Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “so2”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

SO2 on Venus: A final cross-calibration with Pioneer Venus

The three observing programs under NASA Grant NAG5-1913 are described. They are NSOSS, VEOEB, and PCOEB. The scientific objectives for the IUE observation program NSOSS were to: make the first ever UV observations of a near-earth asteroid (4179 Toutatis), an irregular satellite of Jupiter (Himalia), and the Saturnian satellite Hyperion; obtain the first radially-dependent information on the UV color of Saturn's rings; gather the uncontaminated UV spectra of Iapetus's bright and dark hemispheres; and obtain a spectrum of Titania to initiate the comparitive study of UV photometric properties in Uranian system. The VEOEB program studied Venus SO2, an important indicator of key processes in the Venus atmosphere and perhaps Venus 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 injections from the surface or interior of Venus. The PCOEB program studied the Pluto-Charon system, for which evidence of a variable UV light curve has been presented. This program is to complete the coverage of that UV light curve, since only approximately 26% has been observed.

Source record↗
NASA NTRS1994

Detection of the SO2 atmosphere on Io with the Hubble Space Telescope

Observations of the trailing hemisphere of Io made with the Faint Object Spectrograph of the Hubble Space Telescope (HST) in March 1992 have resulted in the first detection of atmospheric SO2 absorption bands in the ultraviolet. These observations represent only the third positive means of detection of what is widely believed to be Io's primary atmospheric constituent. Below approximately 2130 A the geometric albedo of the satellite is dominated by SO2 gas absorption band signatures, which have been analyzed using models that include the effects of optical thickness, temperature, and spatial distribution. The disk-intergrated HST data cannot resolve the spatial distribution, but it is possible to define basic properties and set constraints on the atmosphere at the time of the observations. Hemispheric atmospheres with average column density N = 6 - 10 x 10(exp 15)/sq sm and T(gas) = 110 - 500 K fit the data, with preference for temperatures of approximately 200 - 250 K. Better fits are found as the atmosphere is spatially confined, with a limit of approximately 8% hemispheric areal coverage and N approximately equal to 3 x 10(exp 17)/sq cm with colder 110 - 250 K temepratures. A dense (N greater than or equal to 10(exp 16)/sq cm), localized component of SO2 gas, such as that possibly associated with active volcanoes, can generate the observed spectral constrast only when the atmosphere is cold (110 K) and an extended component such as Pele is included. The combination of a dense, localized atmosphere with a tenuous component (N less than 10(exp 16)/sq cm, either patchy or extended) also fits the data. In all cases the best fit models imply a disk-averaged column density larger than exospheric but approximately 10 - 30 times less than the previous upper limit from near-UV observations.

Ballester, G. E.↗
NASA NTRS2008

Middle UV to Near-IR Spectrum of Electron-Excited SO2

We investigated the electron impact-induced fluorescence spectrum of SO2 to provide excitation cross sections for modeling Io's mission spectrum and analyzing Cassini Imaging Science Subsystem observations. The electron-excited middle-ultraviolet visible optical near-infrared (VOIR) emission spectrum of SO2 gas was generated in the laboratory and studied from 2000 to 11,000 A at a resolution of (Delta)(lamda) approximately 2.5 A full width at half maximum (FWHM). The VOIR laboratory spectrum longward of 6000 A consists entirely of S I, II and O I, II multiplets for electron impact energies above approximately 15 eV. Between 2000 and 6000 A, we find previously identified molecular bands from both SO and SO2. This work represents a significant improvement in spectral resolution over our earlier work done at 18 A FWHM. From a measurement of the medium-resolution spectrum, we provide detailed 25- and 100-eV emission cross sections for spectral features from 2000 to 11,000 A . On the basis of these data, we suggest future ground-based and satellite telescopic observations in the VOIR that are of promise for understanding Io's atmosphere.

sulpher dioxide↗
NASA NTRS2010

Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction

Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux).

Hwang, S. M.↗
NASA NTRS2016

Regional and Global Climate Response to Anthropogenic SO2 Emissions from China in Three Climate Models

We use the HadGEM3-GA4, CESM1, and GISS ModelE2 climate models to investigate the global and regional aerosol burden, radiative flux, and surface temperature responses to removing anthropogenic sulfur dioxide (SO2) emissions from China. We find that the models differ by up to a factor of 6 in the simulated change in aerosol optical depth (AOD) and shortwave radiative flux over China that results from reduced sulfate aerosol, leading to a large range of magnitudes in the regional and global temperature responses. Two of the three models simulate a near-ubiquitous hemispheric warming due to the regional SO2 removal, with similarities in the local and remote pattern of response, but overall with a substantially different magnitude. The third model simulates almost no significant temperature response. We attribute the discrepancies in the response to a combination of substantial differences in the chemical conversion of SO2 to sulfate, translation of sulfate mass into AOD, cloud radiative interactions, and differences in the radiative forcing efficiency of sulfate aerosol in the models. The model with the strongest response (HadGEM3-GA4) compares best with observations of AOD regionally, however the other two models compare similarly (albeit poorly) and still disagree substantially in their simulated climate response, indicating that total AOD observations are far from sufficient to determine which model response is more plausible. Our results highlight that there remains a large uncertainty in the representation of both aerosol chemistry as well as direct and indirect aerosol radiative effects in current climate models, and reinforces that caution must be applied when interpreting the results of modelling studies of aerosol influences on climate. Model studies that implicate aerosols in climate responses should ideally explore a range of radiative forcing strengths representative of this uncertainty, in addition to thoroughly evaluating the models used against observations.

sulfates↗
NASA NTRS2016

Computing Highly Accurate Spectroscopic Line Lists for Characterization of Planetary Atmospheres: CO2 and SO2 Line Lists Needed for Modeling Venus

Over the last decade, it has become apparent that the most effective approach for determining highly accurate rotational and rovibrational line lists for molecules of interest in planetary atmospheres and other astrophysical environments is through a combination of highresolution laboratory experiments coupled with state-of-the art ab initio quantum chemistry methods. The approach involves computing the most accurate potential energy surface (PES) possible using state-of-the art electronic structure methods, followed by computing rotational and rovibrational energy levels using an exact variational method to solve the nuclear Schrödinger equation. Then, reliable experimental data from high-resolution experiments is used to refine the ab initio PES in order to improve the accuracy of the computed energy levels and transition energies. From the refinement step, we have been able to achieve an accuracy of approximately 0.015 cm-1 for rovibrational transition energies, and even better for purely rotational transitions. This combined "experiment / theory" approach allows for determination of essentially a complete line list, with hundreds of millions of transitions, and having the transition energies and intensities be highly accurate. Our group has successfully applied this approach to determine highly accurate line lists for NH3, CO2 and isotopologues, and SO2 and isotopologues. Here I will report our latest results for CO2 and SO2 including all isotopologues. Comparisons to the available data in HITRAN2012 and other available databases will be shown, though we note that our line lists for SO2 are significantly more complete than any other databases. Since it is important to span a large temperature range in order to model the spectral signature of Venus as well as exoplanets, we will demonstrate how the spectra change on going from low temperatures (100 K) to higher temperatures (500 K to 1500 K).

potential energy surface (PES)5405 PLANETARY SCIEN↗
NASA NTRSDate not supplied

A Modeling and Simulation Study for the GeoXO Atmospheric Composition Instrument (ACX): System Level SO2 and O3 Retrieval Performance as a Function of SNR

NOAA’s Geostationary Extended Observations (GeoXO) program is planning to include a hyperspectral UV/visible atmospheric composition instrument in geostationary orbit slated for operations by the early 2030s. Trace gas retrievals provide critical information about our Earth’s system as it relates to both natural and anthropogenic activity. This work focused on the impacts of the signal-to-noise ratio (SNR) on the retrieval uncertainty of SO2 and O3. An end-to-end physics-based imaging system and scene modeling and simulation framework was developed to assess instrument performance considerations in support of the planned GeoXO atmospheric composition instrument (ACX). The framework is composed of three primary components: 1) simulated at-sensor radiance via radiative transfer models of a known atmospheric composition, 2) a noise model driven by previous and planned sensor specifications, and 3) a physical retrieval algorithm. In this analysis, the tropospheric concentrations of SO2 and O3 in the atmospheric column were varied in the boundary layer (0-3 km) and at an elevation of 5 km with a thickness of 1-2 km; the uncertainty in retrieval was studied for various SNR levels for multiple viewing geometries and solar zenith angles. This effort supports the development of the GeoXO ACX instrument by providing a simulated ACX performance assessment of the system-level retrieval performance as a function of SNR, particularly with respect to the wavelength range of interest (approximately 305 – 340 nm) for SO2 and O3 trace gas retrievals.

Monica Cook↗
DOE OSTI2020

Materials Data on P4(SO2)3 by Materials Project

P4(SO2)3 is beta Np structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four P4(SO2)3 clusters. there are four inequivalent P+4.50+ sites. In the first P+4.50+ site, P+4.50+ is bonded to one S2- and three O2- atoms to form distorted corner-sharing PSO3 tetrahedra. The P–S bond length is 1.88 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. In the second P+4.50+ site, P+4.50+ is bonded to one S2- and three O2- atoms to form distorted corner-sharing PSO3 tetrahedra. The P–S bond length is 1.88 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. In the third P+4.50+ site, P+4.50+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. All P–O bond lengths are 1.68 Å. In the fourth P+4.50+ site, P+4.50+ is bonded to one S2- and three O2- atoms to form distorted corner-sharing PSO3 tetrahedra. The P–S bond length is 1.88 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a single-bond geometry to one P+4.50+ atom. In the second S2- site, S2- is bonded in a single-bond geometry to one P+4.50+ atom. In the third S2- site, S2- is bonded in a single-bond geometry to one P+4.50+ atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sn(SO2)2 by Materials Project

Sn(SO2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two Sn(SO2)2 clusters. Sn4+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Sn–O bond distances ranging from 2.28–2.33 Å. There are two inequivalent S2+ sites. In the first S2+ site, S2+ is bonded in a water-like geometry to two O2- atoms. Both S–O bond lengths are 1.53 Å. In the second S2+ site, S2+ is bonded in a water-like geometry to two O2- atoms. Both S–O bond lengths are 1.53 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Sn4+ and one S2+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Sn4+ and one S2+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sn4+ and one S2+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Sn4+ and one S2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3PH16(SO2)4 by Materials Project

Na3PH16(SO2)4 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two Na3PH16(SO2)4 sheets oriented in the (0, 1, 0) direction. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted square co-planar geometry to two equivalent S2- and four O2- atoms. Both Na–S bond lengths are 3.12 Å. There are two shorter (2.35 Å) and two longer (2.49 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded to two equivalent S2- and four O2- atoms to form distorted NaS2O4 octahedra that share corners with two equivalent PS4 tetrahedra and edges with two equivalent NaO6 octahedra. Both Na–S bond lengths are 2.89 Å. There are two shorter (2.37 Å) and two longer (2.43 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to one S2- and five O2- atoms. The Na–S bond length is 3.17 Å. There are a spread of Na–O bond distances ranging from 2.34–2.51 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form edge-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.42–2.49 Å. P5+ is bonded to four S2- atoms to form PS4 tetrahedra that share a cornercorner with one NaS2O4 octahedra. The corner-sharing octahedral tilt angles are 67°. There are a spread of P–S bond distances ranging from 2.04–2.08 Å. There are sixteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted single-bond geometry to one Na1+ and one P5+ atom. In the second S2- site, S2- is bonded in a bent 120 degrees geometry to one Na1+ and one P5+ atom. In the third S2- site, S2- is bonded in a distorted bent 120 degrees geometry to one Na1+ and one P5+ atom. In the fourth S2- site, S2- is bonded in a single-bond geometry to one P5+ atom. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two H1+ atoms. In the eighth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3AsH16(SO2)4 by Materials Project

Na3AsH16(SO2)4 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two Na3AsH16(SO2)4 sheets oriented in the (0, 1, 0) direction. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted square co-planar geometry to two equivalent S2- and four O2- atoms. Both Na–S bond lengths are 3.12 Å. There are two shorter (2.35 Å) and two longer (2.47 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded to two equivalent S2- and four O2- atoms to form distorted NaS2O4 octahedra that share corners with two equivalent AsS4 tetrahedra and edges with two equivalent NaO6 octahedra. Both Na–S bond lengths are 2.88 Å. There are two shorter (2.37 Å) and two longer (2.42 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to one S2- and five O2- atoms. The Na–S bond length is 3.11 Å. There are a spread of Na–O bond distances ranging from 2.35–2.52 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form edge-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.41–2.50 Å. As5+ is bonded to four S2- atoms to form AsS4 tetrahedra that share a cornercorner with one NaS2O4 octahedra. The corner-sharing octahedral tilt angles are 69°. There are a spread of As–S bond distances ranging from 2.17–2.21 Å. There are sixteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted water-like geometry to one Na1+ and one As5+ atom. In the second S2- site, S2- is bonded in a water-like geometry to one Na1+ and one As5+ atom. In the third S2- site, S2- is bonded in a distorted bent 120 degrees geometry to one Na1+ and one As5+ atom. In the fourth S2- site, S2- is bonded in a single-bond geometry to one As5+ atom. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two H1+ atoms. In the eighth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(SO2)2 by Materials Project

Ba(SO2)2 crystallizes in the orthorhombic Pbcn space group. The structure is two-dimensional and consists of two Ba(SO2)2 sheets oriented in the (0, 0, 1) direction. Ba2+ is bonded in a 5-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.59–3.37 Å. There are two inequivalent S3+ sites. In the first S3+ site, S3+ is bonded in a single-bond geometry to one O2- atom. The S–O bond length is 1.55 Å. In the second S3+ site, S3+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.49 Å) and one longer (1.50 Å) S–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ba2+ and one S3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ba2+ and one S3+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and one S3+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Ba2+ and one S3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effects of Different Stratospheric SO2 Injection Altitudes on Stratospheric Chemistry and Dynamics

Strategic geoengineering has been proposed to reduce some of the known side effects of stratospheric aerosol modifications. Specific climate goals could be reached depending on design choices of stratospheric sulfur injections by latitude, altitude, and magnitude. Here we explore in detail the stratospheric chemical and dynamical responses to injections at different altitudes using a fully coupled state-of-the-art climate model. Two different sce-narios are explored that produce approximately the same global cooling of 2?C over the period 2042 – 49, a high altitude injection case using 24 Tg SO2 yr-1 at 30 hPa (˜ 25km altitude), and a low altitude injection case using 32 Tg SO2 yr-1 injections at 70 hPa (˜ 20 km altitude), with annual injections divided equally between 15?N and 15?S. Both cases result in a warming of the lower tropical stratosphere up to 10 and 15?C for the high and low altitude injection case and in substantial increase of water vapor of 2 and 4 ppm, respectively, compared to no geoengineering conditions. Polar column ozone in the Northern Hemisphere is reduced by up to 18% in March for the high altitude injection case and up to 8% for the low altitude injection case. However, for winter mid- and high northern latitudes, low altitude injections result in column ozone greater than without geoengineering. These changes are mostly driven by dynamics and advection. Antarctic column ozone in 2040-49 does not recover from present day values for both cases.

Tilmes, S↗
DOE OSTI2019

Comparing surface and stratospheric impacts of geoengineering with different SO2 injection strategies

Geoengineering with stratospheric sulfate aerosols can, to some extent, be designed to achieve different climate objectives. Here we use the the state-of-the-art Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model as its atmospheric component (CESM1(WACCM)), to compare surface climate and stratospheric effects of two geoengineering strategies. In one, SO2 is injected into the tropical lower stratosphere at the equator to keep global mean temperature nearly constant under an RCP8.5 scenario, as has been commonly simulated in previous studies. In another, the Geoengineering Large Ensemble (GLENS), SO2 is injected into the lower stratosphere at four different locations (30°N/S and 15°N/S) to keep global mean temperature, the interhemispheric temperature gradient, and the equator-to-pole temperature gradient nearly unchanged. Both simulations are effective at offsetting changes in global mean temperature and the interhemispheric temperature gradient that result from increased greenhouse gases, but only GLENS offsets changes in the equator-to-pole temperature gradient. GLENS results in a more even aerosol distribution, whereas equatorial injection tends to result in an aerosol peak in the tropics. Many other aspects of surface climate changes, including precipitation and sea ice coverage, also show reduced changes in GLENS as compared to equatorial injection. Stratospheric changes, including heating, circulation, and effects on the quasi-biennial oscillation are greatly reduced in GLENS as compared to equatorial injection.

Kravitz, Benjamin S.↗
NASA NTRS1975

Measurements of SO2 absorption coefficients using a tunable dye laser

High-resolution measurements of SO2 absorption coefficients in the UV are presented in the wavelength interval between 2962 and 3011 A using a frequency-doubled dye laser as the radiation source. These measurements have application to pollution monitoring of SO2 using the differential absorption scattering (DAS) technique. The spectral resolution of the measurements was 0.2 A (determined by the linewidth of the dye laser) and the generated spectra exhibited considerable rotational structure on the (000) double prime to (060) prime, (070) prime, and (080) prime electronic-vibrational transitions. The latter transitions correspond to center wavelengths of 3001.8, 2981.0, and 2962 A, respectively. The laser measurements were obtained with a signal-processing technique which eliminated calibration procedures associated with conventional optical-absorption measurements. Using this technique, the statistical uncertainty associated with measured absorption coefficients has been reduced to less than plus or minus 2% with a wavelength uncertainty of the laser source of plus or minus 0.1 A.

Thompson, R. T., Jr.↗
NASA NTRS1975

Computer simulation of an aircraft-based differential absorption and scattering system for retrieval of SO2 vertical profiles

The feasibility of using the differential absorption and scattering technique from aircraft altitudes for remotely measuring the vertical distribution of SO2 was studied via a computer simulation. Particular care was taken in this simulation to use system parameters (i.e., laser energy, telescope size, etc.) which can be accommodated on an aircraft and can be realized with commercially available technology. The vertical molecular and aerosol profiles were chosen to simulate the types of profiles which might be experienced over a large city. Results are presented on the retrieval of the assumed SO2 profile which show the effects of systematic errors due to interfering gases and aerosols, as well as random errors due to shot noise in the return signal, detector and background noise, and instrument-generated noise.

Hoell, J. M., Jr.↗
NASA NTRS1976

A four-channel portable solar radiometer for measuring particulate and/or aerosol opacity and concentration of NO2 and SO2 in stack plumes

Solar absorption radiometry has been investigated as a method of measuring stackplume effluents. A simple and inexpensive instrument was constructed for observing the sun at four wavelengths: 800, 600, 400, and 310 nm. Higher wavelength channels measured the effect of the particulates and NO2, and an ultraviolet channel measured the contribution of SO2 to the attenuation. Stack-plume measurements of opacity and concentration of NO2 and SO2 were in basic agreement with in-stack measurements. The major limitation on the use of the radiometer is the requirement for an accessible viewing position which allows the sun-plume-observer relationship to be attained. It was concluded that the solar radiometer offers an inexpensive method for monitoring plume effluents when the viewing position is not restricted.

Exton, R. J.↗