Search NASA⌕ Search

SEARCH · Search NASA

Results for “VERTICAL DISTRIBUTION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Comparison of ozone concentrations obtained from Skylab eclipse and ozonesonde measurements

The satellite eclipse technique of ozone measurement is evaluated to determine its accuracy and resolution. The method of obtaining ozone concentrations from ground-based observations of eclipsing satellites is described, the theory of this method is outlined, and the data reduction procedure is summarized. It is shown that the satellite eclipse technique successfully measures the vertical distribution of ozone from 15 to 40 km with precisions ranging from + or - 12% between 20 and 35 km and + or - 25% at both 15 and 40 km. The ozone profile is found to be in good agreement with in situ measurements obtained from an ozonesonde launched near the eclipse tangent point at local sunset, the percent differences being less than 14% from 20 to 40 km.

Mcdougal, D. S.↗
NASA NTRS1979

On the nature of the blue and ultraviolet absorption in the Jovian atmosphere

Spatially resolved reflectivities from 3000 to 6600 A of three positions from the center to the limb of the Jovian Equator, North Equatorial Belt, and North Tropical Zone are analyzed to determine the vertical distribution and wavelength dependence of various sources of blue and uv absorption. Six different models of the distribution of absorbing dust particles are examined. In each model, the variation of dust optical depth and cloud single-scattering albedo are determined. Only those models having dust above the upper NH3 cloud layer will fit the data. The high altitude dust distribution is approximately uniform over the three regions examined. The contrast in reflectivity of the belts and zones may be modeled by a different cloud single-scattering albedo in the different regions.

Cochran, W. D.↗
NASA NTRS1979

Spatially resolved methane band photometry of Jupiter. I - Absolute reflectivity and center-to-limb variations in the 6190-, 7250-, and 8900-A bands. II - Analysis of the south equatorial belt and south tropical zone reflectivity

Spatially resolved measurements of the absolute reflectivity and center to limb variations of Jupiter in the 6190, 7250 and 8900 A methane bands and nearby continuum regions are presented and analyzed for the south equatorial belts (SEBs) and south tropical zone (STrZ). It is found that the polar hoods, equatorial zone, Red Spot and north tropical zone have highest methane reflectivities, with the temperate zones and polar regions having low reflectivity and the STrZ and SEBs having intermediate values. The data on the SEB and STrZ are analyzed in terms of diffuse reflecting-scattering and two-cloud models of the vertical distribution of aerosols in the Jovian atmosphere. To fit observations, the STrZ cloud top must have between 0.55 and 0.43 bar total pressure and optical depth between 1.5 and 2.5. The reflecting-scattering models are not suitable for the SEBs. The SEB upper cloud is deeper, cloud thickness is less and the lower cloud is deeper than in the STrZ. A forward scattering haze layer accounts for limb darkening in the continuum.

West, R. A.↗
NASA NTRS1979

The 12- to 20-micron spectrum of Venus - Implications for temperature and cloud structure

The spectrum of Venus was measured between approximately 500 and 800 kaysers (12 to 20 microns) at a resolution of 3.12 kaysers from the NASA C141 G. P. Kuiper Airborne Observatory on 22 and 24 February 1977. The spectrum clearly shows the detailed structure of CO2 absorption in the vicinity of the nu-2 fundamental band at 667 kaysers. In addition, details of model fitting demonstrate the possibility for a cold and thin haze of sulfuric acid droplets along with an optically opaque cloud top near 250 K. Such clouds represent major differences from other H2SO4 main cloud deck models in the recent literature and may be indicative of changes in the vertical distribution of aerosols on a global scale. The temperatures retrieved for pressures at or below 10 mbar are largely independent of the cloud model assumed and they are some 16 to 20 K warmer than the 1972 NASA model. All retrieved temperatures lie within the range of Mariner 5 and Mariner 10 radio occultation inversion results.

Aumann, H. H.↗
NASA NTRS1979

Tropospheric and lower stratospheric vertical profiles of ethane and acetylene

The first known vertical distributions of ethane and acetylene which extend into the lower stratosphere are reported. The average upper tropospheric concentrations, between 20,000 ft and 35,000 ft, near 37 deg N-123 deg W were 1.2 micrograms/cu m (1.0 ppb) for ethane and 0.24 micrograms /cu m (0.23 ppb) for acetylene while the values near 9 N-80 W were 0.95 micrograms/cu m (0.77 ppb) and 0.09 micrograms/cu m (0.09 ppb), respectively. Detectable quantities of both ethane and acetylene are present in the lower stratosphere. There is a sharp decrease in the levels of these two compounds as one crosses the tropopause and ascends into the lower stratosphere. The observed levels of ethane and acetylene may allow some impact on the background chemistry of the troposphere and stratosphere.

Cronn, D.↗
NASA NTRS1980

The estimation of the propagation delay through the troposphere from microwave radiometer data

The uncertainity in propagation delay estimates is due primarily to tropospheric water, the total amount and vertical distribution of which is variable. Because water vapor both delays and attenuates microwave signals, the propagation delay, or wet path length, can be estimated from the microwave brightness temperature near the 22.235 GHz transition of water vapor. The data from a total of 240 radiosonde launches taken simultaneously were analyzed. Estimates of brightness temperature at 19 and 22 GHz and wet path length were made from these data. The wet path length in the zenith direction could be estimated from the surface water vapor density to an accuracy of 5 cm for the summer data and 2 cm for winter data. Using the brightness temperatures, the wet path could be estimated to an accuracy of 0.3 cm. Two dual frequency radiometers were refurbished in order to test these techniques. These radiometers were capable of measuring the difference in the brightness temperature at 30 deg elevation angle and at the zenith to an accuracy of about 1 K. In August 1975, 45 radiosondes were launched over an 11 day period. Brightness temperature measurements were made simultaneously at 19 and 22 GHz with the radiometers. The rms error for the estimation of wet path length from surface meteorological parameters was 3.2 cm, and from the radiometer brightness temperatures, 1.5 cm.

Moran, J. M.↗
NASA NTRS1980

DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2lasers

A parametric analysis of DIAL sensitivity with heterodyne detection is presented and comparisons with direct detection are discussed. Examples are given for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system. Results indicate that maximum sensitivity at minimum laser energy per measurement requires multiple pulse operation with the energy per pulse selected so that the measured photon rate is approximately equal to the detector IF bandwidth. Measurement sensitivities can be maximized and interference effects minimized by fine adjustment of measurement frequencies using the tunability of high pressure lasers. The use of rare isotope lasers minimizes loss due to CO2 atmospheric absorption.

Brockman, P.↗
NASA NTRS1980

DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2 lasers

Atmospheric trace constituent measurements with higher vertical resolution than attainable with passive radiometers are discussed. Infrared differential absorption lidar (DIAL), which depends on Mie scattering from aerosols, has special advantages for tropospheric and lower stratospheric applications and has great potential importance for measurements from shuttle and aircraft. Differential absorption lidar data reduction involves comparing large amplitude signals which have small differences. The accuracy of the trace constituent concentration inferred from DIAL measurements depends strongly on the errors in determining the amplitude of the signals. Thus, the commonly used SNR expression (signal divided by noise in the absence of signal) is not adequate to describe DIAL measurement accuracy and must be replaced by an expression which includes the random coherent (speckle) noise within the signal. A comprehensive DIAL computer algorithm is modified to include heterodyne detection and speckle noise. Examples for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system are given.

Brockman, P.↗
NASA NTRS1979

Aircraft search for millimeter-wavelength emission by stratospheric ClO

Three millimeter-wavelength transitions of ClO were searched for in the stratospheric emission spectrum during May-August 1977 using aircraft-based instruments. The measurements indicate that if stratospheric ClO has a vertical distribution of the form predicted by present photochemical models, then the ClO volume mixing ratio at the profile peak did not exceed 10 to the -9th at the time and place of the measurements. The observed spectra suggest the presence of ClO in the stratosphere but do not provide a definitive detection.

Waters, J. W.↗
NASA NTRS1979

Viking radio occultation measurements of the atmosphere and topography of Mars - Data acquired during 1 Martian year of tracking

The results of one Martian year of radio occultation measurements of the atmosphere and topography of Mars obtained using the Viking Orbiters are briefly summarized. Determinations of the vertical distribution of tropospheric gas refractivity and ionospheric electron density obtained from atmospheric Doppler frequency perturbations of the S and X band radio tracking frequencies indicate large meteorological variations, with near-surface temperatures ranging from 150 to 250 K, 5-km atmospheric pressure ranging from 3.5 to 4.8 mbar, inversion layers over the polar caps and dust storms, and seasonal pressure variations. Double- and single-layered upper atmospheric electron density profiles were observed on the sunlit and dark sides of the planet, respectively. A topographic map of the Martian surface, obtained from the limb diffraction effects observed at ingress and egress, is found to agree well with the elevation contours of US Geological survey map M 25M 3 RMC, with the exception of the south polar and Alba Patera regions.

Lindal, G. F.↗
NASA NTRS1980

Remote infrared heterodyne radiometer measurements of atmospheric ammonia profiles

An infrared heterodyne radiometer has been used to study the seasonal variation of the vertical distribution of atmospheric ammonia. The ammonia profiles are inferred from high-resolution atmospheric solar transmittance measurements around the ammonia absorption feature at 927.32323 kaysers. The transmittance data are obtained from six IF channels with spectral resolutions ranging from .0067 to .033 kaysers. Results from this study show a marked decrease in the tropospheric ammonia level with a decrease at ground level from approximately 10 ppb in March 1979 to 1.3 ppb in August 1979.

Hoell, J. M.↗
NASA NTRS1981

The solar ultraviolet source for the ionosphere and its variation

Ion production in the ionospheric E and F regions is primarily due to solar EUV fluxes at wavelengths below 102.7 nm, where the flux ratios of maximum/minium for the present solar cycle were found to range from values around 3 for the dominant chromospheric emissions to much higher values for coronal emissions, resulting in a factor of about 4 in the integrated flux of the range 14-102.7 nm. The vertical distribution of ion production depends not only on the incident solar EUV fluxes but also on the structure of the absorbing neutral atmosphere (thermosphere). As the latter is strongly affected by solar EUV fluxes above 130 nm (production of atomic oxygen and heating), the observed increase, with ratios ranging from about 1.2 around 175-185 nm to about 2.3 around 140 nm, is at least indirectly important in the solar cycle variation of the ionosphere. The EUV variability models of the ionosphere using non EUV indices such as F sub 10.7, R sub Z or Ca2 plage indices are valuable as a crude guide only, but not for quantitative representations.

Hinteregger, H. E.↗
NASA NTRS1981

Design, development, and field testing of Infrared Heterodyne Radiometer (IHR) for remote profiling of tropospheric and stratospheric species

The performance of a dual-channel infrared heterodyne radiometer, designed to remotely monitor the concentration and vertical distribution of selected atmospheric species, is described. Ground based solar viewing measurement using the IHR were performed at selected laser transitions for ammonia (NH3 and ozone O3). Flight tests were conducted aboard the Galileo II, NASA Ames CV-990, on the Latitude Survey Mission. Ozone was the selected atmospheric species for the airborne flight measurements because of the scientific interest in this atmospheric species, the availability of in situ monitors, the coordinated ozone measurements, and the availability of ground truth data. The IHS was operated in the solar viewing mode to determine ozone distributions in the stratosphere and in the nadir viewing mode to determine the ozone distribution in the troposphere. Airborne atmospheric propagation measurements also were carried out at selected CO2 laser transitions.

Lange, R.↗
NASA NTRS1980

Planetary boundary-layer wind model evaluation at a mid-Atlantic coastal site

Detailed measurements of the mean flow and turbulence were made with the use of a micrometeorological facility consisting of an instrumented 76-m tall tower located within a 100-m distance from the Atlantic Ocean at Wallops Island, Virginia. Under moderately strong wind conditions, the popular neutral boundary layer flow model fails to provide an adequate description of the actual flow. In addition to detailed flow information for all wind directions, averages of the important flow parameters used for design such as vertical distribution of mean velocity, turbulence intensities and turbulence integral scales were presented for wind direction sectors with near uniform upstream terrain. Power spectra of the three velocity components for the prevailing northwesterly and southerly winds are discussed.

Tieleman, H. W.↗
NASA NTRS1981

Atmospheric ammonia - Measurements and modeling

Ammonia possesses a unique position in the terrestrial atmosphere in that it is the only gaseous basic constituent. Ammonia readily forms aerosols, and by virtue of its high solubility controls the pH of cloud droplets and precipitation. Over the past year a ground-based solar viewing Infrared Heterodyne Radiometer has been used at Langley Research Center to infer the vertical distribution of ammonia. Ground level in situ measurements of ammonia have also been obtained to supplement the profile data. The ammonia profiles have been analyzed and interpreted with a one-dimensional photochemical model of the troposphere to assess the sources and sinks of NH3.

Hoell, J. M., Jr.↗
NASA NTRS1980

High spatial and spectral resolution 10-micron observations of Jupiter

Ten-micrometer spectra of the North Tropical Zone, North Equatorial Belt, and Great Red Spot at a spectral resolution of 1.1/cm are compared to synthetic spectra. These ground-based spectra were obtained simultaneously with the Voyager 1 encounter with Jupiter in March, 1979. The NH3 vertical distribution is found to decrease with altitude significantly faster than the saturated vapor pressure curve and is different for the three observed regions. Spatial variability in the NH3 mixing ratio could be caused by changes in the amount of NH3 condensation or in the degree of the NH3 photolysis. The C2H6 emission at 12 microns has approximately the same strength at the North Tropical Zone and North Equatorial Belt, but it is 30% weaker at the Great Red Spot. A cooler temperature inversion or a smaller abundance of C2H6 could explain the lower C2H6 emission over the Great Red Spot.

Tokunaga, A. T.↗
NASA NTRS1981

Measurements of CF2Cl2, CFCl3, and N2O in the lower stratosphere between 2 deg S and 73 deg N latitude

Mixing ratios are presented for CF2Cl2, CFCl3, and N2O in the lower stratosphere. They are derived from measurements made on samples collected by a high-altitude aircraft during a survey in the northern hemisphere in the summer of 1977. The vertical distributions of the mixing ratios of these species show a decrease with increasing altitude and a marked decrease at a given altitude with increasing latitude from 2 deg S to 73 deg N latitude. These results agree with measurements at similar latitudes in the fall of 1976 and with results of other experiments. The experimental apparatus and procedures are described in greater detail than in previous papers.

Vedder, J. F.↗
NASA NTRS1982

The relevance of the IUE results on young stars for Earth's paleoatmosphere

Using the latest IUE results for seven T Tauri stars, which are believed to represent the young Sun and a detailed photochemical chemical model of the paleoatmosphere, the vertical distribution of Oxygen and Ozone in the early atmosphere was calculated. The calculations indicate that the surface Oxygen mixing ratio is as much as six orders of magnitude larger than previously estimated, but appears low enough for the formation of amino acids via the Urey-Miller type of experiments. It is believed that the quantification of the oxygen level in the Earth's paleoatmosphere presented can reconcile the demands of both biological and geological considerations.

Canuto, V. M.↗