| Description |
Observations and analyses of ozone concentrations and near-surface wind are examined during the latter half of June 2015 when the highest ozone levels of the 2015 summer were observed in the urban areas of northern Utah referred to locally as the Wasatch Front. A novel mix of ozone observations from sensors at fixed sites as well as mobile platforms (vehicles, light rail car, and news helicopter) help to define the spatiotemporal distribution of ozone along the Wasatch Front and the nearby Great Salt Lake. The ozone and wind observations are assimilated separately using a two-dimensional variational analysis system to obtain ozone and 10-m wind analyses at 1-km horizontal resolution every hour to determine the best representation of ozone distribution throughout the region. Two case studies are used to illustrate the diurnal evolution and transportation of ozone concentrations relative to local wind circulations driven primarily by lake-land and mountain-valley thermal contrasts. Ozone pollution roses at the fixed sensor locations for day and night periods and composites of the 1-km resolution analyses during the 15-day period as a function of time of day help to define common diurnal patterns. This study provides information on how ozone is distributed throughout the region and indicates that areas of high ozone concentrations are a function of the complex interaction of thermal flows in urban, rural, and lake boundary layers. |
