The first press release announcement thread is getting big and unwieldy, and some commenters can’t finish loading the thread, so I’m providing this one with some updates.
1. Thanks to everyone who has provided widespread review of our draft paper. There have been hundreds of suggestions and corrections, and for that I am very grateful. That’s exactly what we hoped for, and can only make the paper better.
Edits are being made based on many of those suggestions. I’ll post up a revised draft in the next day.
2. Some valid criticisms have been made related to the issue of the TOBS data. This is a preliminary set of data, with corrections added for the “Time of Observation” which can in some cases result in double max-min readings being counted if not corrected for. It makes up a significant portion of adjustments prior to homogenization adjustments as seen below in this older USHCN1 graphic. TOBS is the black dotted line.
TOBS is a controversial adjustment. Proponents of the TOBS adjustment (Created by NCDC director Tom Karl) say that it is a necessary adjustment that fixes a known problem, others suggest that it is an overkill adjustment, that solves small problems but creates an even larger one. For example, from a recent post on Lucia’s by Zeke Hausfather, you can see how much adjustments go into the final product.
The question is: are these valid adjustments? Zeke seems to think so, but others do not. Personally I think TOBS is a sledgehammer used to pound in a tack. This looks like a good time to settle the question once and for all.
Steve McIntyre is working through the TOBS entanglement with the station siting issue, saying “There is a confounding interaction with TOBS that needs to be allowed for…”, which is what Judith Curry might describe as a “wicked problem”. Steve has an older post on it here which can be a primer for learning about it.
The TOBS issue is one that may or may not make a difference in the final outcome of the Watts et al 2012 draft paper and it’s conclusions, but we asked for input, and that was one of the issues that stood out as a valid concern. We have to work through it to find out for sure. Dr. John Christy dealt with TOBS issues in his paper covered on WUWT: Christy on irrigation and regional temperature effects
Irrigation most likely to blame for Central California warming
A two-year study of San Joaquin Valley nights found that summer nighttime low temperatures in six counties of California’s Central Valley climbed about 5.5 degrees Fahrenheit (approximately 3.0 C) between 1910 and 2003. The study’s results will be published in the “Journal of Climate.”
Most interestingly, John Christy tells me that he had quite a time with having to “de-bias” data for his study, requiring looking at original observer reports and hand keying in data.
We have some other ideas. And of course new ideas on the TOBS issue are welcome too.
In other news, Dr. John Christy will be presenting at the Senate EPW hearing tomorrow, for which we hope to provide a live feed. Word is that Dr. Richard Muller will not be presenting.
Again, my thanks to everyone for all the ideas, help, and support!
=============================================================
UPDATE: elevated from a comment I made on the thread – Anthony
Why I don’t think much of TOBS adjustments
Nick Stoke’s explanation follows the official explanation, but from my travels to COOP stations, I met a lot of volunteers who mentioned that with the advent of MMTS, which has a memory, they tended not to worry much about the reading time as being at the station at a specific time every day was often inconvenient.. With the advent of the successor display to the MMTS unit, the LCD display based Nimbus, which has memory for up to 35 days (see spec sheet here http://www.srh.noaa.gov/srh/dad/coop/nimbus-spec.pdf) they stopped worrying about daily readings and simply filled them in at the end of the month by stepping through the display.
From the manual http://www.srh.noaa.gov/srh/dad/coop/nimbusmanual.pdf
Daily maximum and minimum temperatures:
· Memory switch and [Max/Min Recall] button give daily
highs and lows and their times
The Nimbus thermometer remembers the highs and lows for
the last 35 days and also records the times they occurred. This
information is retrieved sequentially day by day. The reading
of the 35 daily max/min values and the times of occurrence (as
opposed to the “global” max/min) are initiated by moving the
[Memory] switch to the left [On].
So, people being people, rather than being tied to the device, they tend to do it at their leisure if given the opportunity. One fellow told me (who had a Winneabago parked in is driveway) when I asked if he traveled much, he said he “travels a lot more now”. He had both the CRS and MMTS/Nimbus in his back yard. He said he traveled more now thanks to the memory on the Nimbus unit. I asked what he did before that, when all he had was the CRS and he said that “I’d get the temperatures out of the newspaper for each day”.
Granted, not all COOP volunteers were like this, and some were pretty tight lipped. Many were dedicated to the job. But human nature being what it is, what would you rather do? Stay at home and wait for temperature readings or take the car/Winnebago and visit the grand-kids? Who needs the MMTS ball and chain now that it has a memory?
I also noticed many observers now with consumer grade weather stations, with indoor readouts. A few of them put the weather station sensors on the CRS or very near it. Why go out in the rain/cold/snow to read the mercury thermometer when the memory of the weather station can do it for you.
My point is that actual times of observation may very well be all over the map. There’s no incentive for the COOP observer to do it at exactly the same time every day when they can just as easily do it however they want. They aren’t paid, and often don’t get any support from the local NWS office for months or years at a time. One woman begged me to talk to the local NWS office to see about getting a new thermometer mount for her max/min thermometer, since it wouldn’t lock into position properly and often would screw up the daily readings when it spun loose and reset the little iron pegs in the capillary tube.
Some local NWS personnel I talked to called the MMTS the “Mickey Mouse Temperature System” obviously a term of derision. Wonder why?
So my point in all this is that NWS/NOAA/NCDC is getting exactly what they paid for. And my view of the network is that it is filled with such randomness.
Nick Stokes and people like him who preach to us from on high, never leaving their government office to actually get out and talk to people doing the measurements, seem to think the algorithms devised and implemented from behind a desk overcome human urges to sleep in, visit the grand-kids, go out to dinner and get the reading later, or take a trip.
Reality is far different. I didn’t record these things on my survey forms when I did many of the surveys in 2007/2008/2009 because I didn’t want to embarrass observers. We already had NOAA going behind me and closing stations that were obscenely sited that appeared on WUWT, and the NCDC had already shut down the MMS database once citing “privacy concerns” which I ripped them a new one on when I pointed out they published pictures of observers at their homes standing in front of their stations, with their names on it. For example: http://www.nws.noaa.gov/om/coop/newsletters/07may-coop.pdf
So I think the USHCN network is a mess, and TOBS adjustments are a big hammer that misses the mark based on human behavior for filling out forms and times they can’t predict. There’s no “enforcer” that will show up from NOAA/NWS if you fudge the form. None of these people at NCDC get out in the field, but prefer to create algorithms from behind the desk. My view is that you can’t model reality if you don’t experience it, and they have no hands on experience nor clue in my view.
More to come…
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
I re-read the report to identify the data referenced … here is the list I came up with.
I even included the NCDC station history metadata link in case you don’t want to do the extensive visual and/or onsite inspection Anthony and his help spent well over a year doing.
Seems everything is there to reproduce the work for the people who question the results. I did it on my own – would saved me half an hour if I’d simply read the References 😉
The USHCN Version 2 Serial Monthly Dataset page – scroll down to find the 4 data sets for each set of station ratings, along with the MMTS and Cotton Region Shelter (Stevenson) site information used for Menne (2010):
http://www.ncdc.noaa.gov/oa/climate/research/ushcn/
The NCDC Station Histories appear to be here:
http://www.ncdc.noaa.gov/oa/climate/stationlocator.html
WMO-CIMO endorsement of Leroy(2010) standard is here:
http://www.wmo.int/pages/prog/www/CIMO/CIMO15-WMO1064/1064_en.pdf
Leroy(2010) is here:
http://www.jma.go.jp/jma/en/Activities/qmws_2010/CountryReport/CS202_Leroy.pdf
Watts(2009) is here:
http://wattsupwiththat.files.wordpress.com/2009/05/surfacestationsreport_spring09.pdf
And Muller’s Station data is here:
http://berkeleyearth.org/pdf/berkeley-earth-station-quality.pdf
Fall (2010):
http://pielkeclimatesci.files.wordpress.com/2011/07/r-367.pdf
http://www.surfacestations.org/fall_etal_2011.htm
NOAA’s Climate Reference Network Site Handbook (see Sec. 2.21)
http://www1.ncdc.noaa.gov/pub/data/uscrn/documentation/program/X030FullDocumentD0.pdf
Watts Surface Stations Project site master list:
http://www.surfacestations.org/USHCN_stationlist.htm
(the brief notes should provide an initial screen of suspect stations)
Pardon my ignorance here but is TOBS really a factor? If there is an error introduced by TOBS I suggest the same error will occur in those badly sited stations as in the better sited stations so the effect is nullified and therefore it does not need to calculated.
A Scott says “Why wouldn’t the TOB adjustment simply be a single, identifiable, “step” change, easily discerned in the data?”
As I understand it TOBs adjustment for a single change should not be a step change, it should be a spike. The subsequent Tmin Tmax range should then return to normal since you are still looking at the range for a single 24 period. The real problem is when the TOBs (which is recorded, faithfully you would hope) changes on a daily basis.
Smokey, do a google news (past week) search on “Richard Muller”. Then do the same search on “Anthony Watts”. The result is what you would expect, but you will probably be amazed at the orders of magnitude difference.
Do I get that right: In the age of computers and automatic measuring the quality does not get better, but worse? And the time of observation was a problem during the last 30 years?
When I had a close look at US-Meteorology 20 years ago (aviation-related, at ERAU in Daytona Beach), I had the impression they knew what they were doing.
Introduction of “sommertime”!
It varies between coutries. In Sweden it was introduced in 1980. It was made uniform in EU 1996 and I havent found out how the other EU countrys and countrys outsida the EU have applied sommertime and I havent a clue how this change have influensed readings. It ought to be cinsidered by TOBS? Or is it irrelevant?
If as Anthony says: “they stopped worrying about daily readings and simply filled them in at the end of the month by stepping through the display.”. Then this suggests that the Max/Min temps would be recorded on a strictly daily basis (i.e. midnight to midnight). This being the case when the old base station was replaced by the new Nimbus, the practice of relying on stored temp data would have resulted in effectively a change in time of observation from the morning to midnight.
And that would have introduced a warming bias.
I haven’t heard of anyone discussing this let alone adjusting for it. Is this an issue? Can it explain why Anthony is finding the lower trend?
Kelly Haughton says:
July 31, 2012 at 6:18 pm
“It will be interesting to see what the “peers” do for the peer-reviewed journal. How will the peers be selected? What will they say? Will they read all the comments?”
This should help you understand the peer review process.
http://www.agu.org/pubs/authors/pdf/PeerReview_Guide.pdf
.
Using atmospheric temperature to assess the amount of heat in the atmosphere shows ignorance of physics.
Averaging atmospheric temperatures compounds the nonsense.
Arguing over the time of observation of the temperatures is akin to arguing over the color of the angels wings that are to be counted on the head of the pin.
I still don’t get why so many are hammering the TOBS thing. I have understood for years that reading the units at different times can make a minuscule difference.
But this paper is about the way the “adjustments” are made. The paper is about the huge amount of poorly sited units which read warmer due to location and then have even more upward adjustments made to them — and to beat all, the good sites are adjusted upwards to match the bad ones!
TOBS is a smokescreen in the context of this paper.
@Steve Huntwork For a pure daily cycle, then the time of observation is irrelevant.
The problem arises when warm/cold spells of a few days’ duration (i.e. weather) are combined with a daily wave form (i.e. diurnal cycle).
Consider what happens if you have a diurnal cycle varying from 10 degrees at dawn (say 5am) to 20 degrees in early afternoon (say 2pm), and you’re doing the readings at 4pm – i.e. in the afternoon shortly after the daily max. Each day’s min/max observations will come up as 10/20 degrees at 5am/2pm, and everything is fine.
But now think what happens when you have a warm spell lasting 7 days, which raises the overall temperature by 5 degrees so the cycle now goes from 15 degrees at 5am to 25 degrees at 2pm. For the first 7 days, you’re fine: it records the daily min/max as 15/25 degrees at 5am/2pm, exactly as it should. On the eighth day, you’ll record the min correctly as 15 degrees at 5am, since the warm spell is over and you’ve dropped back to the previous normal. However, the max will get recorded as something like 24 degrees at 4:01pm on the previous day; i.e. the last day of the warm spell gets double counted. A seven-day warm spell has contributed 7 times to the daily min, and 8 times to the daily max, and the average has therefore been subtly boosted slightly higher than it should be.
There’s no deliberate cheating or lies associated with this. The same issue can works in reverse: for stations taking observations near dawn, then the last day of any given cold spells will get double counted. The overall effect is in principle symmetric: stations taking readings at 4pm will tend to read higher than the “true” value since they double-count warm days, while stations taking readings at 4am will tend to read lower than the “true” value since they double-count cold nights. However, humans being humans, you don’t *get* large numbers of weather stations all taking their readings at 4am, whereas in the first half of the century 4pm was a common time to take daily readings. This applies particularly to rural stations with reduced accessibility. So, rural stations tended to slightly overstate temperatures in the first half of the record, and thus the raw values from these stations will underestimate the true warming trend – exactly as Anthony sees in this work.
The fact that the new station rating shows no difference in trends in the homogenised data is strong evidence that the homogenisation procedures correctly remove both UHI and time-of-observation bias.
Dear God.
And bear in mind that I’m an atheist.
How the hell can anyone come remotely close to quantifying such “randomness” in order to set some sort of value on the degrees of uncertainty in the whole “NWS/NOAA/NCDC” melange?
Billions of dollars have been spent on “research” to support the ginormous “We’re All Gonna Die!” AGW fraud and Mr. Watts reports that:
Like most SF magazines, Analog actually reaches its subscribers as much as a couple of months before its stated publication date. The November 2009 edition was therefore in print and in the hands of readers long before FOIA2009.zip hit the ‘Net. In that edition – written long before the issue went to print – physicist and SF writer Jeffery D. Kooistra published his “The Alternate View” column (titled “Lessons From the Lab“) about Mr. Watts’ early SurfaceStations project report, Is the U.S. Surface Temperature Record Reliable? (May 2009).
Kooistra started by recalling his experience as an undergraduate, in which he learned something that all former science majors can readily appreciate:
He then went on briefly to discuss Mr. Watts’ project and recently published monograph, concluding:
This particular “popular science” article in a pulp magazine helps explain why fans of “hard” science fiction – Analog‘s staple product – have tended overwhelmingly to be skeptical about the great AGW boojum since its inception, and why few of us were surprised (though most of us were delighted) by Climategate 1.0 on 17 November 2009.
We’ve been tracking this hoax-based hysteria among the mundanes for decades.
This understood, to learn that things are actually as bad in the “NWS/NOAA/NCDC” surface stations system as Mr. Watts describes…
…is to me the equivalent of hearing that the Mayo Clinic has been given over wholly to the practices of homeopathy.
Not that I don’t believe Mr. Watts, but it’s kinda difficult to get my hands around just how rotten this “global” pretense of precise climate knowledge actually is. It’s like something out of a sick and twisted horror novel.
And, remember, I’m a fan of “hard” science fiction.
davidmhoffer says:
July 31, 2012 at 6:26 pm
Entropic Man;
I see some papers to make one wince, too. Nevertheless, these are the ground rules that scientists and scientific journals go by.
>>>>>>>>>>>>>>>>>
Will there be more crap on the internet because it is accessible to all? Of course. Will a tiny cabal of politicaly motivated scientists be able to get editors fired and legitimate science suppressed?
Not a chance. Welcome to the new world.
————————————————————————————————————————–
If your baseball team wants to play in a league, you play by that league’s rules. If you want to publish, you go through peer review. Most scientists use it as a filter to keep their reading list manageable by winnowing out the worst of the rubbish.
To get some perspective on this problem, look at http://arxiv.org/
This archives e-prints of unpublished and unreviewed papers. Some are good science, put there to establish priority in advance of publication. Others are there because they bad science that will never reach publishable standard.
Without peer review there is no way for someone reading the papers online to distinguish between good and bad. Like all systems human peer review is imperfect, but better than nothing at all.
There is discussion of ways to update quality control of scientific papers in a digital age, though any solution would still have to winnow the wheat from the chaff.
Several comments about TOBs.
An early paper by Schaal et al 1977 identified a 1.0 – 1.5 C cooling impact on the US temperature record due to TOBs changes. This was for the period 1910 to 1975 where a large percentage of the COOP observer network progressively changed. For each individual station, a single change in TOBs represents a single step change in bias.
Given the way the older system worked, with thermometers recording max & min temperatures, with the thermometers being reset when the observer takes the reading, having a reading schedule close to the time of day when either the maximum or minimum temperature occurs increases the likelihood that the value at that time may end up being counted for 2 days, whether max or min. The earliest schedule used by COOP, as reported by Schall et al, was to measure at midnight. This was an ideal time, a substantial number of hours away from the normal time of max & min. The schedules then progressively shifted to 7 AM & 7 PM. 7 AM, a particularly problematic time. In winter, in darkness, the minimum can easily occur around then. So you can easily record a minimum twice because the thermometers don’t tell you when the minimum occurred.
Schall et al reported that by 1975, 55% of the COOP network had changed their schedules, up from 10% that were on that schedule in 1910.
1975 is near the starting point of this study. And the MMTS units weren’t being rolled out till decades later. What proportion of the 45% of COOP sites that hadn’t switched their TOBs already did so over the study period.
Then the introduction of MMTS automatically constitues a TOBs change. Now it isn’t getting max/min based on observation time, but max/min for a particular day. So intrinsically it is cancelling out and previous TOBs bias, which is itself a TOBs bias.
Another question or issue. Is there any correlation between station siting ratings and TOBs bias. Is there any pattern in which stations experienced TOBs changes, and does this correlate with station ratings. Could stations with poor siting due to being in less pristine environments have been more or less likely to experience a TOBs change. For example, in an environment that is getting built up, could the observer for that site be someone who now works nearby and takes the reading during office hours, whereas in the past they where someone who lived nearby and sampled before going to work.
A final comment on TOBs biases and how they can be important. John Christy is listed as a co-author. John has years of experience with the Satellite Temperature record at UAH and how it is analysed. One significant issue that was addressed nearly a decade ago was the problem of Diurnal Drift. The satellites are in orbits that are meant to be Sun Synchronous. As they fly over the Earth they are meant to pass over each point below at either solar Noon or solar Midnight. To do this their orbits are given a planned precesion so that over the course of a year thier orbit slowly changes to remain Sun Synchronous. However the satellites don’t have thrusters to adjust their orbits so over time due to atmospheric drag and the fluctuation of gravity as they pass over different parts of the Earth, their orbits deviate and they are no longer quite Sun Synchronous. So they now pass over the Earth at times different from Noon & Midnight. This is Diurnal Drift. UAH (and RSS) developed methods to adjust for this. And the results made substantial differences to the trends reported by both groups, adding a significant amount to the trends. Diurnal Drift mattered!
Diurnal Drift is a TOBs bias!
So I wonder what input John had as a co-author in advising on just how important it was to consider TOBs biases.
The simples approach that the authors could take in the short term, until perhaps a more detailed cross-referencing of TOBs vs other factors can be done for each individual station is to cofine comparisons to looking at different station categories within only individual data sets. Compare only Raw against Raw, TOBs adjusted against TOBs adjusted, Fully adjusted against Fully adjusted. When comparing across the data sets you simply can’t have any confidence in what you are reporting. Ascibing differences to one factor when multiple factors are involved and haven’t been separately evaluated isn’t worth very much.
For example, the paper comments that good quality stations have been given warm afjustments to bring them into line with the poor quality stations. What about the possibility that the good quality stations had a TOBs change before the start of the survey period, the 55% reported by Schaal. Perhaps the good quality stations were more likely to be given MMTS upgrades compared to the poor quality ones.
I don’t know the answer to these questions. But nothing written in the paper says the authors have any idea either. And without being able to evaluate this, the conclusions of the paper simply cannot be backed up from what they have presented.The methodology is currently flawed.
If the authors wish to report some of the findings from applying part of the required methodology, fine. But this is extremely preliminary data that could change radically when all the relevent factors are considered.
So press releases and such claims to the effect that “Our findings show…..” are simply, totally unjustified. The findings don’t show anything yet; they are too preliminary.
REPLY: What Zeke illustrates is what I see as the biased nature of the whole network. There’s so many problems that all sorts of issues have to be invented to deal with it, and all the corrections they invent go UP. And like NCDC, Zeke’s trying to find the answers in the data, rather than looking at the reality of the measurement environment. Nobody wants to deal with that side of it. Color me unimpressed with the whole adjustment crusade. – Anthony
Anthony
Colour me disgusted.
Terry,
My concern exactly. If a change in observation time did introduce a step change in daily TMAX/TMIN observations, wouldn’t that be obvious in the raw data? Wouldn’t the accumulated TOBS biases over time tend to go back and forth, rather than requiring an additional bias be applied to the data that always seems to drive the temperature up?
Last year I wrote this article- carried here- which seems highly relevant to this subject; The following comments are taken from a book I referenced for the article, written by a famous climatologist over 100 years ago
Extracts;
“If the mean is derived from frequent observations made during the daytime only, as is still often the case, the resulting mean is too high…a station whose mean is obtained in this way seems much warmer with reference to other stations than it really is and erroneous conclusions are therefore drawn on its climate, thus (for example) the mean annual temperature of Rome was given as 16.4c by a seemingly trustworthy Italian authority, while it is really 15.5c.”
That readings should be routinely taken in this manner as late as the 1900′s, even in major European centers, is somewhat surprising.
There are numerous veiled criticisms in this vein;
“…the means derived from the daily extremes (max and min readings) also give values which are somewhat too high, the difference being about 0.4c in the majority of climates throughout the year.”
Other complaints made by Doctor von Hann include this comment, concerning the manner in which temperatures are observed;
“…the combination of (readings at) 8am, 2pm, and 8pm, which has unfortunately become quite generally adopted, is not satisfactory because the mean of 8+2+ 8 divided by 3 is much too high in summer.”
And; “…observation hours which do not vary are always much to be preferred.”
That the British- and presumably those countries influenced by them- had habits of which he did not approve, demonstrate the inconsistency of methodology between countries, cultures and amateurs/professionals.”
http://wattsupwiththat.com/2011/05/23/little-ice-age-thermometers-%E2%80%93-history-and-reliability-2/
That there have been problems with the instruments AND the manner in which they are read can be traced throughout the instrumental record. The BEST record to 1750 seems to be based on the data of around ten heavily adjusted stations to 1750 and is neither remotely ‘global’ nor, with the huge error bars, especially scientific-although it adds a little to our general knowledge which is to be welcomed and those involved in the number crunching to be congratulated on their diligence.
I can not really comment on the current Watts et al paper in detail as it seems to be (quite rightly) a work in progress, but I am sure Anthony-with his background-knows of the problems as much as anyone, whether you are dealing with modern or historic records.
Add in all the problems described in my article and the complications of siting, uhi, station move etc etc and i have come to believe over the last five yearsthat it is very foolish for politicians to bet the house on a CAGW scenario that-looking at history-is very difficult to see as based in reality
tonyb
But Anthony is measuring only from 1979, not 1900.
I understand why tobs leads to a bias; I just don’t see how one can correct for it using the available data.
Consider this scenario.
During the winter a shifting wind or passing front will lead to a bigger shift in temperature than the diurnal cycle. This is the case for the Netherlands; I bet there will be locations in the USA with a simular situation.
As a result, when the front passes, the warmest moment during the day can be at any point during the day. It’s not uncommon that when a cold front moves in around dawn, that the warmest moment was during the night! And on the other hand, when a warm front moves in during the night, it might be warmer at night than it was during the day.
The problem is that one can’t judge from the min/max values at which time the front moved in. Did the cold front move in at dawn, so the maximum is the maximum of the previous night (which could be the maximum at 8:01 pm on the previous day)? Or did the cold front move in at 1 pm, which would result in a ‘proper’ Tmax at 0:59 pm? In the former case, Tmax should be adjusted, in the latter it shouldn’t!
It seems impossible to me to adjust for this situation, without knowing the actual timing of the arrival of the front (which is not recorded).
Someone please explain something to me. When looking at Christy’s satellite data for the lower 48 I see about 0.3 degrees per decade warming for the same time period of Anthony’s study which is pretty much in line with NOAA/NASA/BEST numbers and about twice as large as Anthony’s data for “good” sites. I assume that the satellite data is not fudged. So why are the satellite numbers in much better agreement with the supposedly faulty NOAA/NASA/BEST numbers?
Here are some fixes needed for the Powerpoint presentation. Probably most of them have already been suggested:
P.2, there’s a dot missing in the leader before “Page 2” and there’s an extra space in the next line before “Page 3”
The following words are red-underline-flagged as misspellings by MSFT. They should be added to the spell-check dictionary: gridded, microsite, mesosite, vs., inhomogeneity, vanishingly
PP. 23, 33, 42, 52: Delete “actually” from “What the compliant thermometers actually say:”. It’s argumentative innuendo–or could be seen as such. (And it’s not in sync with the usage on p. 14.)
PP. 13, 22, 32, 41, 53: “poor station” should be “poorly sited station” for parallelism with “well sited station”. Also, “well-sited” should be hyphenated. (But not “poorly sited”!) Also, a closing “)” is missing.
PP. 10, 19, 29, 38, 48: Delete “over” (redundant) from: “cover over 50% or more”
In your main paper, you should request NOAA to make available pictures of the sites you weren’t able to access. You might twit them for not doing so earlier.
So many ” we don’t know for sure” bits and pieces to the puzzle..
Why not just admit it and put error bars +/- 5C on the whole shebang !!!!
Peter Ellis: “The overall effect is in principle symmetric: stations taking readings at 4pm will tend to read higher than the “true” value since they double-count warm days, while stations taking readings at 4am will tend to read lower than the “true” value since they double-count cold nights.”
You were doing fine right up until this point. This is not the case for a single site. It can be the case if someone is so studiously ham-fisted as to attempt to compare two different sites, at two different locations, with two different local conditions, measured at two different times, directly as if they were synonymous with one another under the notion that the Tmin/Tmax pair recorded are somehow valid time pertinent data points rather than extremums of a range collected over the previous 24 hours. And yes, some of the professional eggheads are just this studiously ham-fisted.
The problem is not TOBS. The problem is people trying to force the data to say things that it cannot. Thus far every presentation of the ‘problem’ and the ‘need for a cure’ has relied on trying to turn a Tmin/Tmax pair that occur at some unknown time during the prior 24 hours into instantaneous measurements taken at specific times. The data is simply not there for such shenanigans. Taking hourly measurements will not give a valid Tmin/Tmax, and Tmin/Tmax measurements will not give valid hourly values.
It has been asserted that NOAA adjusted the data of rural stations upwards to match the urban stations. However, it is countered here that the adjustments were made because a change in thermometer type meant that readings fell:
“”In the press release it is also emphasised that the temperature trend after homogenization is stronger than in the raw data. Maybe Mr Watts thinks this is new, but, e.g., Menne et al. (2009) already stated that the introduction of automatic weather stations (the transition from Liquid in Glass thermometers to the maximum–minimum temperature system) caused a temperature decrease in the raw data of 0.3 to 0.4 °C. This temperature jump has to be and was removed by homogenization.”
The increase in the temperature trend is thus not due to adjustment of stations with a low trend to the ones with a strong trend, but due to the change in the way the temperature is measured, the transition from LiG to MMTS and also probably due to a change in the time of observation. Homogenization removes these artificial jumps and because they caused artificial cooler temperatures, the homogenized data shows a stronger trend. There is no evidence in Watts et al. that the good stations are adjusted to the bad ones. Watts et al. does not even study how homogenization algorithms function.”
Source: http://variable-variability.blogspot.co.uk/2012/07/blog-review-of-watts-et-al-2012.html
I hope this helps.
John Wilbye says:
August 1, 2012 at 2:08 am
Pardon my ignorance here but is TOBS really a factor? If there is an error introduced by TOBS I suggest the same error will occur in those badly sited stations as in the better sited stations so the effect is nullified and therefore it does not need to calculated.
Seems reasonable – but it needs to be investigated whether there is some correlation here (what if, for instance, badly sited stations have more TOBS issues because they in general have been more sloppily maintained?). Anyway, as long as the TOBS issue is as full of pitfalls as it is, I think Anthony did just the right thing by leaving it out of this report.