HomeNewsUncertainty Estimates for Routine Temperature Information Units. – Watts Up With That?

Uncertainty Estimates for Routine Temperature Information Units. – Watts Up With That?


Half One.

Geoff Sherrington

Trendy local weather analysis generally fails ample recognition of three guiding rules about uncertainty.

  1. Uncertainty estimation is crucial to understanding.

It’s typically agreed that the usefulness of measurement outcomes, and thus a lot of the knowledge that we offer as an establishment, is to a big extent decided by the standard of the statements of uncertainty that accompany them.”

2. Uncertainty estimation has two dominant components.

“The uncertainty in the results of a measurement typically consists of a number of elements which can be grouped into two classes in keeping with the way in which through which their numerical worth is estimated:

 A. these that are evaluated by statistical strategies,

 B. these that are evaluated by different means.”


3. Uncertainty estimation must worth numerous views.

“In 2009, the Obama Administration recognized six rules of scientific integrity.” (Together with these two) –

“Dissent. Science advantages from dissent throughout the scientific neighborhood to sharpen concepts and considering. Scientists’ means to freely voice the authentic disagreement that improves science shouldn’t be constrained.

“Transparency in sharing science. Transparency underpins the sturdy technology of information and promotes accountability to the American public. Federal scientists ought to be capable to converse freely, if they want, about their unclassified analysis, together with to members of the press.”


This text examines how properly the Australian Bureau of Meteorology, BOM, satisfies these necessities in respect of the uncertainty estimated for routine every day temperatures.

Half One offers extra with the social elements like transparency. Half Two addresses arithmetic and statistics.

This text makes use of Australian apply and examples dominantly involving BOM. Importantly, the conclusions apply World-wide, for there may be a lot to restore.

The distinguished, sensible information to uncertainty is by the France-based Bureau Worldwide des Poids at Mesures, BIPM, with their Information to the Expression of Uncertainty in Measurement (GUM).

Information to the expression of uncertainty in measurement – JCGM 100:2008 (GUM 1995 with minor corrections – Analysis of measurement knowledge (bipm.org)

A number of years in the past, in  electronic mail correspondence with BOM, I began to ask this query:

If an individual seeks to know the separation of two every day temperatures in levels C that enables a assured declare that the 2 temperatures are completely different statistically, by how a lot would the 2 values be separated?

BOM has been attempting to reply this query with a number of makes an attempt. They’ve permitted me to cite from their correspondence on the situation that I reference the complete quote, which I do right here.


On March 31st 2022, BOM despatched the newest try to reply the query. Here’s a desk with a few of their textual content.

(Begin quote) “The uncertainties, with a 95% confidence interval for every measurement expertise and knowledge utilization, are listed under. Sources which were thought-about in contributing to this uncertainty embody, however should not restricted to, discipline and inspection devices, calibration traceability, measurement electronics or observer error, comparability strategies, display measurement and growing older.

Measurement Know-how Extraordinary Dry Bulb Thermometer PRT Probe and Electronics
Remoted single measurement – No close by station or supporting proof ±0.45 °C ±0.51 °C
Typical measurement – Station with 5+ years of operation with 10+ years of operation with no less than 5 verification checks.   ±0.23 °C ±0.18 °C   ±0.23 °C ±0.16 °C
Lengthy-term measurement – Station with 30+ years of aggregated information with 100+ years of aggregated report   ±0.14 °C ±0.13 °C   ±0.11 °C ±0.09 °C

I’d stress that in reply to your particular query of “If an individual seeks to know the separation of two every day temperatures in levels C that enables a assured declare that the 2 temperatures are completely different statistically by how a lot would the 2 values be separated”, the ‘Typical measurement’ Uncertainty for the suitable measurement expertise can be essentially the most appropriate worth. This worth isn’t applicable for wider utility to evaluate long-term local weather tendencies, given typical measurements are extra liable to measurement, random, and calibration error than verified long-term datasets.”  (Finish quote)

These confidence intervals are primarily for one A part of the 2 Elements that comprise a whole estimation of confidence. They’re largely the Half A kind that’s derived from statistical strategies. They’re incomplete and unfit for routine use with out extra consideration to Half B, these which are evaluated by different means.

There’s a important distinction within the interpretation of temperature date, particularly in time collection, if the uncertainty is ±0.51 °C or ±0.09 °C, to make use of excessive estimates from the BOM desk. It’s critical to know how the uncertainty of a single remark turns into a lot smaller when there are a number of observations mixed in a roundabout way. Is that mixture a sound scientific act?

Within the case of routine temperature measurements (the check topic of this text), Sort B may embody, however not be restricted to, all of these results adjusted by homogenization of time collection of temperatures. On this article, we use the BOM adjustment procedures for creating the Australian Local weather Observations Reference Community – Floor Air Temperature (ACORN-SAT).

ACORN-SAT commences with “uncooked” temperature knowledge as enter. That is then examined visually and/or statistically for breaks in an anticipated (easy) sample. Typically a sample at one station is in contrast with efficiency of different stations as much as 1,200 km distant. Temperatures are adjusted, singly or in in blocks or patterns, to offer a smoother-looking output, extra in settlement with different stations, extra pleasing to the attention maybe, however usually inadequately supported by metadata documenting precise modifications made prior to now. Typically, there may be private collection of when to regulate and by how a lot, that’s, guesswork.

The BIPM tips haven’t any recommendation on how one can create uncertainty bounds for “guesses” – for good scientific causes.

http://www.bom.gov.au/local weather/change/acorn-sat/paperwork/About_ACORN-SAT.pdf

http://www.bom.gov.au/local weather/knowledge/acorn-sat/#:~:textual content=ACORNpercent2DSAT

Another related elements affecting BOM uncooked knowledge embody:

  1. Information started with the Fahrenheit scale, then moved to Celsius scale.
  2. There have been durations of years when a thermometer remark was reported in complete levels, with no locations after the decimal. (“Rounding results.”)
  3. Virtually each ACORN-SAT station of the 112 or so was moved to a distinct location a while in its life.
  4. Some stations have had new buildings and floor surfaces like asphalt put near them, probably affecting their measurements. (“City Warmth Island results, UHI).
  5. Thermometers modified from liquid-in-glass to platinum resistance.
  6. Display screen volumes modified over the a long time, typically turning into smaller.
  7. Screens have been proven to be affected by cleansing and sort of exterior end.
  8. The recording of station metadata, noting results with potential to have an effect on measurements, was initially sparse and continues to be insufficient.
  9. Some handbook observations weren’t taken on Sundays, The Sabbath, at some stations.
  10. And so forth.


In mid-2017, BOM and New Zealand officers met and emailed to provide a report that touched on the variables simply listed however targeting the efficiency of the Computerized Climate Station, AWS, these days dominant, with largely PRT sensors.

Review_of_Bureau_of_Meteorology_Automatic_Weather_Stations.pdf (bom.gov.au)

Some electronic mail correspondence inside BOM and New Zealand about this assessment turned public although a Freedom of Data request. Related FOI materials is right here.


Listed below are some extracts from these emails. (Some names have been redacted. My bolds).

“Whereas not one of the temperature measurements resident within the local weather database have an express uncertainty of measurement, the traceability chain again to the nationwide temperature requirements, and the processes used each within the Regional Instrument centre (the present identify of the metrology laboratory within the Bureau) and the sector inspection course of recommend that the possible 95% uncertainty of a single temperature measurement is of the order of 0.5⁰C. That is estimated from a mixture of the sector tolerance and check course of uncertainties over a temperature vary from -10 to +55⁰C.”

“(We) ought to take care of the discrepancy between the BOM’s present 0.4⁰C uncertainty and the 0.1⁰C WMO aspirational objective.”

By reference to the desk above, the PRT column presents an identical uncertainty of +/-0.51⁰C for “Remoted single measurement – No close by station or supporting proof”; additionally +/-0.37⁰C for “Typical measurement – Station with 5+ or 10+ years of operation”; additionally ±0.11⁰C for “Lengthy-term measurement – Station with 30+ years of aggregated information.”

One doesn’t know why there’s a additional providing for AWS of ±0.09 °C for “information with 100+ years of aggregated report.” Hugh Callendar developed the primary commercially profitable platinum RTD in 1885, however its use in automated climate stations appears to have began concerning the time of the 1957-8 Worldwide Geophysical Yr. There may be no examples of 100+ years.

Recall that for some 5 years earlier than mid-2022, I had been asking BOM for estimates of uncertainty, which query was not answered by mid-2022. This must be thought-about towards the data revealed on this 2017 electronic mail trade, with the possible 95% uncertainty of a single temperature measurement is of the order of 0.5⁰C.” It’s cheap to think about that this estimate was hid from me. One of many BOM employees who has been answering my latest emails was current and named among the many electronic mail writers of 2017 trade.

Why did BOM fail to say this estimate? They have been inspired to offer a solution by my primary query, however they didn’t.

This brings us to the beginning of this text and its three governing rules, one in every of which is ““Transparency in sharing science. Transparency underpins the sturdy technology of information and promotes accountability to the American public. Federal scientists ought to be capable to converse freely, if they want, about their unclassified analysis, together with to members of the press.”

As for America, additionally for Australia.

It occurs that I’ve stored some previous writings by officers of the BOM over time. Listed below are some.

Recall that in Climategate, the BOM’s Dr David Jones emailed to colleagues on 7th September 2007.

Thankfully in Australia our sceptics are quite scientifically incompetent. It’s also simpler for us in that we’ve got a coverage ofproviding any complainer with each single station remark once they query our knowledge (this normally snows them) and the Australian knowledge is in fairly good order anyway. 

David Jones had not reached an apologetic temper by June 16, 2009, when he emailed me his response to a technical query:

Geoff, your identify seems very broadly in letters to editors, on blogs and your repeatedly electronic mail individuals in BoM asking the identical questions. I’m properly aquatinted with letters similar to this one – http://www.jennifermarohasy.com/weblog/archives/001281.html . You even have a protracted observe report of placing personal correspondence on public blogs. I gained’t be baited.

Additional, there may be an electronic mail involving BOM Media and Massive Boss Andrew Johnson and others within the AWS assessment, 24 August 2017 9:58 AM:

“I anticipate we’ll reply to this one with: The Bureau doesn’t touch upon any third-party analysis.”

Persevering with the theme is that this 2017 BOM electronic mail in response to mine asserting with knowledge that Australian heatwaves should not turning into longer, hotter or extra frequent.

The Bureau is unable to touch upon unpublished scientific hypotheses or research, and we encourage you to publish your work in an acceptable journal. Via the peer reviewed literature, you’ll be able to take up any criticism you’ve got of present methodologies and have these revealed in a format and discussion board that’s accessible to different scientists. Regards,  Local weather Monitoring and Prediction.

This fortress BOM temper may need began from the highest. One redacted identify at that 2017 electronic mail session revealed that –

 “I’m primarily ‘exterior’ as an emeritus researcher, however was head of the infrastructure/procurement/engineering/science measurement space once I retired from the Bureau in March 2016 final 12 months.”

This individual  may or won’t have been former BOM Director Dr Rob Vertessy. Newspapers in 2017 reported resignation feedback from him. They ship a message.

“Vertessy’s company was below constant assault from local weather science denialists who would declare, usually by way of the information and opinion pages of the Australian, that the climate bureau was intentionally manipulating its local weather information to make latest warming appear worse than it actually was.

“From my perspective, individuals like this, working interference on the nationwide climate company, are unproductive and it’s really harmful,” Vertessy advised me. “Each minute a BoM govt spends on this nonsense is a minute misplaced to managing danger and defending the neighborhood. It’s a actual downside.”


Word the widespread media spin strategies on this press article. The BOM have seen an issue, framed it in their very own means and specific emotion with out denial of the accusations.

At this stage of this text, I submit some phrases by others to point the dimensions of the issues which are rising.

“An irreproducibility disaster afflicts a variety of scientific and social-scientific disciplines, from public well being to social psychology. Far too continuously, scientists can not replicate claims made in revealed analysis.1 Many improper scientific practices contribute to this disaster, together with poor utilized statistical methodology, bias in knowledge reporting, becoming the hypotheses to the information, and endemic groupthink. Far too many scientists use improper scientific practices, together with outright fraud.

Nationwide Affiliation of Students (USA).

Shifting Sands. Unsound Science and Unsafe Regulation

Report #1: Maintaining Depend of Authorities Science: P-Worth Plotting, P-Hacking, and PM2.5 Regulation


From that report, there’s a view concerning the central Restrict Theorem on web page 36.

“The Bell Curve and the P-Worth: The Mathematical Background

“All “classical” statistical strategies depend on the Central Restrict Theorem, proved by Pierre-Simon Laplace in 1810.

“The concept states that if a collection of random trials are carried out, and if the outcomes of the trials are impartial and identically distributed, the ensuing normalized distribution of precise outcomes, when in comparison with the typical, will method an excellent­ized bell-shaped curve because the variety of trials will increase with out restrict.

“By the early twentieth century, as the economic panorama got here to be dominated by strategies of mass manufacturing, the theory discovered utility in strategies of industri­al high quality management. Particularly, the p-test naturally arose in reference to the ques­tion “how possible is it {that a} manufactured half will depart a lot from specs that it gained’t match properly sufficient for use within the remaining assemblage of components?” The p-test, and related statistics, turned normal elements of commercial high quality management.

“It’s noteworthy that through the first century or so after the Central Restrict Theorem had been proved by Laplace, its utility was restricted to precise bodily mea­surements of inanimate objects. Whereas philosophical grounds for questioning the belief of impartial and identically distributed errors existed (i.e., we will by no means know for sure that two random variables are identically distributed), the belief appeared believable sufficient when discussing measurements of size, or temperatures, or barometric pressures.

“Later within the twentieth century, to make their fields of inquiry seem extra “scien­tific”, the Central Restrict Theorem started to be utilized to human knowledge, regardless that no one can probably imagine that any two human beings—the issues now being measured—are really impartial and an identical. Your complete statistical foundation of “ob­servational social science” rests on shaky helps, as a result of it assumes the reality of a theorem that can’t be proved relevant to the observations that social scientists make.”

Dr David Jones emailed me on June 9, 2009 with this sentence:

“Your analogy between a 0.1C distinction and a 0.1C/decade development is unnecessary both – the legislation of enormous numbers or central restrict theorem tells you that random errors have a tiny impact on aggregated values.”


Half Two of this text takes up the arithmetic and statistics related to CLT and LOLN.


Geoff Sherrington


Melbourne, Australia.

20th August 2022.



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