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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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It's microsite influences

What the science says...

Select a level... Basic Intermediate
Microsite influences on temperature changes are minimal; good and bad sites show the same trend.

Climate Myth...

It's microsite influences
U.S. weather stations have been located next to exhaust fans of air conditioning units, surrounded by asphalt parking lots, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat. 89 percent of the stations fail to meet the National Weather Service’s own siting requirements that stations must be 30 metres away from an artificial heating or radiating/reflecting heat source. (Watts 2009)

The website surfacestations.org enlisted an army of volunteers to photograph US surface temperature measurement stations and document stations located near parking lots, air conditioners, or anything else that might impose a warming bias. They found that 89% of the stations did not meet the US weather service siting criteria in one way or another. That is not good. Does this prove that a US warming trend is just the artificial influence of parking lots and air conditioners on the temperature record coming from "bad" stations? 

No. Actually, an analysis shows that "good" and "bad" stations show very similar trends for temperature over time. The chart below compares data from stations that surfacestations.org identified as "good", as well as "bad" stations. Notice that "good" stations track very closely to "bad" stations, and actually the "good" stations show more of a warming trend!

Maximum and Minimum Temperature Anomaly for good and bad sites
Figure 1. Annual average maximum and minimum unadjusted temperature change calculated using (c) maximum and (d) minimum temperatures from good and poor exposure sites (Menne 2010).

The volunteers from surfacestations.org deserve credit for pointing out siting problems of the US Weather Service temperature measurement stations. Unfortunately the fact that "good" and "bad" stations show the same upward trend proves that warming in the US is not just a measurement problem. Temperatures are trending upward around the globe, not just in the US. Microsite influences on temperature measurements in the US can't explain the US temperature rise, much less the global rise.

Last updated on 31 August 2010 by Jim Meador.

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Comments

Comments 1 to 6:

  1. An idle thought....we tend to think of 'bad' stations giving higher readings than 'good' stations as they respond to surrounding heat emitters such as buildings.
    In cold weather the opposite can occur...the 'bad' stations will respond more slowly to increasing T due to the thermal inertia of those same buildings. In other words, the T swing max-min could be greater in the 'bad' stations but dis-appears in the averaging process.
    So maybe there is an element of self-compensation here which could be determined by looking at more detailed data.
  2. Questions: 1) The belgian media jumped on a result similar to what is posted on http://surfacestations.org/ of summer 2009 (no source reference in Belgian media) in which it seems that a lot of american surface stations have a deviations of more than 1°C and that for some "accurate" surface stations the temperature has been decline the last 100 years. Is this already incorporated in the graphs above? (No post date of the graphs).
    2) Why do your graphs only go back to 1980 while other stations have data going back more than 100 years on the graphs of surfacestations.org?
  3. psilax,
    Re. #2, a good question. I looked up the Menne article and the Watts 2009 article to which it is a response. Watts suggests two driving causes for the upward bias of temperatures: The change in paint spec in 1979 and the introduction of the new type of thermometers in the 1980s. I suspect that Menne, et al, restricted their period of reporting to that which Watts was concerned about.
  4. For what it's worth, Watts put his three different boxes closer to each other than I would have, and put the newer paint spec one in the middle. That puts the one he expects to find higher temperatures in between two, too-close, bodies that both reflect SW and radiate LW.

    I can't predict what difference that made, but for someone really concerned about siting of instruments, he introduces his own siting problems.
  5. Capital Weather Gang (now part of Washington Post) noted that the NWS in Sterling VA noted that 2011 is the "warmest summer on record" through Aug 17th at National Airport (KDCA). http://www.washingtonpost.com/blogs/capital-weather-gang/post/pm-update-widely-scattered-storms-this-evening-drier-saturday/2011/08/10/gIQAX4LQQJ_blog.html

    The problem is that it isn't. National has fresh dark gravel spread around their thermometer site (new google satellite compared to old) and they are consistently high by 2-3 degrees on radiational cooling mornings. The anomaly doesn't show up as much on windy or cloudy mornings. National's lows are also 5 to 10 degrees higher than neighboring weatherbug sites (mostly at schools) but that is a river and heat island influence that hasn't changed much over the years.

    If the washpost link above doesn't work (their site is sometimes unruly), the NWS discussion was also quoted here; http://www.americanwx.com/bb/index.php/topic/23896-record-summer-watch-where-will-we-finish/
  6. This needs to be updated to include the results of the BEST (Berkely Eartth Surface Temperature) study, which shows that there was no significant influence on the measured long-term temperature due to the siting of temperature stations. And that the temperature rises from BEST's analysis match the other temperature analyses closely.

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