January 04, 2014

Air Quality Suffers with Northwest High Pressure and Skier's Hope

There has been a lot of  talk about the West Coast drought, particularly with its impacts on mountain snow pack and future water resources.

But the persistent high pressure over the eastern Pacific that has caused the drought is also having another effect:  creating low-level inversions and reducing air quality in many Northwest locations.   It has also made this a particularly foggy fall/early winter.

As an aside, one unfortunate side effect of  the persistent fog occurred on New Year's Eve with FogFireworks, where the upper portion of the display  at Seattle's SpaceNeedle was either invisible or muted for much of the performance.

 Picture courtesy of KING-5 TV Seattle

In December at Seattle-Tacoma Airport, 20 of the 31 days reported fog, many with dense fog. 16 days with fog in November   And who can forget Fogmageddon in October?   I can't tell you how many people have complained to me about the persistent low clouds this year.

The villain has been the persistent high pressure ridge over the eastern Pacific, like this one that occurred at 1 AM on January 1st (upper level, 500 hPa map shown).  You see how the height lines bulge northward?  That's the ridge.  At low levels this is associated with high pressure.

Ridges cause inversions and stable air in two ways.  First, strong sinking with high pressure aloft causes warming above the surface.  High pressure produces clear skies aloft that allows good radiational cooling at the surface.  And high pressure usually brings light winds, thus very little turbulent mixing of air at the surface.   Heat above, cool below, and don't mix....what do you get?

An inversion in which temperature increases with height! 

 Inversions are very stable situations that prevent air from mixing with height.   Pollutants concentrate over time near the surface and as air cools near the surface fog often forms.  This has been the story of much of our fall and early winter.

So what has the air pollution situation been around here?  The Puget Sound Clean Air Agency has a wonderful website where you can plot pollution data from around the state.  Let's take a look at the amount of small particulates (smaller than 2.5 microns, called PM2.5) at a few locations.  Such small particles are quite nasty, capable of being drawn deep into your lungs where they can lessen your respiratory capacity, initiate asthma attacks, or cause heart attacks.

Let's start with Lynnwood, north of Seattle.  The biggest spike of bad air:  July 4th!   You notice that air quality is far better during the summer than during the winter.  That makes sense;  no need for heating during the summer so less combustion byproducts.  And inversions or stable air situations are more frequent during the cooler season with the long nights that allow strong surface cooling.  But this fall was clearly particularly bad, worse than last fall/winter because of the persistent high pressure and inversions. (the previous year is also shown)

Going south to Lake Forecast Park, a location with a significant air quality issue, we see the same pattern, if not worse.  This fall the air quality has been particularly bad...not Beijing or Shanghai bad, but noticeable.

I could show you sites in Seattle, Tacoma, and elsewhere west of the Cascades but the story would be similar.

As long as we are talking about air quality, here is an interesting fact:  air quality varies substantially during the day.  To illustrate, here is a plot at Lynnwood for the last week or so.  Many days have an identifiable peak during the evening hours, a drop during the early morning hours, and a rise during the afternoon.

Makes sense.  Folks turn their heat down at night.  Warm the house for only a hour or so in the morning before heading to work or school.  Turn it up later in the afternoon or early evening.  Also meteorology helps such a pattern, with the atmosphere stabilizing during the late afternoon as the sun declines and the surface cools.  So try to do most of your breathing during the day.  Clearly, a better time for strenuous exercise if you worry about the quality of the air.


      A major circulation change may produce substantial snow in the Cascades later this week:  here is the 72h snow totals ending 4 AM on Saturday.  Several FEET OF SNOW

Fracking and Ozone

UW Professor Becky Alexander has established a page on the Microoryza crowdfunding web site that outlines her project  to understand why natural gas fracking often leads to high ozone values over snow (go here to see it). If you want to learn more about this important project and how you can help it happen, check out the web site.  She is now at 52% and will get nothing if she doesn't reach 100%.  So if you know folks interested in the fracking issue, please let them know about this.


  1. Cliff,
    We have a very serious pollution problem much closer to home that has not been reported... I wish your professor-friend who is working the fracking fields would drive to Issaquah with her students and help the neighborhood there!
    The Cedar Hills landfill has built a biogas electricity generation plant. This is something we'd all normally be in favor of; methane and other toxic gasses generated by the landfill are burned and turned into electricity which is fed back into the grid instead of the gas being wastefully flared-off onsite as has been done for many years.
    However, December 7th the pipeline suffered a catastrophic failure; it was originally claimed to be a "pinhole-sized" leak, but by December 17th, plant operators were admitting to an 8-inch failure in the pipe. Gas emissions have continued and the gasses have flowed directly into a neighborhood just east of the landfill where friends of mine live.
    The toxic-gas concentration in their home has risen above EPA warning levels each time the Puget Sound Clear Air agency has come out to test, which likely means that it's above the warning levels most of the time.
    The Fire Department doesn't know how to handle such leaks despite being listed as the first responders in the emergency plans, the biogas plant engineers have been unable to fix the pipe, the emergency plan is insufficient and poorly understood even by supervisors at the landfill, and the health effects have been so bad that several of the families have evacuated to a hotel for the past few weeks. (It doesn't help, either, that the local emergency rooms don't have any idea how to test these folks for exposure to the toxic gasses known to be leaking from the pipeline).
    I've encouraged my friends to contact you directly but they are overwhelmed by many complicated details, trying to educate themselves on the science double-quick... but this conjunction of atmospheric science, medical science, and chemistry doesn't reveal itself very easily to even the smartest laypeople.
    If you're willing or interested to give us ideas on how to document pollution levels, weather factors, and so on, I'd appreciate it greatly. JuliaZ at Gmail. I can put you in touch with the families who are living through this disaster.
    I also wish the profile of this crisis was higher. There are many people in Issaquah and Hobart that are downwind of this leak right now and they may be experiencing the effects of toxic-gas poisoning without any idea why they feel bad each afternoon (the levels in the neighborhood are typically highest at around 4 pm, just as this blog post discusses).
    Thanks for all you do.

  2. Cliff, will you be commenting more on the "several FEET OF SNOW" you mentioned above, as the week progresses??? :)

  3. a quick aside from a typically edifying post: thank you! to whomever finally got the local profiler back from a long "temporary" absence. it's great to follow along the developing conditions with the expert commentary that we get here.

  4. Prof. Alexander's project is presently at ~$6,800 with another $5,200 needed over the next 11 days. Go, go, go!

  5. You might enjoy seeing these two photos I shot on December 31-January 1:

    ~10:30PM: http://www.flickr.com/photos/aaronbrethorst/11697113305/

    12:01 AM: http://www.flickr.com/photos/aaronbrethorst/11698905346/

  6. Tonight, while doing some research on the effects of wood smoke on air pollution, the air quality index in Maple Falls up by Bellingham was comparable to that of Beijing; the Washington Air Quality Advisory number for Maple Falls was 222, and the Air quality index for Beijing was 208. While the WAQA rates air quality as poorer earlier, still, both are considered very unhealthy. So, thanks to wood burning stoves and fireplaces, rural Maple Falls is enjoying the same air quality as industrial China.

  7. Can you tell us about the polar vortex that is wreaking havoc in the mid-west and east?

  8. Hey Cliff, long-time fan here. I wonder if maybe you'd consider writing an entry about La Nina. I did a search, and it's been quite a while.

    I ask because unless we get a bunch of snow soon, it looks like we're in for a heck of a drought here, and in Oregon and California. That's classic La Nina, right?

    I hope my question isn't one of those kinds that bore you to tears or drive you to distraction. I just really sensed that the weather turned in a pretty big way in 2013 after that stretch of cold, wet, miserable springs and summers, and that we might be in for dry winters and hot summers for a while.


  9. Cliff, there is at least one place where poor air quality sometimes exists in summer. The Duwamish Valley has severe smog conditions on stable hot days. The brown layer is easily seen from I5. Sometimes with the proper vantage point one can see the smog layer extending over this part of western Washington to the base of the mountains. This is different from winter time particulates, but just as noxious.

  10. I still believe that there is no better example than my city, it managed to reduce air pollution twice in few years, look through the data- Alytus and I believe that we managed to reach it only working together. Every city may follow us, and may care about environment as we care!

  11. Thank you for posting this. I found it very helpful when trying to explain what has been happening this past week whenever it came up in a conversation. The news didn't do a very good job explaining it, and i agree that they made it sound much scarier than it actually was. I'm also glad you informed the readers of this blog about the vortex and how it's not connected to global warming.

  12. Haha, wow! Very informative, it's interesting to see things spiral out of control, vortex sounds very foreboding indeed. Thanks for the clarification.

    Jim | http://www.regionaltruck.com/component/content/article/11.html


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