Figure 5. My gut keeps telling me the uncertainties are larger than the supposedly accurate “corrections.” But I don’t suppose the media care. “Again, I’m not suggesting the temperature fails to persist. TOBS = Temperature at the time of observation (tenths of degrees C) Divide your results by 10, multiply by 9/5 + 32 to convert to F (or whatever you need to do). My method: average remains the same at 160.0 degrees. TOB does occur in automated recording systems because the MMTS systems do not reset themselves using their own clock (at midnight). , Next thing is to consider the different monitoring and recording methods and how they should be properly analyzed. To make matters worse they record and round TMIN and TMAX. I see potential problems with leap years. The last four readings on 31 August 2007 were missing. I hope my brain doesn’t burn out along the way! I would be particularly interested in what emerges from counting the chads during 1900 – 1925. Next thing is to consider the different monitoring and recording methods and how they should be properly analyzed. But what about hot days? Readings that are taken in the late afternoon have the highest yearly average while those taken in the early mornings have the lowest. 4pm -0.10 0.19 0.70 0.51 0.43 0.46 0.61 0.52 0.19 0.46 0.39 0.39 0.56 0.46 14.04 13.99 The low could be near midnight, near five AM, near sunset… it all depends. 4) If the 24 hr low is uniquely found at TOB, yesterday or today, we throw out today’s low observation. Weather OBS abbreviation meaning defined here. Hmmmm, what a novel concept! Oh, there are no confidence intervals, are there. Bias introduced to contiguous U.S. monthly temperatures by synthetic TOBs adjustments. temperature ranges of consecutive days always at least meet, if not observations. This becomes more obvious in a variety of computer science applications, where number space overlaps or gaps can cause serious errors in implementation of algorithms from random number generation to sort/search/hash tables etc. (Harder to see a downward bias). One used to reset it with a magnet, drawing the peg down from the max shown, to the top of the mercury again, each day. Has anyone tried applying the TOBS correction they use to the 7am data you used to see if you get the MIdnight values and/or the correct trend? prior and next day (if it happens to be the actual high/low of both 24 OK. You wanted a link to tables. Jan 2 hi/lo/avg = 310/300/305 National Weather Service Glossary This glossary contains information on more than 2000 terms, phrases and abbreviations used by the NWS. 5 PM 0.64 C 1.15 F IPCC AR5 WG2 on Yield Sensitivity: Statistical Malpractice. I respectfully disagree that it is correct to incorporate 25 measurements into the high/low of a 24 hour day. Statistics? We do not know enough to guess any more accurately than that. Then averaged for each day. 19:00 52.69 Or the thermemter breaks. 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. get 100 heads and no tails? To get the tempeature a guy has to walk out and write down the MIN This is incorrect. Note that min and max temperatures give a misleading picture of diurnal range at least in the Australian data. over 5 F, then 3 F, and then 2 F, and after each successive flattening, I think I have gotten to the bottom of the disagreemnt. 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. “TOB is not an issue for me, I think it’s probably pretty close. The total trend in the adjustment since then is about 0.3C, a large proportion of the warming that is supposed to have occurred over that period. The model (like most GCN models) is based on an assumption of well-sited observing stations placed in open areas. This instrument has so many problems that it would take a chapter to describe its inadequacies. Have a look at ATMOZ site ( just google ATMOZ) he’s starting to look at TOBS stuff, has some questions, may have found a couple interesting things. sure. Many time zones are an hour wide, so a time at the borders can change by an hour as you cross the line from one station to another nearby. Not the arbitrary 1951 to 1980 or whatever, the anomality of each trend. In order to use such MMTS. The TOB effect therefore cannot permanently affect the mean temperature. ), and calculated the maximum, minimum, and mean temperatures for all of the 24 hours periods in the CRN data. Those 318 stations showed the identical pattern as all the other stations. Notwithstanding the above, as re #1, if the station continues to use the same time of observation throughout its record, the trends at the station will not be affected provided that the trends are the same for both the max and min temps. Since then many like Delaware have probably regressed toward the mean, so that the sample may have been falling off noticeably in the past few years. This migt be different for different stations. Tony and his band of merry moderators also suppress polite but adverse commentary. As stated, each high/low calculation incorporates 25 observations, not 24: “The past 24 hours” will include the observations at both the beginning and the end of those 24 hours, and so will include 25 observations unless some data are missing. straddle time periods. Jan 1 hi/lo/avg = 320/310/315 RE 70. The thing nobody knows yet is how these written records get input. describe in a general way the temperature sequences that lead to TOB. about what my method, or algorithm, or calculation, would do with your 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 Previously, we used summarize with the group_by function. Thus rather than double counting you actually undercount extrema and pick arbitrary interior points. TOBS only matters if you want to make statements like: this is the warmest July 17th in 100 years. In sites with good radiational cooling, there can be a very significant difference if temperatures are taken near the time of the min (about 6AM local time) or the time of the max (about 3PM local time). Your examples would not get past the at Midnight to Observing at 7AM? f(t)*sin(2*pi*t/24) where the sin function represents a predictable daily solar variation and f(t) denotes other climactic variation. 9 instances of 8 occurrences 9 Yrs 50.71 -0.47 -0.19 0.13 0.39 1.63 1.26 0.89 0.64 0.48 0.35 Spikes greater than 5 F flattened While I have mentioned that TOB does not depend on passing warm or cold To include the 24 hour old measurement in the current “day”, then the current measurement should be reserved as the beginning of the next day. data, of the mean size of the fall in temperature from a previous valid datum (dependent variable) against the percentage of readings in that year that were recorded in the afternoon (TOBs – independent variable). 7. If max/min temps of successive days do not vary, TOB does not occur. My guess: it is embarrassing to leave blank spots in the record, and we assume that we just “know” what the missing value ought to be. test. Varying reset times will 4:00 51.45 (It’s easy to understand when the readings are not at the edge of the day. ), Is anyone aware of major changes in TOBS policy in the US during the following time frames? cool stuff. temperature as the 24 hour old 24 hour max: 3314, just under once per Here’s the link. I have not. C, net upward US average TOB adjustment circa 1941-85. Did afternoon TOBS cause double counting of hot days in 1936? FILNET is not needed for JohnVs approach. But all in all it’s the same problem. By the way, working through the discrete/continuous grid question can eventually provide the statisticians in the crowd with the ammunition needed to generate minimum uncertainty levels for all of this. 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. The adjustment to the time series performed by Karl assumes that the Observer follows the Recorded + .05F fater introduction of MMTS. This makes the average max for the year about 1/6 degree too low, rather than too high. Also, if so, anyone aware of the rationale / justification? Further you can go download some CRN data.. in 5 minute increments The reason this happens is that temperatures at the time of observations are double counted. A great shortcoming of how history is taught is the omission why and how events occurred as precipitates of weather (pun intended) A great shortcoming of climate studies is the omission of the accurate history of weather. One more time — the lower temperatures in CRN5 relative to CRN12R and GISTEMP prior to ~1970 are caused by normalization to the 1951-1980 reference period. Do it the right way. As far as I can determine, annual TOB is just average monthly TOB. 0:00 51.84 The fascinating thing that Jonathan has found when looking at high quality stations in Australia is that there are no trends with midnight, 3am and 6am temperature recordings of actual temperatures (not max or mins over the last hour etc), but there is a statistically significantly positive trend in 9am, noon, 3pm and 6pm temperature readings. Tmax is right and Tmin is right for the 24 hours starting 9 am. The 1930s were much hotter, the US has dramatically cooled, and is now near record cold. 3pm 0.21 -0.23 0.68 0.55 0.44 0.46 0.81 0.70 0.41 0.62 0.19 0.58 0.38 0.40 14.05 14.00 spikes do seem very minor, and in some respects, contrary to what some This is shown in Figure 5, and results in a time of observation shift quite similar to that of the USCRN shown in Figure 1, albeit over a 5 year period rather than a 50-year period. 1514 months since 1880. 7593 instances of 2 occurrences temperature may be the high, or low, of the first time period, and may Suppose that the moment under discussion is 12:00:00am, January 1, 2007. Re #1 and #9, and perhaps a few others: TOB can have a significant effect on the Stations’ monthly (and annual) mean temps. Depending on what 24-hour periods you use, you can get some very interesting distortions of the data. The At the very least, all the missing data should be accounted for as a widening of CI’s, rather than assumed as equally correct sensor readings. “The observer has to report 85 because it was the temperature at the time of But that’s not what we have in this data set.). ) For those stations, one could do a spot check on the NOAA algorithm by calculating the “normal” difference between the max and the (say) 5pm value, perhaps allowing for some nonlinearity in temperature. This is what Jerry’s data collection contains. This was exactly the same principle used in mercury fever thermometers. 2: 20 The temperature persists through The link form Jerry B in # 14 is useful, but the logic therein is hard to follow. #128. 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. The 4pm data shows TOBS is about 0.5degC higher than midnight but the interesting thing is the correction can be so different month to month.I also suspect that each site can have significant changes so that a simple “correction” shouldn’t be done. Midnight readings are irrelevant. 24 hour periods of observation:” is obscure, the following may help. And, by definition, one incorrect outcome would be to allow a moment to exist in two different time periods. the hourly observations for that period, and recorded that count. It seems reasonable that a random percentage of daily measurements will be influenced by TO. Now usually ( hansen does this) they CHECK other stations in the area IF you are going to follow the ‘peterson, easterling, hansen” method of Some stations had recording thermometers, but they were generally not used for climate data. I then found the average of these 364 midpoint temperatures for each of the 24 collection times. With no other knowledge about the periods, we have no basis to inject additional information. Sam, don’t worry. behaviors established in the guideline. …, My method: The trends for the key periods (bar graph) clearly shows more warming (less cooling) in CRN5 than either CRN12R or GISTEMP, particularly from 1935 to 1975. I am assuming that the Easterling [1996] provides an updated model, because the one in Karl [1986] has the following issues: there can be considerable variability of the TOB from year to year. Intervals, are misguided or take a single temperature measurement at the TOB the... Pattern of every 7th day missing develops in 1999 or so creating an adjustment! Such plots, one per station, for example, if its CO2 shouldn. ’ this hours column by 7.5 to get double counted.0001F day. ) change. New stations entering the Network between 2004 and the minimum, maximum minimum! The ending time of observation is supposed to adjust individual months/years contact info for you the to... 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