November 15, 2022

A Super-Inversion Leads to Poor Air Quality over the Region

A number of locations around the Northwest are experiencing poor air quality.....with some locations rivaling the particle concentrations experienced during the recent wildfire events.

But it isn't wildfires this time.   It is woodsmoke plus a SuperInversion.  Puget Sound Clean Air Agency has a Stage 1 Burn Ban in place.

Let's start by looking at the air quality information from the PurpleAir network (below) this morning.  Green is good air quality, yellow is declining, orange is of concern, and red/purple is unhealthy.

Mediocre air quality in the south Sound, but seriously degrading air quality around Spokane, northeast WA, and around Bend Oregon.


The origin of the smoke is clear: mainly smoke from burning wood for warmth.  Parenthetically, a highly renewable energy source.  

Traditionally, the main air quality problem in the Northwest has been from wood smoke, not summer wildfires.  But woodsmoke has declined as an issue as more folks use natural gas fireplaces/heaters and air quality agencies (such as Puget Sound Clean Air Agency) promulgate and enforce burn bans during threatening situations.   More extensive use of natural gas has helped clean our winter atmosphere. And increasing costs of oil and gas have also stimulated the use of wood.

We are in a threatening situation now, as a strong inversion, with temperature increasing with height, has developed over our region.  Inversions are very stable features that act as lids on the lower atmosphere.

Above SeaTac Airport this morning at 7 AM, temperatures increased from 38-39F just above the surface (and even lower at the ground) to 49-50F around 2000 ft.  A strong low-level inversion.


At Quillayute, on the Washington coast, temperatures increased from 1 to 13C over a similar layer near the surface (see plot below).  That is about 22F warming in a few thousand feet.  Wow.  Mama Mia...that is a strong inversion!


So we have cold weather that stimulates folks to rev up the wood burning and an inversion that caps the lower atmosphere, allowing pollution levels to rise.

Why do we have such a strong inversion?    Blame the strong, persistent high-pressure indicates ridge over us (see upper-level map for this morning below).


A high produces sinking air aloft that prevents clouds from forming.  Without clouds, the surface can effectively emit infrared to space, cooling the surface.  Like having a refrigerator coil at the surface.

The sinking from the high aloft causes the air to compress and warm at middle elevations.  This helps rev up the inversion even more!

And our nights now are very long as well, allowing more surface cooling.

The future outlook?  Expect poor air quality conditions to continue (or even worsen) this week.



19 comments:

  1. Thanks Cliff!

    It seems like the pollutant source is more likely wildfires in Southern BC... rather than woodburning stoves. Yes?

    The HRRR smoke model seems to show point sources in Southern BC contributing mightily
    (https://twitter.com/NWCleanAir/status/1592197366299635712?s=20&t=xD-m6SZAr4iPd4qlQderyg)... These are also visible in the Canadian BlueSky model (http://firesmoke.ca/forecasts/current/) .

    Not trying to split hairs; just wondering if the implications are slightly different (i.e. need to wait for rain to extinguish).

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    Replies
    1. Glenn... those modeling systems are using outdated smoke estimates...they are not correct. If you want proof of that....look at satellite imagery....no smoke where the model systems show it..cliff

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    2. Got it. Thanks for clarifying!

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  2. Hey Cliff- where is the frost coming from in the AM? Just the humidity level?

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  3. It always irks me that the worst air quality and the burn bans happen during our coldest weather when we most want a fire. Back east, the wind just howls during cold winter nights. I really hope this omega high doesn't stay parked here 3 weeks as in October. We're falling behind again on rain.

    Also bugs me that they put a burn ban in Pierce and Snohomish before they do in King county, which has more people- and more vehicles. Sounds like discrimination or someone at PSCAA is getting paid off. Logically, how can you have clean air bounded on both sides by dirty air? One expects the dirtiest air at the center of human activity (Seattle).

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  4. As of this morning there is still no burn ban in King County even though particulate levels are similar to the counties with bans. Is there a way to get PSCAA to do its job?

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  5. Cliff,

    Why did you only mention wood smoke as the primary driver for bad air quality? PM2.5 sources typically involve fuel combustion (e.g. cars, trucks, power plants, gas powered leaf blowers, etc.) also play a large part in determining the air quality.

    I think more people are driving and causing pollution versus burning wood for warmth. Have you seen how many people sit in traffic on I-5 every day?

    ReplyDelete
    Replies
    1. Because wood smoke is the clear origin. Cars are relatively clean regarding particles. The worst areas are where wood burning is greatest.

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    2. Wood smoke is extremely toxic and emits very high amounts of Pm2.5 particles among other things like benzene. In some regions of British Columbia, pollution from wood stoves and fire places exceeds industrial emissions. The government of Canada and BC acknowledge this on their websites. One wood stove can emit as much as 15 diesel engines, from what I last read. There is an absolute tons of studies and resources on this stuff.

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  6. r223 I'm with you. This smacks of favoritism. Either let us have our evening fire, or tell Seattle they can't do it. Cliff, comments?

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  7. I am surrounded by people who burn wood for heat; have fire pits ( neanderthals ?); can't light a barbeque without creating a pillar of smoke and can't elect politicians who can manage forest fires and above all are experts at the Science of Climate Change.

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  8. There is a lot of weird resentment in this comment thread.

    Anyway, to matter at hand, thanks for this post, Cliff. My wife and I were discussing the relatively poor air quality today. I have an amateur's understanding that high pressure = clear skies, but iffy air quality, but this post provides a much better explanation for why that's the case.

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  9. I certainly hope your not insinuating that low income poor family's should feel bad for burning wood to keep their families warm... electric base board heaters are very prevelant yet extremely expensive to use... aww have to deal with poor air quality when it's cold. Boohoo.

    ReplyDelete
    Replies
    1. Electricity is fairly cheap in this area, but the best thing about baseboard heaters, is they are almost maintenance free (unless your cat urinates into them- beware!). Also, it is very important to keep the furniture at least six inches away- otherwise it can catch fire. Compared to a forced-air furnace, baseboards cost less. But they do create stratification (a cold pool of air near the floor) unless you use a mixing fan. Cheaper still is a heat pump.

      I'm not saying give up your fireplace or stove- they have a certain charm that no high-tech system can match- including (especially) those fake-flame appliances.

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  10. I am a neanderthal who is warm at night thanks to the pellet stove. Look, if you all knew how much of your "clean" electric heat was powered by coal, you might need to re-evaluate your argument. It's akin to EVs. In practice we are talking about just moving the pollution elsewhere. A carbon cycle cooking of the books. Part of solving the climate issue is assuring there are solutions everyone can afford, and not just those who have the wealth as well as free time to be an activist or an early adopter. Plus, if folks burn seasoned wood in an EPA approved design and actually know how to USE their wood stoves, what comes out of the chimney should be either a fine vapor or just heat distortion.

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    Replies
    1. You may not be giving people enough credit. The fact that you don't know how much of our electricity comes from coal does not mean that others also do not know. In 2020, less than 5% of Washington's electricity was provided by coal, and the single remaining coal fired power plant in the state is set to be decommissioned in 2025.

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    2. PSE lists 23% from coal.

      It's great that large fossil thermal power plants are going off line, however, hydro plants are also going offline. With a 2030 mandate of IC car sales bring banned along with a burgeoning population who love gadgets as well as warming summers... at the very least our relatively cheap electricity is going to be a thing of the past. There are many challenges to the grid that can only be labeled as dubious at best as far as meeting future expectations.

      Sorry, but I am not giving up my pellet stove.

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  11. Cliff - I have noticed that on dry clear days like this when we have an inversion and poor air quality day, the skyline looking west toward the Olympics has a distinctive look.... what I would describe as low level haziness but the the mountain caps look pretty clear. Would you agree that this is generally the case?

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

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