Ozone and Other Pollutant Profiles in Utah's Atmosphere
The USEPA recently lowered the 8-hr ozone standard from 75 ppb to 70 ppb. This means the more densely populated areas in Utah, are more likely to violate the new regulation. A key to finding solutions to avoid exceeding this standard is our ability to effectively monitor and understand the behavior of the vertical structure of both meteorological parameters and the relevant pollutant species.
Flight path of AggieAir UAV measuring ozone levels over the Great Salt Lake near Promontory Point.
Uintah, Basin, Cache Valley, and Great Salt Lake, UT
Utah Division of Air Quality (UDAQ), Air Monitoring Center (AMC), University of Utah, Weber State Univeristy
Clay Woods (PhD)
This project is developing and testing light airborne measurement systems to examine the vertical structure of pollutants. The instrument package is adaptable to different platforms [e.g. tethered balloons and unmanned aerial vehicles (UAVs)]. The need to understand both temporal and spatial O3 formation, along with transport and transformation behaviors has provided an opportunity to apply techniques developed under this project and to implement comparison studies with other investigators. During 2015, the UAV/O3 system was further optimized and used in as a part of a larger study entitled “The Great Salt Lake Summer Ozone Study” (GSLSO3S).
Ozone "curtains" or 2-D concentration maps (in ppb) extending WSW from Promontory Point over the Great Salt Lake
Studies have been completed in the Uintah Basin and in Cache Valley, in conjuction with a large study organized by the Utah Division of Air Qualiity involving many cooperating agencies adn universities. The area along the Wasatch Front was the most recent focus of the study. Flight profiles were conducted over a portion of the Great Salt Lake. The specific east-west transect off the southern-most tip of Promontory Point was the location for which the study was able to obtain FAA flight approval.
Our 2B Technologies Model 202 Ozone Monitor continues to be modified (data acquisition abilities, UAV system integration, spatial logistics, etc.). This past year the O3 and meteorological packages were further modified to fit within the payload bay of a new autonomous unmanned aerial vehicle (UAV) platform. The “Minion” airframe is a new modification to the Utah Water Research Laboratory’s (UWRL) AggieAir UAV program. When the UAV systems are modified, the pollutant measurement systems must be modified as well. The study also included a second real-time sensor (O3/met.) package borrowed from NOAA’s Earth Research Systems Laboratory and used as part of a tethered balloon system by one of the cooperating investigators (Dr. John Sohl, Weber State University).
The figure to the left shows ozone "curtains" or 2-D concentration maps (in ppb) extending WSW from Promontory Point. Note that the scales on the axes are not equivalent. Morning O3 concentrations were 40-50 ppb and indistinct. As the day progressed, the overall O3 increased and seemed to push in from the east (possibly from Wasatch Front). This may also be supported by the predominant easterly wind patterns throughout the day and throught the air column. The late afternoon flight seemed to show increased O3 at lower eleveations over the GSL's open water The observed concentration ranged from about 45 ppb (light blue) to 70 ppb (dark blue). The figure shows moderate levels of O3 on the eastside (near the Wasatch corridor – right side of the figure), while towards the middle (over the Great Salt Lake) there is a build up or storage of near-ground O3. This phenomenon could be significant in ultimate O3 behavior within the region.
Elevationally averaged ozone, temperature, wind speed, and wind direction for the four August 11, 2015 flights. While the wind direction remained relatively constant throughout the observed flight periods, the ozone, temperature, and wind speed profiled changed significantly as the day progressed.
Benefits to Utah
Research and development of effective methods for understanding the vertical and horizontal behavior of locally generated and regionally transported pollutants are of key importance in developing remediation strategies, and may be applicable to other air quality issues, as well. Additional air quality benefits may be achieved as more instruments to measure PM2.5, NOx, CO, and CO are adapted to the test platform.
Work on developing protocols for economically and accurately measuring vertical ozone and meteorological profiles is ongoing. We are also pursuing ways to continue adaptating the instrument systems to the UAV-based platform. The UAV instruments will be used for further studies within Cache Valley and along the Wasatch Front, and may also include other small measurement packages for additional pollutants.