Sea-Tac Heat

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Roughly a year ago, I provided some evidence that the construction of the third Sea-Tac runway, with the ancillary taxiways and removal of a vegetated slopes, has resulted in an anomalous warming at the airport during warm summer days, particularly when the winds are from the north or northwest.  This is important for a number of reasons.  First, Sea-Tac is the spotlighted station on many local TV weathercasts (see image).  Second, it serves as a example of issues with our observational networks, where urbanization and construction can produce a warming signal distinct from the true warming of the general atmosphere.

Well, we had some warm weather recently...do we see the Sea-Tac warm anomaly?
For example, 4 PM this afternoon?  Here is a plot of nearby stations (KSEA is the airport).  72F at the airport (where the winds were north-northwest) and cooler for the nearby locations.



Or a few weeks ago, when the airport was 87F?  Again, nearby locations were cooler.



In the old days, Boeing Field, closer to the urban core of the city, was generally warmer than Sea-Tac.  But is that true now? Here is a plot of the temperatures at these two locations for the last four weeks.  Note that on the warm days (generally ones with lots of sun and northerly winds), Sea-Tac (SEA) was warmer than Boeing Field (BFI), often by several degrees.
Multiple such urbanization/development issues at locations around the world, and it is clear that it can obscure the true background temperature change signal that we are looking for.  Organizations, such as the National Climatic Data Center, have tried to develop algorithms to spotlight or remove such problems, but there success so far is mixed.  Satellite observations of temperature above the surface are a bit less problematic, although they have their own issues (like calibration of replacement satellites).

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I will talk about some of the above issues during my talk on Orcas Island on Wednesday.