A Timely Post on Phoenix UHI

Steve McIntyre, in a timely post for this site given the recent project on Phoenix urban heat islands, has a post on the Phoenix adjustment in the GISS database and Hansen’s dicussion of Phoenix UHI in his 1999 paper. 

One is left to wonder whether a station that has a 2.5C error-corection adjustment tacked on should even be included in a data set that is attempting to measure a warming signal on the order of magnitude of 0.5C, particularly since any reasonable person would argue that the 2.5C adjustment likely has an error bar of at least plus or minus 0.5C.  I stand by my point that the signal to noise ratio in surface temperature measurement is terrible.

However, many GISS adjustments for site location and urbanization are negative, meaning urbanization has been reduced at the location since 1900, certainly an odd proposition.  In fact, if memory serves, the total net adjustment of all stations in the GISS system is negative for site location and urbanization.  I know, from here, the net USHCN adjustment for combined site location and urbanization is negative, adding 0.15F to current temperatures as compared to those in 1900, implying that site location quality has improved over time.  Anyway, McIntyre promises to tackle this issue tomorrow, which I look forward to.

  • Raven

    Hansen and Sato 1999 claims that planting vegetation (i.e. trees) can introduce a cooling bias in urban sites. This would be most evident if a station happens to be in a park that was originally bare ground or in regions where trees are not natural vegetation (i.e. US South West).

    That said, it should be easy to look at a site to determine whether those kinds of effects are likely given the location.

  • TCO

    McIntyre is not answering JohnV’s questions. He has also failed to supply code to Gerd Burger and myself to show his claimed improved method for validation for Mann stuff (which he pulled out of his asshole like a McK consultant fiddling with the NPV to justify a day one). Communist pussy.

  • Scientist

    A downward correction does not mean that “urbanisation has been reduced at the location since 1900”. It doesn’t mean that at all. Please, try not to claim such totally false things as this. You may have reasonable things to say sometimes, but it only damages your credibility when you get it as wrong on such a simple thing as this.

  • Why would trees introduce a cooling bias? Trees and plants increase humidity and net warming (with the exception of in the tropics where soil is dark and water transport effect is less). So do more people and cars. Per capita power consumption…

    It’s ridiculous. It might cause a negative jump, but certainly not a trend (except in rare instances).

  • Tony Edwards

    McIntyre is not answering JohnV’s questions. He has also failed to supply code to Gerd Burger and myself to show his claimed improved method for validation for Mann stuff (which he pulled out of his asshole like a McK consultant fiddling with the NPV to justify a day one). Communist pussy.

    Posted by: TCO | February 29, 2008 at 05:47 PM

    What a singularly nasty and foolish comment. JohnV has been working with Steve McIntyre on code puzzles. As to TCO and Gerd Burger getting information, I have never seen either name on CA, so I don’t know where they are asking for this info.
    Fists Sreve McI is claimed to be an oil company shill, then this reversed insulting comment.
    If I were Steve McI, I think I’d sue, but, anyway, Warren, can you please block this foul-mouthed object and spare the rest of us from this muck?

  • Joel

    TCO, why’d you stop posting at CA a year ago? I miss the brilliance, the humility, the courtesy. -:^)

  • TCO

    I had seen enough.

    For the other commenter: if you don’t know who Burger is…you’re clueless. Get hot.

  • Bill Drissel

    I posted the following comments about temperature correction to the Climate Audit site (link at the bottom), Regards, Bill Drissel

    I understand / misunderstand instrument corrections to be applied so the corrected reading represents the actual physical state of the thing measured. I picture in 1900 a wooden shelter on the lawn of the sewage treatment plant (far) out of town. I can imagine the sun heats the shelter and the LIG [liquid in glass] thermometers inside are warmer than the air so you would want to apply a negative correction to the instrumental readings to get the actual temperature of the air. But what circumstances would lead one to believe the thermometers were ever cooler than the ambient air? Can anyone explain the physics of this?

    Did the scientists of 100 years ago realize their thermometers were not accurately measuring air temperatures? Did they correct data? In what year did thermometer corrections like these begin? Did someone place a “gold standard” instrument next to one of these shelters and find some sort sf systematic difference that would justify adjusting all of the temperatures for a whole year? Century?

    [I] also wonder[s] if anyone has a physical, climatological or instrumental reason the measured / computed difference between the air and the thermometer should change linearly (and stepwise) with time?

    If there is such a mechanism, did anyone notice it change sign in 1980?

    Source web page: Climate Audit – by Steve McIntyre » Positive and Negative Urban Adjustments ( http://www.climateaudit.org/?p=2815 )

  • TCO

    Lot of idle wondering and questions to the crowd, Bill. A very common sort of post both in thought and style.

    The fundamental misconception that you have is that there IS some calibrated gold standard and other instruments are being given offsets to it. That’s not the case.

    POPULATIONS of instruments are being adjusted based on populations of other instruments. And while the reference instruments are posited to be clear (or clearer) in terms of UHI contamination, they are not perfect to other effects (other confounding factors evident as noise). So even if you compare rural to rural, they are not identical in trend.

    Therefore averages are used. Also, therefore some specific adjusted spots will be OVERCOMPENSATED FOR (as part of a normal distribution). And therefore some will be undercompensated. And you have to leave them, because otherwise, you are pruning undercompensated and leaving overcompensated. You’re pruning the data preferentially.

    BTW, none of this is new!!! We’ve had this movied before! But the average commenter here doesn’t even get the basics. In some cases, doesn’t even read previous posts.

    There are a lot of OTHER topics that ARE INTERESTING. For instance, why adjust, versus just using the reference population? Is the non-independance of adjusted stations noted? If there is minimal UHI impact, why go through an adjusting mechanism? If there is minimal UHI impact, does that mean that it’s not that prominent (as a time dependant influencer of the global average) or does it mean that the reference populations are similarly biased by small scale UHI? These are all the obvious interesting next scale questions. But we can’t even get there with the hoi polloi idiocy of the average skeptic commenter. We can’t get there with Steve McI not playing fair and “cherrypicking points of criticism” (and in this case in a method that has already been shown before several months ago to be sophistry…to be argument for effect versus understanding and exploitation of MISUNDERSTANDING such as Bill’s for effect.

    Let’s be GOOD SKEPTICs. Not dummies. Not sophists.

  • WJG

    I send young adults and children to this site to read about climate topics. Please remove Raven’s posting rights. His comments are not helpful.

  • Sorry if this has been mentioned before, but this is my first time on this highly recommended blog.

    The Phoenix official measuring station was located in a parking lot on Buckeye Road for many years – next to the NWS office at Sky Harbor. It has since been moved twice away from the pavement into the desert near Sky Harbor. Sorry I don’t know the exact years. One location was a few hundred meters NE of the E end of the N runway. Don’t know where it is now.

    I suspect moving it has lowered our temps a couple of degrees.

    John in Paradise Valley

  • Sorry if this has been mentioned before, but this is my first time on this highly recommended blog.

    The Phoenix official measuring station was located in a parking lot on Buckeye Road for many years – next to the NWS office at Sky Harbor. It has since been moved twice away from the pavement into the desert near Sky Harbor. Sorry I don’t know the exact years. One location was a few hundred meters NE of the E end of the N runway. Don’t know where it is now.

    I suspect moving it has lowered our temps a couple of degrees.

    John in Paradise Valley