Thursday, September 17, 2020

The Extraordinary Longevity of Wildfire Smoke

 One of the most amazing aspects of this event is the staying power and long-range transport of wildfire smoke.  A view of the eastern Pacific shows bands of smoke pulled offshore from the West Coast, swirling and moving around for many days (see picture).  I have indicated a few offshore smoke features with arrows, as well as  a Pacific low center (L), and a tropical storm (T).  This Pacific will act as a long-term repository of smoke that will move in intermittently for days after we go through the expected clearing on Saturday.

But what I find as stunning is that the U.S. East Coast is smoked in by the West Coast wildfire effluent, as shown by a high resolution image yesterday (see below).  In MANY ways, wildfires are a national problem that decision-makers in DC are literally experiencing.


To get a better view of the amazing long-distance transport of smoke, let me show you some graphics from a modeling system I have not presented on this blog yet--NOAA's RAPSmoke system, which includes a hemispheric scale simulation of smoke.  

 I will show you vertically integrated smoke--the total smoke in a vertical column of the atmosphere.  Here is the predicted distribution at 5 AM PDT this morning,  Smoke concentrations go from low values (blue) to high (dark red).

  Just extraordinary.  You can see smoke swirling into the low center offshore and even into a tropical storm off of Mexico.  The worst smoke is over the NW and California, but dense smoke extends to the east coast and beyond.   These features are confirmed by the satellite imagery


Now lets go forward in time!  The situation at 5 AM Friday shows smoke is still moving into the Washington as the Pacific low weakens and approaches the coast. Smoke is moving into the southeast U.S.


 On Saturday morning at 5 AM,  much cleaner air is moving into western Washington and Oregon, with smoke all over the domain.  Some smoke appears to be heading towards Hawaii.


As I will describe in more detail on my podcast tomorrow, Saturday appears to be the day of substantial improvement west of the Cascade crest.   It will be a great relief.

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15 comments:

  1. I’d be interested in a discussion of the differing air-quality scores I see from different sources. AirNow vs. Weather Underground right now: 175 vs. 137. Five other apps all give differing results. Bottom line they all have landed in the Unhealthy to Very Unhealthy ranges pretty consistently so the general message is clear, but I’m curious why they differ as much as they do.

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  2. Cliff, all I know is when I moved to this area the air was pristine and clean. Now it's literally choking me to death. I didn't sign up for this nonsense.

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    1. Mark Twain's visit to Olympia: https://gritcitymag.com/2017/12/jokes-smokes-and-a-miserable-time-mark-twains-visit-to-tacoma/

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  3. These are fascinating images; the scale of the unfolding event is surprisingly immense! I'm looking forward to learning about RAPSmoke. As terrible a thing as this smoke is, it appears to serve as a "tracer" illustrating the major airflows.

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  4. Looks like the UK may get hit next week. Any news on this?

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  5. Cliff - can you explain what "happens" to the smoke as it clears up? Does it become so dilute that it essentially disappears? Or are the particulates eventually reabsorbed somewhere (e.g. the ocean) and the air becomes progressively cleaner?

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  6. How does the NWS measure the smoke plume and its depth and density? Just visual satellite? Perhaps there more to it than that.

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  7. It really shows how connected we all are, with West Coast smoke extending in some way from Hawaii to Greenland by Saturday.

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  8. How long will the smoke stay in the atmosphere? Will it make it all the way around the world?

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  9. Why do the numbers on the Washington State Department of Ecology air quality maps differ from the EPA AirNow site? The EPA site has been 10 or more points lower every time I have compared. I usually compare the Custer/Loomis Trail site or the Bellingham site. The EPA cites Washington State Department of Ecology as its source.

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    1. They're both based on the same raw numbers for pm2.5 concentrations. Ecology runs the monitoring stations, which is why the EPA cites them. However, the EPA index (AQI) and the Washington/Ecology index (WAQA) calculate their values differently. The WAQA index value is usually higher because the Ecology air quality standards for human health are higher than those of the EPA.

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  10. www.purpleair.com has some explanation of different readings.
    -Dan Dugan, San Francisco

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  11. I remember a few years ago there was smokey skies on our area from fires in Siberia. It would be interesting to see how much and how fast volcanic ash spread around the world in the troposphere from massive eruptions such as Mt Pinatubo in the Philippines in 1991.This type of computer model didnt exist back then. That eruption caused a global cooling of 0.3 Celsius so it must have spread worldwide.

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  12. Hi Cliff, do you have a prediction when the air gets cleaner on the east side of the Cascades? In the Columbia Gorge National Scenic Area? Lots of people live here. Thank you.

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  13. Alex, the air may have been clean a few years ago, but that's not the way that things always go around here. You moved to a Mediterranean climate, and like all Mediterranean climates, fire is a part of the landscape. The risk waxes and wanes over years and even centuries. Back before the arrival of white man, dendrochronology shows that this region suffered periodic wildfires going back to the time of the conquistadors, some of them catastrophic.

    So in short, yes you did sign up for it by moving here. This is fire country. You just wouldn't know it for over half the year.

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