Friday, December 29, 2017

Wacky Waves, Winter Warmth, and Pollution Perspectives

Kory Davis sent me the great cloud photo below taken looking east yesterday at about 8:30 AM from Snowbasin.

Photo courtesy Kory Davis
This is a wonderful example of breaking waves produced by Kelvin-Helmholtz instability, named after physicists Lord Kelvin and Hermann von Helmholtz.  Such instabilities are produced by vertical wind shear, leading to breaking waves that are similar in appearance to waves breaking on a beach.  Such instabilities occur frequently in the atmosphere, and produce turbulence, but aren't always easily seen. 

Moving on to today's weather, there's much to discuss.  First, how about our afternoon temperatures.  At 2242 UTC (3:42 PM MST), many sites along the east bench are running in the 50s, including a 56 at the University of Utah.  Alta is 43, Mountain Dell 51, and Kimball Junction 50.  THIS IS NO WAY TO RUN A WINTER.  

If you look carefully, evidence of the valley inversion is apparent, with temepratures in the 40s in Kearns, Taylorsville, and along the Jordan River north of South Jordan.  Also apparent is the strong influence of the lake breeze, with the Salt Lake Airport sitting at only 44.

How about we give the PurpleAir network a little love today and use it to take a look at the distribution of pollution around the region.  Sometimes caution is needed in interpreting the data collected by these low-cost sensors, but they look to be quite useful today.  Note that the highest PM2.5 concentrations are in the downtown area.  Lower values are found on the east bench, the west bench, and in the southern Salt Lake Valley.  One can find predominantly clean air up I-80 to the east.


The ups-and-downs in air quality over the past few days have been astounding.  The DAQ sensor at Hawthorne Elementary has had periods each day with PM2.5 at levels ranging from unhealthy for sensitive groups to good.

Source: DAQ
Yesterday in the Salt Lake Tribune, head of EPA region 8 noted that he believes that Utah's air quality can be improved, in part because of Colorado's success in Denver.  He notes, correctly, that part of the trick is figuring out the chemistry.  That's all fine and dandy, but here's my three New Year wishes that I would like to see happen now:

1. Upgrade and improve real-time air quality monitoring.  It is an embarrassment that there is only one "official" real-time monitor in Salt Lake County and that the data from this monitor is often more than an hour old.   There are large spatial and temporal variations in air quality that exist in our county (and other non-attainment counties in northern Utah) and citizens deserve better information about what they are breathing right now.   Alternatively, take greater advantage of lower-cost sensors, accounting for observational issues that arise from their design limitations.

2. More proactively work to improve air quality.  As a scientist, I always cringe at rallying cries for more research.  Yes, we do need more research, but the assumption that because we don't know everything, we know nothing is a bad one.  We know enough to move forward on new initiatives today. 

3. Show greater commitment and be results oriented.  I'm sorry, but I've lived here for over 20 years and I have heard the same song and dance for a long time.  If this state truly cared about the air pollution, we would have bent the curve years ago.  Near as I can tell, the primary difference between states that have made substantial air quality improvements (e.g., California) and those that haven't is political will and the desire to do what is difficult. 


After publishing this post, I realized I may have been overly harsh on points 2 and 3.  There have been long-term improvements in many air quality indicators, however, the worst PM2.5 events (98th percentile) have shown little trend over the past 10 years (see  Improvements basically flatlined after 2003.  The shift to tier 3 gas will hopefully help, but more can be done.  It's really a matter of whether or not you are satisfied with the status quo.  I am not.  


  1. While the monitor on our MSI Office roof isn't an "official" monitor for the valley, it is a relatively new and high quality monitor, and we basically run it in an EPA certified manner. Certainly useful if you live/work up near bench level height, and interesting to see the difference in PM readings from the UDAQ Hawthorne site at 4300ft compared to our MSI roof at 5000ft

  2. There is another DEQ site in Salt Lake County. The data is available here:

    1. Thanks for sharing that. Options for two sites do not come up when I click "Salt Lake" on the DEQ Ternd Chart site:

      Adding a link for the two sites would be really nice.

      Ditto for the current Conditions site.