And wherever that grid point is, lies inside only one “box.”. I’ll only cover the simplest situation: the uncertainty of an initial measurement in “grid space.”, Suppose we see 10 degrees at 6am, presumably +/- 0.5 in an ideal world (hah… but let’s assume a perfectly accurate sensor for now!). Weather happens. Okay, I’m obviously not so good at this. The TOB adjustment in the US data (sorry, I don’t have access to the computer where the links are saved) since 1950 has increased from a small negative adjustment to around 0.2C positive adjustment. Weather definition, the state of the atmosphere with respect to wind, temperature, cloudiness, moisture, pressure, etc. I see TOB being a further potential worry when daylight saving chages, coincidental with the thermometer reading being done by custom within an hour of max or min for a day. Actually, it occurs to me now that even with constant daily temperature patterns, TOB will occur, on the day of the conversion, and that this may be what Karl et al (see #458) are trying to quantify. two consecutive time periods.”, Since every moment in time is between two consecutive times periods, Are we in for 300 posts with people arguing minute details? Hmmm…. In 1920 they installed a brand spanking new max/min LIG thermometer and read it at 0700 hours. temperature ranges of consecutive days always at least meet, if not It seems most USHCN sites use the Maximum Minimum Temperature System that automatically records max and min temperatures but is manually read and reset. it’s probably closer to the percentage of sunny days for pavement and summer days for AC and etc, Gentlefolk. The bias in TOB is only relative to the convention of determining average temperature as the mean of min and max temperatures over the 24 hours prior to midnight. Let me try a thirty second introduction to TOB, and why it matters: It does not depend on passing warm, or cold, fronts, or storms. IPCC AR5 WG2 on Yield Sensitivity: Statistical Malpractice. The example you provide does not shed any light on the problem at hand, which is: Given hourly measurements of temperature, what method best emulates the results that would be produced by daily observations recorded on a min/max thermometer so that time-of-observation bias in a min/max regime can be measured? If you keep the time of observation constant over time, this won’t make any different to the long-term station trends. 5 PM 0.64 C 1.15 F And any measurement at that moment is part of 2007, not part of 2006. They’re using the old round-half-up method. Recognize that the “day boundaries” do not lie ON the grid but between grid points: every point on the grid lies inside a single “box.”, If we have a need to “connect the dots” (such as for curve estimation between measurements), we can’t just forget the grid. My goal here is focusing the questions on those areas that have not been questioned and verified. 1 hi/lo/avg = 30/30/30, 2 = 30/20/25, 3=20/10/15, overall avg = 23.3. If you measure the max temperature near the afternoon average temperature peak, on a day that is warmer than both its neighbors, there is a good chance that the temperature near the observation time will also be recorded as the peak for one of the adjacent days. You must adjust for TOBS changes at that site. One reading per year. Very long winded, apologies. the TOB differences would be obscured. Jan 2: 24 samples, 20 degrees. Take two readings in a day and they determine what you know about temperature for that day. This suggests that estimates of TOB from a general model will be most appropriate when applied to a mean derived from a series of years… The technique which we develop in this article is most appropriate when applied to means comprised of a series of years to estimate nonclimatic trends. temperature as the 24 hour old 24 hour min: 3554, just over once per You need to be logged in to post a comment. When the thermometer is read, which time periods might contribute to today’s reading? The maximum (MAX.) commonly persist through many, many, of my moments. Microsite bias is not a spike. In order to use such If you look at USHCN dailies you get the Time of Observation. It does I’m saying Here is an example. It is clear that the shift from afternoon to morning observations in the United States introduced a large cooling bias of about 0.3 C in raw U.S. temperatures. Sensor blackening is another station micro-issue that could have a big effect on measured temperature trends. All that being said, I have no problem with TOB adjustments provided the algorithms used to nomalize time of observation bias be carefully constructed to work with the particular time of day such obs are taken. It simply introduces the potential for error in analysis. 39 instances of 8 occurrences Figure 5. also be the high, or low, of the second time period. Unfortunately in the US you ONLY get these hourly measurements at AIRPORTS. 9 Yrs 50.71 -0.49 -0.20 0.13 0.41 1.68 1.30 0.92 0.66 0.49 0.35 Spikes greater than 2 F flattened. ), and calculated the maximum, minimum, and mean temperatures for all of the 24 hours periods in the CRN data. I would suggest that the Time of Observation itself be abbreviated My gut keeps telling me the uncertainties are larger than the supposedly accurate “corrections.” But I don’t suppose the media care. The fact that hourly, much less six hourly, point temperature Everything name meaning, origin, pronunciation, numerology, popularity and more information about Tobs at NAMEANING.NET No basis, for example, to suggest any slope or curve shape to the period between measurements. Out of 6,028,151 records in the U.S. Social Security Administration public data, the first name Tobs was not present. Consequently it should be quite alarming to most people that the TOBS correction does bias the trend. 2: 20 Here's proof positive of that assertion: http://GreatWhiteCon.info/2015/01/mark-serreze-and-the-arctic-sea-ice-death-spiral/. The time of observation issue arises only because we are trying to measure maximum and minimum temperatures. The “outlier detector” says.. OPPS. (I’ve not yet had a chance to dig out my discrete/continuous number transform resources…will have minimal authoritative material to add until then.). Temperature of browsers ? The USHCN stations were selected for the continuity of their records back in 1999 or so. The Kingston station had its time of observation shifted from 9 PM to 4:30 PM. ), True. What TOB model is used by NASA/Hansen or by GHCN? All hell breaks loose when one assumes the previous/next day data can be “pinned” to the obvious points. Kind of like Kung Fu, bend with the data, don’t force corrections. (i.e., we may be in the middle of a major heating/cooling trend and cannot really tell what is going on. Same environment. One month in the middle of this has a recording of 100C. The temperature at the beginning of the second time period, T2007b. Even if this soil is not in direct sunlight, it would still be receiving indirect reflected radiation off the vanes. The real problem arises when TOB is changed. The charts for the minimum tend to have a high plateau from around 10am to 9pm, with a big dip from 9pm to 10am. The value for 2004 and the value for 2006 are immaterial. It cannot be in both.”. The bias between averages of discrete daily measurements and min/max average measurements is an interesting related issue. The reason that it matters, however, is that depending on the time of observation you will end up occasionally double counting either high or low days more than you should. The TOBS adjustments have a point, but they are very large relative to measured warming and this sort of spot check would be worth doing on some stations where it can be done. NOW, what happens if halfway through the history of this site we SWITCH from Observing Is it a discussion of sampling interval? Could you give the slopes to two or three digits? 7:00 50.97 Time of Observation (TOBS) data have been adjusted to remove the time of observation bias. Mrpete, you suggest a methodology that has much to reccommend it. As contiguous U.S. temperatures have risen about 0.9 C over the last century, not correcting for this bias would give us a significant underestimate of actual U.S. warming. the temperature at the end of the first time period, and it is also the Figure 5. See the latest Michigan Doppler radar weather map including areas of rain, snow and ice. Impact of adjustments on U.S. temperatures relative to the 1900-1910 period, following the … That old Fortran correction code had to forsee these spherical geometry problems. two days of data that do indicate the kinds of differences that cause They do ( I want to audit that) Oh, there are no confidence intervals, are there. The trend is almost identical between the two data sets. Don't miss out on the promotions for Tobs Wicker, buy Tobs Wicker directly online and enjoy big saving on your purchases. Given a certain phase relationship between the min-max measurement period and the signal, there is some probability that min-max will capture the peak and trough. new trend. Analysis: When might the world exceed 1.5C and 2C of global warming? If I measure temp every minute for a day, add all the values, and divide the total by 1440 I have that day’s average temp. Or is it the min/max for the entire period since the last reading? Period 2 hi/lo/avg = 20/10/15 The only place I can see TOBS being important for annual averages is if you are trying to compare different stations on the same day to weed out typographical errors. Those 318 stations showed the identical pattern as all the other stations. Therefore shifting from 5pm to 7am will shift the min/max mean down somewhat. He has presented very clear evidence in the Australian case that there is no significant temperature trend when temperatures are measured at midnight, 3am or 6 am but there is a positive trend at 9am and mid-day. JerryB has 190 sites with hourly data. – Late 1940s into early 1950s If it is colder than the 11 am pseudo reading, then it’s correct. b. It should be remembered,however, that missing data reduces the effective sample size. 13:00 51.89 temperature at the time of observation. Simply rearranging the order should not have impacted the average 3-period temperature at all. Has anyone seen analysts actually invalidating data measurements due to TOB shift? The first step of my method is to find sets of several rather than -5C. Use this to estimate the missing max value when it’s been overridden by the previous day 5 pm value. If the either temp at measurement time is outside of From above comment (trying to use photobucket): [IMG]http://i225.photobucket.com/albums/dd204/beach_040/TOB.jpg[/IMG]. So you are right and I was wrong. fronts, I had never quantified how much it does not depend on them. Note that a positive adjustment could only occur in the real world as a result of a wholesale shift in time of observation from evening to morning. On Karl, Karl based his model for TOBS adjsutment on 7 years of hourly data Let me use the word spike(s) for brief changes of temperature up, then JerryB took time series and emulated the proceedure required for observers at COOP sites. If temps were symmetrical around 0 degrees (positive and negative) that would be fine. Four values, six hours each. Thoughtful contributions most welcome! 10am 0.04 -0.07 0.22 0.18 0.03 0.18 0.24 0.33 0.05 0.26 0.05 0.15 0.15 0.12 13.74 13.68 I’d suggest that those who doubt the efficacy of their approaches do what I did: download the data and take a look for yourself. 5. Sometimes we hammer with a screwdriver. It cannot be in both. BTW, it would seem appropriate that you stop posting false assertions The method of estimation should work correctly anywhere, yes? column. As Philip_B points out in #29 above, however, even Karl et al admit that there is considerable estimation error in their TOB formula, which could be as high as 0.2deg. Thus, high maxes tend to get double counted. You have 1221 stations. This is a real worry. Etc etc. It does recognize that that 7593 instances of 2 occurrences Averages are for Capital City Airport, which is 4 miles from Lansing. The graph at #376 shows a cumulative updrift of +.35 deg F from the 20’s to the 90’s, just from the TOBS adjustment. The old Stephenson screens were supposed to be whitewashed or painted periodically to eliminate a trend in their reflectivity. I wonder if GISS attempts to “correct” for this? The best one can do is create a fuzzy And the sensor records in 25 degree increments: D M T Hi Lo 23:00 51.94. 6am -0.21 -0.96 -0.16 -0.22 -0.31 -0.33 -0.35 -0.06 -0.30 -0.10 -0.33 -0.29 -0.45 -0.39 13.26 13.21 I quickly tossed one idea because it seemed to leave too much missing data to be acceptable. measurements is not in dispute. The plastic housings on the new MMTS sensors don’t require painting, so paint type is not an issue. Perhaps the code does not handle such a case flexibly, but that’s not my problem. When the time of observation is systematically changed from afternoon to morning in the Climate Reference Network, a clear cooling bias emerges. Small wiggles are due to new stations entering the network between 2004 and 2014. How can one comment on TOB when there is so much confusion about it? 10 instances of 9 occurrences However, when times of observation are other than 58 instances of 6 occurrences This is what Jerry’s data collection contains. In 1992 due to Clinton base closures the LIG was replaced with an MMTS station. If they are false, then prove it. Zeke - The folks at WUWT, including Anthony himself, are regularly "economical with the truth". Outside of the box take a fictitious site called FT. Hansen, TX. It is a sneaky bias. This is a substantial increase in relevant information for those stations. The United States, in particular, has large adjustments to temperature data that have the effect of nearly doubling the warming trend since 1900. 14:00 52.10 Let me explain why. Nonetheless, we show clearly that adjustments made to the USHCN produce highly significant warming trends at various temporal scales. midnight, observations like that occur often, even without passing storms, and the 1600, 1700, 1800, and 1900 observations are less than that day’s I mostly see attempts at “correction” for duplicate/missing data! Passing cold snaps, or warm ones, are minor factors of Figure 6. This is what I get: I pulled down the last year of hourly temperatures (01:00 1 September 2006 through 20:00 31 August 2007) for Pittsburgh PA from the National Weather Service web site (http://www.erh.noaa.gov/pbz/hourlyclimate.htm). Here is recipe for creating the TOB for a simple sine wave day, in Excel: Steven Goddard (real name we now know to be Tony Heller) continues to rail about the ludicrousness of TOBS, assuming that any half-way competent weather station volunteer would automatically make an extra trip to the weather station to reset the maximum/minimum if he or she noticed later in the evening that the weather were suddenly changing. McKitrick: What is the Hockey Stick debate about? If I measure the temp on 31 Dec 2006 23:59:59 and then 1 Jan 2007 00:00:01 I have two readings, probably the same number, 2 seconds apart. usually covered by snow in the winter.”. with the original that has already been published. all # Convert list of tuples into normal list: tobs_values = list (np. With a temperature difference of 2.9C, this is typical of the other sites, suggesting that any bias from TOBS is minor. The boundary is not a time period. These are not in the Glossary and they definitely should be. 3: 30. Differences between the Mohonk Lake record of mean annual temperatures and those of nearby stations in the USHCN (see map in Fig. This description is wrong–but the effect is real. It is beside the current point. In short, the Karl et al model, on which the NOAA etc. Yet as I’ve shown, such rearrangements gives an average that varies from 16.7 to 23.3! So what is the result of a convention to read all thermometers at midnight? 73 Steven Mosher, I appreciate that approach it is very normal. No individual moment is in two adjacent days, hours, minutes or seconds. Throwing a lot of data at the problem is not helpful for understanding. period.”. I read your statement saying that the moment now under discussion is also a part of 2006, and should be calculated as such. measurements do not tell us what temperatures occurred between those OK. You wanted a link to tables. morning hours, there will be a cool bias. After the program identified the 24 hour min (or max) for a given 24 hour True, but extraneous. Love it!) Numbers of hourly observations of current 24 hour min temperature in 24 I see no value in this, and much opportunity to make a mess of the data by attempting to “adjust” for TOB. hour periods ending at 36167 hypothetical 24 hour periods of observation: 3 instances of 14 occurrences No matter how finely you chop the times, each moment must apply to only one time period. Also, the second two of them are Click next. Thank you for playing. hour periods.)”. Darker lines show the data with a lowess smoother applied to show longer-term differences. 22:00 52.06 I referenced a paper by Thomas Blackburn a while back on TOB. Nor am I suggesting that time stops. Watts et al paper 2nd discussion thread | Watts Up With That? hypothetical 24 hour max/min observations. 7 instances of 10 occurrences …and imagine that the value for 2005 should somehow be selected as any of 110, 100 or 80. period, it went back and counted how often that temperature occurred in But it is a 24 hour high/low. I look at the five-minute observation curves for sites near me and see a lot of very unpredictable shifts. A vector of Tmean @ 2400. “…records the time at measurement time” : I think you meant the temp Luckily we have yearly data concerning how many stations in the U.S. operated in the afternoon, morning, or other times, as I.e. Suppose the min/max is read and reset at midnight each day. You can almost watch it happen by visiting here and following Interestingly enough, the time of observation adjustment developed by Karl et al 1986 is not strictly necessary anymore. 7 AM to/from 6 PM observation time: 0.70 C (1.26 F) change of bias. In a climate audit, we are supposed to discern the possible errors then uncover methodology “adjustments” by audit to see if they are valid or not. C. net upward adjustment shown in the “Stepwise Differences” graph linked by John V in #376 of the “A Second Look” thread. Suppose as above that the daily highs are always 80 at 2PM and the lows are always 50 at 2AM. Climate data and weather averages in Lansing. In subsequent years, however, the change is a wash, since the year’s own Dec 31 high is just being replaced by the previous year’s Dec 31 high. That’s what this is for) See more. 1: 30 he writes down 26 and sends that data in…. As the temperatures fell and the liquid contracted into the bulb the index would be carried down by the surface tension of the fluid at the interface between the fluid and the vacant portion of the tube. of what you propose, methodological error. I guess my sense is that it’s better to maintain data integrity as long as possible in the analysis “path”, rather than fudge data. Those 318 stations showed the identical pattern as all the other stations. Here is my first question for clarification: 1) Please articulate the definition of the moment at the end of the first time period, M2006e !=== M2007b, (My answer, for reference: for the purposes of this work, M2006e is one measurement interval before M2007b, e.g. However, it appears it’s not and the Tobs is estimated, bizarely IMO to save a small amount of money. (BTW, the movie Longitude is a fascinating look into the history of accurate time measurement!). The thermometer was mounted on a pivot oriented on a horizontal axis with the instrument tilted slightly with the bulb end down. My bottom line: in theory, TOB seems a reasonable calculation. Tobe definition: an outer garment traditionally worn in some parts of north and central Africa, consisting... | Meaning, pronunciation, translations and examples like to have Willis and JeanS and UC and SteveMc and Roman and professional statitiscians The NWS manual MrPete links at #99 above doesn’t tell observers what to do if they miss a day — when they return, should they just reset their thermometers without taking a reading, or should they go ahead and report them as their reading for that day? We’re talking about a simple instrument that captures a high & low over a measurement period, that is then recorded at some time, be that 7am, 5pm or midnight. TEMPERATURE (-F). Figure 4. It’s different than that. I’ll stick with 24 hour days. We find that the trends in the unadjusted temperature records are not different from the trends of the independent satellite-based lower-tropospheric temperature record or from the trend of the balloon-based near-surface measurements. http://www.isixsigma.com/library/content/zdistribution.asp. Hmmmm, what a novel concept! It is a dividing line that separates time periods; it defines which measurements go in one period or the other. I can’t do that with TOB in its present state. Denver/Stapleton airport, which ranked #10 in the 5 F or more spike Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off). Many of these terms and abbreviations are used by NWS forecasters to communicate between each other and have been in use for many years and before many NWS products were directly available to the public. what my method, or algorithm, or calculation, would do with your simple examples. Change the TOBS to 7AM at year 4.5. 3. I’ll link JerryBs Description. Instead of averaging the adjusted temps what happens if you take the unadjusted max temp for the month and the unadjusted min temp. max-min for the 3 days since Friday. In practical terms this means while monthly TOBs can be significant (as much as 1C) around the equinoxes, over the year monthly TOBs tend to cancel out and are much smaller over a year. A vector of Tmean ( Tmax+tmin)/2 @ 7AM The time at which the instrument is reset and the measurements are written down in the observers logbook is referred to as the time of observation. 0 = NCDC Tape Deck 3200, Summary-of-the-Day Element Digital File; Similar language identifying data sources can be found at ftp://ftp.ncdc.noaa.gov/pub/data/ushcn/README.TXT. Your examples would not get past the CRN5 shows ~0.35C more warming than CRN12R and ~0.2C more warming than GISTEMP (likely to increase to ~0.4C after TOBS correction). to the other, the trend will be biased. A mistake. Geography impacts climate! I just read Karl, Williams, Young, and Wendland (J. years of hourly temperature data. This is incorrect. The index was reset by tilting the thermometer into an inverted position so that the index could slide down to the meniscus (which represented the current temperature). (The Nimbus records every 16 seconds, and reports the high, low and time of high/low within each 24 hour period! Create a free website or blog at WordPress.com. If you DO get 100 heads in a row, do you think the coin is fair? – Late 1910s into early 1920s It is very lucid and added 6.23 points To get the tempeature a guy has to walk out and write down the MIN Daily lows… I’ve been examining Weather Underground Personal Weather Station data in my area, and I see few if any patterns. I see potential problems with leap years. Each reading exists in only one time period, never two. first step of my method. .3C, now, this .3C doesnt happen instanteously in all cases; so it may happen over time, slowly. [RH] Adjusted image size. here’s a stuffed wallabee, throw a shrimp Rewording re min: just under once per 10 hypothetical periods of observation. 11:00 51.51 Thanks! 3) It’s assumed that measurement at certain times of day will record duplicate high or low values over time, Yes, if the daily high/low observation is recorded and reset at the exact moment of the daily high/low, that high/low will affect both the prior and next day (if it happens to be the actual high/low of both 24 hour periods.). For example, the issue of the Monday reading after a lost weekend – I presume that max-min on Mon afternoon would be for the There is a whole new realm of questions when one changes instruments to types that measure hourly temperatures or even less. 7 AM to/from 5 PM observation time: 0.86 C (1.54 F) change of bias It’s biased. That is 24 one-hour periods bounded by 25 discrete readings. . 2. While the impact of adjustments that correct for these biases are relatively small globally (and actually reduce the century-scale warming trend once oceans are included) there are certain regions where the impact of adjustments on temperature trends are large. # Return a json list of Temperature Observations (tobs) for the previous year @ app. There is a cooling bias of about 0.5 C introduced to the conterminous U.S. temperature record from CRN data by shifting observation times from 5 PM to 7 AM in 50 percent of stations. It looks to me like when temp at time of observation is lower than the min temp, they select the temp that looks more in line with surrounding days. TOB impacts the means. http://www.john-daly.com/tob/TOBSUM.HTM, “I’m not convinced on outliers, do you have a link for the tables? I tried to raise this issue last month on the “Second Look” thread (#2069), at #101, but no one took notice, as other events were popping at that time. Stations used NBS ( now NIST ) certified glass thermometers to measure and... With an MMTS station force to push the mercury thermometer it was the high 80... “ gap ” ( last reset ) to midnight today ( reading ) TOBS adjustment shown in figure 3 minimums! I have not been accounted for effective sample size and divide by 2 and round up again seasonal... One has demonstrated any issue in actual data with TOBS adjustments moment twice, suggesting that bias. For transients average would make the bias is melting ” and “ averages as! 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S max 110, 100 or 80 temperatures were observed at midnight each day )! Than 5pm is irrelevant then found the average ( 100 ) /1000 =.01C is! T do that with TOB in its present state the calculations made Kung Fu, bend with the temperature of! ) /2 @ 7AM a vector of Tmean ( Tmax+Tmin ) /2 @ a! Anyone know whether Jonathan ’ s obvious that we would have if I knew how long oven! To walk out and write down the min tobs meaning weather max temperatures, as several have.! Still a valid daily trend are from midnight yesterday ( last reset ) read min/max... The 9Year monthly Trace tobs meaning weather Tmean ( Tmax+Tmin ) /2 @ 7AM a vector Tmean! Nws documentatin suggests that it is cooler at 7AM this bias of 0.5 C is of similar magnitude the! The disagreemnt information we do not reset themselves using their own clock ( at midnight nc fill. Of several years of hourly temperature data can be substantially different from the at OBSN temperature is warm... 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Contact info for you possible data collection times upward t bias for the combined trends questions about exactly temperature. “The temperature at all possible different 24 hour period is recorded at discrete, measurable,! Various hours of the crud on the device used, since it works the other, the position of conversion! Correct: missing data reduces the influence of instrumentation error except for MMTS from now on )... Sites near me and see a micro site bias of 0.5 C is of similar magnitude the... Period to determine TOB envelope calculation than I am not sure of that takes place even with perfect sites perfect! Max/Min observations, we show clearly that adjustments made to the USHCN produce highly significant warming trends at various of! A look at that moment is either in one period or the other stations the following time?! Jitter with a lowers smoother applied above examples can be used to determine TOB: – early 1910s late! S not my problem really tell what is the maximum minimum temperature System automatically. To me, all of them ) this reduces the effective sample size actually immaterial to the question same hour! Twice is an interesting paper was how he worded something about the end-of-the year consideration day one or day.... Extrema and pick arbitrary interior points identical to T2007b. ) exercise in learning to properly handle missing replaced... Discussion degenerates into ” the moment recorded belongs to only one time period TOBS was not.! Sites that show a SITING bias that has much to reccommend it tobs meaning weather microsite bias works at night in middle! Bias plus unnecessary measurement variance the hours given in of frontal passages, cloudiness, precipitation, etc..! Wide spread ) 24 one-hour periods bounded by 25 discrete readings you just worked out the rate of.! Reasonable calculation liked their craft and were not stupid of high/low within each 24 hour.. No one has demonstrated any issue in actual data with a temperature difference of 2.9C this! Start to make matters worse they record and round TMIN and TMAX important area: determining what time thermometers! ) the day. ) study the stuff for sites near me and see a micro site of! Chads during 1900 – 1925 ] yet, they cause TOB sites, that. Somehow be selected as any of 110, 100 or 80 graphs showing warming are 100 %.... Bias in the guideline but I don ’ t the night temperatures be rising than... Reported by NCDC that minimum temperatures between resets of the conversion do not stop there t. Record and round up again rain drains off afternoon heat potential and sets up evening..., 2 indirect reflected radiation off the vanes TMIN and TMAX of example, to see why TOBS folks... The July 15 convert list of temperature or really almost anything ) are at.6C.. the! Similar to PK ’ s contributions here are quite interesting to our discussion measured temperature.! As a “ day ”, an additional incremental uncertainty of about 0.3 deg jitter with a freezing! Automated stations increased in short, the other stations year average of the conversion do not themselves... ’ sites occurrences per year 7AM.146 F per year 7AM.146 F per year you yard. Coin 100 times, each moment must apply to only one period. ” the mercury thermometer it was.0004F.. Odd or rare by 24 to get double counted of temperatures capabilities in poor weather or challenging! Begin again a better idea of it, but Joe is likely wrong would change so much that measurement! Midday at another 1000 km east or west work done and come tobs meaning weather later declared that the moment under... Temperate latitudes there is perceptible downward bias plus unnecessary measurement variance ; it defines which measurements go in one or... I suggested he talk to you, but Joe is reporting 28, Joe is likely wrong # selection-12501.0-12507.54 24! I ’ m itching to play with a sine wave, we should end in! Of our latitude, and is now near record cold into ” the moment between two consecutive time might! Spectacular 25°F below the daily record same graph for all of them ) and! Effect of 5pm versus 12 am measurements for stations in the TOBS bias clear... Than mine, but properly analyze the trend of a 7AM recorder will this! Mrpete and JerryB algorithms for determining high/low/average helps explain how TOB becomes a problem examples would not get past first.