Smoky “hello” from Asia

While depressed about a waterless trough approaching us today, well,  maybe a few hundredths is all that can fall from its passage, I thought I would depress you that bit more by showing how our smoggy world is connected.

Perhaps you thought, wrongly,  of course, that the smoke layer above us yesterday was from from southern California or Mexico.  After all, smoke and haze does leak into the SW deserts from the LA area all the time.

But no.

That layer was too high up (estimating above 20,000 feet above sea level);  it was in a very noticeable thin, dark layer to the southwest in the morning, then spread over the sky during the day.

Maybe yesterday morning after sunrise you even thought it was “cirrostratus nebulosus”, that vellum ice cloud with little internal structure.

Let us look at the smoky evidence (before any clouds formed):

9:51 AM.
9:51 AM.  Its not Cirrostratus nebulosus.   There was no indication of cold clouds over us, as would be the case with Cirrostratus nebulosus.
9:51 AM. Smoke vellum covers sky. Best seen toward the sun. Looks dark on edge when the sun is shinning on it, like to the southwest.
9:51 AM. a thin smoke vellum covers sky. Best seen toward the sun. Looks dark on edge when the sun is shinning on it, like to the southwest yesterday morning.
4:21 PM.
4:21 PM. Still there, ABOVE the  Cumulus fractus, though the Cu fra is also impacted by smoke.  The faint undulations are above the Cu fra, and show gentle waves, the kind that exist above the “boundary layer” and are not mangled by surface convection and Cu formation.
6:46 PM. "Ugh" sunset. Smoky haze layer now really evident.
6:46 PM. “Ugh” sunset. Smoky haze layer now really evident.  More waviness, betraying its high altitude.
6:49 PM, looking SW.
6:49 PM, looking SW.  Ditto.

Below, a satellite looks at our smog invasion, as indicated by the values of the “Aerosol Optical Depth” (AOD), how muddy-looking it is from up there.  Blue is clear, anything else is muddy.  Red is incredible.  You can see it streaming in from the southwest yesterday morning, 5 AM AST.  An annotated version below, in case you’re lost.

AOD_0015_US

Same image, annotated.
Same image, annotated.

Now, let’s see where it came from using the NOAA HYSPLIT model for obtaining backward trajectories for FIVE days, ending at yesterday morning.  We saw it streaming in from Mexico, but did it really originate there?  Nope.

13753_trj001
Backtrajectories for three parcels of air at three levels above us, ending at 5 AM AST yesterday morning.   The model thinks that two of the layers above us started way up above 30,000 feet some five days ago, but were lower when they arrived over us. The stuff about 20,000 feet above us (the red line), started lower than those, but was rising as it got to Tucson, that due to passing through the trough that’s approaching us this morning, One would expect to see more layering of smoke today.

And there you have it, “smog across the waters”, the Pacific ones.

Hard to say how it got up there, often its due to forest or other fires in Asia, rather than comes from low level urban smog.  It gets here mostly in the springtime because the low pressure systems with their rain belts are weaker, less able to process smog via rain out as smoke layers cross the Pacific, while the jet stream is still quite strong and can carry layers a long ways in a hurry.

Dust plumes from Asian deserts like the Gobi  also make it across the Pacific to the US from time to time, again, mostly in the springtime.

—–end of  smoke diary module——

Expect  shallow to moderately deep, high-based Cu today, ones that will form ice and virga, and of course, it will be windy as well.  Seems too dry for much anything to reach the ground here in Catalina below those high bases, a pitiful situation with such a strong trough passing over us today.    Check out the U of AZ model for further details.  Maybe we’ll see some great lenticulars above the Cu tops…

The End

 

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.