September 12, 2011

When is a record not really a record?

Today the Seattle Times has an article noting that Seattle (Seattle Tacoma Airport) has beat the all-time record for the number of consecutive days of 80F and higher in September.  Today (Monday) should be much cooler since marine air has pushed into western Washington overnight, with low clouds extending to the Cascades.  The heat wave is over.

Here is the plot of the temperatures the last few days.
You will note that on two of the days the temperatures only got to 82F.   Now here is the question.  As I documented in an earlier blog (click here to see it), the third runway has clearly warmed up the temperature sensor at Seattle by roughly 2F.      On the two days SeaTac reached 82 of the now 9 day streak above 80 the neighborhood surrounding SeaTac had highs of 78 and 79, averaged over 4 schools.  That leaves the obvious question:  would Seattle have reached this record if the third runway was not built?  We cannot be sure.

As I have discussed in this blog a number of times, the implications of human-emitted greenhouse gases are profound and substantial warming is pretty much inevitable.  But there IS an issue of our temperature sensors being in places in which development has occurred, as well as sensors that are simply poorly placed.  I don't think we have a clear understanding of the impact of these sensor problems, even though some research has been done on it.

Just to show you the problem, here are pictures of the temperature sensors at three official climatological observing stations in Washington State.  Remember sensors should be over natural vegetated surfaces, away from buildings and concrete/asphalt, and not near heat sources.

Here is Wilbur, Washington.   Breaks every rule....even near the exhaust of an AC unit!  (The temperature unit looks like a set of stacked plates---that is the temperature enclosure)

 Or Dayton, Washington.  Being above gravel is a no-no, and it is close to a building and concrete.

Or Conconully, Washington.  Above rocks and concrete steps.

The problem folks is I could show you dozens more of these for the Northwest and hundreds for the U.S.  Poor siting, not above natural vegetation, too close to buildings, and more.  And it gets worse---there is development/urbanization going in the neighborhoods of many sensors.  Some of the worse problems are at rural sites, so studies that have tried to determine the "true" temperature signal by separating rural from urban sites have often been flawed.

We have a problem.   The U.S. is now establishing a set of primo instruments in virgin locations, but that doesn't help much in documenting past trends.  TThere is little doubt that some records have been influenced by these siting issues.

Now for those global warming skeptics who are smirking about all this, let us make it clear--poor siting does not mean global warming induced by humans is nonsense.  It means we have to be more careful in separating out sensor issues from the real signal.  The real signal is going to get a lot larger,

Finally, any of you living in North Seattle, please keep your eyes out for my lost dog:  more information here


  1. Cliff, I assume there is a way to, in essence, "revoke" these stations' records from the official list? Or at least give them a Roger Maris-style asterisk?

    As an aside, I'm not sure why some people feel that pointing out real problems like this is akin to denying anthropogenic global warming. It's like Al Gore's famous "those scientists should shut up" comment regarding scientists who were pointing out some issues with then-current global climate models - that in itself makes for bad science. The only way science progresses is for people to identify (and discuss!) current shortcomings so they can be improved upon. Leave politics to the politicians, and science to the scientists.

  2. So, I'm thinking in an urban setting it might be difficult to properly site weather instruments. You've shown us all examples of poor siting. How should they be sited in an ideal situation?

  3. Doesn't this provide evidence of how human expansion does indeed impact the environment? Many people live on or near concrete and in artificial settings, so perhaps for some, it's an accurate reading! And as much concrete and asphalt as we've got going, one has to wonder, if our sensors can't even be accurate while near them! Good luck finding your dog!

  4. Westside guy,

    Menne et al. 2010 is one of several papers examining the surface station record for biases due to location. In this case, it investigated whether siting quality influenced temperature trends (the spoiler: little difference, and a bias in the direction you would not expect). This opens up all sorts of interesting questions...

    Anomalies are not absolute temperatures, of course, so siting quality is a concern for everything but examining trends. I believe that the major surface temperature records, eg HADCrut3, have corrections that they apply to stations to remove things like siting and land-use changes.

  5. I agree that sensor siting is skewing temperature data. At the same time, it sounds from your post that continued development will continue to reduce suitable sensor siting locations, while also contributing to global warming (urban sprawl leading to more car commutes, etc.) If we insist on only placing sensors in the "correct locations" seeking out oases of vegetation in the concrete jungle (sorry for mixed metaphors) is that also skewing the data?

  6. Cliff: You really should discuss the Menne 2010 paper in reference to siting of weather stations.
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, D11108, doi:10.1029/2009JD013094, 2010

  7. Fixed Carbon,
    I could discuss the Mennes paper, but the bottom line is no study has considered both detailed siting issues (like shown in my blog) and urbanization issues....cliff

  8. Thanks for pointing out these issues with siting instruments. I live in Anacortes and usually check the temperature reading at the WSDOT station at the ferry terminal. I have noticed that on warm days the temperature reading are very volatile. For example, last Thursday the temperature read 72, 65, 62, 72 over an hour and 20 minute period. Surely something is wrong with the installation.

  9. "The real signal is going to get a lot larger"

    Care to put a number on that "a lot larger" for future evaluation of predictive skill?

    Or, could you present the reasoning for expecting a larger signal?

  10. Hope you and your dog are soon reunited.

  11. Cliff,
    In my line of work HVAC controls, the siting of the outside air sensor of a building is always an issue. We will always try to locate it in the shade on the North side of a building away from any heat sources like exhaust fans, condensing units etc. I am surprised to see the outdoor air sensors in your examples located in the sunshine. In my experience the "porcupine" shade devices on the outside air sensors do not work as well when they are located in direct sunshine.

  12. Speaking of the siting of things, here's a great camera that takes a photo every 10 minutes of the 520 bridge pontoon construction site: OxBlue SR520 Pontoons. It will be fun to watch the project, but it's also another eye on the peninsula's weather.

  13. It's all perfectly clear in NWS Instruction 10-1302, which was in force when many of the suspect sensor locations went online. How NOAA could fail to police sensor construction and set-up, using their own instruction, is beyond me.

    BTW, my Weather and Climate education started in the mid-1950's, and I remember reading about the "Heat Island Effect" for Paris, France, back in those days, so it's not like we haven't known about this issue.

    Here's a "philosophy of science" question to ponder: If the Poly-Sci people can have their conventions and decide it's ok to apply modern naming standards to old feature-names on maps (the infamous "Squaw..." controversy), why can't Weather & Climate people have a convention and formally close the records of any observation station that fails to meet NWS' standard?

    Inquiring minds need these answers....

  14. If someone has gotten a weather station for one's birthday, and lives on a small corner lot in the city, with a neighbor's driveway on the third side, and a small 1/2 grass and garden, 1/2 concrete patio on the fourth side, any ideas for siting the weather station? Short of buying a house on a wooded acre in the country?

    I realize that my readings won't be "perfect"--but looking at the siting recommendations in the instructions, they seem to be impossible to fulfill in the city. And I wonder, to what extent do all the concrete, obstructions, and other things that make urban sitings less than ideal, actually create different local conditions that an imperfectly sited urban station reflects accurately?


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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