2011-10-27 14:58:37Watts, Surface Stations and BEST
logicman

logicman_alf@yahoo.co...
109.150.180.165

Watts' claim of surface station bias is not borne out by any scientific study.   If there is no bias in the data, then perhaps there is some observer bias in the study of surface stations.  I decided to check that out.  Here is what I have found:

Watts, Surface Stations and BEST

This is a first draft and is probably too long.  I greatly appreciate the help I received in making the Warming Island article very readable.  If we can acheive that standard again by working together I shall be a very happy blogger.

2011-10-27 20:19:02
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.133

You conclude that it's the effect of shielding. But homogenisation is also for this, isn't it? It removes any 'jumps' in the data, like when the station is moved, or a new heater is added next to it.

I also think it's worth referencing the paper that Watts was a co-author on. It concluded UHI and microsite influences didn't affect the trend, but they do affect the diurnal range.

 

Also, I think you could cut out a lot of the wordiness without losing anything (but I always say that). That would give you space for the above 2 points and still the thing should be shorter!

I've attached an edit below which keeps all the paragraphs, but cuts wordcount by about 500. Still need to add reference to Watts and IMO the homogenisation procedure is well worth bringing up (and maybe mentioning how there are also cooling biases, but that migth be tmi).

The only thing I changed was the description of Watts' reaction. Being too smug is a bad thing, I tried to change it more towards the analysis. But maybe I didn't do so well either :P

2011-10-27 20:46:01
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.133

The Berkeley Earth Surface Temperature (BEST) project - was set up to address criticisms of land temperature records.  It has been known since its invention that when using a thermometer to record weather, siting is of vital importance.  It’s also known that a thermometer could not measure air temperature accurately unless it’s shielded from precipitation and heat radiation.  One device used to shield thermometers is the Stevenson Screen.

Stevenson Screens need to be mounted in locations where they are in ambient air with the thermometer bulb or other sensor 2 meters above the ground.  There are various other norms: such as ensuring the door opens away from the Sun.

The so-called surface temperature stations actually record near-surface air temperatures.  As early as 1938, G.S. Callender, in writing of the effects on temperature of atmospheric CO2, made it clear that the siting and quality of surface temperature stations must be considered.

The most comprehensive survey of alleged flaws - microsite influences - in the construction and siting of surface stations is the SurfaceStations.org project begun by meteorologist Anthony Watts.  In a 2009 article published by the Heartland Institute think tank, Watts claimed to show that US surface station records could not be relied on, so why trust any others?

This ignores how scientists handle the data: using strong statistical techniques to remove bias. A study using Watts' own data - Menne 2010 - found that station exposure does not play an obvious role in temperature trends, the same conclusion reached by Watts himself in a later paper.

Most recently, the Berkeley Earth Surface Temperature Project re-examined the surface station data.  Four papers have been published on the BEST web site with all the data and software code so anyone can check.

Watts is on record as having said that he would accept the results of the BEST study:

Briggs on Berkeley’s forthcoming BEST surface temperature record, plus my thoughts from my visit there
Posted on March 6, 2011 by Anthony Watts

... I’m prepared to accept whatever result they produce, even if it proves my premise wrong…let’s not pay attention to the little yippers who want to tear it down before they even see the results…That lack of strings attached to funding, plus the broad mix of people involved especially those who have previous experience in handling large data sets gives me greater confidence in the result being closer to a bona fide ground truth than anything we’ve seen yet. ...

Anthony Watts' response to this very high degree of transparency is that the papers are of no value because they have not been peer reviewed: we agree with Watts that you should be sceptical of non-peer reviewed work, and wish he would apply this scepticism elsewhere, even to things he wants to believe.

Watts et al’s criticism has mostly been to insult the authors rather than help with reviewing, but given the pedigree of the authors and the overwhelming evidence from other sources (10 SIGNS OF GLOBAL WARMING LINK), it seems only a matter of time before these papers pass review and the main conclusion seems unlikely to change much.

Is there a real problem with surface stations?

Judging from Watts' writings on his surface stations project, it seems common sense that badly sited surface stations will produce bad data.  However, independent studies have shown that the sites listed by Watts do not affect the finding of a global warming trend.  Which is most likely to be flawed, the data, or ‘common sense’?  Let’s critically examine the assertions made in Watts' 2009 article Is The US Surface Temperature Record Reliable?

On the front page, Watts asks two questions:

Is the U.S. Surface Temperature Record Reliable?

How do we know global warming is a problem if we can't trust the U.S. temperature record?

The 2nd question carries the implication that if the US temperature record is unreliable, then global warming isn't happening.  Early on, Watts compares three different coatings on Stevenson Screens and finds a difference.

in Figure 3. 1 [I] found a 0.3° F difference in maximum temperature and a 0.8° F difference in minimum temperature between the whitewash- and latex-painted screens. This is a big difference, especially when we consider that the concern over anthropogenic global warming was triggered by what these stations reported was an increase of about 1 .2° F over the entire twentieth century.

 

The graph shows a difference in recorded temperatures over a 24 hour period.  Watts then compares this to an entire century of recorded temperature change. .

The experiment was a single study of one sample of each coating type in a single location over a single day.  He went on to check temperature stations near his home.

... I set out to check the paint on the Stevenson Screens at these locations to see if they had indeed been converted to latex from whitewash. The first station, at the Chico University Experiment Farm, had been converted to latex, but it also contained a surprise. It had two screens, one of which was converted to automated radio reporting. I was surprised to find NWS had installed the radio electronics just inches from the temperature sensor, inside the screen, (See Figure 4.) Surely this station's temperature readings would be higher than the actual temperature of ambient air outside the screen.

To the casual observer, this image shows a temperature probe hanging next to some electronic components. Yet in the picture, the electronics box has been opened to and the lead and probe are hanging free with the probe lead entering the component box through a gland at the bottom.  When the box is closed, the probe is not inside but some inches away from the sealed box.  The probe is also held in place, by what looks like a tie-wrap, so that the sensing tip is at the center of volume of the Stevenson Screen.  The chance that the temperature measured by the probe will be significantly affected by very low power electronic components in a sealed box some inches away is likely to be vanishingly small.

The rest of Watts’ article is descriptions and photographs of what he considers to be factors which will influence temperature records.  He includes some false color infra-red photographs to draw attention to heat sources near thermometers.

 

Rather than draw readers' attention to the hot spots, I would invite readers to compare the color (temperature) of the instrument housing with the color (temperature) of the general surroundings.  In each case, the temperature station casing is - despite being near a source of heat - at the same temperature as the nearby land.

The whole purpose in screening a temperature sensor is to shield it from radiant heat.  The photographs serve only to show the infra-red sources from which the temperature sensors are being shielded – and these shields are probably part of the reason why neither Menne nor Watts found a cooling bias.

Summary

It has been known since the invention of the thermometer that for accurate measurement of air temperature the thermometer must be shielded from radiant heat.  The lack of overall bias in the surface station records would seem to demonstrate what is seen in the infra red photographs: the stations are adequately shielded against influence from local sources of radiant heat.

2011-10-27 22:14:11
Kevin C

cowtan@ysbl.york.ac...
144.32.72.165

Tantalising mention of 'Infra red photographs' in the last para - but to what does this refer. Citation needed!

2011-10-27 22:26:12
nealjking

nealjking@gmail...
84.151.39.200

"Watts et al’s criticism has mostly been to insult the authors rather than help with reviewing, but given the pedigree of the authors and the overwhelming evidence from other sources (10 SIGNS OF GLOBAL WARMING LINK), it seems only a matter of time before these papers pass review and the main conclusion seems unlikely to change much."

This makes it sound as if:

- The likelihood of passing peer review depends on the "pedigree" of the authors

- Passing peer review depends on agreement with the conclusions instead of soundness of methodology

 

Neither are good messages to send out!

2011-10-28 00:20:29
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.133

Fair enough neal, I was trying to get across that 'these guys aren't idiots, they probably didn't fuck it up'. But perhaps agreeing with Watts' earlier quote where he says the methodology looks good is the way to go about it?

2011-10-28 00:34:25
logicman

logicman_alf@yahoo.co...
109.150.180.165

Kevin: Mark's rewrite does not need to include my original pictures, which are here.

Neal: points taken, see below.

Mark: you have done a good job here, thanks.  I'll edit your paragraph changes in, and add a couple of points later today (off out just now).  Nicely spotted digit [1] !  That was from an OCR of the pdf.

From my agreement with Neal, I suggest:

Anthony Watts' response to this very high degree of transparency is that the papers are of no value because they have not been peer reviewed: we agree with Watts that you should be sceptical of non-peer reviewed work, and wish he would apply this scepticism elsewhere, even to things he wants to believe.  In the case of BEST the criticism is not warranted: the papers are in peer review and are available on the web so that more people can assist in improving their quality.  Watts et al’s criticism has mostly been to insult the authors rather than help with public reviewing.

As to the point about data homogenisation, I'm thinking we need to add something like this:

Although homogenisation can smooth out some flaws in the data, the data must be free from overall bias in order to produce scientifically valid findings.  One must conclude from the lack of significant bias proven by multiple studies that the surface stations project shows, not factors found to actually cause bias but things which the casual observer thinks ought to cause bias.

2011-10-28 08:18:56
Glenn Tamblyn

glenn@thefoodgallery.com...
58.164.83.15

logicman

You could also link to the 4 parter I did on the surface temp record some time back. Parts 3 & 4 look at a wide range of factors and why they don't have the impact people might expect, but in very general terms. Your post is looking at some parts of this in more technical detail so they are a good counterpoint to each other.

I am also probably doing a post on Satellite temps and why they may be higher than UAH/RSS report. This will be after the specific rebuttal to Willis Eschenbach's post. That might then be a package of posts around the BEST/Surfacestations/UHI meme from WUWT.

2011-10-28 11:47:57
logicman

logicman_alf@yahoo.co...
109.150.180.165

This blog is now edited to include revisions, especially Mark's major edit.

I have made a number of minor revisions, so the whole thing needs to be checked again - sorry.

In particular, I have remedied the omission of reference to Pielke Sr, who collaborated with Watts on the surface stations project.

Newest version here >

Watts, Surface Stations and BEST

2011-10-30 04:06:10
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

"Watts in a later paper" - should link Fall et al. here.

"Watts et al’s criticism has mostly been to insult the authors rather than help with public reviewing."  You can link to my post here, because I gave two examples of WUWT calling the BEST team media whores.   Might be worth trimming down the preceeding Watts quote too -  it's a bit long.

"and these shields are probably part of the reason why neither Menne nor Watts found a cooling bias."  You mean warming bias?

2011-11-01 08:02:15
logicman

logicman_alf@yahoo.co...
109.150.177.151

Dana: thanks, I've edited to include your suggestions.  I've also linked to Watts' own site where the electronics box is described as being 6 to 8 inches from the tip of the probe.

2011-11-01 10:11:25
Riccardo

riccardoreitano@tiscali...
2.33.129.49

Pedantic mode on

You write in the summary "since the invention of the thermometer [...]". When thermoters had been invented they did not know what heat is, let alone radiant heat. Consider to change it to "modern thermometry" or something like this.

Pedantic mode off

Memorable sentences:

"Which is most likely to be flawed, the data, or ‘common sense’? "

"not factors found to actually cause bias but things which the casual observer thinks ought to cause bias."

Good job.

2011-11-01 10:53:01
logicman

logicman_alf@yahoo.co...
109.150.177.151

Riccardo: thanks.  I could change to something like: "shielded from direct solar heating."

2011-11-02 02:48:07
logicman

logicman_alf@yahoo.co...
109.150.177.151

Further minor edits done to include:

It was also known that a thermometer could not measure air temperature accurately unless it was shielded from precipitation and direct sunlight.

 

direct quote added:

"The reliability of data used to document temperature trends is of great importance in this debate. We can't know for sure if global warming is a problem if we can't trust the data."

'Debate' is a contest of orators: science is a contest of evidence. Watts ignores how scientists handle the data ...

 

When the box is closed, the probe is not inside but some 6 to 8 inches away, as noted by Watts in his own site survey.

 

New paragraph added to summary between 2 previos paragraphs:

It seems likely that the average reader of Watts' articles will have gaps in his or her knowledge of how scientists handle weather station data.  Arguments which rely on those knowledge gaps will fail to impress anyone who has read articles like this SkS series on how weather station data is handled.