Thursday, December 2, 2010

Persistent indeed!

The purpose of this field campaign is to study Persistent Cold Air Pools (PCAPs), and that is exactly what we've got. The Salt Lake Valley has now been in continuous Cold Air Pool conditions since Monday night, and it is not exactly clear just when its going to end. Persistent indeed. We've decided to really ramp up observations this evening and into tomorrow morning in the hopes of capturing some modifications to the cold pool structure accompanying the advent of strong winds above the inversion followed by arrival of some moderately colder air aloft tomorrow. Will we mix out? Will parts of the valley mix out? ... tough to say, which is a big part of why we're studying this. If we don't mix out the already dismal air quality is wont to get worse (courtesy of Utah DAQ).

To give you a sense of what dismal air quality looks like, here is a picture I took this morning from high on the slopes above downtown Salt Lake and the University of Utah.

Today also marked a first for the PCAPS team: With the help of expert pilot and weather enthusiast Chris S. we conducted soundings of the boundary layer with instrumentation mounted on a motorized paraglider. We hope to continue to use this sampling method to augment our measurements of the lower portions of the Cold Air Pools especially near the Great Salt Lake, the influences of which can play an important role. Hopefully we'll be able to share some of the pilots perspective in a future post here.

The cold pool itself has reduced in vertical extend over the past 36 hours, but has only gained in potency. Here are some of the soundings from today:

A few of the issues at play today were strong warm air advection above the inversion top, possible low level jet type dynamics caused by topographic channeling and regional pressure gradients, and the inability of strong winds to penetrate to the surface due to such immense stability.

All eyes are now on tomorrow, which will be a make or break day for this event.

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