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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 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Physical mechanisms of heat, momentum and turbulence fluxes

In a qualitative way, the physical mechanisms which generate fluxes of heat, momentum, and turbulence in the atmosphere are discussed. This material is presented to acquaint people with the Earth science aspects of turbulence as important processes in the atmosphere. To attempt to describe turbulent fluxes of heat, momentum, and moisture in precise mathematical detail becomes an intractable problem. It is burdened by an eighth order set of equations involving more variables than equations. It is a closure problem which requires complicated assumptions that are not necessarily always satisfied, variable boundary conditions, and sparse observational data. Therefore, we must approach the problem in a simplified manner to obtain any kind of solution involving the variables of shear, stress, and heat, moisture, and momentum fluxes. There are other problems, of course, in which the inclusion of the planetary boundary layer is extremely important. Air pollution studies, air-sea exchanges, mesoscale models, and so on, must account for the planetary layer in very specific terms. Some of the physical mechanisms that are involved in generating fluxes are described.

Theon, John S.↗
NASA NTRS2000

The Distribution of Carbon Monoxide in the GOCART Model

Carbon monoxide (CO) is an important trace gas because it is a significant source of tropospheric Ozone (O3) as well as a major sink for atmospheric hydroxyl radical (OH). The distribution of CO is set by a balance between the emissions, transport, and chemical processes in the atmosphere. The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate the atmospheric distribution of CO. The GOCART model is driven by the assimilated meteorological data from the Goddard Earth Observing System Data Assimilation System (GEOS DAS) in an off-line mode. We study the distribution of CO on three time scales: (1) day to day fluctuation produced by the synoptic waves; (2) seasonal changes due to the annual cycle of CO sources and sinks; and (3) interannual variability induced by dynamics. Comparison of model results with ground based and remote sensing measurements will also be presented.

Fan, Xiaobiao↗
NASA NTRS1994

A Coupled Soil-Atmosphere Model of H2O2 on Mars

The Viking Gas Chromatograph Mass Spectrometer failed to detect organic compounds on Mars, and both the Viking Labeled Release and the Viking Gas Exchange experiments indicated a reactive soil surface. These results have led to the widespread belief that there are oxidants in the martian soil. Since H2O2 is produced by photochemical processes in the atmosphere of Mars, and has been shown in the laboratory to reproduce closely the Viking LR results, it is a likely candidate for a martian soil oxidant. Here, we report on the results of a coupled soil/atmosphere transport model for H202 on Mars. Upon diffusing into the soil, its concentration is determined by the extent to which it is adsorbed and by the rate at which it is catalytically destroyed. An analytical model for calculating the distribution of H202 in the martian atmosphere and soil is developed. The concentration of H202 in the soil is shown to go to zero at a finite depth, a consequence of the nonlinear soil diffusion equation. The model is parameterized in terms of an unknown quantity, the lifetime of H202 against heterogeneous catalytic destruction in the soil. Calculated concentrations are compared with a H202 concentration of 30 nmoles/cu cm, inferred from the Viking Labeled Release experiment. A significant result of this model is that for a wide range of H202 lifetimes (up to 105 years), the extinction depth was found to be less than 3 m. The maximum possible concentration in the top 4 cm is calculated to be approx. 240 nmoles/cu cm, achieved with lifetimes of greater than 1000 years. Concentrations higher than 30 nmoles/cu cm require lifetimes of greater than 4.3 terrestrial years. For a wide range of H202 lifetimes, it was found that the atmospheric concentration is only weakly coupled with soil loss processes. Losses to the soil become significant only when lifetimes are less than a few hours. If there are depths below which H202 is not transported, it is plausible that organic compounds, protected from an oxidizing environment, may still exist. They would have been deposited by meteors, or be the organic remains of past life.

Bullock, Mark A.↗
NASA NTRS1981

Coal desulfurization by low temperature chlorinolysis, phase 3

Laboratory scale, bench scale batch reactor, and minipilot plant tests were conducted on 22 bituminous, subbituminous, and lignite coals. Chemical pretreatment and post treatment of coals relative to the chlorination were tried as a means of enhancing desulfurization by the chlorinolysis process. Elevated temperature (500-700 C) hydrogen treatment of chlorinolysis-processed coal at atmospheric pressure was found to substantially increase coal desulfurization up to 90 percent. Sulfur forms, proximate and ultimate analyses of the processed coal are included. Minipilot plant operation indicates that the continuous flow reactor provides coal desulfurization results comparable to those obtained in the batch reactor. Seven runs were conducted at coal feed rates of 1.5 to 8.8 kg per hour using water and methylchloroform solvents, gaseous chlorine feed of 3 to 31.4 SCFH at 21 to 70 C, and atmospheric pressure for retention times of 20 to 120 minutes.

Kalvinskas, J. J.↗
NASA NTRS2021

On the effects of the ocean on atmospheric CFC-11 lifetimes and emissions

The ocean is a reservoir for CFC-11, a major ozone-depleting chemical. Anthropogenic production of CFC-11 dramatically decreased in the 1990s under the Montreal Protocol, which stipulated a global phase out of production by 2010. However, studies raise questions about current overall emission levels and indicate unexpected increases of CFC-11 emissions of about 10 Gg/yr after 2013 (based upon measured atmospheric concentrations and an assumed atmospheric lifetime). These findings heighten the need to understand processes that could affect the CFC-11 lifetime, including ocean fluxes. We evaluate how ocean uptake and release through 2300 affects CFC-11 lifetimes, emission estimates, and the long-term return of CFC-11 from the ocean reservoir. We show that ocean uptake yields a shorter total lifetime and larger inferred emission of atmospheric CFC-11 from 1930 to 2075 compared to estimates using only atmospheric processes. Ocean flux changes over time result in small but not completely negligible effects on the calculated unexpected emissions change (decreasing it by 0.4 ± 0.3 Gg/yr). Moreover, it is expected that the ocean will eventually become a source of CFC-11, increasing its total lifetime thereafter. Ocean outgassing should produce detectable increases in global atmospheric CFC-11 abundances by the mid-2100s, with emission of around 0.5 Gg/yr; this should not be confused with illicit production at that time. An illustrative model projection suggests that climate change is expected to make the ocean a weaker reservoir for CFC-11, advancing the detectable change in the global atmospheric mixing ratio by about 5 yr.

Anthropogenic production of CFC-11↗
DOE OSTI2018

The Role of Organic Aerosol in Atmospheric Ice Nucleation: A Review

Predicting the formation of ice crystals in the atmosphere presents one of the great challenges in physical sciences with important implications for the chemistry and composition of the Earth’s atmosphere, the hydrological cycle, and climate. Among atmospheric ice formation processes, heterogeneous ice nucleation proceeds on aerosol particles ranging from a few nanometers to micrometers in size, commonly referred to as ice nucleating particles (INPs). Research over the last two decades has demonstrated that organic matter (OM) is ubiquitous in the atmosphere, present as organic aerosol (OA) particles or as coatings on other particle types. While it is well understood that mineral dust particles can induce ice nucleation under atmospheric conditions, it is currently not clear how much OA particles including pollution aerosol and secondary organic aerosol (SOA) contributes to the ambient INP population. The physicochemical properties of OM make predicting how OM interacts with water vapor leading ultimately to ice crystals challenging. This review focuses on the role of OM in INPs, summarizing and highlighting recent advances in our understanding of the ice nucleation process gained from theoretical, laboratory, and field studies. Examination of ice residuals and INPs with analytical techniques demonstrates that OM participates in atmospheric ice crystal formation. Molecular dynamic simulations provide insight into the microscopic processes that initiate ice nucleation. The amorphous phase state of OM in the supercooled and metastable regime is identified as a key factor in assessing the particles’ nucleation pathways and rates. A theoretical model is advanced, based on particle water activity, to holistically predict amorphous phase changes and ice nucleation rates of particles coated by OM. The goal of this review is to synthesize our current understanding and propose future research directions needed to fully evaluate how OA particles contribute to INPs in the atmosphere.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

CLOUDS, AEROSOLS, RADIATION AND THE AIR-SEA INTERFACE OF THE SOUTHERN OCEAN: ESTABLISHING DIRECTIONS FOR FUTURE RESEARCH

A workshop sponsored by the Department of Energy was convened at the University of Washington to discuss the state of knowledge of clouds, aerosols and air-sea interaction over the Southern Ocean and to identify strategies for reducing uncertainties in their representation in global and regional models. The Southern Ocean plays a critical role in the global climate system and is a unique pristine environment, yet other than from satellite, there have been sparse observations of clouds, aerosols, radiation and the air-sea interface in this region. Consequently, much is unknown about atmospheric and oceanographic processes and their linkage in this region. Approximately 60 scientists, including graduate students, postdoctoral fellows and senior researchers working in atmospheric and oceanic sciences at U.S. and foreign universities and government laboratories, attended the Southern Ocean Workshop. It began with a day of scientific talks, partly in plenary and partly in two parallel sessions, discussing the current state of the science for clouds, aerosols and air-sea interaction in the Southern Ocean. After the talks, attendees broke into two working groups; one focused on clouds and meteorology, and one focused on aerosols and their interactions with clouds. This was followed by more plenary discussion to synthesize the two working group discussions and to consider possible plans for organized activities to study clouds, aerosols and the air-sea interface in the Southern Ocean. The agenda and talk slides, including short summaries of the highlights of the parallel session talks developed by the session chars, are available at http://www.atmos.washington.edu/socrates/presentations/SouthernOceanPresentations/.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Implementation of a Quasi-3D Multiscale Modeling Framework to ACME

Representation of unresolved cloud processes has been one of the most challenging problems in numerical modeling of the atmosphere. During the last decades, considerable efforts have been spent to better represent the collective effects of those processes in terms of resolved scales (see Arakawa 2004 for a review). Still, the progress on this problem has been unacceptably slow as pointed out by Randall et al. (2003). The large part of the difficulty is inherent in the artificial separation of atmospheric processes into the explicitly simulated resolved scales and the highly parameterized subgrid scales. Arakawa (2004) and Arakawa et al. (2011) suggested two plausible approaches to eliminate the problem of artificial separation ofatmospheric processes: “parameterize everything” and “resolve everything”.

58 GEOSCIENCES↗
NASA NTRS1982

Sources of atmospheric ammonia

The information available on factors that influence emissions from the principal societal sources of ammonia to the atmosphere, namely combustion processes, volatilization of farm animal wastes, and volatilization of fertilizers, is reviewed. Emission factors are established for each major source of atmospheric ammonia. The factors are then multiplied by appropriate source characterization descriptors to obtain calculated fluxes of ammonia to the atmosphere on a state-by-state basis for the United States.

Harriss, R. C.↗
NASA NTRS2003

Satellite and Surface Data Synergy for Developing a 3D Cloud Structure and Properties Characterization Over the ARM SGP. Stage 1: Cloud Amounts, Optical Depths, and Cloud Heights Reconciliation

One of the primary Atmospheric Radiation Measurement (ARM) Program objectives is to obtain measurements applicable to the development of models for better understanding of radiative processes in the atmosphere. We address this goal by building a three-dimensional (3D) characterization of the cloud structure and properties over the ARM Southern Great Plains (SGP). We take the approach of juxtaposing the cloud properties as retrieved from independent satellite and ground-based retrievals, and looking at the statistics of the cloud field properties. Once these retrievals are well understood, they will be used to populate the 3D characterization database. As a first step we determine the relationship between surface fractional sky cover and satellite viewing angle dependent cloud fraction (CF). We elaborate on the agreement intercomparing optical depth (OD) datasets from satellite and ground using available retrieval algorithms with relation to the CF, cloud height, multi-layer cloud presence, and solar zenith angle (SZA). For the SGP Central Facility, where output from the active remote sensing cloud layer (ARSCL) valueadded product (VAP) is available, we study the uncertainty of satellite estimated cloud heights and evaluate the impact of this uncertainty for radiative studies.

Genkova, I.↗
NASA NTRS1999

Photochemistry of Pluto's Atmosphere

This work include studies of two problems: (1) Modeling thermal balance, structure. and escape processes in Pluto's upper atmosphere. This study has been completed in full. A new method, of analytic solution for the equation of hydrodynamic flow from in atmosphere been developed. It was found that the ultraviolet absorption by methane which was previously ignored is even more important in Pluto's thermal balance than the extreme ultraviolet absorption by nitrogen. Two basic models of the lower atmosphere have been suggested, with a tropopause and a planetary surface at the bottom of the stellar occultation lightcurve, respectively, Vertical profiles, of temperature, density, gas velocity, and the CH4 mixing ratio have been calculated for these two models at low, mean, and high solar activity (six models). We prove that Pluto' " s atmosphere is restricted to 3060-4500 km, which makes possible a close flyby of future spacecraft. Implication for Pluto's evolution have also been discussed. and (2) Modeling of Pluto's photochemistry. Based on the results of (1), we have made some changes in the basic continuity equation and in the boundary conditions which reflect a unique can of hydrodynamic escape and therefore have not been used in modeling of other planetary atmospheres. We model photochemistry of 44 neutral and 23 ion species. This work required solution of a set of 67 second-order nonlinear ordinary differential equations. Two models have been developed. Each model consists of the vertical profiles for 67 species, their escape and precipitation rates. These models predict the chemical structure and basic chemical processes in the current atmosphere and possible implication of these processes for evolution. This study has also been completed in full.

Krasnopolsky, Vladimir A.↗
NASA NTRS1988

MECA Workshop on Atmospheric H2O Observations of Earth and Mars. Physical Processes, Measurements and Interpretations

The workshop was held to discuss a variety of questions related to the detection and cycling of atmospheric water. Among the questions addressed were: what factors govern the storage and exchange of water between planetary surfaces and atmospheres; what instruments are best suited for the measurement and mapping of atmospheric water; do regolith sources and sinks of water have uniquely identifiable column abundance signatures; what degree of time and spatial resolution in column abundance data is necessary to determine dynamic behavior. Of special importance is the question, does the understanding of how atmospheric water is cycled on Earth provide any insights for the interpretation of Mars atmospheric data.

Clifford, Stephen M.↗
NASA NTRS1998

Fiber-Optic Coupled Lidar Receiver System to Measure Stratospheric Ozone

The measurement of ozone in the atmosphere has become increasingly important over the past two decades. Significant increases of ozone concentrations in the lower atmosphere, or troposphere, and decreases in the upper atmosphere, or stratosphere, have been attributed to man-made causes. High ozone concentrations in the troposphere pose a health hazard to plants and animals and can add to global warming. On the other hand, ozone in the stratosphere serves as a protective barrier against strong ultraviolet (UV) radiation from the sun. Man-made CFC's (chlorofluorocarbons) act as a catalyst with a free oxygen atom and an ozone molecule to produce two oxygen molecules therefore depleting the protective layer of ozone in the stratosphere. The beneficial and harmful effects of ozone require the study of ozone creation and destruction processes in the atmosphere. Therefore, to provide an accurate model of these processes, an ozone lidar system must be able to be used frequently with as large a measurement range as possible. Various methods can be used to measure atmospheric ozone concentrations. These include different airborne and balloon measurements, solar occulation satellite techniques, and the use of lasers in lidar (high detection and ranging,) systems to probe the atmosphere. Typical devices such as weather balloons can only measure within the direct vicinity of the instrument and are therefore used infrequently. Satellites use solar occulation techniques that yield low horizontal and vertical resolution column densities of ozone.

Harper, David Brent↗
DOE OSTI2017

Flare Energy Release in the Lower Solar Atmosphere near the Magnetic Field Polarity Inversion Line

We study flare processes in the solar atmosphere using observational data for an M1-class flare of 2014 June 12, obtained by the New Solar Telescope (NST/BBSO) and Helioseismic Magnetic Imager (HMI/SDO). The main goal is to understand triggers and manifestations of the flare energy release in the photosphere and chromosphere using high-resolution optical observations and magnetic field measurements. We analyze optical images, HMI Dopplergrams, and vector magnetograms, and use nonlinear force-free field (NLFFF) extrapolations for reconstruction of the magnetic topology and electric currents. The NLFFF modeling reveals the interaction of two magnetic flux ropes with oppositely directed magnetic fields in the polarity inversion line (PIL). These flux ropes are observed as a compact sheared arcade along the PIL in the high-resolution broadband continuum images from NST. In the vicinity of the PIL, the NST Hα observations reveal the formation of a thin three-ribbon structure corresponding to a small-scale photospheric magnetic arcade. The observational results are evidence in favor of the primary energy release site located in the chromospheric plasma with strong electric currents concentrated near the PIL. In this case, magnetic reconnection is triggered by the interacting magnetic flux ropes forming a current sheet elongated along the PIL.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1987

Evolutionary helium and CNO anomalies in the atmospheres and winds of massive hot stars

The ubiquitous evidence for processed materials in the atmospheres, winds, and circumstellar ejecta of massive stars is reviewed. A broad array of normal and peculiar evolutionary stages is considered, up to and including Type II supernova progenitors. The quantitative analysis of these spectra is difficult, and until recently for the most part only qualitative or approximate results have been available. However, several important current programs promise reliable abundance calculations. A significant emerging result is that the morphologically normal majority of both hot and cold supergiants may already display an admixture of CNO-cycle products in their atmospheres. It may become possible in this way to identify blue supergiants returning from the red supergiant region, as appears to have been the case for the SN 1987A progenitor.

Walborn, Nolan R.↗
DOE OSTI2016

Collaborative Project: Understanding Climate Model Biases in Tropical Atlantic and Their Impact on Simulations of Extreme Climate Events

Recent studies have revealed that among all the tropical oceans, the tropical Atlantic has experienced the most pronounced warming trend over the 20th century. Many extreme climate events affecting the U.S., such as hurricanes, severe precipitation and drought events, are influenced by conditions in the Gulf of Mexico and the Atlantic Ocean. It is therefore imperative to have accurate simulations of the climatic mean and variability in the Atlantic region to be able to make credible projections of future climate change affecting the U.S. and other countries adjoining the Atlantic Ocean. Unfortunately, almost all global climate models exhibit large biases in their simulations of tropical Atlantic climate. The atmospheric convection simulation errors in the Amazon region and the associated errors in the trade wind simulations are hypothesized to be a leading cause of the tropical Atlantic biases in climate models. As global climate models have resolutions that are too coarse to resolve some of the atmospheric and oceanic processes responsible for the model biases, we propose to use a high-resolution coupled regional climate model (CRCM) framework to address the tropical bias issue. We propose to combine the expertise in tropical coupled atmosphere-ocean modeling at Texas A&M University (TAMU) and the coupled land-atmosphere modeling expertise at Pacific Northwest National Laboratory (PNNL) to develop a comprehensive CRCM for the Atlantic sector within a general and flexible modeling framework. The atmospheric component of the CRCM will be the NCAR WRF model and the oceanic component will be the Rutgers/UCLA ROMS. For the land component, we will use CLM modified at PNNL to include more detailed representations of vegetation and soil hydrology processes. The combined TAMU-PNNL CRCM model will be used to simulate the Atlantic climate, and the associated land-atmosphere-ocean interactions at a horizontal resolution of 9 km or finer. A particular focus of the model development effort will be to optimize the performance of WRF and ROMS over several thousand of cores by focusing on both the parallel communication libraries and the I/O interfaces, in order to achieve the sustained throughput needed to perform simulations on such fine resolution grids. The CRCM model will be developed within the framework of the Coupler (CPL7) software that is part of the NCAR Community Earth System Model (CESM). Through efforts at PNNL and within the community, WRF and CLM have already been coupled via CPL7. Using the flux coupler approach for the whole CRCM model will allow us to flexibly couple WRF, ROMS, and CLM with each model running on its own grid at different resolutions. In addition, this framework will allow us to easily port parameterizations between CESM and the CRCM, and potentially allow partial coupling between the CESM and the CRCM. TAMU and PNNL will contribute cooperatively to this research endeavor. The TAMU team led by Chang and Saravanan has considerable experience in studying atmosphere-ocean interactions within tropical Atlantic sector and will focus on modeling issues that relate to coupling WRF and ROMS. The PNNL team led by Leung has extensive expertise in atmosphere-land interaction and will be responsible for improving the land surface parameterization. Both teams will jointly work on integrating WRF-ROMS and WRF-CLM to couple WRF, ROMS, and CLM through CPL7. Montuoro of the TAMU Supercomputing Center will be responsible for improving the MPI and Parallel IO interfaces of the CRCM. Both teams will contribute to the design and execution of the proposed numerical experiments and jointly perform analysis of the numerical experiments.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2012

Measurement of Clathrate Hydrate Thermodynamic Stability in the Presence of Ammonia

There is a lack of data available for the stability of clathrate hydrates in the presence of ammonia for low-to-moderate pressures in the 0-10 MPa range. Providing such data will allow for a better understanding of natural mass transfer processes on celestial bodies like Titan and Enceladus, on which destabilization of clathrates may be responsible for replenishment of gases in the atmosphere. The experimental process utilizes a custom-built gas handling system (GHS) and a cryogenic calorimeter to allow for the efficient testing of samples under varying pressures and gas species.

clathrate hyudrates↗