Why temperature readings in decimals is important

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By now it appears that the admin of the new WUnderground is
either unwilling or unable to accommodate their patrons in regards to the
display of decimal values for temperature recordings. No surprise there. Perhaps whomever it was within their team that was responsible for this compromise approach to the interface felt somehow justified that whole numbers alone are sufficient when displaying Celsius or Fahrenheit readings - even though this represents a compromise of the integrity of contributors’ weather data from their PWS.

The basis of this post is not to persuade the admin team that this approach is wrong because this is most likely a futile attempt but rather to remind the viewing public why this is so.

Part of the problem perhaps is the insistence of the US to resist the adoption of SI units (the metric system) like every other country in the World. Since the US clings to the archaic default method of measuring temperature in whole degrees Fahrenheit (this is still the accepted method of The National Weather Service) certain companies not mindful of the Global standard think that this is okay and even suppose that conversion to even cruder whole degrees Celsius readings are likewise acceptable. However, WMO guidelines proclaim that the resolution of automatic weather stations should be in 0.1 K (0.1 C) with an uncertainty of 0.2K. (0.1 deg Celsius ~ 0.2 deg Fahrenheit). The meteorological community worldwide recognizes that modern instrumentation is sufficient to display it as such which is why practically every National Meteorological Service in the World records official temperature in a resolution of 0.1 deg Celsius. Likewise, American users have become accustomed to their own weather stations and MesoNets displaying in tenths of degrees Fahrenheit since the manufacturers of even the most basic temperature-recording devices have set the precision of their instruments to this level.

To disregard the virtue of precision in the reporting of scientific data when it is conveniently available does the end-user a disservice and is an embarrassment to the supplier of this data.
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Patrick

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Posted 3 months ago

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Roger Lewis

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I agree with you. and to add to the discussion I have never understood the logic of "rounding up" when it comes to reading and reporting ambient temperature as with 64.4° is read and reported as 64°yet 64.5° is read and reported as 65° when there is ONLY 0.1-degree variance between the two. same as 64.5 and 65.4° are both read and reported as 65°when clearly there is 0.9degree variance. it doesn't seem to be an accurate method. I am VERY disappointed with the so-called "NEW and IMPROVED" Wunderground website. At least there should be a resolution option in the settings to use 0.1 ...OR... the whole number "rounded up" method.
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jachen

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I think this application is being done by a machine (AI). Cannot talk to humans, has no empathy. Eventually improves things as it did on the underlying google map on a MacBook Pro running Chrome.
Its probably very difficult to migrate all WU services one by one to IBM's Watson. It might take years to finish. And we might get back the decimals on temperature. Be patient or leave.
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Salonika

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It is not about being patient or not. It is about doing things properly and right. You cannot be (probably) the most important PWS website providing lots of services and meteorological stuff, and suddenly, throw all of it off the boat without the security of keeping your standards and not bothering all of the people that are, for free, giving you their data to support and feed your business.

A lot of people, me included, rely on this portal to see and check our data since a most of current PWS upload data here without the option of keeping it at our PC's. And all of a sudden, you change it all, lose most of your identity and leave your data providers without such a crucial thing as seeing the data just as it is, with decimals (not to talk about downloading your OWN information). It seems unbelievable that such a big company allows itself to do such a poor work. The fact that we are here discussing, 4 months after the change, of such an obvious thing in meteorology as the resolution of the data is pretty amazing. Updates in websites should always be towards a more clean, detailed, trustworthy and rich content, and this is just non-sense...

I hope we get everything fixed soon.
Regards from a spanish fellow.
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Roger Lewis

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I think they should've made all the changes and so-called updates to the website in BETA and ONLY released when EVERYTHING had been tested and completed... thus leaving us with at least a half functioning website.. in MY opinion, Wunderground has never been the same since they "updated" the website back in 2009-2010 or whenever it was.
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Ul KE

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@Salonika: Well explained and nothing to add on this. I have also written a lot of E-Mails in the meanwhile to address this problem, with no response! If there will not be a change within the next few days, I will discontinue providing my (very accurate data) to this weather service.

This is not that, what I expect from a professional weather site!

I am sorry to do that, but I am really, really pissed off right now about the current situation!
(Edited)
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Paul Grace

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I'm surprised that you guys seem to think you have thermometers that accurately report the actual temperature to a 10th of a degree, even under the best of circumstances.  Read the specs...if is says "± 0.1F" it doesn't.  Precision equipment is expensive to buy and maintain.
Then add in all the rooftops, back decks, fence posts, above lawns, next to the house, close to a tree, near irrigated plants- siting errors and the lack of proper solar shielding and regular calibration ($$$) to a known reference standard and you're off by several degrees.

Folks, you're forgetting the difference between resolution and precision.  Just because your display is printing a number in 10ths doesn't mean that's an actual temperature.  You're in the ballpark, but you can't tell if it's left field or a hotdog cart in the stands behind home plate.

Relax.

(Edited)
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Paul Grace

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"you need the digits to get an accurate result"

Since the decimal digits are not accurate, using them in your average pollutes your average.  It doesn't make your average accurate.
(Edited)
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William J Schmidt

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The best Davis sensor is the 7346.070 SHT31 Upgraded Digital Temperature/Humidity sensor's temperature accuracy is +/-0.5°F (+/-0.3°C)... That means you could be off a whole degree.  And only available after Jan 2016.
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Paul Grace

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Accuracy: The difference between the reported value and the actual value.
Precision: The repeatability of a steady value
Resolution: The smallest change that can be measured.

As noted above, the best Davis sensor's best-case accuracy is only ±0.5°F, ±0.3°C
It is bad to report that with a false precision of 0.1° because it is misleading all of you.

Everyone that believes your consumer equipment is giving you .1° accuracy is mistaken, it isn't - you are being misled.  There are also additional errors caused by mistakes in design and in your installation that can add several degrees of error on top of the basic sensor errors, introduced by humidity, wind, sun, and yes, even by the temperature... above 90°F the accuracy gets even worse.

Just because it's printing numbers on the console doesn't make them real.
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Roger Lewis

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Paul, given your continuous rant on this subject I take it you do not now, or have ever, nor will ever own a PWS due to the inaccuracies you have pointed out. as It would be a complete waste of your money. WHY  on earth would you invest in a product that is incapable of providing TRUE100% accuracy in ALL values of measurements?
 Based on your "knowledge" of this subject I have NO doubt you have been sought out by NOAA and The NWS to assist in calibrating their sensors... which I might add my PWS seems to be just as accurate as my local AWOS sites which I compare my data with regularly Thank you very much.
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William J Schmidt

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One point of clarification from a guy with an advanced math degree...  One never rounds data before averaging it.  You average raw data (one or two or ten or 50 decimal places... valid or not) and then round the final result to the number of significant digits.  If you don't do this, you add additional bias by skewing the solution higher or lower.  If you have a good reference, at least as accurate as the device you are using, It gives you additional data to determine the statistical precision and accuracy within the specified numbers for both sensors.  As I said previously, I have no problem showing additional decimals as an aesthetically pleasing, feel better about my investment, etc. thing.  I just wouldn't get too serious about those decimals as they are probably meaningless... and even worse given the shear differences in suboptimal weather station installations (locations, heights, etc.).
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Charles Modica

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I have a very hard time understanding why they won't adjust the site to show decimal information, because it's still being logger/captured. If you use their widget code to show your weather station data, it will still show temperatures down to the decimal.

The new web interface has been a significant step backwards in terms of how granularly we can access our data (i.e. decimals, specific date ranges, etc)
(Edited)
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Victoria Gardner, Official Rep

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AHEM!!

It's completely possible, I hope, to disagree without falling into ad hominem attacks (calling into question someone else's intelligence, for instance).

The decimal question is quite important for metric users.  We know that.  This is purely a question of allocation of scarce resources (programmers) to problems. 

Fahrenheit users may not need the added level of precision.  Or they may want it anyway.  The beauty of a community is that we do not all need to be exactly the same. 

--Victoria
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DJTH

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Or you can bring back the old page/system untill this is sorted and programmed into the new page/systems.
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Tim Roche, Official Rep

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Folks, this isn't a conspiracy, we're bringing decimals back. 
We haven't released it yet because we're doing thorough testing of the newer API, we've discovered a particularly tricky issue and are working to get it resolved.  Testing takes time. 
Please be civil to one another, one person has already been banned from this board for their comments towards other users, others are close.  
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Ul KE

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Many thanks for that info - hope it will change back to normal soon :-)
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Roger Lewis

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Speaking on behalf of ALL that is waiting for the decibel format to be reimplemented this is good news. however, please excuse MY skepticism....BUT....it probably will not be any time soon perhaps a year or 2 down the road..... OR longer.
(Edited)
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Doc_Bill

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I dont have any problem showing decimals of you feel better about it or if it looks better. But like Paul said... its all statistical randomness in the decimal places/ not real.
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Tim Roche, Official Rep

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The folks who view the data in Celcius do have a point, 1 degree is a pretty big jump, in F I agree its pretty noisy
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Roger Lewis

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William, I am aware of NIST no longer performing the calibration process.. this is why I have been sending my unit to the manufacturer for calibration.
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Paul Grace

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Roger, no, you don't understand me correctly.  I am referring to consumer weather stations, not all possible temperature measuring instruments.

All you have to do is read the specifications of the equipment you are using.  You will find they have about 1°F error figures or worse, depending on various errors in siting and conditional non-linearity (meaning you can't offset for them)

"at ANY GIVEN TIME my station is within ± 0.5° or 1° ( whole number value ) of that station's readings"

I simply don't believe that.  Even 760 feet away the actual temperature would not always be within 1 degree, so it points to both of you having severe errors, like stuck sensors (which I also doubt).  AWOS provides a 5 minute moving-average temp, once a minute, sited near the touchdown area of a primary runway..  Is that what you are comparing your instantaneous temps to?   Is your station sited on a runway apron?  Are you using the same radiation shield?  AWOS uses a platinum wire RTD, which your ISS does not.  

Finally, the spec for the AWOS temperture, here I am pasting from the ASOS guide:

Parameter         Range              RMS Error       Max Error       Resolution
 Ambient     -58°F to +122°F         0.9°F               ±1.8°F              0.1°F
   Temp

(FYI the errors double outsdide of that range)

The average (RMS) error is 0.9°F  Worst case is ±1.8°F, and (this bit made me laugh) "These 5-minute averages are rounded to the nearest degree Fahrenheit"

And you think you are getting 0.1°F accuracy?  The airport doesn't get close, and neither do you.

When you make wild claims like this it makes me wonder what you are trying to accomplish.  What exactly are you comparing to?

I'm glad you're happy with your readings, but something is going seriously wrong.

Here's the NOAA spec for you to read yourself, straight from the guys who wrote the book on the subject...They don't bother with 10ths either.  See page 12
https://www.weather.gov/media/asos/aum-toc.pdf

Is that bold enough for you? 

Cheers, friend!
(Edited)
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William J Schmidt

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Hey as a cheerful side note...

Once in a while I will look at the WUG map that shows the PWS's around me and will just take note of the difference in readings (like temperature, wind speed, direction, heading, etc.).  I notice that for the most part, my station is at the median (reports the same number as the majority of PWSs).  That's about all I care about.  It's really irrelevant if we all report the exact right number.  I just don't want to see my station reporting a number that is 20% higher or lower than my neighbors.  The collective is what is important for forecasting.  The more (good) data points the better.
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Roger Lewis

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Ok, Paul, you got me! I must admit  OVER EXAGGERATING!...lol... not "at ANY given time"... BUT... there are many times when I call the automated ASOS minute observations number of this particular ASOS station which is updated every minute I will have to convert the readings from C to F for the ambient temp. then compare to my readings for that specific time reference on my data logger which is set for1-minute intervals and it's fairly close... for the most part... but NOT ± 0.5° at any given time... I also look at the 5-minute tabular display of this ASOS station that is uploaded to MesoWest.utah.edu and compare with my station's 5-minute tabular readings.. again, fairly close under NORMAL weather conditions... but NOT "at any given time".  thanx for calling me out on this...lol 

 I used to have a subscription to anyawos.com to retrieve the ASOS 1-minute observations either by a phone call or online. but now I just periodically call for the 1-minute obs..

I appreciate you providing the info on the ASOS users guide.  I actually have on file...and have read it before.. always good to refresh my memory.  THANX.
(Edited)
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Paul Grace

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Yes, I suspected you were exaggerating.

"which is updated every minute" - don't forget, ASOS "1-minute observations" are moving 5-minute averages.  The ASOS specification is to not publish instantaneous observations, so you are comparing AWOS average temps to your instantaneous temps.  Not exactly apples and oranges, but let's say grapefruit and oranges...  And they are rounded to the nearest whole degree F, so you can't even tell if you are within 0.5F.  Add in the error from your preference for truncating decimals instead of rounding them, and you can be sure that you are off by at least 0.5F about half the time.

You also have very different siting particulars, so you'll get more delta from that.

You are also going to be way off whenever the temps are changing rapidly (like whenever a fast front moves in) because your temps will lead the airport averages.

When all is said and done, I'm sure you're not within 0.5F from the airport temps.  It just isn't possible when we consider the facts that everything that can be different, is different, between your observations and the airport observations 760 feet away.

Don't sweat it though.  It seems like you are running a well-calibrated PWS, and the tenths don't matter.

Cheers!

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juan parra

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Por favor devolver los decimales a la temperatura. Es una lástima que se actualice la página y en el momento de mejorar lo que se hace es empeorar. Creo que no está tratando bien con los usuarios y no creo que sea muy costoso el añadir los decimales. Son millones de estaciones y con ello millones de datos que se utilizan sin que los usuarios reciban nada a cambio, al menos añadir los decimales
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Doc_Bill

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Lo es más eficaz dirigirse cuestiones en un idioma eso no es nativo al anfitrión?