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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Need for measurements in the lower atmosphere

Areas of investigation that are discussed include: the relative importance of the turbopause versus winds in determining the composition of the thermosphere; the mechanism of the coupling between the mesosphere and the thermosphere and how important wave dissipation is in this coupling; and the morphology and variation of magnetospheric energy inputs at high latitudes. The need to investigate the propagation characteristics of atmospheric gravity waves in the altitude region between 100 and 200 km is emphasized.

Reber, C. A.↗
NASA NTRS1980

Pioneer Venus gas chromatography of the lower atmosphere of Venus

A gas chromatograph mounted in the Pioneer Venus sounder probe measured the chemical composition of the atmosphere of Venus at three altitudes. Ne, N2, O2, Ar, CO, H2O, SO2, and CO2 were measured, and upper limits set for H2, COS, H2S, CH4, Kr, N2O, C2H4, C2H6, and C3H8. Simulation studies have provided indirect evidence for sulfuric acid-like droplets and support the possibility of water vapor at altitudes of 42 and 24 km. The paper discusses the implications of these results for the origin, evolution, and present state of Venus' atmosphere.

Oyama, V. I.↗
NASA NTRS1981

Dynamics and drift minimization of a momentum biased spacecraft in the lower atmosphere

This paper addresses the dynamic characteristics of a momentum biased spacecraft (Magsat) which was placed in an elliptic, sun synchronous, low earth orbit. It discusses various dynamic phenomena observed, develops models for their plausible explanation, and suggests techniques for preventing or minimizing adverse phenomena. An aerodynamic coefficient model which accounts for atmospheric superrotation is proposed. This model is used to conduct analysis and simulations, the results of which are shown to be compatible with data taken by Magsat. A control philosophy is developed, and analytic expressions for the long term motion of the momentum biased axis for special cases are derived.

Saxena, A. K.↗
NASA NTRS1982

Gaseous infrared absorption in the lower atmosphere of Venus

Possibly important sources of infrared opacity in the Venusian atmosphere was identified. It is shown that which is the major atmospheric constituent comprising about 97 percent of the atmosphere, is the dominant infrared opacity source. Not shown is N2 which comprises about 3 percent of the atmosphere. The mixing ratio of water vapor varies considerably with altitude but falls in the range of about 20 to 200 parts per million (ppm). The mixing ratio of SO2 falls in the range of 100-200 ppm. This number is about 5000 times larger than estimates obtained earlier via Earth-based observations. The abundance of some of the other minor constituents is also shown.

Chackerian, C., Jr.↗
NASA NTRS1983

The 11-year cycle - An assessment of thermal, wind, and planetary wave changes in the middle and lower atmosphere due to UV flux variations

A solar UV flux variation is assumed to be associated with the 11-yr solar cycle. Radiative equilibrium calculations are used to evaluate the related temperature changes, and wind field changes are derived. Wind field changes are used with a linear, stationary, quasi-geostrophic model to estimate changes in the structure of planetary wave numbers 1 and 2. Changes of 2 percent or less are found in the troposphere. In the vicinity of the stratopause, changes of up to 43 percent, compared to the reference atmosphere, are determined.

Callis, L. B.↗
NASA NTRS1985

An assessment of thermal, wind, and planetary wave changes in the middle and lower atmosphere due to 11-year UV flux variations

Hines (1974) speculated that solar-induced modifications of the middle and upper atmosphere may alter the transmissivity of the stratosphere to upwardly propagating atmospheric waves. It was suggested that subsequent constructive or destructive interference may result in a change of phase or amplitude of these waves in the troposphere leading to weather or climate changes. The present investigation has the objective to bring together both radiative transfer and planetary wave studies in an effort to assess specifically whether Hines mechanism can be initiated by the solar ultraviolet flux variability assumed to be associated with the 11-year solar cycle. The obtained results suggest that the presently studied mechanism, which links solar-induced zonal wind changes in the stratosphere and mesosphere to planetary wave changes in the troposphere, is not strong enough to cause substantive changes in the troposphere.

Callis, L. B.↗
NASA NTRS1985

Temperature structure in the lower atmosphere of Venus - New results derived from Pioneer Venus entry probe measurements

The Pioneer Venus Small-Probe Net Flux Radiometer temperature sensor and its calibration, the thermal model of the sensor head, the procedure for deriving atmospheric temperature from the sensor temperatures, and the new temperature results for each entry probe are reported. The new results are compared with those of the Small-Probe Atmospheric Structure experiment and with simple models of diurnal and latitudinal temperature contrasts. A dynamical inconsistency between these results and low-latitude measurements by the Sounder probe is described, and possible ways to resolve it are considered.

Sromovsky, L. A.↗
NASA NTRS1986

Tidal coupling with the lower atmosphere (invited review)

The various ways are reviewed in which propagating tidal components excited in the mesophere and below affect the structure of the thermosphere and ionosphere above 100 km. Dynamo effects are not treated here. The physical processes affecting the propagation of upward propagating tides are examined and how they are interrelated in the context of a numerical model. Propagating diurnal and semidiurnal tides which reach thermospheric heights are excited primarily by insolation absorption by tropospheric water vapor (0 to 5 km) and stratospheric/mesospheric ozone (40 to 60 km), respectively. Simulation of these oscillations requires consideration of mean zonal winds and meridional temperature gradients, and the damping effects of turbulent and molecular dissipation, radiative cooling, and ion drag. These effects must be considered on a spherical rotating atmosphere extending from the ground to above 300 km, as they are in the model developed by Forbes depicted schematically.

Forbes, J. M.↗
NASA NTRS1986

Extinction and visibility measurements in the lower atmosphere with UV-YAG-lidar

With the intention to investigate methods for slant path visibiltiy measurements and to develop information for modelling of extinction profiles in the atmospheric boundary layer, measurements were performed with a lidar based on a YAG-laser. The third harmonic at 355 nm in the ultraviolet was used and thus eye safety problems are avoided. At this wavelength the lens of the human eye is not transparent and the safety distance for the laser is a 50 meters as compared to several km for a corresponding green laser. The lidar is a coaxial system with a turnable mirror system for beam steering. The extinction coefficient at both 355 and 532 nm was measured and the ratio determined. Provided that the wavelength dependence of the aerosol extinction is range independent, the measured extinction profile at 355 nm can be converted to a corresponding profile at 532 nm, which is more relevant for visibility. In order to calculate the extinction profile the lidar equation is inverted by a method, which is based on Klett's method.

Hagard, A.↗
NASA NTRS1986

The lower atmosphere of solar flares; Proceedings of the Solar Maximum Mission Symposium, Sunspot, NM, Aug. 20-24, 1985

The topics discussed by the present conference encompass the chromospheric flare phenomenon, white light flares, UV emission and the flare transition region, the flare corona and high energy emissions, stellar flares, and flare energy release and transport. Attention is given to radiative shocks and condensation in flares, impulsive brightening of H-alpha flare points, the structure and response of the chromosphere to radiation backwarming during solar flares, the interpretation of continuum emissions in white light flares, and the radiation properties of solar plasmas. Also discussed are EUV images of a solar flare and C III intensity, an active region survey in H-alpha and X-rays, dynamic thermal plasma conditions in large flares, the evolution of the flare mechanism in dwarf stars, the evidence concerning electron beams in solar flares, the energetics of the nonlinear tearing mode, macroscopic electric fields during two-ribbon flares, and the low temperature signatures of energetic particles.

Neidig, Donald F.↗
NASA NTRS1989

Correspondence between solar fine-scale structures in the corona, transition region, and lower atmosphere from collaborative observations

The Soft X-Ray Imaging Payload and the High Resolution Telescope and Spectrograph (HRTS) instrument were launched from White Sands on 11 December 1987 in coordinated sounding rocket flights to investigate the correspondence of coronal and transition region structures, especially the relationship between X-ray bright points (XBPs) and transition region small spatial scale energetic events. The coaligned data from X-ray images are presented along with maps of sites of transition region energetic events observed in C IV (100,000 K), HRTS 1600 A spectroheliograms of the T sub min region and ground based magnetogram and He I 10830 A images.

Moses, J. Daniel↗
NASA NTRS1992

Chemistry of the surface and lower atmosphere of Venus

A comprehensive overview of the chemical interactions between the atmosphere and surface of Venus is presented. Earth-based, earth-orbital, and spacecraft data on the composition of the atmosphere and surface of Venus are presented and applied to quantitative evaluations of the chemical interactions between carbon, hydrogen, sulfur, chlorine, fluorine, and nitrogen-containing gases and possible minerals on the Venus surface. The calculation results are used to predict stable minerals and mineral assemblages on the Venus surface to determine which, if any, atmospheric gases are buffered by mineral assemblages on the surface, and to critically review and assess prior work on atmosphere-surface chemistry on Venus. It is concluded that the CO2 pressure on Venus is comparable to the CO2 equilibrium partial pressure developed by the calcite + wollastonite + quartz assemblage at the mean Venus surface temperature of 740 K.

Fegley, B., Jr.↗
NASA NTRS1992

The Martian lower atmosphere

The topics are presented in viewgraph form and include the following: mass and composition; photochemical processes; temperatures and winds; general circulation; and dust storms.

Haberle, Robert M.↗
NASA NTRS1992

Modeling of the initiation and evolution of a laser-ionized column in the lower atmosphere - 314.5 nm wavelength resonant multiphoton ionization of naturally occurring argon

A 3+1 resonant multiphoton ionization process in naturally occurring argon is studied at 314.5 nm as a candidate for providing a long ionized channel through the atmosphere. Results are presented which indicate peak electron densities up to 10 exp 8/cu cm can be created using laser intensities on the order of 10 exp 8 W/sq cm.

Fetzer, G. J.↗
NASA NTRS1994

Evaluation of the production and the destruction of ozone in the lower atmosphere

Observed surface ozone mixing ratio X(sub ob) is partitioned into two parts; X(sub tr), transported from the free troposphere and X(sub ch), chemically produced or destructed in the boundary layer. X(sub tr) is estimated from the ozone concentration in the free troposphere and the wind speed. The ozone in the free troposphere estimated from surface ozone observations is consistent with that of ozonesonde data. X(sub ch) is obtained from the difference between X(sub ob) and X(sub tr). X(sub tr) increases with wind speed, while X(sub ch) shows maximum at hourly wind speed of 1-2 m/s in the daytime. Contribution of X(sub tr) to X(sub ob) is larger than X(sub ch) except for a short period in summer. X(sub ch) is positive for April-October, but X(sub ch) can be negative in winter, showing the net chemical destruction in the boundary layer. X(sub ch) increases linearly with solar radiation, and is negative for daily global solar radiation below 8 MJ/sq m, which is about equal to the monthly mean in winter.

Muramatsu, H.↗
NASA NTRS1994

Solar fine scale structures in the corona, transition region, and lower atmosphere

The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV 10(exp 5), HRTS 1600 A spectroheliograms of the T(sub min) region, and ground-based magnetogram and He I 10830 A images. We examined the relationship of He I 10830 A dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He I dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km/s, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km/s velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events than expected from the results of a previous Spacelab 2 HRTS disk survey. We attribute this at least partly to better spatial resolution with the newer HRTS data. The full-disk X-ray image shows a pattern of dark lanes in quiet Sun areas. The number density of C IV events is twice as large inside as outside a dark lane (4.6 x 10(exp -3) vs. 2.3 x 10(exp -3) explosive events per arcsec (exp 2)). The dark lane corresponds to an old decaying magnetic neutral line. We suggest that this provides an increased opportunity for small-scale convergence and reconnection of opposite polarity magnetic field features, in analogy with the results of Webb et al. for XBPs but at a reduced scale of reconnection.

Moses, Dan↗
NASA NTRS1996

Radiative Transfer in the Lower Atmosphere Based on TOMS/ADEOS Measurements

The long-term objective of this research is to develop and apply methods to compute the solar ultraviolet (UV) spectral irradiance at the earth's surface using information to be provided by the TOMS/ADEOS data set. The broad philosophy is to view the TOMS measurements as a probe of the radiative transfer properties of the earth's atmosphere. Prior to the launch of ADEOS, we have focused on analysis of the Nimbus 7 TOMS data base as well as the development of numerical models for eventual use with ADEOS measurements. The emphasis of recent work has been on numerical modeling of the radiative effects of cloudy skies in the UV part of the spectrum.

Frederick, John E.↗