Wednesday, December 13, 2017

Incredible PM2.5 Observations from KSL Chopper

Following up on the previous post, our intrepid MesoWest Team has partnered with KSL-TV to collect PM2.5 observations from their helicopter, Chopper 5 (much thanks to KSL for enabling this incredible resource).  The data today is simply incredible.

Below shows one period during which the chopper was flying across the Salt Lake Valley and over portions of the Wasatch Front.  The chopper position varies, as well as its altitude, and it is clear that sometimes it it flying in clean air (blues) other times "dirty" air with much higher PM2.5 values (red).

The scattergram below illustrates all the PM2.5 measurements during that period based on altitude. Below about 2100 meters, the helicopter frequently flew in the valley pollution.  PM2.5 values were generally above 35 ug/m3.  There are, however, a few places at those elevations where the air was fairly clean.  This is not surprising given the tendency for there to be waves and other features on the inversion. 

Between about 2100 and 2600 meters, the air is mostly clean.  All observations were below about 30 ug/m3 and the vast majority were < 5 ug/m3.  

However, go higher up and there are some horrible PM2.5 values again, some as high (or higher) as in the polluted air in the valley.  This is what I suspect is the smoke from the California fires.  This smoke isn't uniform.  There are some pockets of clean air, but the PM2.5 levels are quite high in some locations.  

This is simply incredible data.  I've never seen anything like it.  Wintertime pollution trapped in the valley.  Smoke from extreme wildfires at upper levels.  Remarkable.  Thanks to the MesoWest team and KSL for making this happen.  Note that this data is freely available in real time at


  1. Quite remarkable and is consistent with my experience this morning. Drove up to Brighton for some clean air and was gasping (literally!). Did notice driving down the canyon the air improvement at mid elevations. Fascinating. Great post

  2. Interesting, and thanks for the explanation. I drove east on Hwy 40 and was disappointed to see that the conditions didn’t look different from the valley, and I was baffled that the brown cloud appeared to be shrouding the Uintas.

  3. At Alta it was also snowing relatively heavily just before 4pm today. It wasn't 'inversion snow', and there were low clouds draping the surrounding peaks and even some gusty winds. Was this due to a weak, passing cold front adding to all the atmospheric excitement today?!?

  4. This is amazing. Thanks for your great work. I am an air quality engineer, but this is above and beyond.