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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Tidal waves within the thermosphere

The eigenfunctions of the atmosphere (the Hough functions within the lower atmosphere below about 100 km) change their structure and their propagation characteristics within the thermosphere due to dissipation effects such as heat conduction, viscosity, and ion drag. Wave dissipation can be parameterized to a first-order approximation by a complex frequency, the imaginary term of which simulates an effective ion drag force. It is shown how the equivalent depth, the attenuation, and the vertical wavelength of the predominant symmetric diurnal tidal modes change with height as functions of effective ion drag. The boundary conditions of tidal waves are discussed, and asymptotic solutions for the wave parameters like pressure, density, temperature, and wind generated by a heat input proportional to the mean pressure are given. Finally, diffusion effects upon the minor constituents within the thermosphere are described.

Volland, H.↗
NASA NTRS1974

Radiative transfer of visible radiation in turbid atmosphere

Methods are presented for solving radiative transfer problems; they include the doubling method and the closely related matrix method, iterative method, Chandrasekhar's method of discrete ordinates, and Monte Carlo method. To consider radiation transport through turbid atmosphere, an atmospheric model was developed characterizing aerosols by parameters. Intensity and polarization of radiation in turbid atmospheres is discussed, as well as lower atmospheric heating due to solar radiation absorption by aerosols.

Yamamoto, G.↗
NASA NTRS1987

Comparison of in situ stratospheric ozone measurements obtained during the MAP/GLOBUS 1983 campaign

Data from five types of in situ ozone sensors flown aboard ballons during the MAP/GLOBUS 1983 campaign were found to agree to within 5 percent uncertainty throughout the middle atmosphere. A description of the individual techniques and the error budget is given in addition to explanations for the discrepancies found at higher and lower altitudes. In comparison to UV photometry values, results from two electrochemical techniques were found to be greater in the lower atmosphere and to be lower in the upper atmosphere. In general, olefin chemiluminescence results were within 8 percent of the UV photometry results. Ozone column contents measured by the indigo colorization technique for two altitude regions of about 6 km height were greater than measurements from other techniques by 52 and 17 percent, respectively.

Aimedieu, P.↗
NASA NTRS2014

Double Bright Band Observations with High-Resolution Vertically Pointing Radar, Lidar, and Profiles

On 11 May 2010, an elevated temperature inversion associated with an approaching warm front produced two melting layers simultaneously, which resulted in two distinct bright bands as viewed from the ER-2 Doppler radar system, a vertically pointing, coherent X band radar located in Greenbelt, MD. Due to the high temporal resolution of this radar system, an increase in altitude of the melting layer of approximately 1.2 km in the time span of 4 min was captured. The double bright band feature remained evident for approximately 17 min, until the lower atmosphere warmed enough to dissipate the lower melting layer. This case shows the relatively rapid evolution of freezing levels in response to an advancing warm front over a 2 h time period and the descent of an elevated warm air mass with time. Although observations of double bright bands are somewhat rare, the ability to identify this phenomenon is important for rainfall estimation from spaceborne sensors because algorithms employing the restriction of a radar bright band to a constant height, especially when sampling across frontal systems, will limit the ability to accurately estimate rainfall.

ER-2 Doppler radar↗
NASA NTRS2016

Observations and Simulations of the Na I D-1 Line profiles in an M-Class Solar Flare

We study the temporal evolution of the Na I D1 line profiles in the M3.9 flare SOL2014-06-11T21:03UT, using observations at high spectral resolution obtained with the Interferometric Bidimensional Spectrometer instrumentation the Dunn Solar Telescope combined with radiative hydrodynamic simulations. Our results show a significant increase in the intensities of the line core and wings during the flare. The analysis of the line profiles from the flare ribbons reveals that the Na I D1 line has a central reversal with excess emission in the blue wing (blue asymmetry).We combine RADYN and RH simulations to synthesize Na I D1 line profiles of the flaring atmosphere and find good agreement with the observations. Heating with a beam of electrons modifies the radiation field in the flaring atmosphere and excites electrons from the ground state 3s 2S to the first excited state 3p 2P, which in turn modifies the relative population of the two states. The change in temperature and the population density of the energy states make the sodium line profile revert from absorption into emission. Furthermore, the rapid changes in temperature break the pressure balance between the different layers of the lower atmosphere, generating upflow/downflow patterns. Analysis of the simulated spectra reveals that the asymmetries of the Na I D1 flare profile are produced by the velocity gradients in the lower solar atmosphere.

methods: numerical↗
NASA NTRS1984

Sulfur and oxygen escape from Io and a lower limit to atmospheric SO2 at Voyager 1 encounter

Estimates of the abundance of sulfur, sodium and oxygen ions and neutrals observed by Voyager 1 in the plasma torus and neutral cloud associated with the Jovian satellite Io are used to investigate the physical characteristics of the Io atmosphere. Specific attention is given to two questions about the Io atmosphere: the necessity of an atmosphere to account for the supply of sulfur and oxygen observed in the plasma torus, and, if an atmosphere is necessary, the lower limit to such atmosphere. It is found that an SO2 atmosphere is most likely needed on Io as an intermediate buffer so that the sulfur and oxygen can be transported to the plasma torus. The minimum atmosphere needed for this process is calculated to be 1.4 x 10 to the -10th bar with an SO2 column density of about 10 to the 16th per sq cm and an SO2 surface density of about 1.2 x 10 to the 10th per cu cm. A complete list of all the atmospheric escape fluxes for Io is provided.

Kumar, S.↗
NASA NTRSDate not supplied

Simulating the Martian Middle and Upper Atmosphere with the NASA Ames Mars GCM.

The NASA Ames Mars Global Climate Model (MGCM) continues to be utilized to examine the dynamical coupling between the lower atmosphere and middle/upper atmosphere. This coupling impacts the transport of water, dust, and chemistry which augments the thermal structure and circulation. The interactions and coupling within the atmosphere are important for understanding the present-day and past atmosphere and climate. MGCM simulations are compared with observations from recent Mars missions to provide model constraints, and in turn, the simulations can then provide context to the observations. This cycle is important to move us forward in our understanding of planetary atmospheres. We will present on one of the fundamental atmospheric features, the thermal structure, and how the physics in the MGCM can elucidate the observed diurnal and seasonal behavior. Additionally, we will focus on the distribution of chemical species which influences the thermal structure and provides additional information on the coupling between the lower and middle/upper atmosphere. Lastly, we will provide a summary of the model capabilities, as the MGCM continues to be improved upon to properly simulate Mars’ atmosphere from the ground to ~250 km.

Amanda Susanne Brecht↗
NASA NTRS1976

The photochemistry of ammonia in the Jovian atmosphere

A reinvestigation of the ammonia photochemistry in the Jovian lower atmosphere above the cloud tops is conducted in connection with certain questions concerning the model proposed by Strobel (1973). Chemical reactions and their rate coefficients are considered along with the model atmosphere, solar fluxes, the continuity equations, and numerical details. Differences between the newmodel and Strobel's model are related to more moderate ammonia depletion relations. The height profiles of H, NH2, N2H3, N2H4, and NH3 concentrations are presented in a graph.

Prasad, S. S.↗
NASA NTRS1982

Technology Needs Assessment of an Atmospheric Observation System for Multidisciplinary Air Quality/Meteorology Missions, Part 2

The technology advancements that will be necessary to implement the atmospheric observation systems are considered. Upper and lower atmospheric air quality and meteorological parameters necessary to support the air quality investigations were included. The technology needs were found predominantly in areas related to sensors and measurements of air quality and meteorological measurements.

Alvarado, U. R.↗
NASA NTRS2004

Solar Activity and its Impact on Earth's Climate

The Sun's activity is now approaching an expected 2006 minimum, following the dramatic maximum of Solar Cycle 23, that included events such as the 2001 "Bastille Day" Coronal Mass Ejection, and the record-setting Oct-Nov 2003 solar flares, with their associated sunspots and variations in Total Solar Irradiance, or TSI. On Nov 4,2003 the largest X-ray flare ever detected (X-28) was observed in detail. We discuss recent satellite measurements of TSI by ACRIM 2 and 3 and Virgo, and new precision observations of TSI and SSI (Solar Spectral Irradiance) from the SORCE mission, that launched on January 25,2003. TSI variations recorded during the June 8,2004 transit of Venus show the unprecedented precision of the SORCE Total Irradiance Monitor (TIM) instrument, the first of its kind to employ phase-sensitive detection. The SORCE spectral instruments, XPS, Solstice, and SIM, record the Sun's changes over a wide range of wavelengths, from 1 to more than 2000 nanometers, for the first time covering the peak of the solar spectrum, including spectral components that provide energy inputs to key components of the climate system - ultraviolet (UV) into the upper atmospheric ozone layer, infrared (IR) into the lower atmosphere and clouds, and Visible into the Oceans and biosphere. Succeeding satellite missions are planned to monitor both TSI and SSI through Cycle 24. We summarize current ideas about decadal and longer solar variability, and associated potential impacts on Earth's climate on time scales from decades to centuries, especially highlighting the role of feedbacks in the climate system.

Cahalan, Robert F.↗
NASA NTRS1988

Near-infrared observations of Venus

Ground-based near-infrared observations of the Venus night side reveal anomalous bright features at wavelengths near 1.7 and 2.3 micrometer (Allen and Crawford, 1984; Allen, 1987). These features are thought to be formed as thermal radiation from the hot lower atmosphere leaks through holes in the middle and/or lower sulfuric acid cloud decks. Because these holes allow radiation to escape from deep in the troposphere, they provide an opportunity to significantly improve our understanding of the composition, thermal structure, and dynamics of this region of the Venus atmosphere. New near-infrared observations of the Venus night side are needed to address these questions. During the first year of this program, researchers requested and received observing time at six sites and organized a highly-skilled team. The wide array of sites should allow researchers to collect the data needed to meet all of the proposed objectives. High resolution spectra of the Venus night side was obtained. Researchers are currently collecting the first images of Venus from Kitt Peak and Table Mountain. The state-of-the-art infrared array detectors that are being used at these sites are allowing researchers to collect hundreds of high-quality images during each observing day. These images show the expected bright features, but they have not yet begun to track these features.

Crisp, D.↗
NASA NTRS1973

Mariner 9 ultraviolet spectrometer experiment - Morning terminator observations of Mars

Mariner 9 ultraviolet morning terminator data indicate the presence of a high, optically thin scattering layer in the equatorial region of Mars extending to 50S. This is consistent with the afternoon terminator results, which showed the presence of a scattering layer for latitudes as far north as 50N. For both types of terminator observations, the magnitude of the reflectivity for large shadow heights and the apparent scale height of the signal are too large to be explained by a homogeneous atmosphere. The terminator observations poleward of 50S were modeled by a homogeneous atmosphere of molecular and particulate scatterers. As the lower atmosphere began to clear from the dust storm, a progressive change was noted in the magnitude of the terminator reflectivity which is attributed to a changing albedo for single scattering. The shape of the morning terminator reflectivity measured as a function of shadow height indicates larger apparent scale heights than were observed in the afternoon. The difference is attributed to an increase in thickness of the scattering layer during the night.

Ajello, J. M.↗
NASA NTRS1989

How will changes in carbon dioxide and methane modify the mean structure of the mesosphere and thermosphere?

A global average model of the coupled mesosphere, thermosphere, and ionosphere is used to examine the effect of trace gas variations on the overall structure of these regions. In particular, the variations caused by CO2 and CH4 doublings and halvings from present day mixing ratios are presented. The results indicate that the mesosphere and thermosphere temperatures will cool by about 10 K and 50 K, respectively, as the CO2 and CH4 mixing ratios are doubled. These regions are heated by similar amounts when the trace gas mixing ratios are halved. Compositional redistributions also occur in association with changes in the temperature profile. The results show that global change will occur in the upper atmosphere and ionosphere as well as in the lower atmosphere during the 21st century.

Roble, R. G.↗
NASA NTRS1992

Mars global reference atmosphere model (Mars-GRAM)

Mars-GRAM is an empirical model that parameterizes the temperature, pressure, density, and wind structure of the Martian atmosphere from the surface through thermospheric altitudes. In the lower atmosphere of Mars, the model is built around parameterizations of height, latitudinal, longitudinal, and seasonal variations of temperature determined from a survey of published measurements from the Mariner and Viking programs. Pressure and density are inferred from the temperature by making use of the hydrostatic and perfect gas laws relationships. For the upper atmosphere, the thermospheric model of Stewart is used. A hydrostatic interpolation routine is used to insure a smooth transition from the lower portion of the model to the Stewart thermospheric model. Other aspects of the model are discussed.

Justus, C. G.↗
NASA NTRS1995

Performance Model for Reversible Fluid Balloons

The Altitude Control Experiment (ALICE) is a balloon system that consists of a helium lifting balloon and a buoyancy-controlling freon R114 balloon. Condensation of freon gas in the cooler upper atmosphere and vaporization of liquid freon in the warmer lower atmosphere can be effectively used to adjust the net buoyant force so that the balloon system may float between desirable ranges of altitudes.This report summarizes efforts to produce an analytical model to predict the performance of this type of altitude control balloon in the earth's atmosphere. Various interactive parameters that are influential to the dynamics of the system were identified and treated. The analytical model developed herein correlated well with three ALICE day flight trajectories and one ALICE night flight trajectory in the earth's atmosphere. A similar approach can be applied to the design of a Venusian balloon system that could repeatedly travel to the lower, hot altitudes or surface of Venus for imaging or science experiments and then float higher in order to cool the electronics.

balloon↗
NASA NTRS1992

Atmospheric effects on ejecta emplacement and crater formation on Venus from Magellan

Surface signatures of energy partitioning are used as a framework for testing extrapolations from laboratory experiments and other planetary settings to assess the effects of both gravity and an atmosphere on impact crater formation on Venus. The dense lower atmosphere of Venus is found to assume the role of a low-density target for bodies smaller than about 4 km in diameter. Air blasts created by cratering in the atmosphere produce distinctive surface signatures that allow the derivation of an independent assessment of impactor energy at the limit of break up. Dynamic pressures during entry of larger bodies will exceed their strength limit but may not prevent penetration of the atmosphere due to aerodynamic reshaping that minimizes the drag coefficient. This process may account for the formation of unusually small craters (1-3 km). The dense atmosphere of Venus preserves signatures of early time cratering processes on the surface that are typically lost on atmosphere-free surfaces.

Schultz, Peter H.↗