Super Inversion But Decent Air Quality

I will define a Super Inversion when temperature increases by more than 20F in the lower atmosphere (from the surface to roughly 3000 ft).

As noted many times in this blog, temperatures normally decrease with height, but in inversion situations that opposite occurs.

Inversions represent stable situations that suppress vertical mixing, and thus encourages low level fog and pollution.

The lower-atmosphere temperature structure near SeaTac Airport is shown below, based on observations taken by aircraft arriving or leaving the airport.

Around 43 F near the surface and 63F around 2200 ft.  Wow.

The effects of the inversion were obvious in the surface temperatures around our region (see below).   East of Seattle, an observation location on the slopes of Squak Mountain was 51 F, but 33 F was observed at lower elevations not more than a mile away.

Or consider the situation near Route 2.  57F near  Gold Bar but near freezing a few miles away to the west at lower elevations.

The strong inversion was evident in the observations from the balloon-based radiosonde at Quillautye on the WA coast (below).  The red line is temperature (in °C), and the height (y-axis) indicates pressure (700 in about 10,000 ft, 850 is about 5000 ft). 

At this location, temperature increases by 13 °C (23F) in the lower few thousand feet.   Wow again.

Mama Mia!  That is an inversion.

Such strong low-level inversions result in an atmosphere lens that bends the radar signal down to the surface.  

And it happened this morning, as the radar beam from the Langley Hill radar near Hoquium was bent to the ocean surface and was reflected back, creating a false echo that suggested offshore precipitation (see below).  No precipitation was there.

Finally, what about air quality?  Normally, inversions produce poor low-level air quality, since inversions suppress vertical motion in the atmosphere, allowing low level polution to concentrate.

Here are the latest air quality maps over the region.  Generally good air quality except for an area in the South Sound.

But why?  Inversions can suppress vertical mixing, allowing pollutants to concentrate.

According to an associate of mine in the Puget Sound Clean Air Agency, the relatively warm temperatures (high around 60F) today result in less burning of wood, a prime emitter of particulates.    And, of course, there are no wildfires going on this time of the year.

The warm surface temperatures during the day also weaken the inversion at low levels, improving air quality.