by John Goetz
On September 15, 2008, Anthony DePalma of the New York Times wrote an article about the Mohonk Lakes USHCN weather station titled Weather History Offers Insight Into Global Warming. This article claimed, in part, that the average annual temperature has risen 2.7 degrees in 112 years at this station. What struck me about the article was the rather quaint description of the manner in which temperatures are recorded, which I have excerpted here (emphasis mine):
Mr. Huth opened the weather station, a louvered box about the size of a suitcase, and leaned in. He checked the high and low temperatures of the day on a pair of official Weather Service thermometers and then manually reset them…
If the procedure seems old-fashioned, that is just as it is intended. The temperatures that Mr. Huth recorded that day were the 41,152nd daily readings at this station, each taken exactly the same way. “Sometimes it feels like I’ve done most of them myself,” said Mr. Huth, who is one of only five people to have served as official weather observer at this station since the first reading was taken on Jan. 1, 1896.
That extremely limited number of observers greatly enhances the reliability, and therefore the value, of the data. Other weather stations have operated longer, but few match Mohonk’s consistency and reliability. “The quality of their observations is second to none on a number of counts,” said Raymond G. O’Keefe, a meteorologist at the National Weather Service office in Albany. “They’re very precise, they keep great records and they’ve done it for a very long time.”
Mohonk’s data stands apart from that of most other cooperative weather observers in other respects as well. The station has never been moved, and the resort, along with the area immediately surrounding the box, has hardly changed over time.
Clearly the data collected at this site is of the highest quality. Five observers committed to their work. No station moves. No equipment changes according to Mr. Huth (in contrast to the NOAA MMS records). Attention to detail unparalleled elsewhere. A truly Norman Rockwell image of dedication.
After reading the article, I wondered what happened to Mr. Huth’s data, and the data collected by the four observers who preceded him. What I learned is that NOAA doesn’t quite trust the data meticulously collected by Mr. Huth and his predecessors. Neither does GISS trust the data NOAA hands it. Following is a description of what is done with the data.
Let’s begin with the process of getting the data to NOAA:
Mr. Huth and other observers like him record their data in a “B91 Form”, which is submitted to NOAA every month. These forms can be downloaded for free from the NOAA website. Current B91 forms show the day’s minimum and maximum temperature as well as the time of observation. Older records often include multiple readings of temperature throughout the day. The month’s record of daily temperatures is added to each station’s historical record of daily temperatures, which can be downloaded from NOAA’s FTP site here.
The B91 form for Mohonk Lake is hand-written, and temperatures are recorded in Farenheit. Transcribing the data to the electronic daily record introduces an opportunity for error, but I spot-checked a number of B91 forms – converting degrees F to tenths of degree C – and found no errors. Kudos to the NOAA transcriptionists.
Next comes the first phase of NOAA adjustments.
The pristine data from Mohonk Lake are subject to a number of quality control and homogeneity testing and adjustment procedures. First, data is checked against a number of quality control tests, primarily to eliminate gross transcription errors. Next, monthly averages are calculated from the TMIN and TMAX values. This is straightforward when both values exist for all days in a month, but in the case of Mohonk Lake there are a number of months early in the record with several missing TMIN and/or TMAX values. Nevertheless, NOAA seems capable of creating an average temperature for many of those months. The result is referred to as the “Areal data”.
The Areal data are stored in a file called hcn_doe_mean_data, which can be found here. Even though the daily data files are updated frequently, hcn_doe_mean_data has not been updated in nearly a year. The Areal data also seem to be stored in the GHCN v2.mean file, which can be found here on NOAA’s FTP site. This is the case for Mohonk Lake.
Of course, more NOAA adjustments are needed.
The Areal data is adjusted for time of observation and stored as a seperate entry in hcn_doe_mean_data. TOB adjustment is briefly described here. Following the TOB adjustment, the series is tested for homogeneity. This procedure evaluates non-climatic discontinuities (artificial changepoints) in a station’s temperature caused by random changes to a station such as equipment relocations and changes. The version 2 algorithm looks at up to 40 highly-correlated series from nearby stations. The result of this homogenization is then passed on to FILNET which creates estimates for missing data. The output of FILNET is stored as a seperate entry in hcn_doe_mean_data.
Now GISS wants to use the data, but the NOAA adjustments are not quite what they are looking for. So what do they do? They estimate the NOAA adjustments and back them out!
GISS now takes both v2.mean and hcn_doe_mean_data, and lops off any record before 1880. GISS will also look at only the FILNET data from hcn_doe_mean_data. Temperatures in F are converted and scaled to 0.1C.
This is where things get bizarre.
For each of the twelve months in a calendar year, GISS looks at the ten most recent years in common between the two data sets. For each month in those ten most recent years it takes the difference between the FILNET temperature and the v2.mean temperature, and averages them. Then, GISS goes through the entire FILNET record and subtracts the monthly offset from each monthly temperature.
It appears to me that what GISS is attempting to do is remove the corrections done by NOAA from the USHCN data. Standing back to look at the forest through the trees, GISS appears to be trying to recreate the Areal data, failing to recognize that v2.mean is the Areal data, and that hcn_doe_mean_data also contains the Areal data.
Here is a plot of the difference between the monthly raw data from Mohonk Lake and the data GISS creates in GISTEMP STEP0 (yes, I am well aware that in this case it appears the GISS process slightly cools the record). Units on the left are 0.1C.
Even supposedly pristine data cannot escape the adjustment process.
Here’s the latest from NASA where they acknowledge urban heat islands. Must be a first.
http://www.nasa.gov/topics/earth/features/heat_wave_los_angeles.html
Mr Smokey said (20:00:48) :
“Thank you CPT. Charles for that excellent link!
Those who want to understand exactly how climate science has been hijacked and corrupted by the Greens/Leftists should read Prof. Richard Lindzen’s expose”
If I might say so, Mr Smokey, you overstate the position. My interpretation of Professor Lindzen’s article is that he was pointing out one way in which the debate has been influenced. Just because some people whom I might consider to be a sandwich short of a picnic have argued for something does not, of itself, mean their position is wrong. Many a nutter is right, just for the wrong reasons. I don’t believe the tree hugging, touchy-feely, no-shampoo-for-me-thank-you mob to be right but whether they are or not is not determined by the amount of hand-chewed raffia clothing they wear but by the strength of the case they present. Equally, that I am urbane, sophisticated and have charm you could iron linen with does not mean I am right.
The value of Professor Lindzen’s article is that it promotes caution and objective analysis in an attempt to separate scientific investigation from political grandstanding.
F Rasmin (20:33:35) :
Dave Dodd and LarryOldTimer. Never mind these new fangled devices such as slide-rules! Have you ever attempted to do temperature adjustments involving Farenheit to Centigrade and back using an abacus whilst penning your work with Roman Numerals?
To which I might add….With a chisel…on stone tablets???
Rick and Paul,
Thanks for your help. What I figured out was that the tropics at the time of the Eocene were about 8-10 degrees F cooler than they are now, according to studies of the Eocene period. I don’t know how it would have affected flora and fauna, apart from being certain that it would have, but it is interesting. It appears at that time that Minnesota could well have been warmer overall than Colombia, which is fascinating in all kinds of ways.
I got the impression that the weather station pictures that littered one episode of the BBC Iain Stewart series, were taken from Anthony Watts’ superb records. Anthony – you said somewhere earlier you’d been contacted by the BBC. If so, this would be surely another misrepresentation a lot bigger than Wunsch’s complaints re Swindle, since your aim is to check the still-unresolved serious doubts about the records?
Thanks Fat Bigot for wise words about Prof Lindzen’s new paper – also visible at ICECAP. I too think it deserves a thread here or at CA but it’s extremely difficult not to get carried away with emotions when dealing with these issues of vulnerability to corruption in Climate Science – as the recent blog on Hansen here shows – and that helps nobody in the end.
But we all do it at times… as Steve would say, take a deep breath…
Converting F to C? No problem. C=(F-XXXII)*V/IX
Any measurement has an error budget. From a variety of sources, including the observer. Mercury thermometers are no execption. Assuming pure mercury (perhaps a WAG in itself) there should be no diffusion loss. The vapor pressure doesn’t come into play (an alcohol thermometer is another story). While glass does sag, thet process is extremely slow.
The two big questions are: variations in capillary diameter and calibration. The thin hole in the measuring part does vary in size. How much is a good question. It affects linearity. How good is the match between this thermometer and the next? That’s the calibration part. Not easy to generate precise temperatures. 0 C is not too hard, anything else depends on a lot of factors.
So I have serious questions about “pristine” data, adjusted or not. I spent many years measuring stuff, temperature included. I also saw a lot of abuses, papers published out to four decimal places with equipment that had 1% accuracy at best. Lots of digits impress people. Gives the impression you know what you are doing, even if it is floobydust. (h/t to Robert Pease)
<1 degree C in a hundred years? That’s below the noise threshold.
FatBigot:
“The value of Professor Lindzen’s article is that it promotes caution and objective analysis in an attempt to separate scientific investigation from political grandstanding.”
That was my point. What other well known climatologist has been willing to author a paper that shows how the environmental lobby has inserted numerous partisan promoters of AGW/runaway global warming into positions in which they speak out on behalf of the entire organization?
Prof. Lindzen says explicitly what other climate scientists have only hinted at, and he names names. When an environmentalist advocate, who has no grounding in climatology or meteorology, and in some cases no scientific background at all manages to become the spokesperson for an entire scientific organization, naturally the media will report what the partisan non-climatologist says. And that is exactly the purpose of these enviro-machinations.
The more people that see how the climate issue is being dishonestly manipulated by partisan advocates of a predetermined outcome, the better, IMHO.
John,
Thanks for your excellent post.
Mr. dePalma’s reference to phenological records is interesting, especially the longest and “best” of these, the Kyoto cherry blossom record. A good summary w/ pictures and graphs of that record, with explanation of its validity as a temp record, is here:
http://arnoldia.arboretum.harvard.edu/pdf/articles/1893.pdf
A-a-n-n-d another block quote bites the dust. Here, in plain quotes, the Kyoto Cherry Blossom record summary:
“The calculations show that during the 11th through the 13th centuries, average temperatures were at their warmest averages, often as high as 8° C , as indicated by early dates of the cherry blossom festival. There were occasionally very cold years, as indicated by late flowering years, but on the whole this was the warmest average period.”
John Goetz,
I’m sure that you know that the daily temperature data from the Mohonk Lake surface station can be found for the interval 05/1948 through 12/2005 at
http://cdiac.ornl.gov/cgi-bin/broker?_PROGRAM=prog.climsite.sas&_SERVICE=default&id=305426
I selected a random sample of ten completed B91 Forms for Mohonk Lake from the site that you referenced
http://www7.ncdc.noaa.gov/IPS/coop/coop.html?_page=2&state=NY&foreign=false&selectedCoopId=305426&_target3=Next+%3E
and verified that the values for TMAX(F) and TMIN(F), with one exception, were identical. The exception which occurred on 07/12/1956 is an obvious transcription error; the value (67°F) listed in the “At OBSN” column was recorded for TMIN(F) instead of the correct value (64°F). In addition to TMAX(F) and TMIN(F), the USHCN site also lists TAVE(F) which equals [TMAX(F) + TMIN(F)]/2 rounded to the next higher integer when either TMAX(F) or TMIN(F) is an odd integer. Therefore, I believe the data archived at the site that I referenced is the “RAW” daily temperature data for station 305426.
So far, so good …
I then calculated the monthly averages for TAVE(F), TMAX(F) and TMIN(F), for the interval 05/1948 through 12/1959 and compared the results with the corresponding monthly values that I downloaded from
http://cdiac.ornl.gov/cgi-bin/broker?_PROGRAM=prog.climsite_monthly.sas&_SERVICE=default&id=305426
How did they compare? Not so good!!
The average differences for the 139 month interval are (s.d. shown in parentheses):
RAW TAVE(F) – HCN TAVE(F) = 1.39°F (0.43°F)
RAW TMAX(F) – HCN TMAX(F) = 1.43°F (0.62°F)
RAW TMIN(F) – HCN TMIN(F) = 0.83°F (1.17°F)
What adjustments do you think were made by NCDC that caused these differences?
I may add to this post after I complete my examination of the 1948:2005 RAW data set.
John Goetz,
I’m sure that you know that the daily temperature data from the Mohonk Lake surface station can be found for the interval 05/1948 through 12/2005 at
http://cdiac.ornl.gov/cgi-bin/broker?_PROGRAM=prog.climsite.sas&_SERVICE=default&id=305426
I selected a random sample of ten completed B91 Forms for Mohonk Lake from the site that you referenced
http://www7.ncdc.noaa.gov/IPS/coop/coop.html?_page=2&state=NY&foreign=false&selectedCoopId=305426&_target3=Next+%3E
and verified that the values for TMAX(F) and TMIN(F), with one exception, were identical. The exception which occurred on 07/12/1956 is an obvious transcription error; the value (67°F) listed in the “At OBSN” column was recorded for TMIN(F) instead of the correct value (64°F). In addition to TMAX(F) and TMIN(F), the USHCN site also lists TAVE(F) which equals [TMAX(F) + TMIN(F)]/2 rounded to the next higher integer when either TMAX(F) or TMIN(F) is an odd integer. Therefore, I believe the data archived at the site that I referenced is the “RAW” daily temperature data for station 305426.
So far, so good …
I then calculated the monthly averages for TAVE(F), TMAX(F) and TMIN(F), for the interval 05/1948 through 12/1959 and compared the results with the corresponding monthly values that I downloaded from
http://cdiac.ornl.gov/cgi-bin/broker?_PROGRAM=prog.climsite_monthly.sas&_SERVICE=default&id=305426
How did they compare? Not so good!!
The average differences for the 139 month interval are (s.d. shown in parentheses):
RAW TAVE(F) – HCN TAVE(F) = 1.39°F (0.43°F)
RAW TMAX(F) – HCN TMAX(F) = 1.43°F (0.62°F)
RAW TMIN(F) – HCN TMIN(F) = 0.83°F (1.17°F)
What adjustments do you think were made by NCDC that caused these differences?
I may add to this post after I complete my examination of the 1948:2005 RAW data set.
Reply: Anthony’s spam bucket tends to grab stuff with a high link-to-text ratio. I think your post was above whatever that limit is. It looks like one of the moderators did find it and let it get through.
As for what you are seeing, I suspect it is homogenization, TOBS, and FILNET differences.
Moderator,
I tried to post a comment a short time ago but I didn’t receive the usual response “awaiting moderation.” I tried subnitting it again but still no response.
Did you receive anything from me?
hmccard
Reply: No – Anne
More: Nevermind, found them in the spam bucket – Anne
Yes, fantastic writing!!
Here comes a stuuupid question, To Goetz or anyone:
Goetz you write:
“Here is a plot of the difference between the monthly raw data from Mohonk Lake and the data GISS creates in GISTEMP STEP0 (yes, I am well aware that in this case it appears the GISS process slightly cools the record). ”
Hmmm…
If GISS in 1880 is 0,4 degrees COLDER than Mohonk
– and in 2000 is 0,0 degrees COLDER than Mohonk
Yes, then the COOLING done by GISS is bigger in 1880 than 2000 ?
And then GISS has induced a WARMING TREND !?
– ups i have the feeling that i got something wrong, but i have to mention…
K.R. Frank
Reply by John Goetz: By cooling the record, I mean the trend from 1896 – 2006 in GISS is slightly less warm than the trend in the raw data. GISS actually warms the older temperatures and cools the later ones, thus reducing the overall trend.
John Goetz,
Thanks, I’m a novice in this field and do not fully understand NCDC’s homogenization, TOBS, and FILNET adjustments. Here are a few of my comments and observations:
Homogenization: I really don’t know anything about that aspect.
TOBS: TOBS is a mystery to me. I read BarryW’s September 24th, 2008 at 12:50 pm comment to your post on CA and I have read the general discussion of the subject on the USHCN website. Referencing al station data to midnight may be logical but it is not apparent to me how that adjustment is made.
FILNET: Surprisingly, the 1948:2005 daily RAW data set with 3X21062 data points has only 14 missing data points; two days where TAVE and TMAX are both missing, two days where TAVE and TMIN are both missing and two days where TAVE, TMAX and TMIN are all missing. On each of these six days, the values for TMAX and TMIN were listed on the B91 Forms. Therefore, it doesn’t appear to me that FILNET was of much use.
As regards Mohonk Lake, I examined the 12 B91 Forms for 1951 and noted that 4 PM was the Hour of Observation on all forms. For 1951, the monthly differences between RAW and HCN temperatures (∆Ts) are:
MONTH ∆TAVE ∆TMAX ∆TMIN
JAN 1.33°F 1.03°F 1.08°F
FEB 1.64°F 1.56°F 1.30°F
MAR 1.19°F 1.01°F 0.85°F
APR 1.32°F 1.23°F 0.88°F
MAY -1.05°F -3.21°F 0.73°F
JUN 1.05°F 1.09°F 0.69°F
JUL 1.04°F 1.16°F 0.54°F
AUG 1.25°F 1.32°F 0.76°F
SEP 1.53°F 1.66°F 0.93°F
OCT 1.39°F 1.13°F 1.18°F
NOV 1.42°F 1.32°F 1.22°F
DEC 1.06°F 0.88°F 0.91°F
AVE 1.10°F 0.85°F 0.92°F
I chose 1951 to review because of the negative values for ∆TAVE and ∆TMAX in May. It turns out that the value of 77°F recorded on the B91 Form for that month was transcribed in the RAW data set as -77°F. It appears to have been corrected by NCDC before including it in the HCN data set.The reasons for the other differences are not apparent to me.
Reply by John Goetz: The homogenization algorithm does catch the type of outlier you describe (the transcription error). However (and I have not seen the code), I do not believe it will necessarily take a -77°F value and change it to 77°F. It might change it to a 63 or 84 or some other number that is based on the values of the “closely correlated” nearby stations.
Ideally, NOAA would spit out a list of the outliers and have a transcriptionist go back and manually double-check the B91. They just need to do that once, and then once a month after that on all newly-added data.
Re: My 09/26/08 (12:33:15) Post
The second sentence in the last paragraph should have read: “It turns out that the value of 77°F recorded on the B91 Form for second day of that month…”
John Goetz,
Thanks again for your insights. I have commented previously on this blog that I have been puzzled by what appeared to me to be step-wise adjustments that NCDC makes to surface station data. As I’m sure you know, WRDC archives surface station data which I compared to USHCN data for several surface stations and observed the step-wise differences. I wondered if the similar step-wise differences might be observed between NCDC’s daily and monthly data sets for Mohonk Lake,NY (305426). I have completed my analysis and observed similar step-wise differences between the daily and monthly data sets.
I use Excel but, unfortunately, I haven’t learned how to export Excel graphics to WordPress. It would be much easier to convey what I have observed if I could do so. If you permit me, I’ll try to briefly explain what I have observed.
First, I refer to the HCN data set as the RAW data set. I updated the RAW data set by correcting the -77°F transcription error and using the B91 Forms to fill the data cells for the missing six days. While doing that, I realized that the entire B91 Form for April 1965 had not been transcribed properly. Therefore, I incorporated the B91 Form data.
I then calculated the monthly averages for TAVE(F), TMAX(F) and TMIN(F), for the interval 05/1948 through 12/2005 and compared the results with the corresponding monthly values that I downloaded from
http://cdiac.ornl.gov/cgi-bin/broker?_PROGRAM=prog.climsite_monthly.sas&_SERVICE=default&id=305426
I defined the following adjustments:
1. Adj RAW TMAX = RAW TMAX – HCN TMAX
2. Adj RAW TMIN = RAW TMIN – HCN TMIN
3. Adj RAW TMED = Adj RAW TMAX – Adj HCN TMAX
4. Adj RAW TAVE = Adj RAW TMED + RAW del TAVE – HCN del TAVE
Where
1. RAW del TAVE = RAW TAVE – RAW TMED
2. HCN del TAVE = HCN TAVE –HCN TAV3
Briefly, here are some of my observations:
1. Stepwise adjustments occurred in 1954-56 and in 1990.
2. Steps-wise changes in Adj RAW TAVE:
Average 1949:1954 = 0.39°F
Average 1956:1980 = 0.63°F
Average 1991:2005 = 0.03°F
3. Steps-wise changes in Adj RAW TMAX:
Average 1949:1954 = 1.27°F
Average 1956:1980 = 1.85°F
Average 1991:2005 = 1.20°F
4. Steps-wise changes in Adj RAW TMIN:
Average 1949:1954 = 0.92°F
Average 1956:1980 = 1.02°F
Average 1991:2005 = 1.62°F
So … does this make any difference from a climate change perspective? I don’t know. For the 1949:2005 interval, simple linear regression shows the following:
RAW TAVE = 1.79°F
HCN TAVE = 1.55°F
RAW TMAX = 2.56°F
HCN TMAX = 2.97°F
RAW TMIN = 1.01°F
HCN TMIN = 0.19°F
I guess that it depends upon on your perspective.
Re: My last post
HCN del TAVE = HCN TAVE –HCN TAV3
should have read
HCN del TAVE = HCN TAVE –HCN MED
Sorry about that …
I am glad you clarified that, Harold.
Re: My 09/28 (16:18:10) Post
I should have noted that under “…some of my observations:” the step-wise changes in Adj RAW TAVE, Adj RAW TMAX and Adj RAW TMIN were with respect to the average annual temperature.
Also, another correction:
3. Adj RAW TMED = Adj RAW TMAX – Adj HCN TMAX
should have read
3. Adj RAW TMED = [Adj RAW TMAX + Adj RAW TMIN]/2
Again, sorry about the confusion. I guess I was in too much of a hurry to go to dinner.
Solution for the Greenland gulfstream slowdown
http://www.guardian.co.uk/flash/0,,1656541,00.html
Clean water ,clean energy ,and the solution for the Greenland gulfstream slowdown:
Put in sea a construction of windmills combined with electric boilers, these get preheated by suncollectors and sunmirrors.
the steam they produce gets used by steam engines wich produce again electricity ,salt and when you condesate the steam coming from the steam engines sweet water.
You take out salt water coming from the warm gulfstream and the left over salt from the steam engines gets used to release in the cold stream.
So the cold stream gets saltier again and and won’t mingel with the warm gulfstream becaurse before it was less saltier caursed by the melting gletchers and slowing down the warm gulfstream becaurse less saltier water is lighter.
Preventing an possibel iceage.
The sweet water can then be used to make hydrogen ,so if there is for exampel a lot of wind and you don’t need all that electricity , you are abel to stock it and use it later.
The rest of the steam you blow in the air.
The oxygen deriving from turning water into hydrogen can be devided in sea to clean the water and to make more suitabel for marinelife.
So you produce electricity and /or hydrogen
Am I missing something, but does one have to pay to access “raw” USHCN data?
REPLY: Yes and no, you can get the absolute RAW B91 data forms free, but you have to hand transcribe. If you want a CD of data, then yes you have to pay for it to NCDC. – Anthony
Aw geez….It’s a nice easy but big download from Environment Canada and current data is viewable and cut and pastable into Excel for all stations.
John Goetz,
TOBS continues to be a mystery to me. I have compared the areal data with the COBS data in hcn_doe_mean_data file for the 1900:2006 interval and was perplexed by the results. Significant step-wise changes in the difference between the areal and COBS data occurred in 1909 and 1955. All difference values were constant between the changes as listed below:
MONTH 1900-08 1909-55 1956-2006
JAN 1.10°F 1.10°F 1.40°F
FEB 1.10°F 1.50°F 1.80°F
MAR 0.70°F 0.90°F 1.30°F
APR 0.60°F 1.10°F 1.50°F
MAY 0.50°F 1.30°F 1.60°F
JUN 0.30°F 0.88°F 1.20°F
JUL 0.30°F 0.80°F 1.00°F
AUG 0.50°F 1.00°F 1.20°F
SEP 0.70°F 1.31°F 1.60°F
OCT 0.80°F 1.11°F 1.50°F
NOV 1.30°F 1.31°F 1.70°F
DEC 0.90°F 0.90°F 0.90°F
AVE 0.72°F 1.10°F 1.41°F
DJF 1.00°F 1.18°F 1.43°F
MAM 0.58°F 1.09°F 1.47°F
JJA 0.37°F 0.90°F 1.13°F
SON 0.94°F 1.23°F 1.60°F
I also compared the areal data with the COBS data in hcn_doe_max_data and hcn_doe_min_data files for the 1900:2006 interval and observed the same step-wise pattern, although the values were different.
I have also made the same comparisons for other surface station and observed similar perplexing differences between areal and TOBS data. For example, Fort Collins, CO (053003) for the 1900:2006 interval displayed significant step-wise changes in TAVG, TMAX and TMIN in 1905 and 1940 but there was no difference between the areal and TOBS data between 1905 and 1940.
Can anyone explain to me how NCDC calculates TOBS?
Re: My last message
I should have indicated that the first part of my message pertained to Mohonk Lake.
Harold,
Is COBS a typo, and you meant TOBS?
I cannot explain the algorithm behind the TOBS adjustment, because I have not obtained a copy of Karl, et al. 1986; Vose et al., 2003 (see the links in the main body of this post). TOBS has been discussed at length on Climate Audit, particularly on this thread. You should be able to pick up some interesting insight from the comments (I myself need to reread it). In particular, one of the early comments points you to a pretty good description of TOBS here.
As for getting an Excel chart into WordPress. Here is a very simple procedure:
1. Click on the chart object, then press CTL-C to copy the chart (make sure you click on the chart near the edge, and not a location closer to the center, otherwise you end up with just the plot area or an axis.)
2. Open Microsoft Paint. An empty artboard will appear.
3. Press CTL-V to past the chart image into paint.
4. From Paint, click File>Save As and save as a GIF image into a directory of your choice.
Now, when you go into WordPress you can upload your GIF image and reference it.