July 12, 2024 Ozone Exceedance Event

(Double click on one of the images and then you can scroll easily over the figures.)

Seven DAQ stations in Salt Lake and Davis County had 8-h averages over 70 ppb on July 12.

The highest 8-h ozone concentrations occurred at Bountiful (QBV).

The most extreme concentrations hourly and sub-hourly concentrations were observed during 2-3 PM LT on the U/U campus, particularly at the co-located sites at the mouth of Red Butte: MTMET and DAQ site QUURB.

Step through the following snapshots at hourly intervals from 11 AM to 5 PM MT for the spatial evolution of ozone during the day. Each image has observations within the 2 h preceding those times.

The following illustrate the low level winds from the TDWR. Step through from 12 UTC (6 AM MT) to  0 UTC 13 July (6 PM LT). Blues are inbound winds and oranges are outbound winds (radar located at black dot). Note push of lake breeze down west side of valley.

Surface winds tend to be complicated in this and most cases. Erly lake breeze in northwestern quadrant evident. At 2 h intervals from 11 UTC to 23 UTC. Highest peak ozone on east bench when easterly winds reverse to westerly carrying precursors from urban area.

Ozone decreases on east bench when winds shift from easterly (bringing regional background concentrations) to weak southwesterly from urban area. Then peak ozone after winds shift from southwesterly to northwesterly.

Time height of boundary layer winds and reflectivity near the TDWR (Farmington Bay area) illustrate multiple layers and wind shifts. Early morning southerly, switching to northerly after 13UTC. Stable layer likely aloft above 600 m until 19 UTC when mixes fully out.