Northern Utah Is So Filthy!

Source: Google/Dictionary.com

After a slight dip in PM2.5 concentrations yesterday, they are on the climb again today and are now at their highest of the current inversion event in Salt Lake City, reaching a 24-hour average of 61.6 ug/m3 at 10 am this morning.

Source: Utah Division of Air Quality

I don't know about you, but I feel like crap and have a nagging cough.  Whether or not it's pollution related or coincidence is unclear, but I'm sick of it!

Bad air is found in the lowlands all over northern Utah.  Joining in on the fun are Brigham City, Roosevelt, and Vernal, which are now joining locations in Cache, Weber, Davis, Salt Lake, Tooele, and Utah Counties at or near the 24-hour National Ambient Air Quality Standard (NAAQS) for PM2.5.

Source: Utah Division of Air Quality

I've included ozone concentrations in the graphs above as those are elevated (but below the NAAQS) at Roosevelt and Vernal too.  Elevated wintertime ozone is commonly observed during intense inversions around natural gas fields (e.g., Schnell et al. 2009).

A deep trough approaching from the west should finally bring an end to this sordid episode later this week.

Hopefully the strong southerly flow ahead of that trough will begin to scour things out Wednesday night and Thursday.  The sooner we're rid of this filth, the better.

Additional Contributors to Misery

Nobody likes breathing dirty air, but further contributing to the January gloom in the lowlands along the Wasatch Front is the lack of sunshine.

Over the past five days, our observing site across the street from Alta Ski Area measured a maximum in incoming solar radiation of almost 650 Watts per square meter (yellow line below).   The only day that was lower was yesterday when there were high clouds around.

In contrast, at our observing site at the University of Utah, we've only reached a maximum of about 475 Watts per square meter (yellow line below), a reduction of about 25%.

The reduction is due all the haze and smog in the valley, which reflects some of the incoming sunlight back to space before it reaches the ground.  This is an extreme local example of what is known as global dimming, which is a slight reduction in the average incoming solar radiation at the Earth's surface due to the presence of smog and haze from the burning of fossil fuels, forests, etc.  This global dimming has a slight cooling effect and helps to offset a portion of the warming due to the increase in greenhouse gasses in the atmosphere.   However, we're getting a huge dose of it, adding to our misery by reducing sunlight and keeping afternoon temperatures down.

Pollution Event in Perspective

Mechanical Engineering Professor Eric Pardyjak pointed out that Division of Air Quality has a graph showing the highest PM2.5 levels by year for 1998–2007.  Although not quite up to date, it allows us to provide some context for the current event.

I've taken the liberty of adding to the graph a couple of horizontal lines that roughly denote the current 24-h averaged PM2.5 concentrations at the Salt Lake City (54 ug/m3) and North Provo (74.1 ug/m3) based on provisional data available on the Division of Air Quality web site.  In accordance with school spirit, Salt Lake is red and North Provo blue.

While this is a bad event in Salt Lake, current PM2.5 levels are not exceptional compared to past events (compare horizontal red line to the green "Hawthorne" line).  All but one year during the 10 year period below saw at least one event with higher concentrations.

Source: DAQ (my horizontal red and blue lines annotated)

On the other hand, it appears that the current event features unusually high PM2.5 concentrations at the North Provo observing site (compare horizontal blue line to purple "North Provo" line).  It's a bit tough to see all the trend lines in the graph above, but it appears that current PM2.5 concentrations are at or above those observed during the 1998–1007 period at that or any other site in Utah county.

And, adding to the misery, it now appears that Tooele has joined the other Wasatch Front counties with an exceedance of the National Ambient Air Quality Standard.

Source: DAQ

Frightful Conditions

PM2.5 conditions and trends continue to be frightful.  Data from the Utah Division of Air Quality shows that Utah county is now officially in the "unhealthy" category, which means 24-h PM2.5 concentrations are above 55.4 ug/m3, up from "unhealthy for sensitive groups."  Salt Lake and Cache Counties are also approaching that "unhealthy" category.

 

 

Unfortunately, the models have flopped back to a solution that splits the system moving into the western US early this week.  This gives us little hope for a full mix out in the near future.  There's just a slight increase in flow and cooling at mountaintop level, with some high clouds and perhaps a spot or two of snow.  I'm not hopeful for anything more than perhaps a slight drop in air pollution levels.

Our best hope for a more major mix out is later in the week when a strong front moves into the state.

Right now, the models suggest that front should at least partially if not fully mix out the inversion, but it is dangerously close to a splitting system.  We will have to watch and see how things look during the week.

As PM2.5 levels continue to climb, it would be interesting to hear how this event compares to others during the past decade.  Based on the PM concentrations above, it seems this is an event for Utah and Salt Lake Counties that is getting up there amongst the worst events over the past decade (perhaps not so for Cache County).  Anyone out there have hard numbers?  

Welcome to Wasangeles

If the online data provided by the Utah Division of Air Quality is to be believed, exceedances of the National Ambient Air Quality Standards for 24-hour average PM2.5 during the present inversion now stretch from Utah to Cache County.

Isn't that lovely.

Ick!

Real-time data from the DAQ suggests we are now above the National Ambient Air Quality Standwars for PM2.5 (24-h average).  Hourly averages have been very high the past few hours.  

We were up servicing a station we have near Alta earlier today and observed a temperature fall from 35ºF to 13ºF between the base of Snowbird and the lower canyon.  I have no idea why we bothered to return to town.