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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Sulfur dioxide and its variations

UV spectroscopy from the Pioneer Venus Orbiter shows a decline in the cloud top abundance of SO2 from about 100 ppb to about 10 ppb in the period 1978-1986. A consistent decline in polar haze has occurred over the same period with the correlation coefficient between these two observables of 0.8. Star calibrations determine the instrument sensitivity to within 10 percent, which rules out the possibility that this is an instrumental effect. Systematic errors could increase the SO2 abundance to twice the inferred values in later orbits. Tracking of SO2 features and power spectral analysis give rotation periods for the longer lived features of 3.6-5.2 d, consistent with cloud tracked winds observed at other wavelengths. The behavior of SO2 and polar haze can be plausibly explained by episodic injection of SO2 into the cloud top regions, for example, by active volcanism.

Esposito, Larry W.↗
NASA NTRS1993

The abundance of sulfur dioxide below the clouds of Venus

We present a new method for determining the abundance of sulfur dioxide below the clouds of Venus. Absorption by the 3nu3 band of SO2 near 2.45 microns has been detected in high-resolution spectra of the night side of Venus recorded at the Canada-France Hawaii telescope in 1989 and 1991. The inferred SO2 abundance is 130 +/- 40 ppm at all observed locations and pertains to the 35-45 km region. These values are comparable to those measured by the Pioneer Venus and Venera 11/12 entry probes in 1978. This stability stands in contrast to the apparent massive decrease in SO2 observed at the cloud tops since these space missions. These results are consistent with laboratory and modeling studies of the SO2 destruction rates in the lower atmosphere of Venus. The new spectroscopic technique presented here allows a remote monitoring of the SO2 abundance below the clouds, a likely tracer of Venusian volcanism.

Bezard, Bruno↗
NASA NTRS1995

IUE observing programs: NSOSS, VEOEB, and PCOEB

The data reduction and analysis of IUE observations were completed. These results were presented from Venus SO2 (of the VEOEB program). The three IUE observing programs were NSOSS, VEOEB, and PCOEB. NSOSS consisted of comparative UV studies. The objectives of NSOSS included: making the first UV observations of 4179 Toutatis (a near-Earth asteroid), Himalia (a satellite of Jupiter), and Hyperion (the Saturnian satellite); obtaining the first radially-dependent information on the UV color of Saturn's rings; gathering uncontaminated UV spectra of Iapetus's bright and dark hemispheres; and obtaining a spectrum of Titania to initiate the comparative study of UV photometric properties in the Uranian system. VEOEB, as stated above, was a study of the SO2 of the Venus atmosphere and surface. Based on past Pioneer Venus and IUE observations, significant SO2 variations have been interpreted as indicating that the long term atmospheric SO2 abundance may be related to large, episodic infections from the surface or interior of Venus. If episodic events occur, then continuing observations of SO2 in the Venus atmosphere play a vital role in understanding Venus's current and past geologic evolution. PCOEB was a study of the Pluto-Charon system. The primary objective of PCOEB was to complete the coverage of the system's UV light curve in order to analyze the surface properties of Pluto-Charon. Publications, abstracts and articles, resulting from this grant are appended to this report.

Source record↗
NASA NTRS1994

Is H20 present on Io? The detection of a new strong band near 3590/cm (2.79 micrometer)

A strong absorption band at 3590 +/- 20/cm (2.790 +/- 0.015 microns) has been discovered in the spectrum of Io using the Kuiper Airborne Observatory (KAO). The 2 nu(sub 1) + nu(sub 3) comination mode of solid SO2 falls at this position. Since SO2 is abundant on Io it must contribute to the new band. However, a band due to H2O was predicted near this frequency in Io's spectrum based on laboratory experiments of H2O:SO2 mixed Io ice analogs which were used to assign the two weak, variable features at 3370 and 3170/cm (2.97 and 3.15 microns) to trace amounts of H2O frozen in solid SO2 on Io. The new band probably originates from both SO2 and H2O. Unfortunately, the spectral resolution of the data is insufficient to settle the issue of whether there are two resolvable components.

Salama, F.↗
NASA NTRS1994

Is H2O present on Io? The detection of a new strong band near 3590/cm (2.79 microns)

A strong absorption band at 3590 +/- 20/cm (2.790 +/- 0.015 microns) has been discovered in the spectrum of Io using the Kuiper Airborne Observatory (KAO). The 2nu(sub 1) + nu(sub 3) combination mode of solid SO2 falls at this position. Since SO2 is abundant on Io it must contribute to the new band. However, a band due to H2O was predicted near this frequency in Io's spectrum based on laboratory experiments of H2O:SO2 mixed Io ice analogs which were used to assign the two weak, variable features at 3370 and 3170/cm (2.97 and 3.15 microns) to trace amounts of H2O frozen in solid SO2 on Io. The new band probably originates from both SO2 and H2O. Unfortunately, the spectral resolution of the data is insufficient to settle the issue of whether there are two resolvable components.

Salama, F.↗
NASA NTRS1994

New narrow infrared absorption features in the spectrum of Io between 3600 and 3100 cm (2.8-3.2 micrometers)

We report the discovery of a series of infrared absorption bands between 3600 and 3100/cm (2.8-3.2 micrometers) in the spectrum of Io. Individual narrow bands are detected at 3553, 3514.5, 3438, 3423, 3411.5, and 3401/cm (2.815, 2.845, 2.909, 2.921, 2.931, and 2.940 micrometers, respectively). The positions and relative strengths of these bands, and the difference of their absolute strengths between the leading and trailing faces of Io, indicate that they are due to SO2. The band at 3438/cm (2.909 micrometers) could potentially have a contribution from an additional molecular species. The existence of these bands in the spectrum of Io indicates that a substantial fraction of the SO2 on Io must reside in transparent ices having relatively large crystal sizes. The decrease in the continuum observed at the high frequency ends of the spectra is probably due to the low frequency side of the recently detected, strong 3590/cm (2.79 micrometer) feature. This band is likely due to the combination of a moderately strong SO2 band and an additional absorption from another molecular species, perhaps H2O isolated in SO2 at low concentrations. A broad (FWHM approximately = 40-60/cm), weak band is seen near 3160/cm (3.16 micrometers) and is consistent with the presence of small quantities of H2O isolated in SO2-rich ices. There is no evidence in the spectra for the presence of H2O vapor on Io. Thus, the spectra presented here neither provide unequivocal evidence for the presence of H2O on Io nor preclude it at the low concentrations suggested by past studies.

Sandford, Scott A.↗
NASA NTRS1993

An intercomparison of aircraft instrumentation for tropospheric measurements of sulfur dioxide

As part of the NASA Tropospheric Chemistry Program, a series of field intercomparisons have been conducted to evaluate the state-of-the art for measuring key tropospheric species. One of the objectives of the third intercomparison campaign in this series, Chemical Instrumentation Test and Evaluation 3 (CITE 3), was to evaluate instrumentation for making reliable tropospheric aircraft measurements of sulfur dioxide, dimethyl sulfide, hydrogen sulfide, carbon disulfide, and carbonyl sulfide. This paper reports the results of the intercomparisons of five sulfur dioxide measurement methods ranging from filter techniques, in which samples collected in flight are returned to the laboratory for analyses (chemiluminescent or ion chromatographic), to near real-time, in-flight measurements via gas chromatographic, mass spectrometric, and chemiluminescent techniques. All techniques showed some tendency to track sizeable changes in ambient SO2 such as those associated with altitude changes. For SO2 mixing ratios in the range of 200 pptv to a few ppbv, agreement among the techniques varies from about 30% to several orders of magnitude, depending upon the pair of measurements intercompared. For SO2 mixing ratios less than 200 pptv, measurements from the techniques are uncorrelated. In general, observed differences in the measurement of standards do not account for the flight results. The CITE 3 results do not unambiguously identify one or more of the measurement techniques as providing valid or invalid SO2 measurements, but identify the range of 'potential' uncertainty in SO2 measurements reported by currently available instrumentation and as measured under realistic aircraft environments.

Gregory, Gerald L.↗
NASA NTRS1995

The detection of a new strong band near 3590 cm(exp -1) (2.79 microns) in the spectrum of Io

A strong absorption band at 3590 +/- 20 cm(exp -1) (2.790 +/- 0.015 microns) has been discovered in the spectrum of Io using the Kuiper Airborne Observatory (KAO). The 2 nu(sub 1) + nu(sub 3) combination mode of solid SO2 falls at this position. Since SO2 is abundant on Io it must contribute to the new band. However, a band due to H2O was also predicted near this frequency in Io's spectrum based on laboratory experiments of H2O:SO2 mixed Io ice analogs which were used to assign the two weak, variable features at 3370 and 3170 cm(exp -1) (2.97 and 3.15 microns) to trace amounts of H2O frozen in solid SO2 on Io. The new band probably originates from both SO2 and H2O. Unfortunately, the spectral resolution of the data is insufficient to settle the issue of whether or not there are two resolvable components.

Salama, F.↗
NASA NTRS1999

Instrumentation Working Group Summary

The Instrumentation Working Group compiled a summary of measurement techniques applicable to gas turbine engine aerosol precursors and particulates. An assessment was made of the limits, accuracy, applicability, and technology readiness of the various techniques. Despite advances made in emissions characterization of aircraft engines, uncertainties still exist in the mechanisms by which aerosols and particulates are produced in the near-field engine exhaust. To adequately assess current understanding of the formation of sulfuric acid aerosols in the exhaust plumes of gas turbine engines, measurements are required to determine the degree and importance of sulfur oxidation in the turbine and at the engine exit. Ideally, concentrations of all sulfur species would be acquired, with emphasis on SO2 and SO3. Numerous options exist for extractive and non-extractive measurement of SO2 at the engine exit, most of which are well developed. SO2 measurements should be performed first to place an upper bound on the percentage of SO2 oxidation. If extractive and non-extractive techniques indicate that a large amount of the fuel sulfur is not detected as SO2, then efforts are needed to improve techniques for SO3 measurements. Additional work will be required to account for the fuel sulfur in the engine exhaust. Chemical Ionization Mass Spectrometry (CI-MS) measurements need to be pursued, although a careful assessment needs to be made of the sampling line impact on the extracted sample composition. Efforts should also be placed on implementing non-intrusive techniques and extending their capabilities by maximizing exhaust coverage for line-of-sight measurements, as well as development of 2-D techniques, where feasible. Recommendations were made to continue engine exit and combustor measurements of particulates. Particulate measurements should include particle size distribution, mass fraction, hydration properties, and volatile fraction. However, methods to ensure that unaltered samples are obtained need to be developed. Particulate speciation was also assigned a high priority for quantifying the fractions of carbon soot, PAH, refractory materials, metals, sulfates, and nitrates. High priority was also placed on performing a comparison of particle sizing instruments. Concern was expressed by the workshop attendees who routinely make particulate measurements about the variation in number density measured during in-flight tests by different instruments. In some cases, measurements performed by different groups of researchers during the same flight tests showed an order of magnitude variation. Second priority was assigned to measuring concentrations of odd hydrogen and oxidizing species. Since OH, HO2, H2O2, and O are extremely reactive, non-extractive measurements are recommended. A combination of absorption and fluorescence is anticipated to be effective for OH measurements in the combustor and at the engine exit. Extractive measurements of HO2 have been made in the stratosphere, where the ambient level of OH is relatively low. Use of techniques that convert HO2 to OH for combustor and engine exit measurements needs to be evaluated, since the ratio of HO2/OH may be 1% or less at both the combustor and engine exit. CI-MS might be a viable option for H2O2, subject to sampling line conversion issues. However, H2O2 is a low priority oxidizing species in the combustor and at the engine exit. Two candidates for atomic oxygen measurements are Resonance Enhanced Multi-Photon Ionization (REMPI) and Laser-Induced Fluorescence (LIF). Particulate measurement by simultaneous extractive and non-extractive techniques was given equal priority to the oxidizer measurements. Concern was expressed over the ability of typical ground test sampling lines to deliver an unaltered sample to a remotely located instrument. It was suggested that the sampling probe and line losses be checked out by attempting measurements using an optical or non-extractive technique immediately upstream of the sampling probe. This is a possible application for Laser Induced Incandescence (LII) as a check on the volume fraction of soot. Optical measurements of size distribution are not well developed for ultrafine particles less than about 20 nm in diameter, so a non-extractive technique for particulate size distribution cannot be recommended without further development. Carbon dioxide measurements need to be made to complement other extractive measurement techniques. CO2 measurements enable conversion of other species concentrations to emission indices. Carbon monoxide, which acts as a sink for oxidizing species, should be measured using non-extractive techniques. CO can be rapidly converted to CO2 in extractive probes, and a comparison between extractive and non-extractive measurements should be performed. Development of non-extractive techniques would help to assess the degree of CO conversion, and might be needed to improve the concentration measurement accuracy. Measurements of NO(x) will continue to be critical due to the role of NO and NO2 in atmospheric chemistry, and their influence on atmospheric ozone. Time-resolved measurements of temperature, velocity, and species concentrations were included on the list of desired measurement. Thermocouples are typically adequate for engine exit measurements. PIV and LDV are well established for obtaining velocity profiles. The techniques are listed in the accompanying table; are divided into extractive and non-extractive techniques. Efforts were made to include a measurement uncertainty for each technique. An assessment of the technology readiness was included.

Zaller, Michelle↗
NASA NTRS1998

Contributions of Nimbus 7 TOMS Data to Volcanic Study and Hazard Mitigation

Nimbus TOMS data have led to advancements among many volcano-related scientific disciplines, from the initial ability to quantify SO2 clouds leading to derivations of eruptive S budgets and fluxes, to tracking of individual clouds, assessing global volcanism and atmospheric impacts. Some of the major aspects of TOMS-related research, listed below, will be reviewed and updated: (1) Measurement of volcanic SO2 clouds: Nimbus TOMS observed over 100 individual SO2 clouds during its mission lifetime; large explosive eruptions are now routinely and reliably measured by satellite. (2) Eruption processes: quantification of SO2 emissions have allowed assessments of eruption sulfur budgets, the evaluation of "excess" sulfur, and inferences of H2S emissions. (3) Detection of ash: TOMS data are now used to detect volcanic particulates in the atmosphere, providing complementary analyses to infrared methods of detection. Paired TOMS and AVHRR studies have provided invaluable information on volcanic cloud compositions and processes. (4) Cloud tracking and hazard mitigation: volcanic clouds can be considered gigantic tracers in the atmosphere, and studies of the fates of these clouds have led to new knowledge of their physical and chemical dispersion in the atmosphere for predictive models. (5) Global trends: the long term data set has provided researchers an unparalleled record of explosive volcanism, and forms a key component in assessing annual to decadal trends in global S emissions. (6) Atmospheric impacts: TOMS data have been linked to independent records of atmospheric change, in order to compare cause and effect processes following a massive injection of SO2 into the atmosphere. (7) Future TOMS instruments and applications: Nimbus TOMS has given way to new satellite platforms, with several wavelength and resolution modifications. New efforts to launch a geostationary TOMS could provide unprecedented observations of volcanic activity.

Krueger, Arlin J.↗
NASA NTRS2010

Direct Retrieval of Sulfur Dioxide Amount and Altitude from Spaceborne Hyperspectral UV Measurements: Theory and Application

We describe the physical processes by which a vertically localized absorber perturbs the top-of-atmosphere solar backscattered ultraviolet (UV) radiance. The distinct spectral responses to perturbations of an absorber in its column amount and layer altitude provide the basis for a practical satellite retrieval technique, the Extended Iterative Spectral Fitting (EISF) algorithm, for the simultaneous retrieval of these quantities of a SO2 plume. In addition, the EISF retrieval provides an improved UV aerosol index for quantifying the spectral contrast of apparent scene reflectance at the bottom of atmosphere bounded by the surface and/or cloud; hence it can be used for detection of the presence or absence of UV absorbing aerosols. We study the performance and characterize the uncertainties of the EISF algorithm using synthetic backscattered UV radiances, retrievals from which can be compared with those used in the simulation. Our findings indicate that the presence of aerosols (both absorbing and nonabsorbing) does not cause large errors in EISF retrievals under most observing conditions when they are located below the SO2 plume. The EISF retrievals assuming a homogeneous field of view can provide accurate column amounts for inhomogeneous scenes, but they always underestimate the plume altitudes. The EISF algorithm reduces systematic errors present in existing linear retrieval algorithms that use prescribed SO2 plume heights. Applying the EISF algorithm to Ozone Monitoring Instrument satellite observations of the recent Kasatochi volcanic eruption, we demonstrate the successful retrieval of effective plume altitude of volcanic SO2, and we also show the improvement in accuracy in the corresponding SO2 columns.

Yang, Kau↗
NASA NTRS2016

Ames S-32 O-16 O-18 Line List for High-Resolution Experimental IR Analysis

By comparing to the most recent experimental data and spectra of the SO2 628 ν1/ν3 bands (see Ulenikov et al., JQSRT 168 (2016) 29-39), this study illustrates the reliability and accuracy of the Ames-296K SO2 line list, which is accurate enough to facilitate such high-resolution spectroscopic analysis. The SO2 628 IR line list is computed on a recently improved potential energy surface (PES) refinement, denoted Ames-Pre2, and the published purely ab initio CCSD(T)/aug-cc-pVQZ dipole moment surface. Progress has been made in both energy level convergence and rovibrational quantum number assignments agreeing with laboratory analysis models. The accuracy of the computed 628 energy levels and line list is similar to what has been achieved and reported for SO2 626 and 646, i.e. 0.01-0.03 cm(exp −1) for bands up to 5500 cm(exp −1). During the comparison, we found some discrepancies in addition to overall good agreements. The three-IR-list based feature-by-feature analysis in a 0.25 cm(exp −1) spectral window clearly demonstrates the power of the current Ames line lists with new assignments, correction of some errors, and intensity contributions from varied sources including other isotopologues. We are inclined to attribute part of detected discrepancies to an incomplete experimental analysis and missing intensity in the model. With complete line position, intensity, and rovibrational quantum numbers determined at 296 K, spectroscopic analysis is significantly facilitated especially for a spectral range exhibiting such an unusually high density of lines. The computed 628 rovibrational levels and line list are accurate enough to provide alternatives for the missing bands or suspicious assignments, as well as helpful to identify these isotopologues in various celestial environments. The next step will be to revisit the SO2 828 and 646 spectral analyses.

Sulfur dioxide↗
NASA NTRS2019

Monitoring Volcanic Eruptions by OMI/OMPS, ASTER, and MERRA-2

Volcanic lava flows and/or the gas eruptions are the most common characteristics that can be remotely monitored with satellite technology in the global perspective and on different timescales. Atmospheric Sulfur Dioxide (SO2), one of the most abundant gases from volcanic eruptions apart from atmospheric common gases Carbon Dioxide and water vapor, can be directly detected by space-based sensors on satellites. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is one of the 12 Distributed Active Archive Centers (DAACs) within NASA's Earth Observing System Data and Information System (EOSDIS), which archives SO2 data sets from the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) in 1978, till the ongoing Ozone Monitoring Instrument (OMI) on NASA's EOS-Aura satellite, the Ozone Mapping Profiler Suite (OMPS) Nadir Mapper (NM) on both the Suomi National Polar-Orbiting Partnership (Suomi-NPP or SNPP) and the Joint Polar-orbiting Satellite System-1 (JPSS-1) satellites, into the future JPSS missions. In addition to the standard OMI/Aura and OMPS/S-NPP SO2 products, SO2 products created under the charter of the Making Earth System Data Records for Use in Research Environments (MEaSUREs) project, are also archived at GES DISC, through which NASA enacts to expand understanding the Earth system using consistent data records. The Land Processes Distributed Active Archive Center (LP DAAC) is another EOSDIS's DAAC that provides land data products and operates as a partnership with the U.S. Geological Survey (USGS). The LP DAAC has been archiving the satellite imagery from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's EOS-Terra satellite, a high spatial resolution (15 meters) and 14 band multispectral instrument. The ASTER imagery is one of the land products contributing to the application for monitoring hot spots and land terrain changes caused by volcanic eruption events. The data potential in GES DISC and LP DAAC to monitor volcanic sources of SO2 and the influence of wind fields on the gas plume spread will be demonstrated with the most recent 2018 May-July Kilauea Volcano eruption.

Zeng, Jian↗
NASA NTRS2019

Using GES DISC Data to Study Kilauea Volcano of 2018

Kilauea volcano in Hawaii which erupted in early May 2018 injected massive amount of SO2 and ash into the atmosphere. The lava flow during the eruption destroyed many home and neighborhoods. The SO2 plume during the eruption of Kilauea volcano is analyzed from May to August 2018 using multiple satellite products such as Level 2 TROPspheric Monitoring Instrument (TROPOMI) and Level 3 Ozone Monitoring Instrument (OMI) from the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). GES DISC hosts multi-disciplinary Earth science data sets that can be used to analyze natural disasters, such as the Kilauea volcano. Additionally, GES DISC's Giovanni tool can be used to visualize these data. We acquired OMI through the subsetting function, which is processed by the GES DISC in-house developed backend software Level3/4 Regrider and Subsetter (L34RS) and TROPOMI using OPeNDAP.Data from the OMI OMSO2e product showed elevated levels of SO2 amounts during the eruption between May to August 2018. Similarly, ground-based stations at Hawaii Volcanoes National Park recorded higher SO2 concentrations during the same time period. This study uses wind direction from Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) to analyze the transport and dispersion of SO2 plume and map lava flows from the volcano using thermal images from Visible Infrared Imaging Radiometer Suite (VIIRS). Furthermore, satellite observations combined with socioeconomic and public health data are used to analyze its impact in public health.

KC, Binita↗
NASA NTRS2018

Linking Improvements in Sulfur Dioxide Emissions to Decreasing Sulfate Wet Deposition By Combining Satellite and Surface Observations With Trajectory Analysis

Sulfur dioxide (SO2), a criteria pollutant, and sulfate (SO42−) deposition are major environmental concerns in the eastern U.S. and both have been on the decline for two decades. In this study, we use satellite column SO2 data from the Ozone Monitoring Instrument (OMI), and SO42− wet deposition data from the NADP (National Atmospheric Deposition Program) to investigate the temporal and spatial relationship between trends in SO2 emissions and the downward sulfate wet deposition over the eastern U.S. from 2005 to 2015. To establish the relationship between SO2 emission sources and receptor sites, we conducted a Potential Source Contribution Function (PSCF) analysis using HYSPLIT back trajectories for five selected Air Quality System (AQS) sites - (Hackney, OH, Akron, OH, South Fayette, PA, Wilmington, DE, and Beltsville, MD) - in close proximity to NADP sites with large downward SO42− trends since 2005. Back trajectories were run for three summers (JJA) and three winters (DJF) and used to generate seasonal climatology PSCFs for each site. The OMI SO2 and interpolated NADP sulfate deposition trends were normalized and overlapped with the PSCF, to identify the areas that had the highest contribution to the observed drop. The results suggest that emission reductions along the Ohio River Valley have led to decreases in sulfate deposition in eastern OH and western PA (Hackney, Akron and South Fayette). Farther to the east, emission reductions in southeast PA resulted in improvements in sulfate deposition at Wilmington, DE, while for Beltsville, reductions in both the Ohio River Valley and nearby favorably impacted sulfate deposition. For Beltsville, sources closer than 300 km from the site contribute roughly 56% observed deposition trends in winter, and 82% in summer, reflecting seasonal changes in transport pattern as well as faster oxidation and washout of sulfur in summer. This suggests that emissions and wet deposition are linked through not only the location of sources relative to the observing sites, but also to photochemistry and the weather patterns characteristic to the region, as evidenced by a west to east shift in the contribution between winter and summer. The method developed here is applicable to other regions with significant trends such as China and India, and can be used to estimate the potential benefits of emission reduction in those areas.

sulfur dioxide emissions↗
NASA NTRSDate not supplied

Combining Earth System Modeling and Machine Learning to Investigate Volcanic Sulfate Deposition in Polar Ice Cores

Volcanic eruptions emit large amounts of sulfur dioxide (SO2), water, and other chemicals into the atmosphere, both in the troposphere and the stratosphere. Most of the SO2 is converted to sulfate aerosol, which is eventually deposited following long-range transport. The deposits from large eruptions are potentially detectable in ice cores, but there are many cases in which sulfate layers have not been linked to their source volcanoes. As volcanoes can act as significant shocks to the global climate system, we are interested in locating these eruptions in order to increase understanding of the volcanic record. To narrow down the search, we performed 140 simulations of volcanic eruptions using the GISS ModelE Earth system model. We varied the latitude, longitude, Julian day, plume top, plume bottom, and injected SO2 and H2O amounts using a Latin hypercube sampling approach, and analyzed correlations between these parameters and sulfate depositions at ice core sites in Antarctica and Greenland. Using machine learning and parameter estimation, we generated probability distributions and maximum likelihood estimates for the parameters given sulfate deposition data, which can predict latitude with some skill. We find that the volcano latitude and SO2 content are best correlated with sulfate depositions at each pole, while longitude, Julian day, and H2O have small or insignificant effects. Plume altitude and thickness are important because they determine how much of the SO2 is injected into the stratosphere, which has implications for sulfur transport and lifetimes.

Earth system models↗
NASA NTRS2020

Inconsistencies in Sulphur Dioxide Emissions from the Canadian Oil Sands and Potential Implications

Satellite-derived and reported sulfur dioxide (SO2) emissions from the Canadian oil sands are shown to have been consistent up to 2013. Post-2013, these sources of emissions data diverged, with reported emissions dropping by a factor of two, while satellite-derived emissions for the region remained relatively constant, with the discrepancy (satellite-derived emissions minus reported emissions) peaking at 50 kt(SO2) yr−1 around 2016. The 2013–2014 period corresponds to when new flue-gas desulfurization units came on-line. Previous work has established a high level of consistency between at-stack SO2 emissions observations and satellite estimates, and surface monitoring network SO2 concentrations over the same multi-year period show similar trends as the satellite data, with a slight increase in concentrations post-2013. No clear explanation for this discrepancy currently exists. The implications of the discrepancy towards estimated total sulfur deposition to downwind ecosystems were estimated relative to 2013 emissions levels, with the satellite-derived values leaving the area of regional critical load exceedances of aquatic ecosystems largely unchanged from 2013 values, 335 000 km2, and reported values potentially decreasing this area to 185,000 km2.

Sulphur dioxide (SO2) emissions↗
DOE OSTI2012

Effect of sulfur loading on the desulfation chemistry of a commercial lean NOx trap catalyst

We investigate the effects of initial sulfur loadings on the desulfation chemistry and the subsequent final activity of a commercial LNT catalyst. Identical total amounts of SO2 are applied to the samples, albeit with the frequency of desulfation varied. The results indicate that performance is better with less frequent desulfations. The greater the amount of sulfur deposited before desulfation, the more amount of SO2 evolution before H2S is observed during desulfation, which can be explained by two sequential reactions; initial conversion of sulfate to SO2, followed by the reduction of SO2 to H2S. After completing all sulfation/desulfation steps, the sample with only a single desulfation results in a fairly uniform sulfur distribution along the z-axis inside of the monolith. We expect that the results obtained in this study will provide useful information for optimizing regeneration strategies in vehicles that utilize the LNT technology.

Environmental Molecular Sciences Laboratory↗