Mobile Column Measurements of HCHO, NO2, NH3, and C2H6 in Colorado during FRAPPE

Abstract:

Gases from anthropogenic sources have the potential to have a profound impact on air quality. Emissions from large cattle feedlots and ONG (Oil and Natural Gas) sites are comprised of NH₃ (ammonia) and C₂H₆ (ethane) as pollutants. C₂H₆ contributes to photochemical ozone (O₃) production and oxidation production of HCHO (formaldehyde). NH₃ is a major source for reactive nitrogen to form particulate matter 2.5, which negatively affects human health. NO₂ (nitrogen dioxide), emitted during combustion, is considered a large-scale pollutant and contributes to the formation of O₃. Deploying an innovative suite of remote sensing instruments in a mobile laboratory, a Multi Axis Differential Optical Absorption Spectrometer (MAX-DOAS), a UV-Vis Spectrometer, and a Fourier Transform Infrared Spectrometer, we obtain mobile column measurements at high spatial and temporal resolution, 2 seconds for the UV-Vis and IR spectrometers and 20 seconds for the MAX-DOAS. Within the scope of the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) we measure total columns of HCHO, NO₂, NH₃, and C₂H₆ using the University of Colorado mobile laboratory. Emissions of urban areas, agriculture, and ONG sites were studied. For the measurement of total columns the solar occultation flux method has been applied. We measured significant variability in the columns. The measurement of total columns allows one to determine the emission flux and source strength when driving a closed box around or upwind and downwind of a source with the mobile laboratory. We present results from select research drives.