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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.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Synoptic Mapping of Chemical Composition, Thermal Structure, and Air Motion from UARS Observations

An operational mapping algorithm was developed to process measurements of individual species observed by different satellite instruments on board UARS. Based on Fast Fourier Synoptic Mapping (FFSM), the algorithm accounts for the precessing orbit of UARS, the error of individual instruments, and gaps associated with instrument duty cycle and the satellite yaw maneuver. It provides synoptic structure and evolution on periods as short as 1 day, derived collectively from all observations of an individual species. The algorithm was applied to synoptically map temperature, thickness, and several chemical constituents observed by the instruments: MLS, CLAES, ISAMS, and HALOE. Each field variable observed by these instruments was mapped twice-daily in continuous global time series several months long. Mapped behavior produced via FFSM was compared against standard archived products generated via Kalman filtering. The standard map products reveal similar behavior, but are limited to features of larger scale. Tracer structure that develops through flow deformation and attending transport is therefore represented in those products more coarsely, eventually being sheared down to scales that are no longer represented properly. The synoptic time series also reveal a diurnal cycle for several of the constituents, one that emerges clearly in their space-time spectra. The zonal and meridional structure of diurnal variability was mapped by filtering the space-time spectrum, an intermediate product of FFSM, to those scales resolved by the UARS sampling. Geographical variations of the diurnal cycle have also been evaluated in its seasonal-mean structure by compositing distributions at individual local times. Both were compared to diurnal variations in chemical models and in dynamical models that account for transport by the diurnal tide. Diurnal variations were found to introduce spurious behavior into the archived products generated via Kalman filtering, behavior that is misrepresented in those synoptic time series. Aliasing by under-sampled diurnal variations introduces a bias into the time-mean structure of archived products. That systematic error is manifested as anomalous wave structure in the time-mean fields. By contrast, synoptic time series generated via FFSM faithfully represent such behavior as varying diurnally, so it does not corrupt time-mean structure. Tracer structure mapped via the above algorithm was being applied to determine the Brewer-Dobson circulation of the stratosphere through Lagrangian considerations. Preliminary results are encouraging: They reveal diabatic ascent in the tropics, balanced by diabatic descent over the winter hemisphere. This Lagrangian description of transport derived from UARS tracer measurements would be potentially valuable for diagnosing interannual changes of transport, specifically, in relation to interannual changes of total ozone. Regrettably, support was reduced to 50% of the approved funding level, leaving this component incomplete.

Salby, Murry L.↗
NASA NTRS1980

The importance of energetic particle precipitation on the chemical composition of the middle atmosphere

The present review deals with the importance of three distinct classes of precipitation which directly deposit energy into the middle atmosphere, viz. galactic cosmic radiation, energetic solar protons and relativistic electron precipitation from the earth's radiation belts. Chemical considerations during particle precipitation are discussed, with special emphasis on the relative production rate of odd nitrogen and odd hydrogen species during ionizing particle precipitation. The long residence time of NO in the upper stratosphere, where catalytic interaction with O3 is most effective, requires that this mechanism be included in future modeling of global distribution of O3. Other situations causing O3 depletion are also identified.

Thorne, R. M.↗
NASA NTRS2003

Aerosol Chemical Composition in Asian Continental Outflow during the TRACE-P Campaign: Comparison with PEM-West B

Aerosol associated soluble ions and the radionuclide tracers (7)Be and (210)Pb were quantified in 414 filter samples collected in spring 2001 from the DC-8 during the Transport and Chemical Evolution over the Pacific (TRACE-P) campaign. Binning the data into near Asia (flights from Hong Kong and Japan) and remote Pacific (all other flights) revealed large enhancements of NO3(-), SO4(-), C2O4(-), NH4(+), K(+), Mg2(+), and Ca2(+) near Asia. The boundary layer and lower troposphere were most strongly influenced by continental outflow, and the largest enhancements were seen in Ca2(+) (a dust tracer) and NO3(-) (reflecting uptake of HNO3 onto the dust). Comparing the TRACE P near Asia bin with earlier results from the same region during PEM-West B (in 1994) shows at least twofold enhancements during TRACE P in most of the ions listed above. Calcium and NO3(-) were most enhanced in this comparison as well (more than sevenfold higher in the boundary layer and threefold higher in the lower troposphere). Independent estimation of Asian emissions of gaseous precursors of the aerosol-associated ions suggest only small changes between the two missions, and precipitation fields do not suggest any significant difference in the efficiency of the primary sink, precipitation scavenging. It thus appears that with the possible exception of dust, the enhancements of aerosol-associated species during TRACE P cannot be explained by stronger sources or weaker sinks. We argue that the enhancements largely reflect the fact that TRACE P focused on characterizing Asian outflow, and thus the DC-8 was more frequently flown into regions that were influenced by well-organized flow off the continent.

Dibb, Jack E.↗
NASA NTRS2011

Dependences of Ratio of the Luminosity to Ionization on Velocity and Chemical Composition of Meteors

On the bases of results simultaneous photographic and radio echo observations, the results complex radar and television observations of meteors and also results of laboratory modeling of processes of a luminescence and ionization, correlation between of luminous intensity Ip to linear electronic density q from of velocities and chemical structure are investigated. It is received that by increasing value of velocities of meteors and decrease of nuclear weight of substance of particles, lg Ip/q decreased more than one order.

Narziev, M.↗
NASA NTRS1980

On the chemical composition of L-chondrites

Radiochemical neutron activation analysis of Ag, As, Au, Bi, Co, Cs, Ga, In, Rb, Sb, Te, Tl, and Zn and major element data in 14 L4-6 and 3 LL5 chondrites indicates that the L group is unusually variable and may represent at least 2 subgroups differing in formation history. Chemical trends in the S/Fe rich subgroup support textural evidence indicating late loss of a shock formed Fe-Ni-S melt; the S/Fe poor subgroup seemingly reflects nebular fractionation only. Highly mobile In and Zn apparently reflect shock induced loss from L chondrites. However, contrasting chemical trends in several L chondrite sample sets indicate that these meteorites constitute a more irregular sampling of, or more heterogeneous parent material than do carbonaceous or enstatite chondrites. Data for 15 chondrites suggest higher formation temperatures and/or degrees of shock than for LL5 chondrites.

Neal, C. W.↗
NASA NTRS1976

The Surface Chemical Composition of Lunar Samples and Its Significance for Optical Properties

The surface iron, titanium, calcium, and silicon concentration in numerous lunar soil and rock samples was determined by Auger electron spectroscopy. All soil samples show a large increase in the iron to oxygen ratio compared with samples of pulverized rock or with results of the bulk chemical analysis. A solar wind simulation experiment using 2 keV energy alpha -particles showed that an ion dose corresponding to approximately 30,000 years of solar wind increased the iron concentration on the surface of the pulverized Apollo 14 rock sample 14310 to the concentration measured in the Apollo 14 soil sample 14163, and the albedo of the pulverized rock decreased from 0.36 to 0.07. The low albedo of the lunar soil is related to the iron + titanium concentration on its surface. A solar wind sputter reduction mechanism is discussed as a possible cause for both the surface chemical and optical properties of the soil.

Gold, T.↗
NASA NTRS1985

Effects of breaking gravity waves on the chemical composition of the mesosphere and lower thermosphere

Eddy diffusion and momentum forcing in the mesosphere and lower thermosphere arise principally from the effects of breaking gravity and waves. The propagation and dissipation of gravity waves depend strongly on season and latitude because of its relationship to the background zonal wind. These processes have significant effects on the transport of chemical species in that region, so that observations of variations in chemical constituents provide useful tracers for dynamical theory. A parameterization of gravity wave propagation and dissipation was incorporated in the coupled dynamical-chemical model to study these effects. Several easily observable airglow features of the mesosphere-thermosphere region are shown to provide sensitive indications of gravity wave influence. In particular, theoretical predictions of large seasonal and latitudinal variations in the atomic oxygen green line, the Meinal bands of excited OH, and the O3 densities inferred from O2 (delta supra 1 sub g) emission at altitudes from 75 to 90 km are shown to be in remarkably good agreement with observations. Implications of these sensitive chemical tracers for the dynamics of the mesosphere-lower thermosphere region and its relationship to gravity waves are discussed.

Solomon, S.↗
NASA NTRS2013

Evolution of the Stratospheric Temperature and Chemical Composition over One Titanian Year

Since the Voyager 1 (V1) flyby in 1980, Titans exploration from space and the ground has been ongoing for more than a full revolution of Saturn around the Sun (one Titan year or 29.5 Earth years was completed in May 2010). In this study we search for temporal variations affecting Titans atmospheric thermal and chemical structure within that year. We process Cassini CIRS data taken during the Titan flybys from 2006-2013 and compare them to the 1980 V1IRIS spectra (re-analyzed here). We also consider data from Earth-based and -orbiting observatories (such as from the ISO, re-visited). When we compare the CIRS 2010 and the IRIS data we find limited inter-annual variations, below the 25 or35 levels for the lower and middle, or the high latitudes, respectively. A return to the 1980 stratospheric temperatures and abundances is generally achieved from 50degN to 50degS, indicative of the solar radiation being the dominating energy source at 10 AU, as for the Earth, as predicted by GCM and photochemical models. However, some exceptions exist among the most complex hydrocarbons (C4H2 and C3H4), especially in the North. In the Southern latitudes, since 2012, we see a trend for an increase of several trace gases, possibly indicative of a seasonal atmospheric reversal. At the Northern latitudes we found enhanced abundances around the period of the northern spring equinox in mid-2009 (as in Bampasidis et al. 2012), which subsequently decreased (from 2010-2012) returning to values similar to those found in the V1 epoch a Titanian year before.

radiative transfer↗
NASA NTRS1974

Chemical composition of rocks and soils at Taurus-Littrow

Seventeen soils and seven rock samples were analyzed for major elements, minor elements, and trace elements. Unlike the soils at previous Apollo sites, which showed little difference in composition at each collection area, the soils at Taurus-Littrow vary widely. Three soil types are evident, representative of (1) the light mantle at the South Massif, (2) the dark mantle in the valley, and (3) the surface material at the North Massif. The dark-mantle soils are chemically similar to those at Tranquillitatis. Basalt samples from the dark mantle are chemically similar although they range from fine to coarse grained. It is suggested that they originated from the same source but crystallized at varying depths from the surface.

Rose, H. J., Jr.↗
NASA NTRS1980

Response of the global climate to changes in atmospheric chemical composition due to fossil fuel burning

Tropospheric ozone and methane might increase in the future as the result of increasing anthropogenic emissions of CO, NOx and CH4 due to fossil fuel burning. Since O3 and CH4 are both greenhouse gases, increases in their concentrations could augment global warming due to larger future amounts of atmospheric CO2. To test this possible climatic impact, a zonal energy-balance climate model has been combined with a vertically-averaged tropospheric chemical model. The latter model includes all relevant chemical reactions which affect species derived from H2O, O2, CH4 and NOx. The climate model correspondingly incorporates changes in the infrared heating of the surface-troposphere system resulting from chemically induced changes in tropospheric ozone and methane. This coupled climate-chemical model indicates that global climate is sensitive to changes in emissions of CO, NOx and CH4, and that future increases in these emissions could enhance global warming due to increasing atmospheric CO2.

Cess, R. D.↗
NASA NTRS1994

Chemical Composition and Flow Velocity as a Function of Operating Conditions for an Arc Jet Heater

We have used laser-induced fluorescence (LIF) to carry out a detailed, systematic survey of the properties of the free stream of the 20 Megawatt Aerodynamic Heating Facility at NASA/Ames Research Center. In both air and nitrogen flows we have measured the atomic nitrogen absolute number density and flow velocity at each operating condition. In air flows we have also measured the atomic oxygen absolute number density and rotational/translational temperature at each operating condition. These results have been used to provide, for the first time, a direct, nonintrusive measurement of the enthalpy on the centerline of the flow. In addition, the observed arc jet properties can be used to test and improve computer simulations of the arc jet flow which include detailed chemical rate processes (especially nitrogen atom recombination) taking place during the supersonic expansion.

Bamford, Douglas J.↗
NASA NTRS2013

Chemical Composition of Four Shergottites from Northwest Africa (NWA 2800, NWA, 5214, NWA 5990, NWA 6342)

Shergottites represent the majority of recovered Martian meteorites. As basic igneous rocks, they formed from magmas that were emplaced in the Martian crust [1]. Due to the low ambient pressure of the Martian atmosphere, subaerial lavas and shallow magma chambers are expected to outgas volatile metals (e.g., Cd, Te, Re, Bi) [2]. The planetary abundances of the volatile siderophile and chalcophile elements are important at establishing the depth of core formation for Mars, and must be known as a baseline for understanding volcanic outgassing on Mars, particularly the large enrichments of S and Cl observed in modern Martian soils [3]. There is little data on volatile siderophile and chalcophile elements from Martian meteorites, excluding a few well-analyzed samples [2]. Further, a large number of shergottites being recovered from North West Africa are in need of chemical analysis. All of the shergottites are in need of state-of-the art analysis for such ratios as Ge/Si and Ga/Al, which can now be accomplished by LA-ICP-MS [2].

Yang, S.↗
NASA NTRS1990

Chemical compositions of refractory inclusions from the Vigarano and Leoville carbonaceous chondrites

The contents of the major and the trace elements of three refractory inclusions from Leoville and two hibonite-rich refractory inclusions and a dark clast from Vigarano were investigated using INAA technique, and the results were compared with results reported for an Allende inclusion. It was found that two out of the three refractory inclusions from Leoville and both inclusions from Vigarano have lower Na and Au contents than the coarse-grained inclusion from Allende. It is shown that the concentrations of all volatile elements in refractory inclusions in the Leoville and Vigarano meteorites tend to be either below or at the low end of their concentration ranges in Allende coarse-grained inclusions. This is considered to be due to the fact that the former were altered in parts of the solar nebula where grain-bias separation processes removed the inclusions from chemical communication with the gas at a higher temperature or after a shorter time than for the inclusions from Allende.

Mao, Xue-Ying↗
NASA NTRS2014

Global and Regional Impacts of HONO on the Chemical Composition of Clouds and Aerosols

Recently, realistic simulation of nitrous acid (HONO) based on the HONO / NOx ratio of 0.02 was found to have a significant impact on the global budgets of HOx (OH + HO2) and gas phase oxidation products in polluted regions, especially in winter when other photolytic sources are of minor importance. It has been reported that chemistry-transport models underestimate sulphate concentrations, mostly during winter. Here we show that simulating realistic HONO levels can significantly enhance aerosol sulphate (S(VI)) due to the increased formation of H2SO4. Even though in-cloud aqueous phase oxidation of dissolved SO2 (S(IV)) is the main source of S(VI), it appears that HONO related enhancement of H2O2 does not significantly affect sulphate because of the predominantly S(IV) limited conditions, except over eastern Asia. Nitrate is also increased via enhanced gaseous HNO3 formation and N2O5 hydrolysis on aerosol particles. Ammonium nitrate is enhanced in ammonia-rich regions but not under ammonia-limited conditions. Furthermore, particle number concentrations are also higher, accompanied by the transfer from hydrophobic to hydrophilic aerosol modes. This implies a significant impact on the particle lifetime and cloud nucleating properties. The HONO induced enhancements of all species studied are relatively strong in winter though negligible in summer. Simulating realistic HONO levels is found to improve the model measurement agreement of sulphate aerosols, most apparent over the US. Our results underscore the importance of HONO for the atmospheric oxidizing capacity and corroborate the central role of cloud chemical processing in S(IV) formation

Global and regional impacts↗
NASA NTRS2014

Global and Regional Impacts of HONO on the Chemical Composition of Clouds and Aerosols

Recently, realistic simulation of nitrous acid (HONO) based on the HONO/NO(sub x) ratio of 0.02 was found to have a significant impact on the global budgets of HO(sub x) (OH + HO2) and gas phase oxidation products in polluted regions, especially in winter when other photolytic sources are of minor importance. It has been reported that chemistry-transport models underestimate sulphate concentrations, mostly during winter. Here we show that simulating realistic HONO levels can significantly enhance aerosol sulphate (S(VI)) due to the increased formation of H2SO4. Even though in-cloud aqueous phase oxidation of dissolved SO2 (S(IV)) is the main source of S(VI), it appears that HONO related enhancement of H2O2 does not significantly affect sulphate because of the predominantly S(IV) limited conditions, except over eastern Asia. Nitrate is also increased via enhanced gaseous HNO3 formation and N2O5 hydrolysis on aerosol particles. Ammonium nitrate is enhanced in ammonia-rich regions but not under ammonia-limited conditions. Furthermore, particle number concentrations are also higher, accompanied by the transfer from hydrophobic to hydrophilic aerosol modes. This implies a significant impact on the particle lifetime and cloud nucleating properties. The HONO induced enhancements of all species studied are relatively strong in winter though negligible in summer. Simulating realistic HONO levels is found to improve the model measurement agreement of sulphate aerosols, most apparent over the US. Our results underscore the importance of HONO for the atmospheric oxidizing capacity and corroborate the central role of cloud chemical processing in S(IV) formation.

HONO↗