This method may or may not have merit – readers are invited to test the merit of it themselves, the method is provided – Anthony
Guest essay by Ron Clutz
People in different places are wondering: What are temperatures doing in my area? Are they trending up, down or sideways? Of course, from official quarters, the answer is: The globe is warming, so it is safe to assume that your area is warming also.
But what if you don’t want to assume and don’t want to take someone else’s word for it. You can answer the question yourself if you take on board one simplifying concept:
“If you want to understand temperature changes, you should analyze temperature changes, not the temperatures.”
Analyzing temperature change is in fact much simpler and avoids data manipulations like anomalies, averaging, gridding, adjusting and homogenizing . Temperature Trend Analysis starts with recognizing that each microclimate is distinct with its unique climate patterns. So you work on the raw, unadjusted data produced, validated and submitted by local metrorologists. This is accessed in the HADCRUT3 dataset made public in July 2011.
The dataset includes 5000+ stations around the world, and only someone adept with statistical software running on a robust computer could deal with all of it. But the Met Office provides it in folders that cluster stations according to their WMO codes.
Anyone with modest spreadsheet skills and a notebook computer can deal with a set of stations of interest. Of course, there are missing datapoints which cause much work for temperature analysts. Those are not a big deal for trend analysis.
The method involves creating for each station a spreadsheet that calculates a trend for each month for all of the years recorded. Then the monthly trends are averaged together for a lifetime trend for that station. To be comparable to others, the station trend is normalized to 100 years. A summary sheet collects all the trends from all the sheets to provide trend analysis for the geographical area of interest.
I have built an Excel workbook to do this analysis, and as a proof of concept, I have loaded in temperature data for Kansas . Kansas is an interesting choice for several reasons:
1) It’s exactly in the middle of the US with no (significant) changes in elevation;
2) It has a manageable number of HCN stations:
3) It has been the subject lately of discussion about temperature processing effects;
4) Kansas legislators are concerned and looking for the facts; and
5) As a lad, my first awareness of extreme weather was the tornado in OZ, after which Dorothy famously said: “We’re not in Kansas anymore, Toto.”
I am not the first one to think of this. Richard Wakefield did similar analyses in Ontario years ago, and Lubos Motl did trend analysis on the entire HADCRUT3 in July 2011. With this simplying concept and a template, it is possible for anyone with modest spreadsheet skills and a notebook computer to answer how area temperatures are trending. I don’t claim this analysis is better than those done with multimillion dollar computers, but it does serve as a “sanity check” against exaggerated claims and hype.
For the Kansas example, we see that BEST shows on its climate page that the State has warmed 1.98 +/-0.14°C since 1960. That looks like temperatures will be another 2°C higher in the next 50 years, and we should be alarmed.
Well, the results from temperature trend analysis tell a different story.
From the summary page of the workbook:
| Area | State of Kansas, USA | |
| History | 1843 to 2011 | |
| Stations | 26 | |
| Average Length | 115 | Years |
| Average Trend | 0.70 | °C/Century |
| Standard Deviation | 0.45 | °C/Century |
| Max Trend | 1.89 | °C/Century |
| Min Trend | -0.04 | °C/Century |
So in the last century the average Kansas station has warmed 0.70+/-0.45°C , with at least one site cooling over that time. The +/- 0.45 deviation shows that climate is different from site to site even when all are located on the same prairie.
And the variability over the seasons is also considerable:
| Month | °C/century | Std Dev |
| Jan | 0.59 | 1.30 |
| Feb | 1.53 | 0.73 |
| Mar | 1.59 | 2.07 |
| Apr | 0.76 | 0.79 |
| May | 0.73 | 0.76 |
| June | 0.66 | 0.66 |
| July | 0.92 | 0.63 |
| Aug | 0.58 | 0.65 |
| Sep | -0.01 | 0.72 |
| Oct | 0.43 | 0.94 |
| Nov | 0.82 | 0.66 |
| Dec | 0.39 | 0.50 |
Note that February and March are warming strongly, while September is sideways . That’s good news for farming, I think.
Temperature change depends on your location and time of the year. The rate of warming is not extreme and if the next 100 years is anything like the last 100, in Kansas there will likely be less than a degree C added.
Final point:
When you look behind the summary page at BEST, it reports that the Kansas warming trend since 1910 is 0.75°C +/-0.08, close to what my analysis showed. So the alarming number at the top was not the accumulated rise in termperatures, it was the Rate for a century projected from 1960. The actual observed century rate is far less disturbing. And the variability across the state is considerable and is much more evident in the trend analysis. I had wanted to use raw data from BEST in this study, because some stations showed longer records there, but for comparable years, the numbers didn’t match with HADCRUT3.
Not only does this approach maintain the integrity of the historical record, it also facilitates what policy makers desperately need: climate outlooks based on observations for specific jurisdictions. Since the analysis is bottom-up, microclimate trends can be compiled together for any desired scope: municipal, district, region, province, nation, continent.
If there is sufficient interest in using this method and tool, I can provide some procedural instructions along with the template.
The Kansas Excel workbook is provided as an example: HADCRUT3 Kansas.xls
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
I’m off traveling again today, so won’t be able to respond to comments.
My understanding of the AGW theory (whoops; hypothesis) is that the most pronounced warming should be present in the coldest and driest air masses, and during winter. While that’s interpreted to be polar regions I think Kansas during the winter is in a position to compete. It’s interesting, therefore, that while February and March exhibit the strongest upward seasonal trend (seemingly validating the hypothesis; oops, theory), December and January exhibit the smallest upward trend (contradicting the … oh, forget it) excepting September. And following February and March the next highest trend was in July which is where it shouldn’t be.
Another example of the mysterious AGW thingy that also backflips when it comes to Arctic and Antarctic regions.
September is when briefly neither heating nor air conditioning are used much in buildings so the urban heat island effect on thermometer stations is lessened.
CET is the best known and the longest regional data set. It may come as a surprise to many that its 360 year long record conclusively shows that increased insolation suppresses long term temperature up-trend ( see link )
“For the Kansas example, we see that BEST shows on its climate page that the State has warmed 1.98 +/-0.14°C since 1960. That looks like temperatures will be another 2°C higher in the next 50 years, and we should be alarmed.”
This is misinterpreting the BEST results. The page clearly labels the result as “Warming since 1960
(°C / century)”. Ron gets it right later, but there is no reason to say BEST is misleading anyone. It does NOT look like it will be warming 2C in 50 years; it looks exactly like the warming will be 2C in the next 100 years.
“Since the analysis is bottom-up, microclimate trends can be compiled together for any desired scope: municipal, district, region, province, nation, continent.”
But what you would really want is some sort of weighted average. If the eastern half of Kansas had 20 stations and the western half (with far fewer people and cities) had 6, simply averaging these will not give a good estimate of the warming for the state. Similar problems continue when going to national or global estimates.
“So in the last century the average Kansas station has warmed 0.70+/-0.45°C …
One rather interesting thing here is that this means there was COOLING for the first half of the century, and warming for the second half. If the stations warmed ~ 1 C in the last 50 years (ie 2 C/century), then simple subtraction says the stations must have cooled by ~ 0.3 C in the previous 50 years to get the 0.7 C figure for the entire 100 years.
If anyone is interested in looking a little deeper into the weather station trends, here are a few pointers.
First, the weather station data is the air temperature measured in an enclosure placed at eye level 1.5 to 2 m above the ground. The minimum temperature is an approximate measure of the bulk air temperature of the base of the local weather systems as they pass through. The maximum temperature is a measure of the convective mixing of the warm air rising from the solar heated ground below with the cooler air at the thermometer level. This depends on cloud cover and the surface evaporation.
In many regions, the prevailing weather systems are formed over the oceans. The trend in the minimum temperature could have a strong signal from the trend in ocean surface temperature in the region of origin. For example, in California, the PDO sticks out like a sore thumb. In the UK and surrounding regions it is the AMO.
To start, download the relevant ocean trend, (AMO. PDO etc.), do a 5 year rolling average for both the ocean and station data, do an XY plot and look for the ‘fingerprint’. Then run a linear fit to the 5 year averages and get the slope from the Excel ‘Trendline’ function. The differences in slope should give information on the local urban heat island effects.
Now subtract the maximum temperatures from the minimum and look at the trend in the delta T. The delta T will increase with sunlight and low rainfall (less surface evaporation).
By the way, none of this has anything to do with CO2 ……..
Further details can be found at:
http://scienceandpublicpolicy.org/originals/pacific_decadal.html
http://www.venturaphotonics.com
Unless you use some funky, made up definition of “climate,” a few degrees change does NOT constitute climate change. My Cwa would still be Cwa with a few degrees change.
http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification
Feb. and Mar. this year , in “my” part of Ks were 8.37 and 2.75 deg F below avg.(high temps )
( Per AccuWeather records) And if Big Joe B . is right , this trend may continue …Brrrr…
Since I have the spreadsheet skills on par with a “Climate Scientist” could someone tell me if possibly one of the station records is a reliable one and would pass Mr. Watts station sighting criteria for minimal UHI? And if so what is its trend all by itself?
When you look behind the summary page at BEST, it reports that the Kansas warming trend since 1910 is 0.75°C +/-0.08
===============
Paul Homewood:USHCN Adjustments In Kansas
In addition to recent temperatures being adjusted upwards, we also find that historical ones have been adjusted down. So, for instance we find that the January 1934 mean temperature at Ashland has been adjusted from 3.78C to 3.10C, whilst at Columbus there is a reduction from 4.00C to 3.52C.
In total, therefore, there has been a warming trend of about 1C added since 1934
http://notalotofpeopleknowthat.wordpress.com/2014/06/28/ushcn-adjustments-in-kansas/
Hiding The Decline In Kansas City
http://stevengoddard.wordpress.com/2012/06/30/hiding-the-decline-in-kansas-city/
Or there is The Old Farmer’s Almanac (also cheaper than a super computer).
Here is the prediction for Topeka, KS for 2014
>> http://www.almanac.com/weather/longrange/KS/Topeka
For August about 3°F above average
It would be interesting to see how the Almanac compares with the author’s spreadsheet.
I did a similar analysis in February 2010, using HADCRUT3 data, for 87 US cities in the database. Results are sorted by state and posted at
http://sowellslawblog.blogspot.com/2010/02/usa-cities-hadcrut3-temperatures.html
@ur momisugly F Ross at 9:21 am…The AccuWeather record and forecast has July being 1.77 deg below avg.
TOFA says a couple deg. above..will be interesting to see which is closest to actual temps.
“For the Kansas example, we see that BEST shows on its climate page that the State has warmed 1.98 +/-0.14°C since 1960. That looks like temperatures will be another 2°C higher in the next 50 years, and we should be alarmed.”
STOP. This is just the stupid simplistic kind of thing that AGW is based on.
First there is no reason to fit a linear model to climate data because nothing about it is linear. It’s a fallacy before you do the calculation. Second and probably worst is the idea that the average straight line through all the ups and downs of climate will be the same for the next 100 years as it was for the last 100 (or 50 or 35 or whatever amount of data you happen to have for one area) . What on earth is that idea based on?
The whole problem is this idea of a “trend”. Climate does not “trend”, it changes rather irratically. Somewhere in this word “trend” is unspoken assumption that once a “trend” is measured we can assume that it will be “likely” to continue. THIS IS A FALLACY.
“If you want to understand temperature changes, you should analyze temperature changes, not the temperatures.”
That’s great. I’ve been saying this for years but stick to looking at rate of change of temperature and stop thinking of “trends”.
BTW the land data you are looking is not HadCrut3, that is a land and sea dataset made from combining HadSST2 and CRUTem3. I think you mean CRUTem3 . It does wonders for cred. it you at least know the name of dataset you are using and know the difference between land and sea.
You should probably correct this in the article.
Another problem you have with this approach is what I call “cosine warming”.
http://climategrog.wordpress.com/?attachment_id=209
It depends upon where you start and finish in the data. This has been heavily discussed, usually with reference to “cherry picking”. Even if you do not cherry pick but use the data you have, if each station you look has a different time span, your idea of “nomalising” then all to a per century “trend” will be heavily biased by where any particular records starts and ends.
You make the erroneous assumption that they are all somehow comparable once you have “normalised” them.
This is a major problem since you can easily double a rate of change found in a cosine, which has zero long term trend anyway. The whole thing is a fiction.
http://www.metoffice.gov.uk/hadobs/hadcrut3/
“HadCRUT3 dataset
The gridded data are a blend of the CRUTEM3 land-surface air temperature dataset and the HadSST2 sea-surface temperature dataset. ”
However, having read the page you linked to I can see why you were confused. It certainly reads like HadCrut3 is the land station data you used. This is very poor presented.
For the last several months I have been downloading Environment Canada data for sites that I have interest in, sometimes because people have said it is warming and I really haven’t noticed much.
The data says some places are warming, some places are not. Some show that there is significant MEAN warming, but what virtually every data set I have looked at shows NO INCREASE in Extreme Maximum or Mean Maximum temperatures. What they do show, is that it is getting LESS COLD. That is, the Extreme Minimum and the Mean Minimum Temperatures are not as low as they were 60, 80 or 100 years ago. That increases the Mean Temperature and provides a Global Warming “Signal” even though it isn’t getting hotter – at least in my terms.
And in those locations where the Extreme Maximum Annual temperatures and the Maximum Mean Annual temperatures do show an upward trend, it is because seasonally low maximums (winter) have increased, not because summer temperatures have increased. In fact in several cases I have looked at (Winnipeg, Manitoba for example) the summer maximum temperatures show a slight decline in trend (cooling) while the winter maximum temperatures show a slight rise in trend (warming). In fact, I see a number of CONVERGING trend lines in the data when plotting sites with 80 to over 100 years of temperature data.
I have seen some papers on WUWT suggesting that Average global warming is more due to LESS cold than actual warming. Of course, that is net warming but I think it is important to know what is causing that warming in the data because it isn’t because it is getting so hot we are all going to have to move towards the poles. It seems that weather is simply getting less extreme, with low mean and low extreme temperatures getting LESS cold.
With the exception of our desire in my region to see extreme cold weather to kill the western pine beetle, this would seem to be a benefit. It isn’t any hotter in the summer (the hot years were back in the 30’s and 40’s) and you don’t have to use so much heat in the winter (as also opposed to the 30’s and 40’s and the turn of the century as where I live temperatures regularly hit -45 C and even lower – Dec 1924 & Jan 1935: -53.9, Feb 1936: -55.6, Environment Canada data, Rocky Mountain House, AB)
I am not a statistician, climatologist or mathematician, just an old engineer/rancher interested in comparing data to what I have experienced and heard from my prairie ancestors.
I have no idea if the Environment Canada data has been adjusted but I draw my speculation from what I have downloaded from the EC site at this site. I also admit that I have at times spliced data due to changes in the local stations since one will have a record from say 1917 to 1940 and a second from 1942 to 2007. A lot of stations stop at 2007 for some reason. And a lot of stations have missing data and breaks especially some of the really old and rural sites.
And finally, since what I have provided is just anecdotal so far, I have posted two sites I just started some work on yesterday for people to examine if they wish.
Rocky Mountain House, AB: https://www.dropbox.com/s/j2bu889j037q6j6/Rocky%20Mountain%20House.ods
Winnipeg, MB:
https://www.dropbox.com/s/98i6yrkf94o8zpx/Winnipeg.ods
The local rag ran an article about the warming of the Northeast and Southwest and a companion article, in which they claim that the average summer temps in Carson City, NV have risen by 6.8 degrees F since 1984.
The last couple of summers we have not had more than 1-2, or NO days of 100+ temps.
This June seems to be warmer than usual. The incompetent idiots who supply the weather data to the NV Appeal, always have highs 1-4 degrees higher than anything the TV weather stations report.
In any event, an increase 6.8 degrees seems over the top!
Maybe the temps are recorded beside a compost pile? Since they are all in for AGW, I wouldn’t put it past them.
I like this approach because whenever you take any kind of average you are losing information and in this case, the averaging is being done AFTER the trend analysis rather than before making each of them easier to both understand and address. Thus, if someone wants to argue that the mean for the state needs weighting, they can do that to their heart’s content separately from the trend analysis and if someone wants to complain that the trends are not calculated properly, they can do that separately from the averaging.
The bad thing about it is that is gives people lots of scope to do exactly that – keep playing around with weighting and trend analysis until they get an answer that suits them. This is the crux of the matter with land temperature records – they are full of so many little problems (TOBS bias, UHI effects, station site changes) that you can pretty much justify almost any manipulation you like until to come to the answer you are looking for.
At the end of the day, historical surface records are only ever going to be a battle-ground in the climate change argument and one in which the equivalent of trench warfare ca. 1914-1918 is being undertaken: Lots of effort and many casualties for little overall gain.
ecowan says:
July 12, 2014 at 11:26 am
Take a look at the minimum temperatures in Carson. Per my post above, I suspect the minimums have rising thus causing the “Average” temperature to rise. I have looked at several sites and most of them show this warming bias due to the low temperatures becoming LESS cold over time.
I would not trust HAdcrut
rather use tutiempo.net
I looked at the average change per annum, see here for my procedure
http://blogs.24.com/henryp/2013/02/21/henrys-pool-tables-on-global-warmingcooling/
Again folks
there is no man made warming
whatsoever
There simply is no room for it in my last [established] equation
(at the end of the minima table)
Thank you so much for this. I have been collecting data from the longest records in the world in CRUTem4. I will probably end up with 28 stations with good full year coverage both before and after 1850 (which people seem to use as the start of the industrial era)
Brisbane hits coldest temperature in 103 years
http://www.theaustralian.com.au/news/brisbane-hits-coldest-temperature-in-103-years/story-e6frg6n6-1226986116278?nk=9fe3cbf4f5bf37a6dc3f771dfd4654b8
Gee, warming very little in summer and strongly in winter?? Quelle horreur!