Case Study of the 6-16 February 2016 Salt Lake Valley Persistent Cold-Air Pool

The Salt Lake Valley PM_2.5 Pollution Study conducted from December 2015 through February 2016 combined detailed chemical and meteorological observations to investigate the reactive pathways of secondary particulate pollution formation and the influences of meteorological processes on the temporal and spatial variation of particulate pollution concentrations. Observations included measurements of particulate pollutants (PM_2.5), precursor gases, and chemical species relevant for secondary particulate formations at two sites within the Salt Lake City Basin - one at the valley floor, the other on the northeastern valley sidewall on a rooftop 155 m above the valley floor. Additional measurements of PM_2.5 concentrations were taken at fixed locations (near the mouth of a tributary canyon, and in the southern and western part of the Salt Lake City Basin) as well as on mobile platforms (on board light rail, a mobile lab, a tethered balloon, and on a news helicopter). In addition, vertical aerosol backscatter profiles were collected using ceilometers deployed at three locations in the basin. The evolution of the basin thermal structure was recorded using inexpensive temperature dataloggers deployed on a pseudo-vertical transect from the valley floor to the top of the basin sidewall (1307 to 2179 m ASL) and with the twice-daily radiosondes launched by the National Weather Service from the Salt Lake City International Airport. The wind field in the Salt Lake City Basin and boundary layer turbulence was observed with a Doppler wind lidar positioned at the valley floor.

This presentation will focus on the 6-16 February persistent cold air pool and combines the rich data resources to illustrate the onset and evolution of this wintertime particulate pollution event. The impact of meteorological processes such as nighttime down-valley flows from tributary canyons and shallow daytime convective layers on the spatial and temporal variations of PM_2.5 pollution concentrations will be highlighted.