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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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NASA NTRS1973

Use of 4-D atmospheric models in the simulation of radiometric measurements

Atmospheric moisture data contained in the Global 4-D Atmospheric Models developed in previous studies were analyzed to establish regional differences. The regional values of precipitable water along latitudinal belts were compared with values derived from the corresponding atmospheric models defined in the U.S Standard Atmosphere Supplement. The effects of the differences between the 4-D Models and the Standard Atmosphere Models on radiometric computations in the infrared window and water vapor absorption band regions were evaluated using a standard computation model of radiation transfer through a cloudless atmosphere. The significance of these differences in simulation is discussed.

Chang, D. T.↗
NASA NTRS1973

Enhancement of Earth Resources Technology Satellite /ERTS/ and aircraft imagery using atmospheric corrections.

The studies considered are concerned with the magnitude of the atmospheric effects in multispectral earth resources data taken by satellites and aircraft. The atmospheric effects are present in all space oriented and aerial data even in the so-called atmospheric 'windows' through which all sensors observe the ground. Atmospheric effects are quite varied and depend on several parameters. An atmospheric model developed by Turner et al. (1971) is discussed. The model is applied to the test site, which is located in North Dakota. The results are used to obtain atmospheric correction data for ERTS-1 scanner data.

Sharma, R. D.↗
NASA NTRS1974

UCLA International Conference on Radiation and Remote Probing of the Atmosphere, University of California, Los Angeles, Calif., August 28-30, 1973, Proceedings

Approaches for solving multiple scattering problems in planetary atmospheres are considered along with the solution of the radiative transfer theory problems by the Monte Carlo method, the radiative transfer of visible radiation in turbid atmospheres, aspects of scattering and absorption from poly-dispersed aerosols, and multiple scattering in cloud layers. Other subjects discussed include particulate sizes from polarization measurements, lidar observations of atmospheric particulate content, methods of calculating infrared transfer, molecular absorption parameters in atmospheric modelling, and infrared remote sounding. The influence of the atmosphere on spectral radiance and contrasts of natural formations measured from space is investigated and analytical results for radiative transfer in thick atmospheres are presented. Individual items are announced in this issue.

Kuriyan, J. G.↗
NASA NTRS1974

Models of Mars' atmosphere (1974)

Atmospheric models for support of design and mission planning of space vehicles that are to orbit the planet Mars, enter its atmosphere, or land on the surface are presented. Quantitative data for the Martian atmosphere were obtained from Earth-base observations and from spacecraft that have orbited Mars or passed within several planetary radii. These data were used in conjunction with existing theories of planetary atmospheres to predict other characteristics of the Martian atmosphere. Earth-based observations provided information on the composition, temperature, and optical properties of Mars with rather coarse spatial resolution, whereas spacecraft measurements yielded data on composition, temperature, pressure, density, and atmospheric structure with moderately good spatial resolution. The models provide the temperature, pressure, and density profiles required to perform basic aerodynamic analyses. The profiles are supplemented by computed values of viscosity, specific heat, and speed of sound.

Source record↗
NASA NTRS1975

The ionosphere and atmosphere of Io

A neon atmosphere and ionosphere is proposed for Io, based on Pioneer 10 observations of the peak electron number density, height of the peak above the surface, and the topside plasma scale height. Calculations of mass, momentum and energy equations for a neon atmosphere yield results that are in reasonable agreement with the observations. A nitrogen atmosphere and a neon-argon-helium atmosphere are also considered. Calculations of the electron number density of a neon ionosphere also yield reasonable agreement with observations. It is noted that Io has about the same mass and radius as the moon, and that Apollo mass spectrometer measurements indicated an abundance of neon in the lunar atmosphere. The presence of other elements, such as hydrogen, helium, and sodium, in Io's atmosphere is also discussed.

Whitten, R. C.↗
NASA NTRS1975

Test evaluation of potential heat shield contamination of an Outer Planet Probe's atmospheric sampling system

An Outer Planets Probe which retains the charred heatshield during atmospheric descent must deploy a sampling tube through the heatshield to extract atmospheric samples for analysis. Once the sampling tube is deployed, the atmospheric samples ingested must be free of contaminant gases generated by the heatshield. Outgassing products such as methane and water vapor are present in planetary atmospheres and hence, ingestion of such species would result in gas analyzer measurement uncertainties. This paper evaluates the potential for, and design impact of, the extracted atmospheric samples being contaminated by heatshield outgassing products. Flight trajectory data for Jupiter, Saturn and Uranus entries are analyzed to define the conditions resulting in the greatest potential for outgassing products being ingested into the probe's sampling system. An experimental program is defined and described which simulates the key flow field features for a planetary flight in a ground-based test facility. The primary parameters varied in the test include: sampling tube length, injectant mass flow rate and angle of attack. Measured contaminant levels predict the critical sampling tube length for contamination avoidance. Thus, the study demonstrates the compatibility of a retained heatshield concept and high quality atmospheric trace species measurements.

Kessler, W. C.↗
NASA NTRS1976

Stellar occultation spikes as probes of atmospheric structure and composition

The characteristics of spikes observed in occultation light curves of Beta Scorpii by Jupiter are discussed in terms of the gravity-gradient model. The occultation of Beta Sco by Jupiter on May 13, 1971, is reviewed, and the gravity-gradient model is defined as an isothermal atmosphere of constant composition in which the refractivity is a function only of the radial coordinate from the center of refraction, which is assumed to lie parallel to the local gravity gradient. The derivation of the occultation light curve in terms of the atmosphere, the angular diameter of the occulted star, and the occultation geometry is outlined. It is shown that analysis of the light-curve spikes can yield the He/H2 concentration ratio in a well-mixed atmosphere, information on fine-scale atmospheric structure, high-resolution images of the occulted star, and information on ray crossing. Observational limits are placed on the magnitude of horizontal refractivity gradients, and it is concluded that the spikes are the result of local atmospheric density variations: atmospheric layers, density waves, or turbulence.

Elliot, J. L.↗
NASA NTRS1976

Jupiter: Studies of the interior, atmosphere, magnetosphere and satellites; Proceedings of the Colloquium, Tucson, Ariz., May 19-21, 1975

This volume is a comprehensive technical text covering all scientific aspects of Jupiter's interior, atmosphere, magnetosphere, and satellites. The chapters deal with such general subjects as the origin and interior structure of Jupiter, the planet's atmosphere and ionosphere, as well as its magnetosphere, radiation belts, and satellites. Specific topics include a review of theories on the origin and structure of Jupiter and its satellites, interior models of Jupiter, the planet's gravity field, its thermal and atmospheric structure, model ionospheres, chemistry and spectroscopy of the atmosphere, the IR spectrum of the planet, and the meteorology of the atmosphere. Other chapters discuss radio observations of Jupiter, the dynamics of the Jovian magnetosphere, structural and thermal models of the icy Galilean satellites and Io's atmosphere and optical emissions. Results are evaluated for the IR radiometer experiment on Pioneers 10 and 11, radio occultation measurements from the Pioneer probes, Pioneer 10 UV photometric observations of the planet and its satellites, Pioneer 10 and 11 imaging polarimetry, the plasma analyzer experiment on the two probes, and observations of energetic Jovian electrons and protons. Individual items are announced in this issue.

Gehrels, T.↗
NASA NTRS1976

The atmosphere of Io

Observations of Io suggest that it may have an atmosphere in which sodium vapor, ammonia, and nitrogen are important constituents. Several atmospheric models consisting of these gases are tested as a function of total content against the Pioneer 10 observations and for stability against escape. The results suggest that the atmosphere is very tenuous and that the interpretation of the ionosphere detected by Pioneer 10 by a static model may be inconsistent with the sodium-cloud observations. It is postulated that ionization may also be escaping and that sodium may be comparable in content in the atmosphere with some molecular constituent such as NH3 or N2. Sodium and this molecular component then dominate the atmosphere. It is also suggested that particle precipitation contributes to heating of the atmosphere and to the production of ionization; the difference between day- and nighttime ionospheres and possible trailing and leading side effects may relate to the nature of the particle energy distributions. These distributions may result from the peculiar interaction of Io with the Jovian magnetosphere.

Gross, S. H.↗
NASA NTRS1977

Atmospheric transformation of solar radiation reflected from the ocean

Airborne measurements of the brightness spectrum of the Atlantic Ocean in the wavelength region from 0.4 to 0.7 micron are analyzed. These measurements were made over a tropical region of the Atlantic from an aircraft at heights of 0.3 and 10.5 km during the TROPEX-72 experiment. The results are used to estimate the contribution of the atmosphere to the overall brightness of the ocean-atmosphere system. It is concluded that: (1) the atmosphere decreases the absolute brightness of the ocean by a factor of 5 to 10 and also strongly affects the spectral behavior of solar radiation reflected from the ocean surface; (2) the atmospheric contribution to overall brightness may vary considerably under real conditions; (3) finely dispersed particles and Rayleigh scattering affect the spectral distribution of solar radiation; and (4) the spectral composition of ocean-atmosphere brightness may be completely governed by the atmosphere.

Malkevich, M. S.↗
NASA NTRS1978

Effects of atmospheric structure on radiative heating for Jupiter entry probe

New estimates of the radiative heat load to a Jupiter entry probe have been obtained for revised models of Jupiter's atmosphere based on the latest data from Pioneer 10 and 11 missions and earth-based experiments. The new estimates of the radiative heat load are compared with results obtained for the previous atmospheric models. The changes in Jupiter's atmospheric models cause a substantial reduction in the radiative heat load for the atmosphere denoted as 'cool', but only moderate reductions for the atmospheres denoted as 'nominal' and 'warm'. Results are also presented showing the effects of inertial entry angle for off-equatorial entries in the revised model atmospheres.

Sutton, K.↗
NASA NTRS1979

Thermal infrared properties of the Martian atmosphere. I - Global behavior at 7, 9, 11, and 20 microns

Infrared observations of Mars by the Viking infrared thermal mapper (IRTM) are presented for conditions of both a relatively clear and a dust-laden atmosphere. The 7-, 9-, 11-, and 20-micron bands of the IRTM respond differently to radiation emitted through and by a dusty atmosphere, permitting characterization of the global atmospheric state, monitoring of secular changes, and derivation of optical depth information. Surface temperature behavior is found to be greatly modified by the diminution of insolation and thermal blanketing resulting from global dust storms. Brightness temperature at 7 microns is employed to estimate surface temperatures in the presence of dust absorption. The difference (T7) is indicative of airborne dust when thermal contrast exists between the surface and atmosphere. The diurnal behavior of T7-T9 reveals changes in the contrast; the sign of the differential reverses as the surface, warmer than the atmosphere in daytime, becomes cooler than the atmosphere at night. IRTM observations of local areas at varying emission angle yield optical depths indicative of global trends. Two global dust storms in 1977 produced large optical depth changes: at 9 microns the optical depth became as large as 2.0.

Martin, T. Z.↗
NASA NTRS1979

The evolution and variability of atmospheric ozone over geological time

The rise of atmospheric O3 as a function of the evolution of O2 has been investigated using a one-dimensional steady-state photochemical model based on the chemistry and photochemistry of Ox(O3, O, O(1D)), N2O, NOx(NO, NO2, HNO3), H2O, and HOx(H, OH, HO2, H2O2) including the effect of vertical eddy transport on the species distribution. The total O3 column density was found to maximize for an O2 level of 0.1 present atmospheric level (PAL) and exceeded the present total O3 column by about 40%. For that level of O2, surface and tropospheric O3 densities exceeded those of the present atmosphere by about an order of magnitude. Surface and tropospheric OH densities of the paleoatmosphere exceeded those of the present atmosphere by orders of magnitude. It was also found that in the O2-deficient paleoatmosphere, N2O (even at present atmospheric levels) produces much less NOx than it does in the present atmosphere.

Levine, J. S.↗
NASA NTRS1980

Analytical investigation of fan tone noise due to ingested atmospheric turbulence

The atmospheric turbulence involved in the fan noise generation is evaluated with an existing model for the atmospheric turbulence and an extended version of an existing model concerned with the effects of a flow contraction on convected turbulence. Fan tone noise due to ingested atmospheric turbulence is evaluated with existing fan noise models. The results indicate that the difference in fan narrowband noise due to atmospheric turbulence between static and flight landing approach conditions is in the order of 30 dB. It is concluded that fan noise due to atmospheric turbulence is insignificant in flight conditions for the fans used in the current high bypass ratio engines. The difference in fan narrowband noise between the two conditions is primarily due to the low intensity of the turbulence involved in fan noise generation in flight conditions. Fan noise due to atmospheric turbulence in static conditions should be reduced below the flight fan broadband noise levels which is best achieved with a reduction in the intensity of the fan inflow turbulence. Such a reduction can be obtained with the use of an inflow control device, low wind velocities, small surface roughness in the test stand environment, and large engine axis height above the ground. Peak sound power levels for fan tone noise due to ingested turbulence occur for transverse integral scales in the order of 25% of the rotor blade spacing in the fan tip region.

Ganz, U. W.↗
NASA NTRS1979

Effects of dust on the heating of Mars' surface and atmosphere

An analysis performed to determine the effect dust particles suspended in Mars' atmosphere have on the radiation reaching the surface both directly and scattered by the dust is described. Additionally, the fraction of incident sunlight directly absorbed by the atmospheric dust is computed. These calculations are done for ranges of dust opacity, incidence angle, surface albedo, and dust albedo, representative of the conditions on Mars. The effect of atmospheric dust on the Bond albedo is discussed. It is shown that direct heating of the atmosphere by dust absorption of solar radiation is adequate to explain Mars' south polar spring temperature inversion. Under most circumstances the presence of dust in Mars' atmosphere produces a lowering of the average surface temperature; this is probably the cause of the anomalously slow south polar cap retreat of 1977. Explicit forms for both the surface heating and the atmospheric heating as a function of the dust opacity, incidence angle, surface albedo and dust albedo are given.

Davies, D. W.↗
NASA NTRS1981

Electrical coupling between the lower atmosphere and the ionosphere

The evidence for interactions between the ionosphere and troposphere is reviewed as a first step in establishing the role of electrical coupling between two regions. Upward processes appear to include the transfer of energy through gravity waves, or through the transmittance of VLF radio waves induced by lightning. In each case, the excitation of the upper atmosphere by tropospheric sources can stimulate feedback processes returning to the troposphere. Downward coupling involves changes in the global and local electrical structure of the atmosphere, and is often induced by solar activity. These effects are more direct and may possibly bypass the stratosphere. The responses in the atmospheric circuit to local changes are nearly instantaneous, and therefore are looked on with promise for possible influences on weather systems. Emerging experimental evidence indicates that atmospheric electric fields, especially at high latitudes and in the upper atmosphere, are responsive to solar and geomagnetic phenomena. Corpuscular radiations are known to strongly enhance the local atmospheric electrical conductivity and ionizations at stratospheric and mesospheric altitudes. Theories postulate that the electric field perturbations regulated by solar activity may be responsibile for the observed statistical correlations between solar activity and thunderstorms.

Goldberg, R. A.↗
NASA NTRS1980

Venus upper atmosphere structure

Atmospheric densities of Venus were measured from the orbital decay of the Pioneer Venus from Dec. 9, 1978 to Aug. 7, 1979 near the 16 deg latitude between 140 and 190 km during the entire day. Comparative atmospheric densities on earth at 150 km are higher by a factor of 3.5 with only a 1% diurnal variation; an atmospheric composition, temperature, and density model based on the orbiter atmospheric drag (OAD) vertical structure is presented. The model shows that atomic oxygen is the major component in the Venus atmosphere above 145 km at night and above 160 km during the day with mixing ratios over 0.1 near 140 km; drag measurements indicate O concentrations from 1 x 10 to the 9th/cu cm in daytime to 3 x 10 to the 7th/cu cm at night. It is concluded that the neutral upper atmosphere of Venus is surprisingly insensitive to solar extreme UV variations and changes in the solar wind.

Keating, G. M.↗
NASA NTRS1981

Photochemistry in planetary atmospheres

Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes in the earth's ancient atmosphere are described, and problems of interest in the earth's present troposphere are discussed, including the down wind effect, plume interactions, aerosol nucleation and growth, acid rain, and the fate of terpenes. Temperature fluctuations in the four principal layers of the earth's atmosphere, predicted decreases in the ozone concentration as a function of time, and spectra of particles in the earth's upper atmosphere are also presented. Finally, the vertical structure of the Venus cloud system and the thermal structure of the Jovian planets are shown graphically.

Levine, J. S.↗