New instrumentation for the detection of sulfur dioxide in the remote atmosphere

Thesis (Ph.D.) University of Alaska Fairbanks, 1999Sulfur gases are an important chemical component of the atmosphere. Gaseous sulfur compounds effect the acidity of rainwater and are important precursors to aerosol particles which affect public health, climate and visibility of scenic vistas such as the Grand Canyon. Sulfate aerosols are also known to participate in ozone catalysis in the stratosphere. A vast majority of the gaseous sulfur cycling through the atmosphere will exist as sulfur dioxide (SO2) at some time during its atmospheric lifetime. Since SO 2 is a primary component of the atmospheric sulfur cycle, quality measurements of this gas are important to understanding the cycling of sulfur through the atmosphere. The mixing ratio of SO2 in the atmosphere can be as low as a few 10's of parts-per-trillion by volume (pptv) in unpolluted areas and as high as 100's of parts-per-billion by volume (ppbv) near industrial centers. Obtaining SO2 measurements with mixing ratios that can differ by 105 in magnitude is a difficult task, especially for mixing ratios less than a few hundred pptv. The Diffusion Denuder/Sulfur Chemiluminescence Detector (DD/SCD) was developed further and tested in a rigorously blind comparison under controlled laboratory conditions. The DD/SCD exhibited excellent sensitivity and little-to-no interference from other trace gases. The DD/SCD performance was comparable to that of other state-of-the-art instruments developed for measuring SO 2 in the remote atmosphere. The Continuous SO2 Detector was developed to overcome the limitation of long sampling times (4 to 90 minutes) inherent in the DD/SCD and other state-of-the-art techniques. The Continuous SO2 Detector (CSD) was developed based on the design of the DD/SCD, but has been optimized for sensitive, high-time resolved measurements of SO2 in air. Sensitive, high-time resolved measurements would be beneficial for studying atmospheric SO2 over large geographical areas from a moving sampling platform such as an aircraft. The current prototype of the CSD is capable of measuring SO2 at mixing ratios of less than 100 pptv on the order of seconds. The DD/SCD, CSD and an automated, computer controlled dynamic dilution system described in this thesis represent a suite of instruments for the measurement of SO2 in the remote atmosphere

Particle growth in urban and industrial plumes in Texas

Particle size distributions and gas-phase particle precursors and tracer species were measured aboard an aircraft in the plumes downwind from industrial and urban sources in the vicinity of Houston, TX during the daytime in late August and early September 2000. Plumes originating from the Parish gas-fired and coal-fired power plant, petrochemical industries along the Houston ship channel, the petrochemical facilities near the Gulf coast, and the urban center of Houston were studied. Most of the particle mass flux advected downwind of Houston came from the industries and electrical utilities at the periphery of the city rather than from sources in the urban core. In SO2-rich plumes that did not contain elevated concentrations of volatile organic compounds (VOCs), particle volume increased with increasing plume oxidation (age) at a rate consistent with condensation and neutralization of the gas-phase oxidation products Of SO2. In plumes that were rich in both SO2 and VOCs, observed particle growth greatly exceeded that expected from SO2 oxidation, indicating the formation of organic particulate mass. In plumes that were enhanced in VOCs but not in SO2, and in the plume of the Houston urban center, no particle volume growth with increasing plume oxidation was detected. Since substantial particle volume growth was associated only with SO2-rich plumes, these results suggest that photochemical oxidation of SO2 is the key process regulating particle mass growth in all the studied plumes in this region. However, uptake of organic matter probably contributes substantially to particle mass in petrochemical plumes rich in both SO2 and VOCs. Quantitative studies of particle formation and growth in photochemical systems containing nitrogen oxides (NOx = NO + NO2 ), VOCs, and SO2 are recommended to extend those previously made in NOx-VOC systems

New Era of Air Quality Monitoring from Space: Geostationary Environment Monitoring Spectrometer (GEMS)

GEMS will monitor air quality over Asia at unprecedented spatial and temporal resolution from GEO for the first time, providing column measurements of aerosol, ozone and their precursors (nitrogen dioxide, sulfur dioxide and formaldehyde). Geostationary Environment Monitoring Spectrometer (GEMS) is scheduled for launch in late 2019 - early 2020 to monitor Air Quality (AQ) at an unprecedented spatial and temporal resolution from a Geostationary Earth Orbit (GEO) for the first time. With the development of UV-visible spectrometers at sub-nm spectral resolution and sophisticated retrieval algorithms, estimates of the column amounts of atmospheric pollutants (O3, NO2, SO2, HCHO, CHOCHO and aerosols) can be obtained. To date, all the UV-visible satellite missions monitoring air quality have been in Low Earth orbit (LEO), allowing one to two observations per day. With UV-visible instruments on GEO platforms, the diurnal variations of these pollutants can now be determined. Details of the GEMS mission are presented, including instrumentation, scientific algorithms, predicted performance, and applications for air quality forecasts through data assimilation. GEMS will be onboard the GEO-KOMPSAT-2 satellite series, which also hosts the Advanced Meteorological Imager (AMI) and Geostationary Ocean Color Imager (GOCI)-2. These three instruments will provide synergistic science products to better understand air quality, meteorology, the long-range transport of air pollutants, emission source distributions, and chemical processes. Faster sampling rates at higher spatial resolution will increase the probability of finding cloud-free pixels, leading to more observations of aerosols and trace gases than is possible from LEO. GEMS will be joined by NASA's TEMPO and ESA's Sentinel-4 to form a GEO AQ satellite constellation in early 2020s, coordinated by the Committee on Earth Observation Satellites (CEOS)

Eros, literature and the Veroli Casket

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