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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 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Constraining Arctic Climate Projections of Wintertime Warming With Surface Turbulent Flux Observations and Representation of Surface-Atmosphere Coupling

The drivers of rapid Arctic climate change—record sea ice loss, warming SSTs, and a lengthening of the sea ice melt season—compel us to understand how this complex system operates and use this knowledge to enhance Arctic predictability. Changing energy flows sparked by sea ice decline, spotlight atmosphere-surface coupling processes as central to Arctic system function and its climate change response. Despite this, the representation of surface turbulent flux parameterizations in models has not kept pace with our understanding. The large uncertainty in Arctic climate change projections, the central role of atmosphere-surface coupling, and the large discrepancy in model representation of surface turbulent fluxes indicates that these processes may serve as useful observational constraints on projected Arctic climate change. This possibility requires an evaluation of surface turbulent fluxes and their sensitivity to controlling factors (surface-air temperature and moisture differences, sea ice, and winds) within contemporary climate models (here Coupled Model Intercomparison Project 6). The influence of individual controlling factors and their interactions is diagnosed using a multi-linear regression approach. This evaluation is done for four sea ice loss regimes, determined from observational sea ice loss trends, to control for the confounding effects of natural variability between models and observations. The comparisons between satellite- and model-derived surface turbulent fluxes illustrate that while models capture the general sensitivity of surface turbulent fluxes to declining sea ice and to surface-air gradients of temperature and moisture, substantial mean state biases exist. Specifically, the central Arctic is too weak of a heat sink to the winter atmosphere compared to observations, with implications to the simulated atmospheric circulation variability and thermodynamic profiles. Models were found to be about 50% more efficient at turning an air-sea temperature gradient anomaly into a sensible heat flux anomaly relative to observations. Further, the influence of sea ice concentration on the sensible heat flux is underestimated in models compared to observations. The opposite is found for the latent heat flux variability in models; where the latent heat flux is too sensitive to a sea ice concentration anomaly. Lastly, the results suggest that present-day trends in sea ice retreat regions may serve as suitable observational constraints of projected Arctic warming.

turbulent fluxes↗
NASA NTRS1982

Space platforms and meteorological applications

The use of Shuttle launched and tended space platforms (SP) for research and earth observations in LEO are examined. SPs will accommodate instruments for extended time periods, requiring a Shuttle visit for maintenance and package exchange once every six months. Designs have included off-the-shelf hardware to reduce cost, and comprise instruments for studies of cosmic rays, solar physics, materials processing, space plasma physics, and environmental observations. Solar cell power arrays are detailed, along with thermal control, data management, and attitude control subsystems. Meteorological applications are discussed in terms of the Lower Atmospheric Research Satellite (LARS), for research into coupling of radiative, chemical, and dynamical processes, interactions between the earth's surface, boundary layer, and troposphere, and dynamic and energetic relationships between lower atmospheric processes. Flight configurations and add-on concepts for the SP to lead to a manned space station are indicated.

Mitchell, K. L.↗
DOE OSTI2015

High-performance ZnO nanowire field-effect transistor with forming gas treated SiO{sub 2} gate dielectrics

The SiO{sub 2} films thermally grown on Si wafer have been annealed in forming atmosphere (N{sub 2}:H{sub 2} = 9:1) prior to use as gate insulators in ZnO nanowire field effect transistors (ZnO NW-FETs). Without the annealing process, ZnO NW-FETs exhibit very poor performance, and most of them even cannot be depleted under a high gate voltage of −100 V; however, with the annealing process in forming atmosphere, the device characteristics can be significantly improved, exhibiting a large turn on-off ratio of ∼10{sup 4} and a low sub-threshold swing ∼1 V/decade. The pre-annealing treatment of SiO{sub 2} (300 nm)/p-Si in N{sub 2}/H{sub 2} ambient may significantly reduce the number of non-bridging oxygen atoms, which blocks the interaction between ZnO nanowires and SiO{sub 2} surface, and finally enhances the electrical characteristics of the back-gated ZnO NW-FETs. In addition, the FET electrode fabrication process introduced in this paper is much simpler than the traditional photo-lithography and lift-off method, which has potential applications in future device fabrication.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2016

Mars Atmospheric In Situ Resource Utilization Projects at the Kennedy Space Center

The atmosphere of Mars, which is 96 percent carbon dioxide (CO2), is a rich resource for the human exploration of the red planet, primarily by the production of rocket propellants and oxygen for life support. Three recent projects led by NASAs Kennedy Space Center have been investigating the processing of CO2. The first project successfully demonstrated the Mars Atmospheric Processing Module (APM), which freezes CO2 with cryocoolers and combines sublimated CO2 with hydrogen to make methane and water. The second project absorbs CO2 with Ionic Liquids and electrolyzes it with water to make methane and oxygen, but with limited success so far. A third project plans to recover up to 100 of the oxygen in spacecraft respiratory CO2. A combination of the Reverse Water Gas Shift reaction and the Boudouard reaction eventually fill the reactor up with carbon, stopping the process. A system to continuously remove and collect carbon has been tested with encouraging results.

oxygen production and recovery↗
NASA NTRS2016

Mars Atmospheric In Situ Resource Utilization Projects at the Kennedy Space Center

The atmosphere of Mars, which is approximately 95% carbon dioxide (CO2), is a rich resource for the human exploration of the red planet, primarily by the production of rocket propellants and oxygen for life support. Three recent projects led by NASA's Kennedy Space Center have been investigating the processing of CO2. The first project successfully demonstrated the Mars Atmospheric Processing Module (APM), which freezes CO2 with cryocoolers and combines sublimated CO2 with hydrogen to make methane and water. The second project absorbs CO2 with Ionic Liquids and electrolyzes it with water to make methane and oxygen, but with limited success so far. A third project plans to recover up to 100% of the oxygen in spacecraft respiratory CO2. A combination of the Reverse Water Gas Shift reaction and the Boudouard reaction eventually fill the reactor up with carbon, stopping the process. A system to continuously remove and collect carbon is under construction.

in situ resource utilization↗
NASA NTRS2004

The Lifecycle of NASA's Earth Science Enterprise Data Resources

A major endeavor of NASA's Earth Science Enterprise (ESE) is to acquire, process, archive and distribute data from Earth observing satellites in support of a broad set of science research and applications in the U. S. and abroad. NASA policy directives specifically call for the agency to collect, announce, disseminate and archive all scientific and technical data resulting from NASA and NASA-funded research. During the active life of the satellite missions, while the data products are being created, validated and refined, a number of NASA organizations have the responsibility for data and information system functions. Following the completion of the missions, the responsibility for the long-term stewardship of the ocean and atmospheric, and land process data products transitions to the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Geological Survey (USGS), respectively. Ensuring that long-term satellite data be preserved to support global climate change studies and other research topics and applications presents some major challenges to NASA and its partners. Over the last several years, with the launch and operation of the EOS satellites and the acquisition and production of an unprecedented volume of Earth science data, the importance of addressing these challenges has been elevated. The lifecycle of NASA's Earth science data has been the subject of several agency and interagency studies and reports and has implications and effects on agency charters, policies and budgets and on their data system's requirements, implementation plans and schedules. While much remains to be done, considerable progress has been made in understanding and addressing the data lifecycle issues.

McDonald, Kenneth R.↗
DOE OSTI2024

Statistical Relations among Solid Precipitation, Atmospheric Moisture and Cloud Parameters in the Arctic

Observations collected during cold-season precipitation periods at Utquagvik, Alaska and at the multidisciplinary drifting observatory for the study of Arctic climate (MOSAiC) are used to statistically analyze the relations among the atmospheric water cycle parameters including the columnar supercooled liquid and ice amounts (expressed as liquid-water and ice-water paths, i.e., LWP and IWP), the integrated water vapor (IWV) and the near-surface snowfall rate. Data come from radar and radiometer-based retrievals and from optical precipitation sensors. While the correlation between snowfall rate and LWP is rather weak, correlation coefficients between radar-derived snowfall rate and IWP are high (~0.8), which is explained, in part, by the generally low LWP/IWP ratios during significant precipitation. Correlation coefficients between snowfall rate and IWV are moderate (~0.45). Correlations are generally weaker if snowfall is estimated by optical sensors, which is, in part, due to blowing snow. Correlation coefficients between near-surface temperature and snowfall rates are low (r < 0.3). The results from the Alaska and MOSAiC sites are generally similar. These results are not very sensitive to the amount of time averaging (e.g., 15 min averaging versus daily averages). Observationally based relations among the water cycle parameters are informative about atmospheric moisture conversion processes and can be used for model evaluations.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2012

Applications of MODIS Fluorescent Line Height Measurements to Monitor Water Quality Trends and Algal Bloom Activity

Recent advances in satellite and airborne remote sensing, such as improvements in sensor and algorithm calibrations, processing techniques and atmospheric correction procedures have provided for increased coverage of remote-sensing, ocean-color products for coastal regions. In particular, for the Moderate Resolution Imaging Spectrometer (MODIS) sensor calibration updates, improved aerosol retrievals and new aerosol models has led to improved atmospheric correction algorithms for turbid waters and have improved the retrieval of ocean color in coastal waters. This has opened the way for studying ocean phenomena and processes at finer spatial scales, such as the interactions at the land-sea interface, trends in coastal water quality and algal blooms. Human population growth and changes in coastal management practices have brought about significant changes in the concentrations of organic and inorganic, particulate and dissolved substances entering the coastal ocean. There is increasing concern that these inputs have led to declines in water quality and have increase local concentrations of phytoplankton, which cause harmful algal blooms. In two case studies we present MODIS observations of fluorescence line height (FLH) to 1) assess trends in water quality for Tampa Bay, Florida and 2) illustrate seasonal and annual variability of algal bloom activity in Monterey Bay, California as well as document estuarine/riverine plume induced red tide events. In a comprehensive analysis of long term (2003-2011) in situ monitoring data and satellite imagery from Tampa Bay we assess the validity of the MODIS FLH product against chlorophyll-a and a suite of water quality parameters taken in a variety of conditions throughout a large optically complex estuarine system. A systematic analysis of sampling sites throughout the bay is undertaken to understand how the relationship between FLH and in situ chlorophyll-a responds to varying conditions and to develop a near decadal trend in water quality changes. In situ monitoring locations that correlated well with satellite imagery were in depths greater than seven meters and were located over five kilometers from shore. Water quality parameter of total nitrogen, phosphorous, turbidity and biological oxygen demand had high correlations with these sites, as well. Satellite FLH estimates show improving water quality from 2003-2007 with a slight decline up through 2011. Dinoflagellate blooms in Monterey Bay, California (USA) have recently increased in frequency and intensity. Nine years of MODIS FLH observations are used to describe the annual and seasonal variability of bloom activity within the Bay. Three classes of MODIS algorithms were correlated against in situ chlorophyll measurements. The FLH algorithm provided the most robust estimate of bloom activity. Elevated concentrations of phytoplankton were evident during the months of August-November, a period during which increased occurrences of dinoflagellate blooms have been observed in situ. Seasonal patterns of FLH show the on- and offshore movement of areas of high phytoplankton biomass between oceanographic seasons. Higher concentrations of phytoplankton are also evident in the vicinity of the land-based nutrient sources and outflows, and the cyclonic bay-wide circulation can transport these nutrients to the northern Bay bloom incubation region. Both of these case studies illustrate the utility MODIS FLH observations in supporting management decisions in coastal and estuarine waters.

Fischer, Andrew↗
DOE OSTI2018

Demonstration of Carbon Capture and Sequestration of Steam Methane Reforming Process Gas Used for Large-Scale Hydrogen Production

The large-scale, on-purpose production of hydrogen in the United States (i.e., ~4600 million standard cubic feet per day) represents one of the most significant industrial sources of CO 2 emissions within the chemical industry. Most of the hydrogen is produced by the steam methane reforming (SMR) process, through which methane and water are converted to H 2 and CO 2 , and virtually all of the co-produced CO 2 is emitted to the atmosphere. However, the process streams in the SMR plants contain CO 2 at concentrations that are amenable to utilization of conventional adsorption and emerging CO 2 capture technologies. If implemented commercially, these technologies could represent an early and sizeable impact in reducing industrial CO 2 emissions. Therefore, Air Products, working closely with the Department of Energy, has conducted a carbon capture and sequestration (CCS) project to demonstrate a first-of-a-kind retrofit system to capture CO 2 from large-scale industrial SMR plants. Working with the support of Denbury Onshore, LLC (“Denbury Onshore”) and its affiliate, Denbury Green Pipeline-Texas, LLC (“Denbury Green Pipeline”), Air Products designed, constructed and continues to operate a state-of-the-art system located at the Valero Port Arthur Refinery in Port Arthur, TX. This system concentrates the CO 2 from two SMR waste streams and delivers it into the Green Pipeline-Texas for transport to and use in the West Hastings Unit enhanced oil recovery (EOR) project. The CO 2 removal units were designed by Air Products and utilize vacuum swing adsorption (VSA) units that were retrofitted into each of the SMR trains upstream of existing pressure swing adsorption (PSA) units. This project is unique because the site has two large-scale, highly integrated SMRs located in proximity to one another. The CO 2 from this project is concentrated from 15% in the SMR waste stream to at least 98%, then flowed into the Green Pipeline-Texas along the eastern Gulf Coast. The Green Pipeline collects CO 2 from a variety of sources that is utilized for tertiary oil recovery in Texas. This project alone can prevent over 1 million tons per year of CO 2 from being emitted into the atmosphere, and thus play a major role in significantly reducing greenhouse gas emissions.

08 HYDROGEN↗
DOE OSTI2014

Polarized scattering with Paschen-Back effect, hyperfine structure, and partial frequency redistribution in magnetized stellar atmospheres

F-state interference significantly modifies the polarization produced by scattering processes in the solar atmosphere. Its signature in the emergent Stokes spectrum in the absence of magnetic fields is depolarization in the line core. In the present paper, we derive the partial frequency redistribution (PRD) matrix that includes interference between the upper hyperfine structure states of a two-level atom in the presence of magnetic fields of arbitrary strengths. The theory is applied to the Na I D{sub 2} line that is produced by the transition between the lower J = 1/2 and upper J = 3/2 states which split into F states because of the coupling with the nuclear spin I{sub s} = 3/2. The properties of the PRD matrix for the single-scattering case is explored, in particular, the effects of the magnetic field in the Paschen-Back regime and their usefulness as a tool for the diagnostics of solar magnetic fields.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1995

Photochemistry and stability of the atmosphere of Mars

An understanding of the composition, structure, transport and photochemical processes of the present atmosphere of Mars is essential for addressing such fundamental questions as the stability, evolution and the origin of the Martian atmosphere. This paper discusses our current knowledge of the photochemistry and stability of the Martian atmosphere, with special emphasis on new models and work in progress.

Atreya, S. K.↗
NASA NTRS2004

Sensitivity of Precipitation in Coupled Land-Atmosphere Models

The project objective was to understand mechanisms by which atmosphere-land-ocean processes impact precipitation in the mean climate and interannual variations, focusing on tropical and subtropical regions. A combination of modeling tools was used: an intermediate complexity land-atmosphere model developed at UCLA known as the QTCM and the NASA Seasonal-to-Interannual Prediction Program general circulation model (NSIPP GCM). The intermediate complexity model was used to develop hypotheses regarding the physical mechanisms and theory for the interplay of large-scale dynamics, convective heating, cloud radiative effects and land surface feedbacks. The theoretical developments were to be confronted with diagnostics from the more complex GCM to validate or modify the theory.

Neelin, David↗
NASA NTRS1974

High latitude minor ion enhancements - A clue for studies of magnetosphere-atmosphere coupling

An investigation is conducted of upper ionosphere molecular ion composition data, which because of the unexpected, abrupt enhancements sometimes exhibited at high latitudes, may indirectly offer additional clues to understanding the processes by which the lower atmosphere becomes perturbed. It is found that molecular ion irregularities are sometimes localized in a relatively narrow region of time and space. The abruptness of these events suggests that lower atmosphere energetic processes presumed responsible for the ion enhancements may also be narrowly distributed.

Taylor, H. A., Jr.↗
DOE OSTI2014

Green Ocean Amazon (GOAmazon 2014-2015 Summary)

Tropical cloud systems are the primary drivers of the global atmospheric circulation—a huge cycle of atmospheric energy and moisture transported around the Earth, affecting both weather and climate. Tropical deep convection under contrasting very clean and polluted conditions in the Amazon and the underlying process that drives it are complex. Efforts to simulate these processes with climate models remain largely unsuccessful. To study the coupled atmosphere-cloud-terrestrial tropical systems that drive tropical deep convection, the Amazonas Research Foundation (FAPEAM), São Paulo Research Foundation (FAPESP), and the U.S. Department of Energy (DOE) are sponsoring an integrated field experiment in Brazil’s Amazon Basin. Using a network of instrumented observation sites, the mission is to advance scientific understanding of how land-atmosphere processes affect tropical hydrology and climate, and improve the representation of these coupled processes in climate models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Probing the Early Stages of Solvation of cis-Pinate Dianions by Water, Acetonitrile, and Methanol: A Photoelectron Spectroscopy and Theoretical Study

Cis-pinic acid is one of the most important oxidation products of α-pinene – a key monoterpene compound in biogenic emission processes affecting the atmosphere. Molecular level understanding of interactions involved in the cluster formations around cis-pinic acid is an important and necessary prerequisite toward ascertaining its role in the aerosol formation processes. In this work, we studied the structures and energetics of the solvated clusters of cis-pinate (cis-PA²⁻), the doubly deprotonated dicarboxylate of cis-pinic acid, with H₂O, CH₃OH, and CH₃CN by negative ion photoelectron spectroscopy and ab initio theoretical calculations. We found that cis-PA²⁻ prefers being solvated alternately on the two -CO₂⁻ groups with increase of solvent coverage, a well-known solvation pattern that has been observed in microhydrated linear dicarboxylate dianion (DC n ²⁻) clusters. Experiments and calculations further reveal an intriguing feature for the existence of the asymmetric type isomers for cis-PA2–(H2O)2 and cis-PA²⁻(CH₃OH)₂, in which both solvent molecules interact with only one of the -CO²⁻ groups – a phenomena that has not been observed in DCn²⁻ water clusters and exhibits the subtle effect of the rigid four-membered carbon ring brought in on the cis-PA²⁻ solvation. The dominant interactions between cis-PA²⁻ and solvent molecules are forming bidentate O–···H–O H-bonds for H₂O, O–···H–O and O–···H–C H-bonds for CH₃OH, and tridentate O–···H–C H-bonds for CH₃CN. The formation of inter-solvent H-bonds between H₂O and CH₃CN is found to be favorable in mixed solvent clusters, distinctly different from that between H₂O and CH₃OH. These findings have important implications for understanding the mechanism of cluster growth and nucleation of atmospheric organic aerosols and the nature of structure-function relationship of proteins containing carboxylate groups under various solvent environments.

Environmental Molecular Sciences Laboratory↗
NASA NTRS1988

Infrared spectroscopy of Jupiter and Saturn

High resolution infrared spectoscopy provides unique insights into the chemistry and dynamics of the atmospheres of Jupiter and Saturn. The 5 micrometer spectral region, which is transparent to deep levels, is particularly useful for the identification of molecules that are present at very low (parts per billion) concentrations. These are tracers of convective and strongly non-equilibrium processes in the atmosphere. High resolution ground-based spectroscopy complements Voyager and Galileo measurements. Spectroscopy is sensitive to lower mixing levels for selected molecules, while the on-board mass spectrometers probe molecules that are spectroscopically inaccessible. Analysis and modeling of the 4.7 micrometer carbon monoxide in Jupiter was completed. CO is present at a mole fraction of 1.6 plus or minus 0.3 x 10 to the 9th power and concentrated in the troposphere. At this abundance, it must be convected upward from much deeper levels in Jupiter where the temperature is near 1100 K. Thus CO is a tracer of the deep atmosphere which is otherwise unobservable. The oxygen abundance in Jupiter (as measured by the CO abundance) is near solar. Chemical or physical process must deplete the major oxygen carrier, water. Germane, GeH4, was discovered on Saturn at amole fraction of 4 plus or minus 2 x 10 to the 10th power.

Knacke, Roger↗
NASA NTRS1985

Balloon-borne observation of Aitken nuclei in the Antarctic stratosphere and troposphere

Aitken nuclei (0.002 or = r or = 0.1 microns in the atmosphere are produced through gas-to-particle conversion processes, and they grow in size by heterogeneous nucleation processes and others to produce larger aerosol particles. In the study of global background aerosol pollution, full knowledge of such aerosol processes in the clean atmosphere is essentially required. In this sense, it is important to examine the behavior of aerosols in a clean atmosphere which is not contaminated directly by aerosols and gases emitted from the Earth's surface. The Antarctic atmosphere is thought to be such a clean atmosphere. From an extensive surface observation of aerosols carried out at Syowa Station (69 deg 00'S, 39 deg 35'E) Antarctica, it has been revealed that various phenomena relating to long-range transport of trace constituents and/or photochemical processes resulting in production or growth of aerosol particles are clearly observed in Antarctica. This paper gives a preliminary report of observations made by balloon-borne Aitken nuclei sonde in 1983, at Syowa Station.

Ito, T.↗