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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

FNAS/LDEF Radiation Data Analysis

The radioactive isotope Be-7 was discovered on the forward-facing side of the LDEF satellite in amounts far exceeding that expected from direct cosmic ray activation of the spacecraft material. This prompted an examination of the production of cosmogenic isotopes in the atmosphere and of the processes by which they may be transported to orbital altitudes and absorbed by a spacecraft. Be-7 is only one of several atmospheric cosmogenic isotopes which might be detectable at orbital altitudes and which might prove to be as useful as tracers of atmospheric circulation processes in the mesosphere and thermosphere, as they have been in the lower layers of the atmosphere.

Gregory, John↗
NASA NTRS2012

Hubble/WFC3 Spectroscopy of the Transiting Exoplanets WASP-19b and WASP-17b

Measurements of transiting exoplanets that target extremes in parameter space offer the best chance to disentangle the structure and composition of the atmospheres of hot Jupiters. WASP-19b is one of the hottest exoplanets discovered to date, while WASP-17b has a much lower equilibrium temperature but has one of the largest atmospheric radii of known transiting planets. We discuss results from HST/WFC3 grism 1.1-1.7 micron spectroscopy of these planets during transit. We compare our integrated-light transit depths to previous IR transit photometry, and derive the 1.4-micron water absorption spectrum. We discuss implications for the atmospheric composition and structure of these hot Jupiters, and outline future observations that will further expand on these results.

Mandell, A.↗
NASA NTRS1993

Dimensional analysis of acoustically propagated signals

Traditionally, long term measurements of atmospherically propagated sound signals have consisted of time series of multiminute averages. Only recently have continuous measurements with temporal resolution corresponding to turbulent time scales been available. With modern digital data acquisition systems we now have the capability to simultaneously record both acoustical and meteorological parameters with sufficient temporal resolution to allow us to examine in detail relationships between fluctuating sound and the meteorological variables, particularly wind and temperature, which locally determine the acoustic refractive index. The atmospheric acoustic propagation medium can be treated as a nonlinear dynamical system, a kind of signal processor whose innards depend on thermodynamic and turbulent processes in the atmosphere. The atmosphere is an inherently nonlinear dynamical system. In fact one simple model of atmospheric convection, the Lorenz system, may well be the most widely studied of all dynamical systems. In this paper we report some results of our having applied methods used to characterize nonlinear dynamical systems to study the characteristics of acoustical signals propagated through the atmosphere. For example, we investigate whether or not it is possible to parameterize signal fluctuations in terms of fractal dimensions. For time series one such parameter is the limit capacity dimension. Nicolis and Nicolis were among the first to use the kind of methods we have to study the properties of low dimension global attractors.

Hansen, Scott D.↗
DOE OSTI2023

Quantifying the Contributions of Aerosol- and Snow-Produced ClNO 2 through Observations and 1D Modeling

Nitryl chloride (ClNO 2 ) is a radical reservoir that forms and accumulates in the nocturnal atmospheric boundary layer influenced by combustion emissions and chloride (e.g., sea salt and road salt). Upon sunrise, ClNO 2 rapidly photolyzes to generate highly reactive chlorine radicals (Cl • ) that affect the air quality by generating secondary air pollutants. Recent studies have shown road salt aerosols and saline snowpack to be sources of ClNO 2 in the wintertime urban environment; however, the quantitative contributions of each chloride source are not known. In this study, we examine the vertically resolved contributions of aerosol particles and saline snowpack as sources of ClNO 2 by using an observationally constrained snow–atmosphere coupled one-dimensional model applied to wintertime Kalamazoo, Michigan, U.S. Model simulations show that ClNO 2 emitted from urban snowpack can be vertically transported throughout the entire atmospheric boundary layer and can be a significant source of ClNO 2 , contributing up to ~60% of the ClNO 2 budget near the surface. Here, modeled snowpack ClNO 2 emission rates were 6 (±7) times higher than the observationally derived emission rates, suggesting that not all snow chloride is available for reaction. ClNO 2 production from both aerosol particles and snow emissions are required to best simulate the observed surface-level ClNO 2 . Using the traditional bulk parameterization for ClNO 2 produced from particles significantly overestimated ClNO 2 due to the assumption of having equivalent dinitrogen pentoxide (N 2 O 5 ) uptake and chloride availability for the entire particle population. In comparison, the chemically resolved surface area-based parameterization slightly underestimated the observations and had uncertainties deriving from ClNO 2 production from residential wood burning particles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1980

Climatic effects due to halogenated compounds in the earth's atmosphere

Using a one-dimensional radiative-convective model, a sensitivity study is performed of the effect of ozone depletion in the stratosphere on the surface temperature. There could be a cooling of the surface temperature by approximately 0.2 K due to chlorofluoromethane-induced ozone depletion at steady state (assuming 1973 release rates). This cooling reduces significantly the greenhouse effect due to the presence of chlorofluoromethanes. Carbon tetrafluoride has a strong nu sub 3 band at 7.8 microns, and the atmospheric greenhouse effect is shown to be 0.07 and 0.12 K/ppbv with and without taking into account overlap with CH4 and N2O bands. At concentrations higher than 1 ppbv, absorption by the nu sub 3 band starts to saturate and the greenhouse effect becomes less efficient.

Wang, W.-C.↗
NASA NTRS2012

Multi-Satellite Synergy for Aerosol Analysis in the Asian Monsoon Region

Atmospheric aerosols represent one of the greatest uncertainties in environmental and climate research, particularly in tropical monsoon regions such as the Southeast Asian regions, where significant contributions from a variety of aerosol sources and types is complicated by unstable atmospheric dynamics. Although aerosols are now routinely retrieved from multiple satellite Sensors, in trying to answer important science questions about aerosol distribution, properties, and impacts, researchers often rely on retrievals from only one or two sensors, thereby running the risk of incurring biases due to sensor/algorithm peculiarities. We are conducting detailed studies of aerosol retrieval uncertainties from various satellite sensors (including Terra-/ Aqua-MODIS, Terra-MISR, Aura-OMI, Parasol-POLDER, SeaWiFS, and Calipso-CALIOP), based on the collocation of these data products over AERONET and other important ground stations, within the online Multi-sensor Aerosol Products Sampling System (MAPSS) framework that was developed recently. Such analyses are aimed at developing a synthesis of results that can be utilized in building reliable unified aerosol information and climate data records from multiple satellite measurements. In this presentation, we will show preliminary results of. an integrated comparative uncertainly analysis of aerosol products from multiple satellite sensors, particularly focused on the Asian Monsoon region, along with some comparisons from the African Monsoon region.

Ichoku, Charles↗
NASA NTRS1998

Operator's Manual for SHEBA Powered Tether Balloon System

The Surface Heat and Energy Budget of the Arctic (SHEBA) was an intensive field project which took place in the Arctic Ocean from October 1997 through October 1998. Its purpose was to measure as many facets of the Arctic environment as possible so that we would be able to better understand the interaction between the ice, atmosphere, and ocean and their interactions with global climate. One aspect of the atmospheric field component was launching tethered balloons to monitor the profiles of temperature, wind, pressure, and humidity, as well as examine the vertical structure of cloud droplet sizes and distributions. The tethered balloon that we used was one specially designed for use in freezing climates by SPEC Corporation in Boulder, Colorado. A special winch that was able to withstand Arctic temperature and weather became necessary when the testing of simple winch systems used in warmer climates failed under these extreme conditions. The purpose of this manual is to acquaint any new user to the powered tethered balloon system deployed at the The Surface Heat and Energy Budget of the Arctic (SHEBA ice camp. It includes a description of the preparations necessary to get ready for a launch, the mechanics of the actual launch, and an account of the proper procedure for taking down the equipment when finished. It will also include tips on how to minimize potential equipment failures, some trouble shooting, and some safety ideas. This manual is designed so that new operators can use the system with minimal previous training. At the end of this manual, the reader will find a quick checklist.

Lappen, Cara-Lyn↗
NASA NTRS1999

Retrieval Assimilation and Modeling of Atmospheric Water Vapor from Ground- and Space-Based GPS Networks: Investigation of the Global and Regional Hydrological Cycles

Uncertainty over the response of the atmospheric hydrological cycle (particularly the distribution of water vapor and cloudiness) to anthropogenic forcing is a primary source of doubt in current estimates of global climate sensitivity, which raises severe difficulties in evaluating its likely societal impact. Fortunately, a variety of advanced techniques and sensors are beginning to shed new light on the atmospheric hydrological cycle. One of the most promising makes use of the sensitivity of the Global Positioning System (GPS) to the thermodynamic state, and in particular the water vapor content, of the atmosphere through which the radio signals propagate. Our strategy to derive the maximum benefit for hydrological studies from the rapidly increasing GPS data stream will proceed in three stages: (1) systematically analyze and archive quality-controlled retrievals using state-of-the-art techniques; (2) employ both currently available and innovative assimilation procedures to incorporate these determinations into advanced regional and global atmospheric models and assess their effects; and (3) apply the results to investigate selected scientific issues of relevance to regional and global hydrological studies. An archive of GPS-based estimation of total zenith delay (TZD) data and water vapor where applicable has been established with expanded automated quality control. The accuracy of the GPS estimates is being monitored; the investigation of systematic errors is ongoing using comparisons with water vapor radiometers. Meteorological packages have been implemented. The accuracy and utilization of the TZD estimates has been improved by implementing a troposphere gradient model. GPS-based gradients have been validated as real atmospheric moisture gradients, establishing a link between the estimated gradients and the passage of weather fronts. We have developed a generalized ray tracing inversion scheme that can be used to analyze occultation data acquired from space- or land-based receivers. The National Center for Atmospheric Research mesoscale model (version MM5) has been adapted for Southern California, and assimilation studies are underway. Additional information is contained in the original.

Dickey, Jean O.↗
NASA NTRS2021

L 98-59: A Benchmark System of Small Planets for Future Atmospheric Characterization

The M3V dwarf star L 98-59 hosts three small (R < 1.6 Rꚛ) planets. The host star is bright (K = 7.1) and nearby (10.6 pc), making the system a prime target for follow-up characterization with the Hubble Space Telescope (HST) and the upcoming James Webb Space Telescope (JWST). Herein, we use simulated transmission spectroscopy to evaluate the detectability of spectral features with HST and JWST assuming diverse atmospheric scenarios (e.g., atmospheres dominated by H2, H2O, CO2, or O2). We find that H2O and CH4 present in a low mean molecular weight atmosphere could be detected with HST in one transit for the two outermost planets, while H2O in a clear steam atmosphere could be detected in six transits or fewer with HST for all three planets. We predict that observations using JWST/NIRISS would be capable of detecting a clear steam atmosphere in one transit for each planet and H2O absorption in a hazy steam atmosphere in two transits or less. In a clear, desiccated atmosphere, O2 absorption may be detectable for all three planets with NIRISS. If the L 98-59 planets possess a clear, Venus-like atmosphere, NIRSpec could detect CO2 within 26 transits for each planet, but the presence of H2SO4 clouds would significantly suppress CO2 absorption. The L 98-59 system is an excellent laboratory for comparative planetary studies of transiting multiplanet systems, and observations of the system via HST and JWST would present a unique opportunity to test the accuracy of the models presented in this study.

Daria Pidhorodetska↗
NASA NTRS1999

Mars Climate Orbiter's Investigation of the Atmosphere and Polar Caps

The Mars Climate Orbiter (MCO) is now on its way to Mars. It carries an atmospheric sounder whose observations will provide a continuous, global data set on weather and climate for a full Martian year. This paper describes the observation strategy and anticipated results from the Pressure Modulator Infrared Radiometer (PMIRR). PMIRR will measure vertical profiles of atmospheric infrared radiance in the 7 to 50 micron wavelength region extending from the surface of Mars to 80-km altitude. The observations have a vertical resolution of 5 km, or one-half the atmospheric scale height. From these radiance profiles we will retrieve profiles of atmospheric temperature, pressure, and the amounts of dust, condensates and water vapor. In addition, PMIRR will measure the radiative balance of the polar regions of Mars in an effort to better understand the short-term climate variability of the planet. The information obtained with PMIRR on MCO will be complementary to data obtained by the Thermal Emission Spectrometer (TES) and Radio Science (RS) experiments on the Mars Global Surveyor. A major emphasis of our research will be the assimilation of PMIRR data into numerical models of the Martian atmosphere. Assimilation schemes, of which several are currently in development, will permit the extension of measurements to spatial and temporal scales and to phenomena (e.g. winds) not observed directly by PMIRR.

McCleese, D. J.↗
NASA NTRS2012

Improvement in Simulation of Eurasian Winter Climate Variability with a Realistic Arctic Sea Ice Condition in an Atmospheric GCM

The present study investigates how much a realistic Arctic sea ice condition can contribute to improve simulation of the winter climate variation over the Eurasia region. Model experiments are set up using different sea ice boundary conditions over the past 24 years (i.e., 1988-2011). One is an atmospheric model inter-comparison (AMIP) type of run forced with observed sea-surface temperature (SST), sea ice, and greenhouse gases (referred to as Exp RSI), and the other is the same as Exp RSI except for the sea ice forcing, which is a repeating climatological annual cycle (referred to as Exp CSI). Results show that Exp RSI produces the observed dominant pattern of Eurasian winter temperatures and their interannual variation better than Exp CSI (correlation difference up to approx. 0.3). Exp RSI captures the observed strong relationship between the sea ice concentration near the Barents and Kara seas and the temperature anomaly across Eurasia, including northeastern Asia, which is not well captured in Exp CSI. Lagged atmospheric responses to sea ice retreat are examined using observations to understand atmospheric processes for the Eurasian cooling response including the Arctic temperature increase, sea-level pressure increase, upper-level jet weakening and cold air outbreak toward the mid-latitude. The reproducibility of these lagged responses by Exp RSI is also evaluated.

sea-ice↗
DOE OSTI2024

Quantification and assessment of the atmospheric boundary layer height measured during the AWAKEN experiment by a scanning LiDAR

The atmospheric boundary layer (ABL) height plays a key role in many atmospheric processes as one of the dominant flow length scales. However, a systematic quantification of the ABL height over the entire range of scales (i.e., with periods ranging from one minute to one year) is still lacking in literature. In this work, the ABL height is quantified based on high-resolution measurements collected by a scanning pulsed Doppler LiDAR during the recent American WAKE experimeNt (AWAKEN) campaign. The high availability of ABL height estimates (≈2200 collected over one year and each of them based on 10-min averaged statistics) allows to robustly assess five different ABL height models, i.e., one for convective thermal conditions and four for stable conditions. Thermal condition is quantified by a stability parameter spanning three orders of magnitude and probed by near-ground 3D sonic anemometry. The free-atmosphere stability, quantified by the Brunt–Väisälä frequency, is both calculated from simultaneous radiosonde measurements and obtained from the best fit of two of the chosen ABL height models. Good agreement is found between the data and three of the chosen models, quantified by mean absolute errors on the ABL height between 281 and 585 m. Furthermore, the seasonal variability of the convective ABL height model parameters (−15% to +23% with respect to the year baseline) agrees with the variability of buoyancy-generated turbulence caused by the variation in solar radiation throughout the year.

17 WIND ENERGY↗
NASA NTRS1981

Sputter ejection of matter from Io

Direct collisional interaction of magnetospheric particles, particularly 520-eV S ions, with Io, cause sputter removal of matter. It is estimated that direct sputtering of a full-disk S-containing atmosphere with an exobase at a few hundred km, can provide up to 5 x 10 to the tenth S atoms per sq cm-s. Supplies of S and O required to stabilize the torus are estimated to be from 10 to the 10th to 10 to the 12th per sq cm-s. Sputtering rates are calculated for an atmosphere containing a one percent concentration of Na and K, and are found to be large enough to supply the fluxes required to maintain the Na and K clouds. Sputtering is found to remove heavy molecules from the atmosphere, and the rate of direct sputtering of unprotected surfaces is calculated for ejections of S and Na. Atomic species on the surface are ejected at a rate proportional to the surface abundance; and plume sputtering, avalanche cascading, and ionic saltation which lead to spatial and temporal variations in the number of ejected particles are observed.

Haff, P. K.↗
NASA NTRS2003

Astrobiology: The Case for Venus

The scientific discipline of astrobiology addresses one of the most fundamental unanswered questions of science: are we alone? Is there life elsewhere in the universe, or is life unique to Earth? The field of astrobiology includes the study of the chemical precursors for life in the solar system; it also includes the search for both presently existing life and fossil signs of previously existing life elsewhere in our own solar system, as well as the search for life outside the solar system. Two of the promising environments within the solar system being currently considered are the surface of the planet Mars, and the hypothesized oceans underneath the ice covering the moon Europa. Both of these environments differ in several key ways from the environments where life is found on Earth; the Mars environment in most places too cold and at too low pressure for liquid water to be stable, and the sub-ice environment of Europa lacking an abundance of free energy in the form of sunlight. The only place in the solar system where we know that life exists today is the Earth. To look for life elsewhere in the solar system, one promising search strategy would be to find and study the environment in the solar system with conditions that are most similar to the environmental conditions where life thrives on the Earth. Specifically, we would like to study a location in the solar system with atmospheric pressure near one bar; temperature in the range where water is liquid, 0 to 100 C; abundant solar energy; and with the primary materials required for life, carbon, oxygen, nitrogen, and hydrogen, present. Other than the surface of the Earth, the only other place where these conditions exist is the atmosphere of Venus, at an altitude of about fifty kilometers above the surface.

Landis, Geoffrey A.↗
NASA NTRS1988

Theoretical investigation of EM wave generation and radiation in the ULF, ELF and VLF bands by the electrodynamic orbiting tether

The goal is to extend the previous analysis of electromagnetic wave generation by an electrodynamic tethered satellite system to a more realistic model that includes the effects on wave propagation and reflection to the boundaries between ionosphere, atmosphere, and earth. One of the major activities was searching the scientific literature for publications that might be relevant to the problem. The software developed as SAO to follow the path of waves along field lines through the ionosphere to the atmosphere starting from an arbitary position in the atmosphere is described. Some preliminary results are presented from applying the code to the location of wave reception hot spots on the earth's surface for satellites operating at 300 and 600 km altitudes. A generalization of the Alfven wing analysis is presented to allow for arbitrary angles between the velocity vector, geomagnetic field, and the veritcal. This will be utilized in the modeling of the problem with boundaries included.

Estes, Robert D.↗
NASA NTRS1992

A reduced atmosphere for early Mars?

One-dimensional, radiative-convective climate calculations indicate that the old model of a warm, dense, CO2 atmosphere on early Mars is no longer viable. The magnitude of the greenhouse effect in a CO2/H2O atmosphere is limited by condensation of CO2 clouds; this phenomenon is not important for Mars today, but has a pronounced cooling effect at the low solar luminosities thought to apply during early solar system history. The failure of this model indicates one of four things: (1) the new climate calculations are incorrect; (2) current solar evolution models are incorrect; (3) the idea that early Mars was warm and wet is incorrect; or (4) the atmosphere of early Mars contained other greenhouse gases (or particles) in addition to CO2 and H2O. Of these explanations, the most plausible is number (4) and the rest of the investigation is a further explanation of number (4).

Kasting, J. F.↗
NASA NTRS2003

A Microphysically-based Approach to Inferring Porosity, Grain Size, and Dust Abundance in the Seasonal Caps from Atmospherically-corrected TES Spectra

One of the highlights of the TES observations in the polar regions has been the identification of a "cryptic" region in the south where CO2 appears to be in the form of a solid slab rather than a fluffy frost. While the exact mechanism(s) by which the cryptic region is formed are still subject of some debate, it appears certain that a type of rapid metamorphism related to the high volatility of CO2 ice is involved. The high volatility of CO2 ice under martian conditions has several Solar System analogs (N2 on Triton and Pluto, SO2 on Io), thus making the martian cryptic region somewhat less cryptic and certainly non-unique among planetary objects. In an endmember scenario, both the formation and the spectral properties of the cryptic region (and of other areas in the seasonal caps) can be quantitatively modeled by considering sintering of an ensemble of quasi-spherical CO2 grains. This model includes the special case of instanteneous slab formation, which occurs when the grains are sufficiently small (in the submicron range) so that their sintering timescale is short relative to the deposition timescale (a situation analogous to the "sintering" of water droplets falling into a pond).

Eluszkiewicz, J.↗
NASA NTRS2013

Evidence of Temporal Variation of Titan Atmospheric Density in 2005-2013

One major science objective of the Cassini mission is an investigation of Titan's atmosphere constituent abundances. Titan's atmospheric density is of interest not only to planetary scientists but also to mission design and mission control engineers. Knowledge of the dependency of Titan's atmospheric density with altitude is important because any unexpectedly high atmospheric density has the potential to tumble the spacecraft during a flyby. During low-altitude Titan flyby, thrusters are fired to counter the torque imparted on the spacecraft due to the Titan atmosphere. The denser the Titan's atmosphere is, the higher are the duty cycles of the thruster firings. Therefore thruster firing telemetry data could be used to estimate the atmospheric torque imparted on the spacecraft. Since the atmospheric torque imparted on the spacecraft is related to the Titan's atmospheric density, atmospheric densities are estimated accordingly. In 2005-2013, forty-three low-altitude Titan flybys were executed. The closest approach altitudes of these Titan flybys ranged from 878 to 1,074.8 km. Our density results are also compared with those reported by other investigation teams: Voyager-1 (in November 1980) and the Huygens Atmospheric Structure Instrument, HASI (in January 2005). From our results, we observe a temporal variation of the Titan atmospheric density in 2005-2013. The observed temporal variation is significant and it isn't due to the estimation uncertainty (5.8%, 1 sigma) of the density estimation methodology. Factors that contributed to this temporal variation have been conjectured but are largely unknown. The observed temporal variation will require synergetic analysis with measurements made by other Cassini science instruments and future years of laboratory and modeling efforts to solve. The estimated atmospheric density results are given in this paper help scientists to better understand and model the density structure of the Titan atmosphere.

Atmosphere↗