Friday, March 9, 2012

Pollution Never Ends

Think the inversion is over and done with for the year?  Think again.

The photo above was taken this afternoon looking down Little Cottonwood Canyon.  Yuk!  The last day of February is sometimes used to mark the end of the winter pollution season, but that's not because the pollution goes away.  It's because inversions are less frequent and persistent in March.

Today, however, we certainly have a deep series of stable layers and inversions in place over the Salt Lake Valley.  Check out this morning's sounding.

Source: NCAR/RAL
Even with the amount of warming we've had today, a max temperature in the low 50s is not sufficient to mix the atmosphere through a layer deeper than the crest of the Wasatch Mountains.  Instead, it's only stirring things up through a depth that extends to about the base of Alta.

As a result, there's plenty of smog around and PM2.5 levels are on the rise.

Source: Utah DAQ
Beyond local pollution sources, there does seem to be a bit of dust in the air.  Yesterday our views from the Oquirrh Mountains simply didn't seem as clear as they should be and the accumulation of dust on my van, which has sat in the driveway for several days, is quite apparent.

I'm not sure if the source of this dust is regional, driven by the strong winds from Tuesday, or global (there are events where dust from Asia is transported across the Pacific and into the western US).  I suspect the former.  We'll probably see more of it this spring.


  1. jim, is it fair to say that the below average moisture this winter will increase the potential for dust/sand transport in the coming months?

    1. Probably - if we get some wind storms. The issue is really dust not sand. Sand particles are too large to get lofted and transported over long distances.