From environmentalist Jennifer Marohasy’s blog in Australia, please pay her a visit here – Anthony
There has been criticism of the potential for official weather stations in the USA to record artificially high temperatures because of the changing environments in which they exist, for example, new asphalt, new building or new air conditioning outlets. Meteorologist, Anthony Watts, has documented evidence of the problem and Canadian academic, Ross McKitrick, has attempted to calculate just how artificially elevated temperatures might be as a consequence.
A reader of this blog, Michael Hammer, recently studied the official data from the US official weather stations and in particular how it is adjusted after it has been collected. Mr Hammer concludes that the temperature rise profile claimed by the US government is largely if not entirely an artefact of the adjustments applied after the raw data is collected from the weather stations.
Does the US Temperature Record Support Global Warming?
By Michael Hammer
IN the US, the National Oceanic and Atmospheric Administration (NOAA) collects, analyses and publishes temperature data for the United States. As part of the analysis process, NOAA applies several adjustments to the raw data.
If we consider, the above graph, which shows, their plot of the raw data (dark pink) and the adjusted data (pale pink), it is obvious that the adjustments have little impact on data from early in the 20th century but adjust later temperature readings upwards by an increasing amount. This means that the adjustments will create an apparent warming trend over the 20th century. [Click on the above chart for a better larger view, this chart can also be viewed at http://cdiac.ornl.gov/epubs/ndp/ushcn/ndp019.html .]
NOAA state that they adjust the raw data for five factors. The magnitude of the adjustments are shown in Figure 2.
Figure 2. Form of individual corrections applied by NOAA. The black line is the adjustment for time of observation. The red line is for a change in maximum/minimum thermometers used. The yellow line is for changes in station siting. The pale blue line is for filling in missing data from individual station records. The purple line is for UHI effects (this correction is now removed). [Click on the chart for a better larger view or visit the same website as for Figure 1.]
It is obvious that the only adjustment which reduces the reported warming is UHI which is a linear correction of 0.1F or about 0.06C per century, Figure 2. Note also that the latest indications are that even this minimal UHI adjustment has now been removed in the latest round of revisions to the historical record. To put this in perspective, in my previous article on this site I presented bureau of meteorology data which shows that the UHI impact for Melbourne Australia was 1.5C over the last 40 years equivalent to 3.75C per century and highly non linear.
Compare the treatment of UHI with the adjustments made for measuring stations that have moved out of the city centre, typically to the airport. These show lower temperatures at their new location and the later readings have been adjusted upwards so as to match the earlier readings. The airport readings are lower because the station has moved away from the city UHI. Raising the airport readings, while not adding downwards compensation for UHI, results in an overstatement of the amount of warming. This would seem to be clear evidence of bias. It would be more accurate to lower the earlier city readings to match the airport readings rather than vice versa.
Note also the similarity between the shape of the time of observation adjustment and the claimed global warming record over the 20th century especially the steep rise since 1970. This is even more pronounced if one looks at the total adjustment shown in Figure 3 (again from the same site as Figure 1). As a comparison, a recent version of the claimed 20th century global temperature record downloaded from www.giss.nasa.gov is shown in Figure 4.
Figure 3. Magnitude of the total correction applied by NOAA
[Click on the charts for a larger/better view.]
Figure 4. Temperature anomaly profile from NASA GISS
Since the total corrections for the US look so similar to the claimed temperature anomaly, it begs the questions as to what the raw data looks like without any corrections. Does it show the claimed rapidly accelerating warming trend claimed by the AGW advocates? To determine this I took the raw data from the USHCN graph shown in Figure 1 and plotted this using a 5 year mean (blue trace), matching the smoothing in the NASA GISS profile shown in Figure 4. The result is shown in Figure 5. Please note that while the plot is one that I generated, the data comes directly from the raw data from Figure 1 published by NOAA.
Figure 5 Plot of raw temperature data versus time (from fig 1) 5 point smoothing. Vertical axis degrees Fahrenheit. Red line is a linear trend line. Green line is a 2nd order (parabolic) trend line.
Clearly the shape of this graph bears no similarity at all to the graph shown in Figure 4. The graph does not even remotely correlate to the shape of the CO2 versus time graph. The warming was greatest in the 1930’s before CO2 started to rise rapidly. The rate of rise in 1920, the early 1930’s and the early 1950’s is significantly greater than anything in the last 30 years. Despite the rapid rise in CO2 since 1960, the 1970’s to early 1980’s was the time of the global cooling scare and looking at the graph in Figure 5 one can see why (almost 2F cooling over 50 years).
A linear least squares trend line, created using the Excel trend line function (Red trace) shows a small temperature rise of 0.09C per century which is far less than the rise claimed by AGW supporters and clearly of no concern. However, the data shown in figure 5 bears little if any resemblance to a linear function. One can always fit a linear trend line to any data but that does not mean the fitted line has any significance. For example, if instead I fit a second order trend line (a parabolic) the result is extremely different. That suggests a temperature peak around 1950 with an underlying cooling trend since. Which trend line is the more significant one? If there was really a strong underlying linear rise over the time period it should have shown up in the 2nd order trend line as well. This suggests that it is questionable whether any relevant underlying trend can be determined from the data.
It would appear that the temperature rise profile claimed by the adjusted data is largely if not entirely an artefact arising from the adjustments applied (as shown in Figure 3), not from the experimental data record. In fact, the raw data does not in any way support the AGW theory.
Based on this data, the US temperature data does not correlate with carbon dioxide levels. The warming over the last 3 decades is completely unremarkable and if present at all is significantly less than occurred in the 1930’s. It is questionable whether any long term temperature rise over the 20th century can be inferred from the data but if there is any it is far less than claimed by the AGW proponents.
The corrected data from NOAA has been used as evidence of anthropogenic global warming yet it would appear that the rising trend over the 20th century is largely if not entirely an artefact arising from the “corrections” applied to the experimental data, at least in the US, and is not visible in the uncorrected experimental data record.
This is an extremely serious issue. It is completely unacceptable, and scientifically meaningless, to claim experimental confirmation of a theory when the confirmation arises from the “corrections” to the raw data rather than from the raw data itself. This is even more the case if the organisation carrying out the corrections has published material indicating that it supports the theory under discussion. In any other branch of science that would be treated with profound scepticism if not indeed rejected outright. I believe the same standards should be applied in this case.
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Notes and Links
Interestingly, there was an earlier version of the NASA GISS data shown in Figure 4 which was originally published at http://www.giss.nasa.gov/data/update/gistemp/graphs/FigD.txt While this site has now been taken down the data was apparently archived by John Daly and available at his website http://www.john-daly.com/usatemps.006. The data is presented in tabular form rather than graphical form but appears to be either identical or extremely similar to that shown in my Figure 5.
Other contributions from Michael Hammer can be read here: http://jennifermarohasy.com/blog/author/michael-hammer/
[scroll down, click on the title for the full article]
Ross McKitrick, Ph.D. – Quantifying the Influence of Anthropogenic Surface Processes on Gridded Global Climate Data
http://www.heartland.org/events/NewYork08/newyork2008-video.html
Anthony Watts – http://wattsupwiththat.com/
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bill (19:00:33) : REPLY: “A strange blog entry as it simply quotes stuff from the referenced page with few invalid statements added.” I’ve added nothing, your statement is in error. The post is the same here as it appears on Marohasy’s blog here:
– Anthony
My statement was meant to reference the original blog, sorry.
By the way I particulary like the scientific use of the fig 5 curve fit, Why on earth would anyone try to fit the curve to that data?
bill
They are even less similar than your plot shows. The NOAA temps are in C but the adjustments you’ve plotted (as did the OP) are in F.
Of interest:
Talking Points related to: Is the U.S. Temperature Record Reliable?
http://www.ncdc.noaa.gov/oa/about/response-v2.pdf
EXAMINATION OF POTENTIAL BIASES IN AIR TEMPERATURE CAUSED BY POOR STATION LOCATIONS
http://ams.allenpress.com/archive/1520-0477/87/8/pdf/i1520-0477-87-8-1073.pdf
REPLY: Old news Bill, we’ve already covered that here
http://wattsupwiththat.com/2009/06/24/ncdc-writes-ghost-talking-points-rebuttal-to-surfacestations-project/
Peterson has no scruples. When I was at NCDC to talk about the weather station survey project, he demanded to be put on the agenda so he could lecture me about his views entirely unrelated to the topic. Even his coworkers were irritated because it wasn’t relevant to the discussion we were having. – Anthony
For the “magic 1221” USHCN1 surface stations, 1900 – 2006 (equally weighted):
Raw: +0.14C
With TOBS adjustment: +0.31C
With FILNET: +0.59C
Therefore, on a station-by-station basis, adjustments are more than quadruple raw and almost double with TOBS.
(USHCN2 puts it at +0.72C, if I recall correctly.)
Bill,
I too feel that the curve fitting in figure 5 is of little value. I also feel that the comparison of USHCN adjustment plots to global data in figure 4 is an unwarranted extrapolation. But the plots in figures 1 to 3 are of great concern.
Figure 2 is of particular interest. Many of the issues pertaining to the reasons for surface station data adjustments have been discussed on this site. I would not be the only reader to notice that historical changes to surface stations that I am aware of are not reflected in the individual adjustments in figure 2. The TOB adjustment is particularly disturbing. This clearly requires more investigation.
Focusing on minor issues such as Michael Hammer’s curve fitting in figure 5 will not make the issues writ large in figures 1 to 3 go away.
Nick Stokes (19:57:22) :
bill
They are even less similar than your plot shows. The NOAA temps are in C but the adjustments you’ve plotted (as did the OP) are in F
Last ime I dealt with deg F was 30years ago when I lived at home. One assumes a science blog would use SI units by now ! :o)
REPLY: “One assumes a science blog would use SI units by now !”
OK that’s just disingenuous, An apology is in order from you, Bill
1) NOAA standardizes on F, where the rest of the world and science uses C or K. NOAA’s entire temperature database is measured in F, recorded in F. It is the unit of the United States and for this reason they must conform to that.
2) I didn’t write the post and I’m not in the business of modifying the work of others to conform to SI, that includes bloggers and NOAA
3) Don’t like F ? Neither do I, complain to NOAA, but don’t throw snark at me because you don’t understand why F is used in studying the US temperature record.
If the surface data is no one say fraudulent, do we assume that the satellite data was ‘calibrated’ against adjusted surface data thus polluting all global temperature datasets?
Dr, Christy says not, and I believe he is trustworthy.
But satellite data measures lower troposphere, not surface, and if there is a warming trend, lower troposphere is said to warm 1.2 to 1.4 (depending on latitude) times more rapidly than surface.
Dr Hansen please explain how when you use the raw data there is now warming?
Dr. Hansen does not use raw data. GISS procedure is as follows:
1.) Take fully adjusted USCHN data.
2.) Apply an “unadjustment” algorithm.
3.) Apply a “readjustment” algorithm.
It is my understanding that the time of day observation adjustment (TOBS) is non controversial. I think Anthony Watts confirmed this once. What does the data look like if the TOBS adjustment is left in.
+0.314C for the average station. (Raw is +0.141C.) This is the straight average for all 1221 USHCN stations.
There remains some question as to how accurate this adjustment is. NOAA does not use the actual time of observation data from the B-91 forms, but uses an algorithm, instead. Therefore is no way of knowing how accurate this adjustment is.
I’d like to repeat your summary of “correction” trends:
Konrad (18:44:50) :
When I first saw this at Jennifer’s blog the my first thought was that it was statistically improbable that all adjustments would be positive. As I look at figure 2 more closely I can see the plots for individual adjustments don’t square with information about surface station history.
Firstly the red plot for thermometer type looks to be the right shape, but is upside down. There should be a negative adjustment for enclosure paint changes around 1979, followed by an gradual adjustment later in the decade for MMTS introduction. Anthony might be able to answer as to the likely direction of MMTS adjustment.
Secondly the pale blue plot for data infilling looks statistically improbable. The infilling appears wholly positive. Surely this plot should appear as noise centered on the X axis?
The yellow plot for station siting excluding UHI appears to be upside down. The general increase in man made structures around surface station could be expected to create a warm bias in station microclimate. An indication of increased siting issues due to the introduction of MMTS on short cables also appears to be missing in this plot.
The purple plot for UHI appears to be the correct orientation, but should show a marked increase in magnitude around the 1990s for rural station dropout.
As to the TOB adjustments, well I don’t know how or why these are made. I would be fascinated to read why time of observation errors are not random in sign or magnitude. Why is it considered that time of observation issues have introduced a negative bias needing such a large correction that is increasing over time?
—
TOB: What specifically changed in time, when was it changed, and why does the TOB bias continue to ramp up? Are they measuring at ever-earlier minutes before noon every year?
Which stations are UHI corrected? What is the regional UHI effect: A down town station should go “up” more than a mid-urban, and and mid-urban station should go more than a mid-suburban, and UHI not at all for a rural station until 1980-1990. How many stations in an area are UHI corrected? Why are downtown areas routinely +10 degrees F HOTTER than suburban temperatures, IF the UHI effect is only 1/2 of one degree C?
“Siting” corrections should NOT be constantly increasing. Unless “all” stations are continuously getting more and more interferences around them? At a uniform rate nationally?
evanmjones (21:27:29) :
Station moves: Ok, a few (100 or 200 maybe out of their claimed 1200) have moved. But they do not continuously “move” and drive a continuously changing “station movement” correction.
Unless the “station movement” plus “TOB” changes are intended to mask/enhance/confuse the gradually increasing UHI change:
And UHI IS the ONLY “continuously ad gradually increasing over time” temperature bias – and the ONLY one that is NOT being corrected in recent records.
As to the TOB adjustments, well I don’t know how or why these are made. I would be fascinated to read why time of observation errors are not random in sign or magnitude. Why is it considered that time of observation issues have introduced a negative bias needing such a large correction that is increasing over time?
The short story is that if measurements are taken in the morning (closer to Tmin), TOBS bias will make them cooler. If taken in the afternoon (Closer to Tmax), the TOBS bias will be warmer.
This is true, and if you set up an example it becomes obvious. (The question is that of degree.)
There has been a shift from afternoon readings to morning readings.
I’m probably coming late to the game here, but how can the time of day observation adjustment (TOBS) continue to rise over the recent decades? This would seem to suggest that the temperature measurement has been made toward cooler and cooler times of day over the years (for example, earlier in the morning, or later in the evening). Is this really what the TOBS adjustment is doing? Or is TOBS addressing something different than “time of day” altogether, notwithstanding its name? Perhaps TOBS is attempting to capture some assumed relative difference vis-a-vis the older temperature data, rather than adjusting the new data per se?
followed by an gradual adjustment later in the decade for MMTS introduction. Anthony might be able to answer as to the likely direction of MMTS adjustment.
It’s slightly positive. About +0.02C since the introduction of MMTS.
I’m probably coming late to the game here, but how can the time of day observation adjustment (TOBS) continue to rise over the recent decades? This would seem to suggest that the temperature measurement has been made toward cooler and cooler times of day over the years (for example, earlier in the morning, or later in the evening).
That’s what they claim. (A shift from afternoon to morning.)
OK, I see Robert A Cook and evanmjones posted while I was still reading the comments and preparing my question.
Follow-up question for evanmjones:
So if I understand you correctly, my third suggestion was actually closest, namely: “Perhaps TOBS is attempting to capture some assumed relative difference vis-a-vis the older temperature data, rather than adjusting the new data per se?”
Specifically, as more stations slowly switch from afternoon readings to morning readings over the years the overall TOBS is increased, not so much to adjust the morning readings themselves, but to instead provide a number that allegedly matches what the new readings would have been had they been taken in the afternoon like the old data.
Station moves: Ok, a few (100 or 200 maybe out of their claimed 1200) have moved. But they do not continuously “move” and drive a continuously changing “station movement” correction.
There are many, many local station moves. Only a very few stations have not been moved. Most have been moved several times. Every time a company closes, a plant moves, or a private volunteer passes on (or loses interest), there is a station move. In most cases when the CRS was converted to MMTS, there was a local move. They move continually. To wit, Lampassas, TX . . .
MMS records of station moves are incomplete, and often inaccurate.
And UHI IS the ONLY “continuously ad gradually increasing over time” temperature bias – and the ONLY one that is NOT being corrected in recent records.
Sometimes the mountain comes to Mohammed. It doesn’t have to be urban, suburban, or exurban creep (though it may be). It can take the form of a new driveway or paving a gravel or dirt road. Or a wing added to the house. Or a new patio. Over time it adds up. No records of any of this exists.
but to instead provide a number that allegedly matches what the new readings would have been had they been taken in the afternoon like the old data.
That is my understanding. At least that is what the NOAA graph shows.
David S “On a more serious note though I think the 64 thousand dollar question is whether the adjustments are legitimate.”
Absolutely! You can find details at CDIAC or at NOAA.
There are three USHCN changes that had substantial effect. Allowance for UHI change gave apparent cooling; TOBS and SHAP increased the apparent heating. TOBS is time of observation bias. It is to do with the choice of reading time during the day – chiefly for min-max observations. This wasn’t standardised for US stations, and changed over time. SHAP concerns the actual movement of individual stations, or other significant changes. Clearly both situations do require adjustment. The basis for them is set out in papers by Karl and others, written in 1986 and 1987. These rules have been followed since. The adjustments are based on lots of public information, and have not been substantially challenged over that time.
There were two others – MMTS, which was a one-off recalibration when they changed min-max thermometers to thermistors in about 1990 (less than 0.1F increase) and FILNET, which interpolates for missing data. Again, FILNET had fairly small effect, and since 1910 has been fairly neutral.
Note that all these adjustments relate to specific issues with US stations. Those issues will not be the same for other land stations, and of course are quite different for sea temperatures. There is no basis for suggesting, as this post does, that they are responsible for global temperature rises.
REPLY: Nick stop saying that, you are putting words in Mr. Hammers and my mouth. You are the only person jumping to this conclusion, and it is wrong.
1- post title – USHCN (not global, not GHCN)
2- conclusion “…artefact arising from the “corrections” applied to the experimental data, at least in the US,” Note US caveat.
3- The GISS global figure is for shape comparison only.
4- The same people that managed USHCN, with all the adjustment issues raised here, also manage GHCN, so it is possible there may be similar issues, but we aren’t looking at GHCN, only USHCN. GHCN will get a look I’m sure.
Until then keep your conclusions, like the title, in the USA. – Anthony
evanmjones (21:39:12) :
“It’s slightly positive. About +0.025C since the introduction of MMTS.”
Does that mean MMTS sensors read hotter or colder than older thermometers? are they reading .025 hotter needing ajustment down or reading colder needing the .05F to .075F upward ajustment shown?
Also with TOB, I thought both Tmax and Tmin were recorded each day. Is there a link to information how both the older and newer surface station equipment works, and standard procedures for readings?
“Totally unrelated to this thread, but this scares the pants off me. The applications are….. unthinkable.”
You cant take three from two,
Two is less than three,
So you look at the four in the tens place.
Now thats really four tens,
So you make it three tens,
Regroup, and you change a ten to ten ones,
And you add them to the two and get twelve,
And you take away three, thats nine.
Is that clear?
Don’t worry until they start applying adjustments to your thoughts . . . “I know what you were REALLY thinking!” (Of course, for those who are married this is old hat.)
Sorry, I got distracted by the light blue infilling plot. I meant .03F upward ajustment for MMTS…
A little closer to 0.04F. (I readjust my estimate to 0.02C.)
Does that mean MMTS sensors read hotter or colder than older thermometers?
A little bit cooler. But that is only if placement is identical to the CRS it replaced. What we have found, however, is that in the large majority of cases, placement of the MMTS is inferior. Anthony believes that this is due to problems related to trenching the cable, and I agree.
John F. Hultquist (15:15:09) :
Bill D (14:05:23) : “no one has claimed that Urban heat effects can influence the temperature of large lakes.”
I wonder why not? Without any data I so claim. Not long ago I commented about irrigators taking water out of streams, rivers, lakes, and ground water. Spread that water out over dark-soil fields and the return flow back to the streams will be warmer. Do I need proof of that?
In urban areas take water and spray it on pavement, lawns, golf greens, wash things (cars, windows, patios +++), use it for food processing, spraying for dust control, impound it (fish ponds, swimming pools, bird baths, road depressions +++), and a few dozen other uses. All of these uses will allow the water to warm before it returns to the streams and lakes.
John:
I’m talking about big deep lakes, including lakes where water renewal from the water shed takes decades. Two of the biggest lakes with strong records of warming in the surface waters (top 100 meters or so) are Lakes Tahoe and Lake Baikal. I know that there was discussion on this blog about how geothermal influences might affect Baikal. However, warming of the deep waters is < 0.1 oC for that lake and nearly all of the warming is in the upper 100 m. If you know anything about LaKe Tahoe (mostly California) you would not expect water shed activities to influence the temperature. In fact, heat budgets for the lakes in question generally show that 99+% of the temperature change of the surface waters is caused by in lake warming. Cold water inflows during winter is the main cause of temperature changes and mixing in the deep waters of lake Baikal, accounting for the small changes (< 0.1oC) and the presence of O2 at great depth.
I think that the articles in press are very good summaries, but you may be able to access articles on Lakes Washington, Tahoe, Zurich and Baikal throughGoogle scholar without fees. The data for Lake Washington goes back about 50 years and shows peaks in temperature associated with ENSO.
This is an off topic question, but I know of know good places to ask besides here. Why is 30 years the important trend? If CO2 and temps over a century are the numbers we are using to extrapolate a trend from, why not compare 100 years of temps?