Historical Note: Greenwich, England Mean Temperature, 35-yr Daily Averages 1815-1849

Guest Essay by Kip Hansen

While researching for a future essay tentatively titled “Whither Original Measurement Error?”, I have been reading up on the origins of the modern meteorological thermometer. Fascinating stuff, those early scientific instrument makers and their creativity and engineering skills.

I came across an interesting little [e]book that was just the sort of thing I was looking for, written by John Henry Belville in 1850, who started work at the Royal Observatory, Greenwich, Kent, England, in 1811 as a meteorologist and was still at it 35 years later. Here I reproduce the Title Page and Preface from his book:

clip_image002

Included in this little volume is the following chart, which I offer here without comment for those interested in the fascinating study of the long-term Central England temperature record. This thirty-five year average, day by day, is fairly well guaranteed not to have been adjusted or modified in any way since its publication in 1850 and might have some use for comparison purposes.

clip_image004

* Concerning the decrease of the mean daily temperature from the 12th to the 14th of May, see Humboldt’s ‘Cosmos,’, vol. i. page 121. Bohn’s edition.

The small note under the chart was included in the book.  It refers to something in the great tome: Humboldt’s COSMOS; or a  Sketch of a Physical Description of the Universe.   Copies are available online, but I was not able to trace the exact reference.

The full Belville book is available to read online free – albeit through Google Play’s eBook app — at:

http://books.google.com/ebooks/app#reader/9L0ZAAAAYAAJ

It is a rather stiffly worded, but enjoyable, trip into the scientific past.

# # #

Moderation Note: I would appreciate links from [any reader] to good sources for historical sources of information on expected measurement errors of meteorological thermometers in use from 1850 to present, including narrative sources of “operator error”. (Example: Several years ago, I did a Surface Station Project interview in Santo Domingo, Dominican Republic, in Spanish, on how the Stevenson Screen thermometers were read there. Acceptable expected error according to the Chief Meteorologist? +/- 1 °C)

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97 Responses to Historical Note: Greenwich, England Mean Temperature, 35-yr Daily Averages 1815-1849

  1. Mike Wryley says:

    Compact prose it is not, but the average educated person of the 1800s appears more able to put a coherent sentence together than his brethren 200 years hence.

  2. Ian L. McQueen says:

    Minor correction to moderator: plurals are not made with an apostrophe, like “reader’s”, above. (Possible exception: Australia; when I lived there in the 70s I got the impression that one could not become a professional signmaker, as in window signs, unless one DID use apostrophes.)
    This is a VERY common practice, but should be avoided at all times.

    Ian M

  3. William Abbott says:

    Thanks for posting this. I share your interest in weather and climate history. Don’t hesitate to post again. I’m going to take a look at the book tomorrow.

  4. bernie1815 says:

    If the weather station was at the Greenwich Observatory, then it is in a relatively open area – part of the Royal Park – at the top of an old flood plain of the Thames – probably 200′ above sea level. There is a cluster of buildings around the Observatory so some local man-made impact is possible. It is unclear whether at earlier times there were additional buildings at the location. It is a beautiful area. I went to school in nearby Blackheath and our cross country runs included the nasty slopes to the left and right of the Observatory. The views of London from the Observatory and General Wolfe’s statue are spectacular.

  5. a reader says:

    Google play also has very early daily obs. for cities in the US, for instance Providence, RI. You can simply search forSmithsonion Contributions to Knowledge and meteorology and an assortment will come up. These are not the same records as are in World Weather Records summary books, but are the source records.

  6. Greg Goodman says:

    The errors introduced by the Stevenson screen itself is something that is worthy of evaluation.

    It was a consistent standard for a long time, which is good. However, even in perfect order as screen will not totally isolate the thermometer from solar heating on a clear day, especially one with little wind.

    There will be a small afternoon warming bias that will be function of sun-hours (clear sky conditions) and wind speed, ie not climate neutral.

    Once the screens have degraded ( see surfacestations.org) the situation gets much worse, leading to an age (time) related bias.

    We now have largely moved to pokey little plastic shielded thermistors which IMO are even more prone to an afternoon bias.

  7. G P Hanner says:

    That’s an interesting set of temperature means. For one thing, they are clearly measured in degrees Fahrenheit; for another, the summer temperatures are over ten degrees cooler than they were when I lived in England (East Anglia) in the early 1980s. Those averages do not reach 70 degrees, while in the early 1980s temperatures in well into the 70s were pretty common. When the temperature hit 80 or more the Brits were complaining that it was a hot day.

  8. Greg Goodman says:

    Time degradation leads to another problem when those who control the data start “homogenisation” . A Stevenson screen wiil degrade over time leaving a warming bias. However, when it gets restored or replaced, it will likely cause a dislocation in the record when compared to surrounding station data. This will lead ‘homogenisors’ to conclude an error in the data and “correct” the cooling by introducing an adjustment.

    That station record gets a few tenths of a degree bump and starts degrading all over again.

    When a neighbouring station gets cleaned, the same happens. Thus the whole record gets homogenised up.

    Time to get back to REAL unpasteurised data , accepting its uncertainties, and realistic uncertainty estimations.

    Speculative “corrections” do not reduce data uncertainty , they increase it.

  9. richard says:

    bit chilly in those days.

  10. Lance Wallace says:

    I may have found the reference in Cosmos regarding the depression of the temperature on May 12-14. (Although it seems to me the “depression” occurs on May 9 and 14).
    I downloaded one version of Cosmos from the gutenberg site http://www.gutenberg.org/ebooks/14565

    On p. 133, von Humboldt refers to a depression in temperature on the 12th of May associated with the November asteroids (?):
    “Since the period that streams of meteoric shooting stars were first considered with reference to the direction of their orbit as a closed ring, the epochs of these mysterious celestial phenomena have been observed to present a remarkable connection with the regular recurrence of swarms of shooting stars Adolph Erman has evinced great acuteness of mind in his accurate investigation of the facts hitherto observed on this subject, and his researches have enabled him to discover the connection of the sun’s conjunction with the August asteroids on the 7th of February, and with the November asteroids on the 12th of May, the latter period corresponding with the days of 
St. Mamert (May 11th), St. Pancras (May 12th), and St. Servatius (May 13th), which according to popular belief, were accounted “cold days.”*

    [footnote] Adolph Erman, in Poggend., Annalen, 1839, bd. xlviii., s. 582-601. Biot had previously thrown doubt regarding the probability of the November stream reappearing in the beginning of May (Comptes Rendus, 1836, t. ii., p. 670). Mädler has examined the mean depression of temperature on the three ill-named days of May by Berlin observations for eighty-six years (Verhandl. des Vereins zur Bedförd, des Gartenbaues, 1834, s. 377), and found a retrogression of temperature amounting to 2.2 degrees Fahr. from the 11th to the 13th of May, a period at which nearly the most rapid advance of heat takes place. It is much to be desired that this phenomenon of depressed temperature, which some have felt inclined to attribute to the melting of the ice in the northeast of Europe, should be also investigated in very remote spots, as in America, or in the southern hemisphere. (Comp. Bull. de l’Acad. Imp. de St. Pétersbourg, 1843, t. i., No. 4.)”

  11. William Cox says:

    As with most books.google.com ebooks, the book is available in a variety of formats, not just their eBook format.

    Go to the “eBook Free” red box and hover; then click on PDF (or whatever format you want usually including PDF and HTML, and often other formats.

    I downloaded the PDF (from scanned images) in this manner, and ran Adobe Acrobat Professional’s OCR on the text for easier searching and (e.g.) table copying.

    Search for the author + title words and you find http://books.google.com/books?id=uzVWAAAAcAAJ&pg=PP7&dq=John+Henry+Belville+meteorological+instrument&hl=en&sa=X&ei=Px0KU46IE_OFyQHq9oHABw&ved=0CDsQ6AEwAQ#v=onepage&q=John%20Henry%20Belville%20meteorological%20instrument&f=false

  12. Kip Hansen says:

    Reply to McQueen ==> Quite right , sir! Dashed this note off without the benefit of my better half and English grad editor. I know all these rules but by old fingers and eyes neither remember to type them nor catch them in my own editing.

    [There are very subtle differences between asking "readers" "any reader" and "all readers" to do something that editors and writers need to agree on, but lettuce not be too picky while choosing how to right a grammatical wrong. Mod]

  13. Ric Werme says:

    G P Hanner says:
    February 23, 2014 at 8:00 am

    That’s an interesting set of temperature means. For one thing, they are clearly measured in degrees Fahrenheit; for another, the summer temperatures are over ten degrees cooler than they were when I lived in England (East Anglia) in the early 1980s. Those averages do not reach 70 degrees, while in the early 1980s temperatures in well into the 70s were pretty common. When the temperature hit 80 or more the Brits were complaining that it was a hot day.

    Being “mean daily temperatures” they are likely the average of the low and high temperature, or probably morning and afternoon temperature.

    I dare say that Brits would complain loudly on days where the average temperature is 80°F.

  14. Elliott M. Althouse says:

    GP Hanner- The average summer average in London peaks at about 63.5 F. I believe you are referring to high temperatures, these are averages of high and low. Last 30 year average for London is high 71 low 56 in mid July.

  15. Elliott M. Althouse says:

    The current London temperatures are only on average 0.6 C. higher in summer now than then, according to these observations. How accurate were the thermometers used then?

  16. Col Mosby says:

    Seems to be measuring the last years of the ittle Ice Age.

  17. Kip Hansen says:

    Reply to Lance Wallace ==> Terrific detective work on Humboldt’s COSMOS. “Cold days” indeed. Very well done, sir. Thank you.

  18. Kip Hansen says:

    Reply to Greg Goodman [x2] ==> Thanks for your helpful input on errors introduced in the normal course of events in the use of Stevenson Screens.

  19. @bernie1815
    That wouldn’t be the ‘Blackwall Tunnel run’ from a school on Lee Terrace by any chance?

  20. Kip Hansen says:

    Reply to Mike Wryly ==> Amem! Certainly more able than I.

  21. JDN says:

    What was the site of these measurements? A hill? A tower? It would be incredible if they did 2 m temperature back then too.

  22. bernie1815 says:

    James: It certainly was!! I was there from 1960-1968. Bros Vincent, Alban, Richard, Leo, etc. Alas they pulled it down 3 or 4 years ago. In a strange twist of fate and time, after growing up in Massachusetts, my daughter lives next to the Park.

  23. Pat Frank says:

    I’ve published two papers in E&E on systematic error in the surface air temperature record; the first here (869.8 KB pdf), and the second here (1 MB pdf). I’ve most of the work done for two more.

  24. sonofametman says:

    My father worked as an observer and forecaster for the UK Met Office for his entire career. He spent 6 years on weatherships in the North Atlantic in the 1950’s. He was concerned that the sea surface and air temperature measurements were affected by things like evaporative cooling of water samples and heat radiation from the vessel (converted naval corvettes). He wanted to do some experiments to try and eliminate these sorts of errors by improving the methods, so he wrote to the top brass, but was ignored. The errors in these measurements will be all over the place depending on the season and the weather.

  25. Barry Cullen says:

    I don’t know if this has been pointed out yet but these “chilly” temperatures were measured towards the end of the last LIA and are therefore to be expected.
    BC

  26. Keith Willshaw says:

    JDN Asked

    > What was the site of these measurements? A hill? A tower?
    > It would be incredible if they did 2 m temperature back then too.

    The Greenwich Royal Observatory which is on a low hill east of London close to the River Thames

    Location 51.476864,-0.000491

    Google maps shows it jut fine.

    Keith

  27. Stephen Richards says:

    bernie1815 says:

    February 23, 2014 at 7:36 am

    Greenwich at that time was a small country village. I don’t know yet when the naval academe was built (but it must be on the web) because a lot of naval activity was focused at Portsmouth.

  28. Stephen Richards says:

    Elliott M. Althouse says:

    February 23, 2014 at 8:50 am
    The current London temperatures are only on average 0.6 C. higher in summer now than then, according to these observations. How accurate were the thermometers used then?
    The thermometer were as accurate as any modern Mercury instrument but the reading may have been suspect. I was trained as a boy to read them (took about 3 minutes) but you can misread quite easily if you are not concentrating on your position relative to the thermometer.

  29. @bernie1815 Well, what a small world!

    I was there 1971-79. Of those names you mentioned only Brother Richard is familiar to me. He was my form teacher for (part of) the second year and taught me Latin.

    My U6 year was the first year of a comprehensive intake. At the same time it went from three-form entry to four-form. Given how crowed things already were, that cannot have helped with the transition. The sixth-form was lost a long time ago (late 80s?) and it continued going downhill.

    Under the Academies programme, it (together with a neaby primary school) was replaced by a newly built school called St Matthew Academy which was built on The Cerdars and opened in 2007. The SJA buildings were demolished after then.

  30. Hoser says:

    Mike Wryley says:
    February 23, 2014 at 7:25 am

    QED. I suggest “thence”, possibly “whence”, or “since then” instead of “hence”.

  31. bernie1815 says:

    JBD – though that can hardly be your real name unless your parents had a strange sense of humour and read SF Comics. I suspect that Bob Mellish was still there, along with Chief and John Hillier. Many of my teachers were getting close to retirement at the time I left. Was Mick Sheridan there at that time? He was a classmate.
    Are you still in the UK or in the States?

  32. Kip Hansen says:

    Reply to Pat Frank ==> Thank you for the two E&E papers. I have been puzzled for the last several years by the lack of any real acknowledgement of original measurement error when the world is in a panic over changes as small as .5°C, which fall well within known likely error in gross measurement error. Time will tell. Thank you.

  33. markstoval says:

    … He wanted to do some experiments to try and eliminate these sorts of errors by improving the methods, so he wrote to the top brass, but was ignored. The errors in these measurements will be all over the place depending on the season and the weather.

    I dare say that there is much error in all our weather data sets and that is without the outright fraud of the government data sets of modern times. But then someone once said you go to war with the data set you have and not the one that you wish you had.

  34. markstoval says:

    Mods.

    And another short post goes to moderation. Please look for it.

  35. Stacey says:

    Kip
    The following link is to Professor Manleys paper on the CET. It may be of interest and actually he discusses the effect of urbanisation in temperature records.
    http://www.rmets.org.uk/sites/default/files/qj74manley.pdf

  36. Nigel S says:

    Royal Naval College, Greenwich was built as the Royal Hospital for Seamen from 1696 to 1712 and designed by Sir Christopher Wren who also designed the Royal Observatory ‘for the Observator’s habitation & a little for Pompe’. Other gems there include The Queen’s House, 1616 by Inigo Jones. Greenwich has been quite built up for at least 300 years.

  37. Elliott M. Althouse says:

    Sir Christopher Wren designed the original building at The College of William and Mary in Williamsburg, Virginia. It was completed in 1693 when the college began its charter. There are a couple of photos on the college website, wm.edu if anyone is interested. William and Mary was the first chartered college in the U.S., although Harvard managed to begin functioning sooner by one year. Williamsburg was the colonial capital of Virginia.

  38. bernie1815 says:

    Nigel: The cluster of buildings remains stunning. The question I have is whether the thermometer was moved and if buildings and/or walls were added or removed during the period. A few feet can also mean a change of 10 feet or more in altitude. My recollection is that there are small courtyards and enclosed areas, currently facing North. I think what may have been the living quarters face South away from the Thames.

  39. Kip Hansen says:

    Reply to Stacey ==> Thank you for the the link to Manley’s paper on Central England temperatures and urbanization.

  40. Kip Hansen says:

    Reply to Stephen Richards and Elliott M. Althouse ==> If they were using Six’s Max-Min thermometers, the original records I am researching list them as “troublesome” and less accurate than could be desired without careful calibration against a known standard. Stephen, are you saying that you received training on reading these? I know there were some museum pieces still around and in use. I’d be fascinated to read your narrative description of the method of reading them correctly.

  41. siliggy says:

    If Maximum recording thermometers were not used back then, these temps all need to be either compared to recordings of the same method or be adjusted UP by an amount that is perhaps greater than the claimed warming since then..

  42. YorkshireChris says:

    There was a paper published in the (UK) “Meteorological Magazine”, vol 106, 1977, by Joyce Laing that looked at temperature records in the UK. This confirms that the temperatures at the Greenwich Royal Observatory were recorded from 1841 in a “Glaisher Stand”, introduced by James Glaisher, the Superintendent at the Observatory. The stand was a vertical board 4 feet above the ground, on which the thermometers were mounted, sheltered from above. The stand was rotated on a central pivot so that the thermometers were always shaded from the sun, but this depended on the conscientiousness of the observers.

    In 1863 Thomas Stevenson designed the louvred “Stevenson Screen”, but this was not used at Greenwich for many years. There was a debate through the 19th Century about which type of screen gave the most accurate results for air temperature and a test was organised by J.G Symons (of British Rainfall fame) at Strathfield Turgiss, Hampshire, in 1868-70. Following these experiments the UK Meteorological Office recommended the use of Stevenson’s Screen as the standard screen in the UK. However, at the Greenwich Observatory the Glaisher Stand continued to be used until 1938, to preserve the homogeneous record. A Stevenson Screen was in place at the observatory from about 1900, but the readings from it were not published and the Glaisher Stand was only replaced as the formal recording location in 1938.

    The comparisons of the screens found that, in summer, often the Stevenson Screen recorded maxima about 1F lower than in the Glaisher Stand, although on some days the difference was as much as 3F. The Met Office no longer now appears to use the temperatures recorded at Greenwich in the Glaisher Stand in the historical record, so the 100F recorded on 9 August 1911 at Greenwich is no longer regarded as almost the highest temperature in the UK. The suggestion is an equivalent Stevenson Screen temperature on that date would have been 96.6F.

  43. bernie1815 says:

    One other commentary on the location of this station. The Observatory is close to a thickly settled area down by the river and to the West. This may be important because when Londoners used to depend almost exclusively on coal for warmth during the winter, the chances of smog were pretty high. Growing up in the 60s, there would be dense fog/smog to the South of the Observatory during the winter months sometimes lasting for days. It was so bad it was faster many times for me to walk home over Shooters Hill rather than stay on the bus. Obviously such local man-made weather conditions can play havoc with the temperature records. The replacement of coal by natural gas, better emission controls and the movement of industry out of London have all served to dramatically reduce the incidence of fog and increase sunlight compared to the 60s at least.

  44. YorkshireChris says:

    Further to my previous post, it would appear that the thermometers used at Greenwich were comparable to the standard maximum and minimum thermometers used in current times and certainly not the “Six’s” pattern of thermometer.

  45. @bernie1815
    Let’s not clutter this thread anymore. You can contact me at ugimill-0223 at yahoo.co.uk (squish).

  46. Jim Jelinski says:

    Hello to all.
    I have a question on the Stevenson screen coatings.
    My understanding is that for many years they were coated with whitewash, which would ‘wash off’ and expose a new, clean white surface with each rain.
    My understanding is that at some point the coating was changed to white latex paint.
    I know that in my local (Gulf South) climate, mildew often grows on latex paint, sometimes ‘white’ surfaces turn a color pretty close to black. This of course increases the heat absorption. The effect is probably not as pronounced in cooler, less humid climates.
    My question is this:
    How do ‘whitewashed’ Stevenson screens compare to white latex painted Stevenson screens?
    What is the effect of the change in coatings on the temperature readings?
    What is the typical effect on the heat absorption of the coating due to mildew, dust accumulation and aging of the latex paint compared to whitewash?
    Have any experiments or studies been done to examine the possible effect on temperature readings resulting from the change in coatings?

  47. Robtin says:

    A 31 day average max of 11F on one day in June and July in London seems remarkable to me.

  48. Robtin says:

    Sorry, that should be a 35 year average.

  49. Mike McMillan says:

    [There are very subtle differences between asking "readers" "any reader" and "all readers" to do something that editors and writers need to agree on, but lettuce not be too picky while choosing how to right a grammatical wrong. Mod]

    You need a comma between ‘readers’ and ‘any reader.’
    A comma should also go between ‘any reader’ and ‘and.’

    [The writer of a right correction to the moderator's written righting of a previous writer's righting of an earlier writer's right to write readers rightly or wrongly should understand that the moderator's right to write rightly about previous writers' rewriting rightly or wrongly is not rightly wound around the right writers' right to write wrongly. Mod]

  50. Louis says:

    If +/- 1 °C is an “acceptable expected error” for a surface station, then isn’t the estimated global warming over the past century of 0.8 degrees within the margin of error?

  51. Mike McMillan says:

    Jim Jelinski says: February 23, 2014 at 2:54 pm

    You’re new here, right?

    The difference between whitewash and latex was how this whole blog and the Surface Stations project got started.
    http://wattsupwiththat.com/about-wuwt/faqs/

  52. Kip Hansen says:

    Reply to Robtin ==> “A 35 year average max of 11F on one day in June and July in London seems remarkable to me”. I can’t seem to find where you get this data from? Can you clarify?

  53. Kip Hansen says:

    Reply to Mike McMillan and Jim Jelinski ==> I’ve asked for information on things that might affect original measurement errors on temperature records. Jim is quite right to inform me of the white wash/latex issue — and yes, if he was an old Surface Stations Project hand, as I am, and as Mike apparently is, he would know that the origins of the Surface Station Project pivot on that very issue. Thank you both for your contributions.

  54. RoHa says:

    All paper copies of this book should be destroyed, and all electronic copies should be deleted immediately, for the following two reasons.

    1. It is written in correct, coherent English.

    2. It contains uncorrected temperature data.

    Both these features are forbidden. The public must be protected from exposure to them.

  55. Kip Hansen says:

    Reply to Louis ==> My anecdote is one surface station in a foreign country. Their standard was, on an average day, +/- 1°C. And, yes, if that was true for ALL surface stations, then “the estimated global warming over the past century of 0.8 degrees” would be “within the margin of error”. It is, however, unlikely, that all the temperature records are of that poor a quality.

  56. Kip Hansen says:

    Reply to RoHa ==> +10 !

  57. Kip Hansen says:

    Reply to Mike McMillan ==> Well, thank goodness we’ve got that sorted.

  58. Kip Hansen says:

    Reply to YorkshireChris ==> Are you referring to the 1815-1849 period? The Sixe’s were still use, though manufactured by others, at the time of the HMS Challenger voyage in 1874 (?).

  59. Thanks, Stacey.
    Good link to Manley, 1974. CET 1659-1973 – qj74manley.pdf
    http://www.rmets.org.uk/sites/default/files/qj74manley.pdf

  60. Brent Walker says:

    There was a very large equatorial volcanic eruption in 1809 that cooled our planet considerably. This was followed by the huge eruption of Mt Tambora in Indonesia in 1815. These two eruptions were responsible for what was known as the coldest decade in 500 years. 25 years of the 35 year period of this study was within the Dalton grand minimum – known as the last phase of the little ice-age but it seems that temperatures in the Northern hemisphere only changed very gradually in the 1840’s.
    Extra volcanic activity in the 21st C is new straw that the warmistas are grasping to explain the 21st C warming hiatus. But there is no precise record of volcanic eruptions over the last few centuries to prove whether or not there is a 21st Century increase in volcanic activity. However there are very good records on the incidence of great (Cat 8 plus) earthquakes since 1950 and any increase in their incidence in the 21st Century would suggest that there would be a knock-on effect of higher volcanic activity. There were 18 of these earthquakes from 1950 to 2000 and 19 from 2001 until now. This suggests that there has been a significant increase in incidence.
    Japanese scientists have also directly linked the increase in galactic cosmic ray activity to increased volcanic activity. Overall galactic cosmic ray activity has been high so far in the 21st Century due to the concurrent low solar magnetic storm activity.
    So the question that the warmistas don’t want asked is: if nature is overriding man’s efforts to warm the planet in the 21st C could it also have also had a significant role in the warming that occurred in the 20th Century?

  61. BioBob says:

    Kip Hansen says: February 23, 2014 at 6:13 pm
    It is, however, unlikely, that all the temperature records are of that poor a quality.
    ——————————-
    that is hilarious !!
    Exactly how does one conclude any level of quality given that virtually ALL stations prior to the ‘electronic age’ had a non-replicated, non-random, sample size of ONE each per day ? Statistically, N=1 means variance is effectively infinite.

    There is nothing wrong with drawing conclusions equivalent to the anecdotal nature of such data. What is wrong is to assume such data has any real element of validity required for statistical rigor and drawing conclusions beyond the inherent level of certainty. Virtually ALL modern climate data assumes much more certainty than is warranted / appropriate given these sampling methods.

  62. goldminor says:

    bernie1815 says:
    February 23, 2014 at 7:36 am
    I went to school in nearby Blackheath and our cross country runs included the nasty slopes to the left and right of the Observatory.
    ——————————————————
    Nasty slopes build character. The coach taught us that If you want to pass up an opponent, pass him on an uphill for a psychological effect.

  63. Kip Hansen says:

    Reply to BioBob ==> I don’t quite get your point. My sample of one can’t auto-magically be applied to a set of thousands. I think we are agreeing… aren’t we? I am willing to assume that there were some more diligent souls keeping weather stations and probably some less diligent souls. I only know about the one station I have personal experience with, so far. Sort me out on this bit if you will.

    Meanwhile,

    I am not interested in “statistical” interpretations. Here I want to know about real original measurement error. Error in the instruments themselves (thermometers), the errors induced by screens and mounts, and the errors induced by operators. The difference between the actual physical temperature at the time of measurement and that registered by the measuring instrument and recorded by the site operator.

  64. Kip Hansen says:

    PS to BioBob ==> “Virtually ALL modern climate data assumes much more certainty than is warranted / appropriate given these sampling methods.” Amen to that! I’m working (for the last 6-9 months) on the original measurement error angle….”Whither Original Measurement Error?”. All we see are CI intervals, statistical artifacts, no estimates of actual errors at all.

  65. Kip Hansen says:

    Replt to Brent Walker ==> “if nature is overriding man’s efforts to warm the planet in the 21st C could it also have also had a significant role in the warming that occurred in the 20th Century?” Dr. Judith Curry asks the same question. May have been in her Senate testimony.

  66. BioBob says:

    You say you want to know about error but are not interested in statistical methods (including random sampling and an adequate number of replicates) that are the only valid means allowing scientists to reveal the magnitude of error. Good luck !

  67. goldminor says:

    Col Mosby says:
    February 23, 2014 at 8:54 am

    Seems to be measuring the last years of the ittle Ice Age.
    ————————————————————————–
    The Dalton gm ended around 1825. The average used for the above work starts in 1815, so 10 years of the Dalton were included in the data set.

  68. Robtin says:

    Kip Hansen,

    Sorry, my mistake, I misread 62.11 as 2 numbers min.max. I see my error now.

  69. DavidCage says:

    Mike Wryley says:
    February 23, 2014 at 7:25 am

    Compact prose it is not, but the average educated person of the 1800s appears more able to put a coherent sentence together than his brethren 200 years hence.

    Rather unfair since the number of educated people then as a percentage was so small that we now have far more than that able to read and write to an equal standard and there are many aspects that we now have to learn to prevent the same level of study of the detail of presentation they could indulge in.

  70. Chris Martin says:

    Reply to Kip Hansen: Six’s thermometers were certainly used in England at climatological stations – in some cases into the late 19thC, but the Meteorological Magazine article in 1977 that looked at British temperature records referred to Greenwich as having ‘standard thermometers’ and some other locations as ‘non standard’. I have taken this to infer that the thermometers at Greenwich were standard (i.e. pretty much like we’d use today) and remember that this observatory prided itself on being the best in the world at that time.

    However, there is another reason we need to be wary of these data for the period up to the 1840s. Greenwich often published mean temperature data based on the daily means of HOURLY temperatures. For example the data were published that way as late as the book by Marshall, in A Century of London Weather, 1952. Later the data were published differently to be based on the modern pattern of the mean of the daily maximum and minimum (for example in Brazell, London Weather, 1968). The mean temperatures can be 1F different by these methods. Certainly the figures shown in the table look very low. Greenwich means for 1921-50 show January at 39.8F and July at 63.7F. However, there were some very cool years in the 1810s…..

  71. ralfellis says:

    .
    I presume to be this cold, these are an average of day and night temperatures.

    ralph

  72. Nigel S says:

    bernie1815 says: February 23, 2014 at 1:14 pm

    Yes, I should have said that my note was a response to the suggestion by Stephen Richards: February 23, 2014 at 10:35 am in response to your: February 23, 2014 at 7:36 am that ‘Greenwich at that time was a small country village.’

    Ordnance Survey maps or Observatory records might help to establish changes to the buildings. The inch to the mile OS map of Kent was first published in 1801.

  73. redress says:

    ” but lettuce not be too picky while choosing how to right a grammatical wrong. Mod]”

    Ha, ha , ha….made my day…..all those correction purists and none noticed….

  74. rgbatduke says:

    JBD – though that can hardly be your real name unless your parents had a strange sense of humour and read SF Comics.

    Please! It just means that he is a Stainless Steel Rat. (Google it, buy the books, they are a light and amusing SF read by Harry Harrison).

    rgb

  75. bernie1815 says:

    rgbatduke: No problem. I had found the source of the name. I connected privately.

  76. rgbatduke says:

    If +/- 1 °C is an “acceptable expected error” for a surface station, then isn’t the estimated global warming over the past century of 0.8 degrees within the margin of error?

    No. Imagine measuring the heights of all of the students in a school with a meter stick. Let’s further imagine that you are a sloppy measurer and your measurements are only accurate within +/- 1 cm, but that your measurements are unbiased, that is, that you are as likely to err 1 cm (or less) up as 1 cm (or less) down. If the school has (say) 1000 students in it, the individual measurement errors will cancel in the mean, leaving you with a measurement-based error in the mean much smaller than 1 mm.

    The problem with temperature measurements are those pesky systematic errors. You are extremely conscientious and always read to the nearest mm or 2. Your friend who is helping you take data is lazy and always rounds down to the nearest cm, never up, and he is only measuring the elementary school students so all low measurements are exaggerated low. Another friend is the opposite — they like to round up, their meter stick is old and has 3mm worn away from the bottom end, and they are measuring the basketball team (who all come out a full cm too tall, on average. Because of the power of averaging, rather than measure every student in all of the classes, people measure the height of just three students from some of the classes, and then extrapolate the measurements across (say) the interval from second grade to tenth grade where sadly, no one thought to measure at all.

    The bulk of the error in the thermometric record is from precisely this sort of thing. For a stupendous stretch in it, we have almost no truly useful measurements for the 70% of the Earth’s surface covered by ocean (John Daly IIRC uncovered some truly horrendous sources of systematic error in the way oceangoing ships sampled sea surface temperatures — when they bothered to do it at all — along the principle shipping lanes, which constitute a tiny fraction of the whole ocean anyway). We have no useful coverage of whole continent-sized areas — Antarctica, central Australia, much of Africa, much of South America, and a good sized chunk of Asia were basically outside of the pale of instrumental civilization throughout the 19th and well into the 20th century, and when they did start to be sampled in the 20th century it was at a few well-defined urban locations that were both accessible and that had a relatively benign climate, not out in the wilds. “The wilds” are still horrendously undersampled and biased in their measurement even in the modern world by all means except satellite, which is one reason I “trust” UAH and RSS far more than I trust GISS or HADCRUT (quite aside from all of the ways the remote past data gets “adjusted” to presumably correct for all of these errors ON TOP of the substantial extrapolation errors introduced by using measurements in a few locations on the periphery of e.g. the Tibetan Plateau or the coast of Antarctica to infer temperatures for millions of square kilometers in a weighted average global surface temperature estimate.

    This is one of the things Lief is struggling to correct in the sunspot record. Even though “the rules” for recording sunspot counts have been consistently enough stated, even though the instrumentation used was unchanged or little changed over very long stretches of time, individual recorders ended up “counting” spots slightly differently over decadal stretches (representing an entire career as an observer), plus noticeable changes as instrumentation quality discretely improved. These biases are (apparently) enough to completely alter the record, to create grand maxima where none really occurred, to exaggerate grand minima. Or are they? In the case of sunspots, it is comparatively easy to check as people recorded sketches at first and later photographs of the sun’s surface for at least a fair number of days of the record, so one can try to second guess their counts against a modern “standard” and use this plus statistical analysis to try to come up with a systematic correction per observer (to the extent that even an observer’s measurement bias is stationary in time — it probably isn’t).

    I am a theoretical/computational physicist, and hence I get to deal with very systematic, typically unbiased error in e.g. Monte Carlo (where the biggest source of systematic bias are things like roundoff errors or biases in the random number generator used and hence managable although there are famous cases of either or both leading to complete garbage in long running computations). However, I work with friends who do experimental physics on e.g. the free electron laser or various accelerators or with ordinary lasers, and they have a hell of a time dealing with errors of all sorts in the analysis of their experimental data. Detectors often have a systematic bias, instrumentation in general has both systematic and random errors, human error creeps in everywhere, and nobody knows what all of the errors are in a complex measurement system and often there is literally no way to measure or infer the error from observation — it is what it is.

    If all you’ve got is a meter stick with a worn end, all of your measurements will be a few millimeters long but you’ll never know it unless/until you have some “gold standard” meter stick you can measure to compare to. It’s great when you do — and of course in the case of actual meters we can define them with great precision — but with thermometers it isn’t so easy.

    Both the Fahrenheit and Celsius thermometers are defined in terms of well-defined thermodynamic equilibrium points — a water/ice mixture, the boiling point of water, for example — with a fixed degree size in between and past both ends. However any actual thermometer’s accuracy depends on things like how precisely a hole can be drawn through glass, how precisely a bulb can be attached to the class with how precise an amount of e.g. mercury inside, how precisely the tube can be etched with a linear scale, how much the volume of the glass changes with temperature (noting that as the glass changes volume, so does the volume of the hole in the glass and hence the linear scale becomes nonlinear), and of course the fact that no material has a precisely linear thermal expansion coefficient so that in order to make a really precise mercury thermometer one has use nonlinear degree sizes. One even has a no-free-lunch element in their design — a very narrow hole makes comparatively large degree sizes (improving precision on the grid) but at the expense of increasing the nonlinear errors and increasing the engineering difficulty of building it in the first place. And at the end of the day, the thermometer is read for decades by a tall human who looks down on the instrument while reading it so that he always reads the meniscus of the mercury too high on the grid by 0.3C, to be replaced by a human who is shorter and reads the same instrument at eye level.

    It is very difficult to repair these measurement problems a century after the fact. As I said, my experimentalist friends have a difficult time either repairing or accounting for them all now, with the most modern of electronic instrumentation — how can one detect a problem with one’s measurement apparatus, after all? Many problems only arise transiently and are entirely absent when calibrating the instrumentation but appear only during actual measurement. Notably when the research professor does the calibrating using 20 years of experience and the greatest of care, but Joe the graduate student who likes to smoke reefer during his lunch break does the boring, repetitive measurements over two years of his life, infilling a bit of data missed because he zones out using from the day before with what he imagines to be “random” noise so nobody will ever know (humans, BTW, make terrible random number generators).

    Records like the one above are indeed useful, because at least it represents a record that is minimally contaminated by this sort of thing. The instrumentation was good, I’m guessing it was periodically checked and recalibrated, observations were made very systematically with respect to location and time, careful records were kept, and averages consistently evaluated. It is difficult for me to tell from the chart exactly how the “daily average” temperature was computed — there are enormously different ways, depending on how the temperature was sampled — but with luck the method used was carefully described in the text.

    Much has been made of resolution error on this list. It is very difficult to compare data with different spatiotemporal resolution. Casual electronic weather stations costing around a few hundred dollars and located in people’s back yards, that use wireless to update a computer with instantaneous temperature, wind speed and direction, humidity, barometric pressure, and cumulative rainfall, are now commonplace and their processed data can be readily accessed on the internet via e.g. the Weather Underground. Any of these stations is probably more precise than anything ever used back in the 19th or almost all of the 20th century even by professionals, and they are no more likely to be badly sited than any of the professional sites from Anthony’s direct observations. Their temporal resolution is astounding — one can actually create a credible true average temperature reading on a daily basis, if one can agree on what to call “a day” (is it midnight to midnight? noon to noon? 6 am to 6 am?) in the specific sense of summing (say) 1440 minute-grid measurements and dividing by 1440. It is rather certain that a record averaged in this way can in no way be compared to the “average” displayed in the chart in the top article, which is far more likely to average the max/min per day for the daily number, or perhaps (if they were willing to pay warm bodies to watch the thermometer all day and all night) hourly measurements. There is no way in hell they recorded temperatures minute by minute, though, as they’d fill paper books with the longhand-written data and they’d have needed multiple observers capable of doing a completely mind-numbing task perfectly for decades for 1440 measurements a day just to avoid huge gaps when somebody has to go to the bathroom.

    And really, there is little to stop modern weather stations from returning data a time granularity of 1 second, or even less. I’m guessing that the latch time on the analog to digital converters, plus the time needed for some electronic processing and the transmission of the actual packet, are the rate limiting factors and those could probably run at a granularity of 0.01 seconds or thereabouts, maybe even faster.

    The weather underground personal weather stations provide a stupendous resource for those seeking to understand things like the UHI. For one thing, they actually sample a (not really random, but “randomer”) field of locations with a spatial resolution of less than 10 km in many locations (e.g. around Durham where I live). For example:

    http://www.wunderground.com/wundermap/?lat=35.979&lon=-78.966&zoom=13

    I live almost exactly halfway between station 51 and the 1717 tag, right up against Duke Forest (the shaded green). Urban Durham is on the right side of the map, and the left side is dominated by rural/suburban neighborhoods mixed in with farmland and forest. Station 51 is terribly sited (I’ve written about it before) and consistently reads 1-2 degrees too hot (I’m guessing it is sitting right above their driveway or air conditioning unit on the southwest side of the house). I use unit 50, located in a field next to Duke Forest at Durham Academy about a mile from my house. It reads very close to what I read in my back yard without a PWS. All of the stations shown are substantially corrupted by UHI, and are located at different heights in the hilly piedmont. I’ve watched temperatures vary (drop) by as much as 3 C just driving from the physics building inside Duke proper (heavily paved and covered with buildings and up on a hill of sorts) down hill, around a corner into Duke Forest, down hill further to a creek, up a hill, and then down a hill into my neighborhood to my house — a total distance of maybe 3 km. They vary by 1-2 C from the front (SW facing, exposed on a hill that amplifies the solar heating of yard and especially driveway) of my house to the back (NE, with tall cypresses maintaining both shade and blocking the wind).

    It would be utterly fascinating to actually do a systematic study and put a dense grid of PWS units on a roughly 1 km grid with microlocation determined by a monte carlo process (to avoid biasing the location to always be someplace easy for humans to get to). I’ll bet that the area around Durham has an entire thermal profile as one goes up hills and down hills into microclimates that differ by 1-5 C in their mean temperature, systematically warming as one goes into Durham from the surrounding countryside on top of any geographical factors. UHI isn’t a simple correction — in fact, trying to correct for it in the absence of this sort of systematic study is probably impossible.

    To conclude, while plus or minus one degree accuracy in measurements doesn’t mean that averages will be that inaccurate, even instrumentation capable of much greater precision can still be even more inaccurate, and can be inaccurate in systematic ways that do not cancel in the mean. One cannot fairly compare data taken at different spatiotemporal resolution — low frequency measurements erase fluctuations that may or may not be themselves biased or that may or may not bias high frequency measurements relative to the low frequency measurements. One cannot easily “correct” the past temperature record or compare it to the present. And one day, I will talk about the dubious nature of treating the “anomaly” as if it were something that is known more precisely than the raw number across instrumentation and decades of time.

    rgb

  77. Kip Hansen says:

    Reply to BioBob ==> “only valid means allowing scientists to reveal the magnitude of error” We are obvious speaking different languages. I believe you are speaking “statistics” and I am speaking simple physical measurement — taking a temperature with a thermometer today (or any ‘today’ in the past), reading a thermometer, how to tell if a thermometer is accurately calibrated. If this explanation doesn’t clear up our disagreement, then we’ll just have to let it lie for now.

  78. Kip Hansen says:

    Reply to Robtin ==> No worries, mate! Glad we cleared it up.

  79. Kip Hansen says:

    Reply to rgb ==> Thank you for your informative (and entertaining) contribution on the effects of random and non-random errors introduced into temperature records. In the case of the Santo Domingo station temperature records, the errors depended greatly on the weather (if it was raining, the reading was done very haphazardly, a glance only) and on the height of the man on duty (as explained by the Chief Meteorologist – who was perfectly aware of the variables) which changed the angle at which the thermometer was actually seen by the recorder (many Dominican’s are quite short). The Chief tried to get the short ones to stand on a concrete block (which was to hand) to take the readings, but he was aware that they resisted this ‘demeaning’ solution.

  80. Kip Hansen says:

    Reply to Chris Martin ==> I’ll admit I haven’t read the whole little book yet. I will and I’ll see if he mentions which type of thermometer is in use at the Royal at the time. Sixe’s was pretty common as a Max-Min recording thermometer, and as I mentioned in another reply, as used on the great HMS Challenger voyage in 1874. Whenever I get to it, I’ll post the information here. As has come up from helpful readers, thermometers in this time period were fairly easily calibrated for freezing and boiling temperatures, but the in-between temps were less precise due to the unevenness of the size of capillary tubes for the mercury.

  81. Kelvin Vaughan says:

    richard says:
    February 23, 2014 at 8:10 am
    bit chilly in those days.

    I checked the average means in the CET for those years and compared them with 2013. Here are the results for each month. Six months of the year were colder in 2013. (-2.8 isn’t an error)

    0.9 -0.9 -2.8 -0.4 -1.0 -1.0 2.6 1.5 0.7 2.7 -0.0 2.2

  82. Kip Hansen says:

    Reply to Kelvin Vaughan ==> Very Interesting. Many other readers had noted that they though the early 1800s appeared chilly, and that Global Warming had warmed up Central England a bit, about 0.5°C — but now you come along and ….hmmm… I was going to say dispel that …. but I’m getting out my little calculator…..== +0.375°C to a rough-back-of-envelope 12-moth-average is a wee-bit warmer, with some months showing exceptional Coolth (especially Spring and early Summer) and Warmth (July, Oct and Dec) , comparatively. Have I got that right?

  83. ES says:

    Kip Hansen

    For records in Canada, the HBC Hudson’s Bay Company (some people call it Here Before Christ), kept temperature records going way back. In 1994 they donated their records to the Archives of Manitoba. Some of these can be searched on line.

    http://www.gov.mb.ca/chc/archives/index.html

  84. jim hogg says:

    rgb – your contributions here always raise the quality average by a statistically significant extent and introduce a long term upward bias in quality potential as a result of emulative, educational, and inspirational effects. I’m currently working on comparisons between the quantifiable results produced by your data x logic x argument + (clarity of expression squared)/reader numbers, and the actual anomalies of such in order that a clearer approximation can be gained of the approximate proximity of useful proxies for determining the utter uselessness of much so called scientific thinking/writing these days. You are saluted again sir . . . lang may yer lum reek . .

  85. Kip Hansen says:

    Reply to ES ==> Thank you, very helpful. [My wife and I have a red Hudson Bay Blanket, three stripes, for frosty nights. In ten years, we’ve needed it once. :-)

  86. Chas says:

    Not only are there random reading errors, but thermometer bulbs shrink in the first few years:
    http://tinyurl.com/pcaqd2k

  87. Dr. Anxiety says:

    The temperature data needs to be adjusted before use.

  88. Keith Minto says:

    How prescient is that book;

    ….observations may be multiplied, their results tortured into every variety of combination, quantity may compensate instrumental errors, but no power of numbers can elicite a substitute for time….

  89. Walt Allensworth says:

    rgbatduke on February 24, 2014 at 6:29 am

    Thanks for taking the time to write that.

    I have spent much of a 33 year career in underwater acoustics sweating absolute sound pressure level calibrations and your post clearly speaks of “been there, done that, got the tshirt.”

  90. rgbatduke says:

    I have spent much of a 33 year career in underwater acoustics sweating absolute sound pressure level calibrations and your post clearly speaks of “been there, done that, got the tshirt.”

    No, I avoided doing that — I’m a theorist. We reason in a cozy ivory tower where we presume that we know exactly what’s going on in a vastly oversimplified model that we hope catches the essential dynamics and works at least approximately to describe nature in some specific neighborhood. The only errors I worry about are things like cumulative roundoff error and algorithmic stability, averaging over carefully specified stochastic noise, etc.

    But I teach classes with an experimental component, I have many experimental friends, and I’m not an idiot. Also, I probably know a lot more than most (even in math/science) about randomness, probability and statistics, as I’ve done decades of work in Monte Carlo, Langevin dynamical models in optics and magnetism, and uber-advanced predictive modelling. So while I feel your pain, I do it from a comfortable armchair where — no, I really don’t:-)

    I do, however, appreciate the fact that “empirical truth” is a just as much an oxymoron as “theoretical truth”. They are “truths” in a precisely describable (but not easily quantifiable) statistical sense, not in the sense people use when doing boolean/aristotelian first order logic.

    rgb

  91. Kip Hansen says:

    Reply to Allensworth and rgb ==> The ever running distinctions between the armchair and the field tent. I admit to having done a bit of both but tend towards the armchair (well, deck chair) now. At present, I am concerning myself, in this particular effort, at discovering facts about the physical errors in the day to day temperature taking and recording in historical climate science. I appreciate your contributions.

  92. Kip Hansen says:

    Reply to Chris Martin ==> John Henry Belville says in his book “A Self-registering Thermometer of simpler construction, by Dr. John Rutherford of Edinburgh, is now in general use.” This implies, but does not definitely state, that the Rutherford registering thermometer set was used at the Royal. Found on Page 7 of Belville’s book..

  93. Chris Martin says:

    That’s interesting. I didn’t know that. The other – perhaps significant point – is that the definitive book by Brazell of London Weather, published in 1968 only published detailed temperature figures from the Greenwich Observatory from 1841 onwards, so that might imply that temperature figures before then may have been from non-standard instruments and/or exposures.

  94. Kip Hansen says:

    Further to Chris Martin ==> If you have an interest in the exposure issue, there is discussion of this in Belville’s book. It’s free online and the chapters are listed. The whole thing is only sixty pages and can be read in half an hour or so. I recommend using the Chrome browser and the Google Play eBook app therein, a slightly better interface (not my usual browser either) for this purpose.

  95. Chris Martin says:

    Further to Kip Hansen===> OK. I may have a look at Belville’s book. Historical weather records have always been an amateur interest of mine – I used to live in the same county of England as Thomas Barker , who made detailed daily weather observations from 1733 to 1795, including temperature. This in a location about 100 miles north of London. This was a key source for Manley when he put together the Central England Temperature Series. It’s when you look at Barker’s register you realise there is a whole bunch of issues prior to the 19thC around type of thermometer (in Thomas Barker’s case a spirit in glass thermometer made by John Patrick of London with zero at 90F and 76 at 32F!!!!!); exposure (often they were kept in an unheated room with open windows) and observation (often it was two temperature measurements a day, before max-min thermometers were invented). Makes me admire Manley’s work even more that he was able to make something out of these and other records. I do sometimes wonder whether some of the higher extreme temperatures reported nowadays are also partly down to the speed with which electronic sensors react to temperature compared to the old spirit or mercury thermometers – and especially if many max temperatures before about 1800 were, I suspect, based on a single observation at 3-5 pm!

  96. Kelvin Vaughan says:

    Kip Hansen says:

    February 24, 2014 at 10:28 am

    Reply to Kelvin Vaughan ==> Very Interesting. Many other readers had noted that they though the early 1800s appeared chilly, and that Global Warming had warmed up Central England a bit, about 0.5°C — but now you come along and ….hmmm… I was going to say dispel that …. but I’m getting out my little calculator…..== +0.375°C to a rough-back-of-envelope 12-moth-average is a wee-bit warmer, with some months showing exceptional Coolth (especially Spring and early Summer) and Warmth (July, Oct and Dec) , comparatively. Have I got that right?

    Yes, it has got mild again and has been mild so far this year as the jet stream has got stuck in mild mode. Over this decade It’s more a case of we are loosing the cold end of the spectrum rather than the hot end climbing up.

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