The ABC of Rutherglen

IF global warming is the greatest moral issue of our time, then the truth really does matter. But this morning, I felt that I had been shut outside, or at least cut-off, without having a chance to tell the whole story.

Jennifer Marohasy feeling left out.

Jennifer Marohasy feeling left out.

Bronwen O’Shea the host of an ABC radio program for the Goulburn Murray, a region that includes the town of Rutherglen, was interviewing me.

Bronwen invited me on to her program, and also someone from the Australian Bureau of Meteorology to discuss the temperature record for Rutherglen. The Bureau declined.

Bronwen began the interview by suggesting that Bureau have only tweaked the figures for Rutherglen. I disagreed. I explained that the Bureau has actually completely trashed the temperature record by changing what had been a slight cooling trend into warming of 1.73 degree C for the last 100 years.

I also explained that this had been achieved by progressively dropping down the original temperatures from 1973. I wanted to explain that the largest change was back in 1913, with the difference between the actual recorded temperature, and the new official temperature a massive 1.8 degree C.

I was cut-off, before I got to explain too much.

I waited, assuming the line had dropped out. But after no one phoned me back I rang back myself. I phoned ABC Goulburn Murray and was put on hold. Guess whom Bronwen was now interviewing?

Answer: the infamous John Cook, a faux sceptic from the University of Queensland.

    Answer: Someone who mentioned the blog site ‘Sceptical science’ and who I assumed was John Cook.**

Mr Cook

    This person

was telling Bronwen that the temperature record for Rutherglen had to be corrected because it was different from everywhere else.

But that is just not true. I haven’t looked at all the weather stations for Victoria. But I have looked at trends for all the stations with long continuous records for the state of New South Wales, which is just across the Murray River from Rutherglen.

Most of the inland records show a very similar trend to Rutherglen. In fact, if we consider the raw data for Deniliquin from 1913 through until the end of the record in 2003 we see a similar pattern of cooling.

Deniliquin is not some random choice of my own. It is listed in the Bureau’s official station catalogue as being one of three nearest sites to Rutherglen, the other two sites listed are Wagga Wagga and Cabramurra. I will look at the data for these locations in due course.

As detailed in my recent paper to the Sydney Institute: after considering all the locations in New South Wales where there are long continuous temperature records available, I have calculated that the net temperature change for New South Wales shows cooling of 0.021 degree per century. That is the net change for the entire state.

In contrast the BOM claims for NSW that there has been a 1 degree C per century warming.

Before I start doing the calculations for all of Victoria, I suggest you get the complete picture for Rutherglen.

To this end I’ve just created a dedicated page for Rutherglen and dedicated it to a real trooper and truth seeker, Judy Ryan.

Here’s the page…

http://jennifermarohasy.com/temperatures/rutherglen/

Now. Before anyone makes comment at this thread, could I suggest they at least scan the information as provided… sort of the ABC of Rutherglen that I wasn’t quite able to communicate this morning on the ABC.

* I have been contacted at my Twitter account to say that it was not John Cook. He apparently even has an alibi. So, sorry for misleading anyone. After I phoned back I was put on hold, and could hear Bronwen talking with someone. I wondered who that was. I heard them recommend the website Sceptical Science and assumed, it now appears incorrectly, that it was John Cook.

—————
Photograph by Lyndon Mechielsen.

43 Responses to The ABC of Rutherglen

  1. Ken Stewart August 28, 2014 at 3:57 pm #

    Hi Jen

    I’ll try and get my charts re those 3 sites to you for you to check sometime this pm…. still painting!

    Ken

  2. jennifer August 28, 2014 at 4:04 pm #

    Hey Ken,

    I look forward to seeing your charts for Deni, Cabramurra and Wagga Wagga!

    I’m concerned your numbers for Deni will only start at 1910… which is sort of wrong. I think we need to stop going along with the BOM on this one and begin the record from the beginning of when we have a record for where the thermometers were kept.

    Do you know when a Stevenson screen was installed at Deniliquin?

    The house must be looking good with all the painting?

    Cheers,

  3. Glen Michel August 28, 2014 at 4:14 pm #

    Unfortunately Cook is one of ourABCs go-to experts,with all that conspiracy ideation whatever and his multi -level knowledge in interdisciplinary science I’m afraid your up against it when you get some hack from regional radio who has no real life experience confirming her confirmation bias.Hope you had a good night at the surf club!

  4. Keith Minto August 28, 2014 at 4:38 pm #

    Jennifer,

    Icecap has a little more information on your find.

    “Ironically the changes in the United also had the biggest change was in 1913. Here in Maine, temperatures cooled by an unbelievable 5F in 1913 after the latest changes made this spring. That early record cooling ensure, the annual temperatures will rank among the warmest every year.

    The only common player in both countries changes was Tom Peterson of NCDC

    who engineered GHCN and USHCN and also was on the consulting committee advising/directing Australia on their updated data set. ”

    More details and hyperlinks at the site.

  5. spangled drongo August 28, 2014 at 5:08 pm #

    Jen, you could ask Bronwen to ask Cook how his 2 bil+ Hiroshima bombs are going in the Pacific lately?

    It seems they are only affecting temperatures in the Atlantic.

    But then they are not really sure.

    But when you need to cook the books, Cook’s your man.

  6. Paul Evans August 28, 2014 at 5:17 pm #

    It’s obvious that the BOM does not have a valid explanation for their adjustments – keep up the pressure Jennifer.

    Well done

    Paul Evans

  7. Debbie August 28, 2014 at 5:28 pm #

    It seems Larry was right when he commented that you must have hit a raw nerve?

    http://blog.hotwhopper.com/2014/08/weather-in-rutherglen-with-wuwt.html

  8. Larry Fields August 28, 2014 at 5:52 pm #

    Jennifer,
    Sorry to hear that you’re feeling left out. Please remember that you have a lot of friends you haven’t met yet — even as far away as the Peoples’ Republic of California!

    Also remember that, with some notable exceptions, there’s not a whole lot of integrity in the journalism biz. Pandering to the target audience, to the sponsors, and to the de facto goobermint censors, is the essence of the profession.

    Telling the truth is a secondary priority. Their attitude is summed up in Jack Nicholson’s famous line from A Few Good Men:
    You can’t handle the truth!

  9. Ken Stewart August 28, 2014 at 6:15 pm #

    I think you’ll enjoy this one Jen- some very odd data records!
    Chris or Lance might know about the Deni screen.
    The house is looking really good, only about a week to go, the living room looks like a bomb hit it tonight so I’ll finish as soon as I can.
    Ken

  10. Beth Cooper August 28, 2014 at 6:57 pm #

    The ends justify the means. The ‘News’
    hasta be ‘cooked.’Verify, verify, always
    verify. Bias confirmation remains
    the name of the game,
    alas!

  11. John Sayers August 28, 2014 at 6:58 pm #

    I’ve got this one Jen

    http://johnlsayers.com/Stuff/Deniliquin.JPG

  12. Ken Stewart August 28, 2014 at 7:43 pm #

    Preliminary charts sent, more investigation needed- I might even post re this tomorrow.

  13. Another Ian August 28, 2014 at 7:47 pm #

    Jen,

    Way back when CSIRO did such things Deni was the home of CSIRO’s rangeland section.

    And IIRC an irrigation research station.

    So there might be other records around.

    Just now – After using the googler I see you’ve probably checked this though

  14. Kathy Collinson August 28, 2014 at 8:06 pm #

    Totally agree with Jennifer Last 72 hour temperatures in Mildura on BOM have had an apparent temperature for some time but try and find out from NOM how they arrive at he apparent temp and they cant or wont tell you. Temperature is temperature it doesnt need adjusting especially it it forms the basis for climate change panic

  15. PaulNZ August 28, 2014 at 8:17 pm #

    I think its time for Tony Abbott to make some serious funding cuts to kill off this agenda driven cancer called the ABC.

    Bronwen O’Shea couldn’t add 2+2 by looking at all the “fluff” her life seems to be about. Poor child.

    On another topic, Have you thought of doing a favicon for your site!?
    Just upload one of your fine pic’s 😉 to http://www.favicon.cc/ and add the resultant
    Favicon to your site. It’ll make a nice bookmark.

  16. jennifer August 28, 2014 at 8:35 pm #

    Correction needed… the ABC apparently did try and phone me back this morning… Jo Nova explains what went wrong for them here… http://joannenova.com.au/2014/08/abc-invites-bom-and-marohasy-to-speak-bom-decline-marohasy-accepts-but-is-cut-off/

  17. cohenite August 28, 2014 at 8:36 pm #

    John Cook gets media dispensation everywhere. One can’t imagine why; his consensus paper is drivel; and did he really say this:

    “Mr Cook was telling Bronwen that the temperature record for Rutherglen had to be corrected because it was different from everywhere else.”

    One can only hope it is different from everywhere else; that’s the point; even the AGW scientists [sic] admit to great regional variation; or at least they use to; who knows what they are saying.

    One also wonders whether Cook rang in and Jennifer was shunted to give way to this VIP [sic] or whether the ABC rang him?

  18. Farmer Gez August 28, 2014 at 9:10 pm #

    Hey folks, don’t blame the presenter its the producers you should be after. Same thing happended during the GMO crop debates. There are back room evangilists at the ABC who tailor content to suit their pre-conceived agendas. You can’t see the damage White Ants do till the house falls down!

  19. Peter C August 28, 2014 at 9:36 pm #

    “Correction needed… the ABC apparently did try and phone me back this morning… Jo Nova explains what went wrong for them here…”

    Really! I did not see that on the JoNova page. I have asked the the ABC for a transcript.

  20. jennifer August 28, 2014 at 10:03 pm #

    Peter C.

    According to Jo they tried to phone me back but accidentally ended up with John Cook on the line. She is joking!

    Hey, I was set-up. But I’m laughing.

    Though if you do manage to get the transcript it would good to see.

    I approach these things with some trepidation…

    Then I was actually completely thrown when Brownen started by making the statement that the Bureau were just tweaking the numbers.

    What was I expecting? Perhaps a question?

  21. toorightmate August 28, 2014 at 10:38 pm #

    Adelaide has it’s fair share of green/left leaning folk who are acutely aware of environmental issues [and pay a bloody high price for power – something to do with wind farms methinks].
    Are these folk aware of the fact that Kent Town records just were not good enough to ALSO suit the “warming song”?
    I guess Kent Town was either too close OR too far from Adelaide?????

  22. Mikky August 28, 2014 at 11:28 pm #

    Surely the BoM versus Jen thing became Jen versus Cook when BoM declined to participate. Much more likely than calling Jen back and getting Cook by mistake.

    Being “cut-off” on live radio is surely commonplace, given that the clock is the ultimate ruler.

  23. A C Osborn August 29, 2014 at 2:20 am #

    Jennifer, I am not sure if you are aware of the work that others have carried out on the US data sets which compare with your (or Ken’s ) analysis.
    The other bloggers looking at what NCDC have done have found exactly the same thing that you have found for Rutherglen on the whole USA data network.
    They have found the same type of past cooling and slight current warming of the Raw data, but they have a lot more in the way of analysis.
    They have found that each time NCDC runs their data “correction” software (monthly) the data for many of the US sites changes each time, ie it in not a one off change.
    They have found many data readings replaced by “Estimated” data, especially over the last few years.
    They have found that the Raw Daily trend data does not match the Final daily data and that the it is even further from the Final Monthly data, ie there are 2 adjustments built in.
    The other bloggers who have analysed the the USA data are
    Steve Goddard (Real science)
    E M Smith (Chefio)
    Paul Homewood (Not A Lot of People Now That)
    Sunshine Hours
    Anthony Watts (WUWT)
    Evan m Jones (WUWT)
    and the latest one
    Walter Dnes (WUWT) whose study is here
    http://wattsupwiththat.com/2014/08/23/ushcn-monthly-temperature-adjustments/

    I am convinced that the Pal oops Peer Reviewed papers mentioned by BOM are those ones created for NCDC on TOBS and UHI and are most likely used by BOM.
    But it has been shown that the TOBS adjustments do not change the trend in line with those papers, they add whole degrees C to the trend not the 0.6 degree shown in the papers.

    Please let me know if you need any more links to the other work.

  24. Peter Azlac August 29, 2014 at 2:57 am #

    MAST values are a combination of heat flux from the surface by radiation, convective evaporation and conduction, and the temperature of the air in the prevailing weather front. The latter depends on the moisture content of the air whilst the former factors are most dependent on the moisture of the surface. This depends on soil structure that determines water capacity; hence heat capacity but also the ease with which that moisture can be evaporated from the surface. These factors differ between soil types with sandy loams having the highest combination of heat capacity and evaporative loss. The net result is that soils such as sandy loams will under the right conditions cause an increase in overnight minimum temperatures much like the urban UHI effect and will lower daytime maximum temperatures through evaporative cooling. The extent of evaporative cooling depends on surface roughness, vegetation, surface insolation, wind speed and atmospheric vapour pressure. These factors and more all come together to determine MAST values as per the model approach of Herb et al. and the data of Trenberth:
    http://static.msi.umn.edu/rreports/2008/319.pdf
    http://acacia.ucar.edu/staff/trenbert/trenberth.papers/i1520-0442-012-08-2451.pdf
    Of these effects that of soil moisture is the strongest as it mediates the flux of sensible heat between the surface and atmosphere:
    http://www.dca.ufcg.edu.br/mna/Anexo-MNA-modulo03g.pdf
    In part, this reflects a decrease in surface albedo with increased moisture content of bare soils:
    http://www.ias.ac.in/jess/aug2010/jess220.pdf
    The effects on Tmin and Tmax have been shown to vary with season:
    http://www.lasg.ac.cn/UpLoadFiles/File/papers/2013/2013-wly-zjy.pdf
    Soils that hold more tightly to water, such as clays and peat, do not show the same evaporative daytime cooling or night-time warming:
    http://www.newton.dep.anl.gov/askasci/wea00/wea00105.htm
    The effect of soil moisture on minimum temperatures is the most important as it has been found to be the main cause of `global warming`due to a narrowing of the diurnal difference between minimum and maximum temperatures and the use of Tmean values as Tmax+Tmin/2 rather than true average hourly temperatures or integration of continuous readings that reflect true heat flux. This is shown in studies in N Carolina and by Roy Spencer:
    https://www.nc-climate.ncsu.edu/sraman/publications/J164.pdf
    http://www.drroyspencer.com/2012/04/ushcn-surface-temperatures-1973-2012-dramatic-warming-adjustments-noisy-trends/
    So when BOM, BEST, CRU, GISS and NOAA use regional sites to correct apparent discontinuities the corrections only have validity if the sites have similar parameters as per the Herb model. The sum of these parameters is reflected in the Net Vegetative Index that reflects both the types of plants that grow on these soils and the yields. In the case of Rutherglen, Denniliquin, Wagga Wagga and Cabramurra this is not so: with Rutherglenn in an area of light soils supporting vines; Wagga Wagga apart from being large enough to have a UHI shadow has alluvial and clay soils that are subject to water-logging; and Denniliquin with clay loams that support wheat, irrigated rice and timber with irrigation known to have a large effect on MAST values as per the papers of Clive Best.

  25. Bob August 29, 2014 at 8:18 am #

    Go to the Australian press council. This is fr**d and the lies Cook tells need to be called out. This is not acceptable from tax pay funded public servants. If you don’t make a formal complaint then nothing will change. You can find the complaint form by doing a Google search. Change only happens if we take action and you are doing a great job 🙂

  26. Peter Nielsen August 29, 2014 at 8:29 am #

    “Fudged data” by any other name is fudged data, i e never as good as real data. That BOM and the ABC can imagine otherwise, let alone act on such woeful ideas as they have here (paid for by our taxes) is ABOMINABLE. Synonyms: loathsome, detestable, hateful, odious, obnoxious, despicable, contemptible, damnable, cursed, accursed, diabolical ! ! ! !

  27. Another Ian August 29, 2014 at 9:32 am #

    Jen,

    Not sure what went on – earlier I couldn’t see these comments. So now check out

    http://stevengoddard.wordpress.com/2014/08/28/understanding-mann-made-climate-change/

  28. nfw August 29, 2014 at 12:11 pm #

    I love this sentence “Mr Cook was telling Bronwen that the temperature record for Rutherglen had to be corrected because it was different from everywhere else.” If the data is “different” then just change it to make it what you want. Sounds entirely scientific and ethical for a warmist. Don’t want any of that pesky truth blotting their models. Keep up the good fight. And as for those above who suggest The Press Council, Their ABC is not bound by it as it has its own in-house checking organisation which no doubt homogenises the facts to ensure Their ABC is never wrong or in error.

  29. Tracey Conlan August 29, 2014 at 1:55 pm #

    And now #theirABC and Cook himself are claiming they were never even interviewed. Lucky we have you to tell us the truth Jen.

  30. jennifer August 29, 2014 at 2:16 pm #

    Thanks Tracey. I’ve just made a correction in the main body of the above post. It would be great if we could get the actual transcript.

  31. Dr Burns August 29, 2014 at 3:12 pm #

    I’m sure Andrew Bolt would give you a good run on the Bolt Report. I’d love to see it.

  32. Peter Azlac August 29, 2014 at 4:27 pm #

    In my previous response in an attempt at `brevity` I did not comment on Cabramurra, the third of the regional sites BOM used for correcting the data at Rutherglen. It is difficult to see why they would even consider this site for this purpose as it is at a much higher elevation, hence lapse rate correction is needed, and on a forested slope facing the Pacific Ocean that has a significant effect on MAST values. Frank Lansner with his Ruti project has shown that sites exposed directly to `ocean air `reflect the temperature of the ocean and have a different temperature trend than inland sites in the `ocean air shadow` He provides data for SE Australia:
    http://hidethedecline.eu/pages/posts/ruti-global-land-temperatures-1880-2010-part-1-244.php
    http://hidethedecline.eu/pages/ruti/coastal-temperature-stations.php
    http://hidethedecline.eu/pages/ruti/australia.php
    Additionally trees are known to increase cloud cover through the chemicals they emit that form nuclei for the formation of water droplets. This reduces surface insolation and increases the flow of ocean air so changing MAST values though increased evaporative cooling from higher wind flow but reducing surface insolation that will give a variable effect with season, in this case with winter snow.
    http://wattsupwiththat.com/2011/09/16/water-evaporated-from-trees-cools-global-climate/#more-47391
    Tim Ball has a good paper showing the impacts of micro, meso and macro climates across a coastal range like the west coast of the USA that fits well with the studies of Lansner.
    http://wattsupwiththat.com/2014/07/16/macro-meso-and-micro-climates-the-importance-of-trees-in-urban-climates/#more-113099

  33. Tracey Conlan August 29, 2014 at 5:00 pm #

    At least Jennifer can acknowledge when she’s made things up – shame the BoM can’t

  34. Robert August 29, 2014 at 5:01 pm #

    Cabramurra for Rutherglen is not far short of outrageous.

  35. cohenite August 29, 2014 at 5:53 pm #

    Peter Azlac, very good posts; Microclimatic Inhomogeneities can confound adjustments to raw data in 2 ways.

    Firstly the site needing adjustments may have particular climatic features unique to its situation which are in addition to the mechanical problems which the metadata may have revealed such as site shifts and discontinuities in the data stream.

    Secondly the neighbouring site which is being used as the reference point for corrections to the first site may have its own Microclimatic Inhomogeneities which may corrupt the transfer of its data to the first site.

    The issue is are these peculiar site climate effects legitimately dealt with in adjustments or not. If a site is warmer or cooler than a neighbour with no metadata revealing an obvious mechanical problem is it fair to correct the inconsistency between the 2 sites.

    The difficulty in distinguishing between localised climate which is genuinely natural and mechanistic Inhomogeneities which are not natural is often overlooked in the literature; for instance in Runnalls and Oke’s paper:

    http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3663.1

  36. Another Ian August 30, 2014 at 6:43 am #

    Jen

    And here

    http://bishophill.squarespace.com/blog/2014/8/29/more-on-cooks-97.html#comments

    and the comments!

  37. Ken Stewart August 30, 2014 at 8:46 am #

    I will try to post re Cabramurra later today (Saturday) or tomorrow. Interesting indeed.

  38. Larry Fields August 31, 2014 at 1:38 pm #

    Dr Ken Lynn August 30, 2014 at 5:46 pm #
    “5. Your work has pulled all the usual climate deniers out of the wood work and feeds the extreme bias of the Austra;ian newspaper for example. I don’t think this at all helpful.”

    Hey Ken,
    Congratulations! You’ve just won the prestigious Tautology of the Day Award. Don’t spend all of it in one place.

    I’ve never met, corresponded with, or even heard of a “climate denier” before. My educated guess is that they don’t exist. If I’m correct about this, then any statement that we choose to make about CDs is vacuously true, by the conventions of formal logic.

    Sample claim: All CDs wear blue robes with white stars, and can jump over tall buildings in a single bound. Since CDs do not exist, you cannot prove that this statement is false, can you? Long live content-free writing!

    Speaking of deniers . . . Jennifer’s blog post, about the open-and-shut case for data diddling at Rutherglen, has caused Pause Deniers to come out of the woodwork. Why? Because this is what typically passes for science in Warmist circles. The three major climate data bases, taken together, are one big goat f**k.

    On the other hand, the satellite data from UAH shows a zero warming trend for 16 years. Of course. this data has inevitable uncertainties, as do all measurement-based quantities. But at least Drs Spencer and Christie are honest scientists. Whatever errors they’ve made were made in good faith, and were not agenda-driven.

    Fragile egos and billions of dollars in goobermint-funded research grants, to support the foregone conclusion of Climate Change Scientology, are at stake here. Circle the wagons, boys! Take no prisoners! And burn all heretics at the stake!

  39. Larry Fields August 31, 2014 at 1:46 pm #

    Oops! Wrong thread. Sorry about that, Chief. My aging ‘puter has been playing tricks on me lately.

  40. Terry Brennan September 1, 2014 at 8:34 pm #

    Same old, same old.

    During the early days of so called water reform in the Macquarie Valley I was an active member of Macquarie River Food and Fibre (MRFF).

    When the draft plan for the Macquarie Marshes was released, there was call for comment etc informal, individual and otherwise from the community.

    It was decided that MRFF would deliver a formal response and individual responses would be provided by means of a form letter individually addressed and signed by each person, rather than a petition.

    My recollection is we distributed and collected something like a thousand of these letters, individually signed and addressed, the greater bulk showing addresser detail in handwriting with signature.

    The government agency classified these letters formally in documentation describing the community response as one letter the reason given as the content of these one thousand odd letters excepting for the ddetail of the addresser and the signature were identical.

    By comparison, there was what could be accurately described as a “handful” from the other side of the debate.

    This handful was also documented.

    Clearly a handful of responses supporting the draft plan would not be a good look against over a thousand responses protesting the equity of the plan.

  41. Peter Azlac September 2, 2014 at 7:17 pm #

    The problem of Rutherglen is indicative of a general problem in the IPCC version of climate science. This depends on the output of computer models, such that MAST values are assigned to the neat grids required in modeling – after being homogenized to provide individual cell values, or where stations are not present in cells invented using spurious techniques such as kriging that only has real application over homogenous areas. The result is computer models that do not reflect reality, as is seen in the IPCC AR5 report. As Briggs says empirical data is the real data and the use of statistics to produce homogenized data does not produce real data that can be used as such:

    Do not smooth times series, you hockey puck! http://wmbriggs.com/blog/?p=195

    Instead climate parameters, including surface temperature, precipitation, wind speed etc, are better represented by the irregular Köppen climate zones that result from such factors. This has been shown by Lohmann et al. – cited by Peel et a. (ironically from the University of Melbourne) in a review of the Köppen system – who found a good correspondence between the output of GCM and the Köppen zones and another paper by Kalvova et al. that compared the gridded climate data to the Köppen maps with good results.

    http://www.hydrol-earth-syst-sci-discuss.net/4/439/2007/hessd-4-439-2007.pdf

    The benefit of using Köppen zones is that they represent a real interaction with human needs for water, food etc with changes at the interface between zones having in some circumstances real consequences, as per the drought cycle that hits the Sahel and other desert areas. That this system is applicable to Australia is evident from the studies discussed by Peel et a. but especially as the country has a limited number of distinct zones that are, as one would expect from the links with agriculture, well covered with data on temperature,precipitation evaporation and some data on wind speeds and surface insolation:

    http://www.science.org.au/sites/default/files/user-content/nc-ess-pan-evap.pdf

    The eight major Köppen zones in Australia are common to similar zones in Western Europe and N Africa that are well represented by the CET temperature record of the UK that is based on records from a very limited number of meteorological sites but which reflects the AMO/NAO cycles. In contrast, for Auystralia, the BEST climate site gives details of some 180 sites with continuous or near continuous temperature records of over 100 years. Of these some 75 have Tmin and Tmax records for the same periods. As Tmin and Tmax are important in determining the causes of any temperature change as reflected in DTR values it is critical that stations used in the compilation of a series such as BEST, CRU, GISS, NCDC and Acorn are based on such records alone.

    Yet Acorn, that BOM claims is based on the best available records, uses only 26 of the BEST sites with 100 years of Tmin and Tmax data; instead using other sites where the Tmin and Tmax records only run post 1940 and for 55 of their 112 stations using sites that only started recording temperatures at all from this time onwards. The result is, as Briggs says, it is not data at all but modeled synthetic data that may conform to other synthetic series like BEST and the rest, but tells us little about the real trends in climate change. This is difficult to understand as as Trewin in a paper given at the Workshop on Pan evaporation – see above reerence – stated:

    All-Australian annual mean maximum and minimum temperature anomalies indicate that temperatures have increased since 1910, and particularly since the mid-20th century (Della-Marta et al. 2004; Figs 3, 4). Using only the observation stations considered to be free from the influence of urbanisation, trends calculated over 1910 to 2003 are 0.06oC/decade for the mean maximum temperature and 0.11oC/decade for the mean minimum temperature. However, the magnitude and sign of these trends varies throughout Australia. Increases in daytime maximum temperatures since 1910 have been particularly strong in the western two-thirds of the country, with isolated parts of central and eastern New South Wales and southern Queensland recording weak cooling trends. Positive trends in minimum temperatures have been stronger than for maximum temperatures, and strongest in the northeast. Trends since 1950 also show warming through most of the country.
    With mean minimum temperatures generally warming faster than mean maximum temperatures, there has been a decline in the mean diurnal temperature range over Australia (Figure 5). This decline was most marked over the period from about 1950 to 1980, and has levelled off since about 1980. This decline in diurnal temperature range over Australia is consistent with global trends (Braganza et al., 2004; Easterling et al., 1997)`.

    The difference in the trend between Tmin and Tmax is the Diurnal Temperature Range or DTR. Whilst it is claimed that there is a general global decrease in DTR values over the 20th century, and especially since the 1960´s this trend is by no means universal and can occur for several reasons, a decrease in Tmax, an increase in Tmin or both simultaneously. Further these trends can differ by season, for example in N China they have found asymmetric effects linked to changes in soil moisture with stronger negative effects of Tmax over Tmin in Summer and Spring and stronger positive effects of increased Tmin over Tmax in Autumn but the magnitude of the responses varies with climate Köppen zones.

    http://bobtisdale.wordpress.com/2013/06/20/model-data-comparison-daily-maximum-and-minimum-temperatures-and-diurnal-temperature-range-dtr/

    This has consequences in using Tmin from one climate zone to correct temperatures in another, as per Rutherglen This is of particular importance in SE Australia where there are six distinct Köppen climate zones with Rutherglen in a different zone to Wagga Wagga, Deniliguion and Cabamurra that are also in different Köppen zones.

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