data of the ACORN-SAT network (+0.94C) is 36% greater than in the ‘unadjusted’ data of the AWAP network (+0.69C). For maxima, the change is 38.9%, and for minima is 34.1%.  In this paper the authors claim that the rise in unadjusted data is “somewhat smaller” than in ACORN-SAT.

Q.3:  In what way can 38.9%, 36%, or 34.1% difference in quadratic change be interpreted as “no difference”, “exactly the same story”, or “the same result”? 

Perhaps you should have told your listeners that the similarity was only since 1955, and that before this, raw data show temperatures (especially maxima) were cooling, but then 60 years is not such a long climate record for making trend analyses, and this may be confusing to those who cannot understand more than a simple climate narrative.

In the Concluding Remarks of CTR-050, p.50, the authors state that “further work will be undertaken to characterise in more detail these changes, particularly at the monthly and seasonal level”.

Q.4:  When can we expect to see the results of this further work published on the ACORN-SAT website?  If it is available elsewhere please refer me to it.  I am particularly interested in any difference in quadratic change in summer maxima between AWAP and ACORN-SAT, as this is relevant to heatwave analysis.

I look forward to your reply.”

For an explanation for my interest in comparison with AWAP data, see my analysis of monthly and seasonal differences in trends between AWAP and Acorn from October last year.  My calculations indicate a 200% increase in trend in summer maxima.

One might think that if Australia wide there has been a five-fold increase in the number of very serious heatwaves, there should also be some discernible increase in the number of very hot days.

To illustrate my incredulity about this claim, here is the timeseries graph of very hot days (BOM definition: >40 degrees Celsius) straight from the Bureau’s website:

 Hot days graph BOM

The linear trend (for what it’s worth) shows an increase of 0.02 days per decade.  That’s 0.2 of a day per hundred years, or 2 days in 1,000 years.  Scarey hey.

I will be following up on the hot days and heatwaves analysis in coming posts.

First Meeting of Technical Advisory Forum

March 27, 2015

The first meeting of the Clayton’s Review Panel was held yesterday.  The press release about the proceedings is here.

“The Technical Advisory Forum held its first meeting today to advise on part of Australia’s official climate record – the Australian Climate Observations Reference Network Surface Air Temperature (ACORN-SAT) data set.

Today’s discussions were robust and productive, and the Forum would like to thank the Department of the Environment for managing the Forum’s membership and assisting the Chair. The Forum would also like to thank the Bureau of Meteorology for providing information and answering questions on the ACORN-SAT data set.

The Technical Advisory Forum was appointed by the Parliamentary Secretary to the Minister for the Environment, the Hon Bob Baldwin MP as an independent advisory body to provide greater transparency and an impartial framework for quality assurance tests and analysis of the Bureau’s data sets.

In line with its Terms of Reference, the Forum discussed three aspects of ACORN-SAT: the extent of the public availability of the ACORN-SAT information; developments since the 2011 Independent Peer Review of the Bureau’s data and analysis methods; and the scientific integrity and robustness of the Australian climate record and the homogenisation process. The Forum considered a broad range of information and data concerning the management and development of the ACORN-SAT data set provided by the Bureau.

The Forum also received some additional information from members of the public about the data set. Members of the Technical Advisory Forum were appointed to provide advice on the basis of their formal expertise, and the Terms of Reference do not therefore require the Forum to receive public submissions. However, this additional information was provided to all Forum members to ensure that Forum members were aware of public concerns regarding the Bureau’s management of ACORN-SAT during their deliberations.

The Forum will deliver its report, including detailed recommendations, by June 2015.”

I’m not holding my breath.


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