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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Remote sensing of row crop structure and component temperatures using directional radiometric temperatures and inversion techniques

A physically based sensor response model of a row crop was used as the mathematical framework from which several inversion strategies were tested for extracting row structure information and component temperatures using a series of sensor view angles. The technique was evaluated on ground-based radiometric thermal infrared data of a cotton row crop that covered 48 percent of the ground in the vertical projection. The results showed that the accuracies of the predicted row heights and widths, vegetation temperatures, and soil temperatures of the cotton row crop were on the order of 5 cm, 1 deg, and 2 deg C, respectively. The inversion techniques can be applied to directional sensor data from aircraft platforms and even space platforms if the effects of atmospheric absorption and emission can be corrected. In theory, such inversion techniques can be applied to a wide variety of vegetation types and thus can have significant implications for remote sensing research and applications in disciplines that deal with incomplete vegetation canopies.

Kimes, D. S.↗
NASA NTRS1983

Thermal infrared constraints on ammonia ice particles as candidates for clouds in the atmosphere of Saturn

Saturn atmosphere thermal IR emission observations have uncovered two phenomena that may be accounted for by large ammonia ice particles: the depression of thermal brightness near the equator, and inconsistent IR and radio occultation results. Ammonia ice particles yield the opacity that can account for the contrast between the equatorial region and a brighter area near 15 deg S, and may also reconcile the 45-micron brightness of these two regions with the mean temperature structure of Voyager 2 radio occultation results. A cloud model whose ice particles are distributed in an equal ratio with gas particles up to the 100 mbar pressure level is found to fit the equatorial data, while a thinner cloud, or one that does not extend higher than the 400 mbar limit of the convective region matches the 15 deg S data.

Orton, G. S.↗
NASA NTRS1984

Planetary observations at a wavelength of 1.32 mm

Observations at a wavelength of 1.32 mm have been made of the Jovian planets, Ceres, the satellites Callisto and Ganymede, and the HII region DR 21. The observed brightness temperatures are presented. Those of the Jovian planets agree with the values expected from model atmosphere calculations, except that of Jupiter, which is lower than expected. Ceres and the satellites do not have atmospheres so their emission arised in their subsurface layers. The observed brightness temperatures are intermediate between those measured at infrared and centimeter wavelengths.

Ulich, B. L.↗
NASA NTRS1986

Composition and stability of the condensate observed at the Viking Lander 2 site on Mars

Surface energy balance and near-surface temperature data from the Viking Lander 2 site taken during the first winter that condensated were observed and analyzed to determine the relative stability of CO2 and H2O frosts. The CO2 frost stability is calculated with an equilibrium surface energy balance model, i.e., the total energy incident on a frost surface is compared with the blackbody energy emitted by the surface. The energy sources considered were IR emission from the atmosphere, sunlight, and the sensible heat flux from the atmosphere. H2O stability was examined as a function of buoyant diffusion and turbulent mixing processes which could remove saturated near-surface gases. The CO2 frost is found to be sufficiently unstable at the time the condensate was observed on the ground, so all CO2 ice deposited at night would boil away in a few hours of sunlight. CO2 ice would not form during a dust storm. Water frost would be stable during the condensate observations, since sublimation would occur at a rate below 1 micron/day. A stable winter thickness of 10 microns is projected for the water ice.

Hart, H. M.↗
NASA NTRS1986

Thermal balance of the atmospheres of Jupiter and Uranus

Two-dimensional, radiative-convective-dynamical models of the visible atmospheres of Jupiter and Uranus are presented. Zonally-averaged temperatures and heat fluxes are calculated numerically as functions of pressure and latitude. In addition to radiative heat fluxes, the dynamical heat flux due to large-scale baroclinic eddies is included and is parametrized using a mixing length theory which gives heat fluxes similar to those of Stone. The results for Jupiter indicate that the internal heat flow is non-uniform in latitude and nearly balances the net radiative flux leaving the atmosphere. The thermal emission is found to be uniform in latitude in agreement with Pioneer and Voyager observations. Baroclinic eddies are calculated to transport only a small amount of the meridional heat flow necessary to account for the uniformity of thermal emission with latitude. The bulk of the meridional heat transfer is found to occur very deep in the stable interior of Jupiter as originally proposed by Ingersoll and Porco. The relative importance of baroclinic eddies vs. internal heat flow in the thermal balance of Uranus depends on the ratio of emitted thermal power to absorbed solar power. The thermal balance of Uranus is compared to that of Jupiter for different values of this ratio.

Friedson, A. J.↗
NASA NTRS1988

The altitude distribution of impulsive signals in the night ionosphere of Venus

A new examination of burst like signals in the night ionosphere of Venus has been undertaken to determine the rate of occurrence of such signals. On average, at all frequencies the bursts occur most often at lowest altitudes. The rates of occurrence of bursts at 0.73, 5.4 and 30 kHz fall off rapidly with altitude. At 350 km these bursts occur about an order of magnitude less often than at 150 km. At 100-Hz the rate of falloff with altitude is less rapid. The occurrence rate decreases from about 50 percent at 150 km to between 20 and 40 percent at 500 km, and then decreases more slowly above 500 km. This decrease suggests a wave source at lowest altitudes, but high altitude sources also appear to be present. The rate of occurrence is quite variable both from season to season and from the inbound to the outbound portion of the orbit. This variability is consistent with either temporally or spatially varying source regions for these impulsive signals. Lightning in the Venus atmosphere could produce emissions consistent with the properties of those signals observed at lowest altitudes.

Russell, C. T.↗
NASA NTRS1990

Infrared measurements of atmospheric constituents

The objective of this program is to obtain data concerning the concentration versus altitude of various constituents of interest in the photochemistry of the stratospheric ozone layer. Data pertinent to this objective are obtained using balloon-borne instruments to measure the atmospheric transmission and emission in the mid infrared. In addition to obtaining constituent profile information, the spectral data obtained are also used to identify absorption or emission features which may interfere with the retrieval of constituent data from satellite instruments using lower spectral resolution. The spectral resolution obtained with the solar spectral system is 0.0025 cm(exp -1) and represents about a factor of 5 greater resolution than any solar spectra previously obtained in this spectral region. As a result of the increase in spectral resolution, a large number of features are observed in these spectra which were not observed in previous studies. Identification and analysis of these features is in progress. The results of this analysis to date shows a number of HNO3 features which have not been observed before, and these occur where they will interfere with the retrieval of other constituents. An example of the interference is the occurrence of features in the 780.2 cm(exp -1) region which overlap the ClONO2 feature which will be used for retrieval of ClONO2 by the CLAES instrument on UARS. A number of features due to COF2 were also identified in the 1250 cm(exp -1) region which may interfere with retrieval of N2O5.

Murcray, David G.↗
NASA NTRS1993

Far-IR Fabry-Perot spectrometer for OH measurements

The Far Infrared Limb Observing Spectrometer (FILOS) is an instrument designed to measure chemical species in the upper atmosphere using limb emission in the FIR region of the spectrum. FILOS uses three Fabry-Perot etalons in series to obtain a resolution of 0.0017/cm near 100/cm (100 microns). It is compact and has low power and low data rate requirements so that it may be flown as an auxiliary balloon payload with larger instruments. FILOS has two 0.05/cm bandwidth channels which are currently tuned to a HCl line at 104.2/cm and a pair of OH lines at 101.3/cm. The instrument is described in further detail and results are presented from two recent balloon flights in which OH was measured as a function of time on one hour centers from sunrise to sunset.

Pickett, Herbert M.↗
NASA NTRS1985

Wind measurements with the High Resolution Doppler Imager (HRDI)

The Upper Atmosphere Research Satellite (UARS), to be launched in 1989, is to provide a global data set required to understand the mechanisms controlling upper atmosphere structure and processes, as well as the response of the upper atmosphere to natural and human perturbations. The High Resolution Doppler Imager (HRDI) is the primary instrument for measuring the dynamics of the stratosphere and mesosphere. The goal of HRDI is to measure wind velocities in the stratosphere and mesosphere during the day and the mesosphere and thermosphere at night with an accuracy of 5 m/sec. HRDI will determine winds by measuring Doppler shifts of atmosphere absorption and emission features. Line of sight winds will be taken in two directions, thus allowing the wind vector to be formed. The HRDI instrument is overviewed. The basis of the measurement is explained, as is an outline of the instrument. Since neither instrument nor observational techniques is fully mature, only a brief sketch is presented.

Skinner, W. R.↗
NASA NTRS1992

Effects of inorganic sulfur addition on fluxes of volatile sulfur compounds in Sphagnum peatlands

Short and long-term impacts of increased S deposition on fluxes of volatile S compounds (VSC's) from Sphagnum peatlands were investigated in an artificially acidified (sulfuric and nitric acids) poor fen (Mire 239) at the Experimental Lakes Area (ELA), Ontario, Canada. Additional experiments were conducted in a poor fen (Sallie's Fen) in Barrington, NH, USA. At Mire 239, emissions of VSC's were monitored, before and after acidification, at control (unacidified) and experimental sections within two major physiographic zones of the mire (oligotrophic and minerotrophic). The experimental segments of the mire received S amendments since 1983, in amounts equivalent to the annual S deposition in the highest polluted areas of Canada and U.S. Dimethyl sulfide (DMS) was the predominant VSC released from the mire and varied largely with time and space (i.e., from 2.5 to 127 nmol/m(sup -2)h(sup -1)). Sulfur addition did not affect DMS emissions in a period of hours to a few days, although it stimulated production of DMS and MSH in the anoxic surficial regions of the peat. DMS emissions in the experimental oligotrophic segment of the mire was approximately 3-fold greater than in the control oligotrophic segment, and approximately 10-fold greater than in the minerotrophic zones. These differences could be due to a combination of differences in types of vegetation, nutritional status, and S input. At Sallie's Fen, DMS fluxes were approximately 8 times higher from a Sphagnum site than from a bare peat site. Fluxes of VSC's were not significantly affected by sulfate amendments at both sites, while DMS and MSH concentrations increases greatly with time in the top 10 cm of the peat column. Our data indicated that although Sphagnum is not the direct source of DMS released from Sphagnum peatlands, it might play a role in regulating DMS emissions to the atmosphere.

Demello, William Zamboni↗
NASA NTRS1994

Airglow response to vertically standing gravity waves

There is currently much interest in fluctuations of airglow emissions caused by atmospheric gravity waves. The fluctuations of brightness tend to be found in phase (or occasionally in antiphase) with the fluctuations of measured temperature, whereas current theory tends to anticipate substantial phase differences. We suggest here that the discrepancy results from failure of the common theoretical assumption that the relevant gravity waves are dominated by a single upgoing component: that, instead, there is an accompanying downgoing component of comparable magnitude, produced by reflection. In the case of total reflection, simple, steady state chemistry and vertical viewing, the phase difference is necessarily zero (or 180 deg).

Hines, Colin O.↗
NASA NTRS1995

EUV spectroscopy of 3 RSCVn binaries

The extreme ultraviolet (EUV) spectroscopy of several binary stars containing cool components is used to define the high temperature plasma structure of these stars and their stellar atmospheres. Different line emission spectra are reported, along with a spectrum analysis of Capella, a nearby bright multiple star system, using data from the EUVE satellite.

Dupree, A. K.↗
NASA NTRS1993

Biomass Burning

Biomass burning may be the overwhelming regional or continental-scale source of methane (CH4) as in tropical Africa and a significant global source of CH4. Our best estimate of present methane emissions from biomass burning is about 51.9 Tg/yr, or 10% of the annual methane emissions to the atmosphere. Increased frequency of fires that may result as the Earth warms up may result in increases in this source of atmospheric methane.

Levine, Joel S.↗
NASA NTRS2000

A Grant from NASA's Office of Space Station Science, Planetary Atmosphere's Program to Boston University

In the past three years of this program we have made contributions to a variety of subjects in research on Jupiter's Atmosphere, the Ultraviolet Spectroscopy of Jupiter, the abundance of CH4 in Pluto's atmosphere, and the emissivity of Pluto's Surface. We also performed work on two projects related to Titan, and an analysis of the visible spectrum of a brown dwarf. The highpoints are briefly summarized and a list of papers supported partly or wholly by this program is also provided.

Yelle, Roger V.↗
NASA NTRS2003

Water Cycling in the North Polar Region of Mars

To date, there has been no comprehensive study to understand the partitioning of water into vapor and ice clouds, and the associated effects of dust and surface temperature in the north polar region. Ascertaining the degree to which water is transported out of the cap region versus within the cap region will give much needed insight into the overall story of water cycling on a seasonal basis. In particular, understanding the mechanism for the polar cap surface albedo changes would go along way in comprehending the sources and sinks of water in the northern polar region. We approach this problem by examining Thermal Emission Spectrometer (TES) atmospheric and surface data acquired in the northern summer season and comparing it to Viking data when possible. Because the TES instrument spans the absorption bands of water vapor, water ice, dust, and measures surface temperature, all three aerosols and surface temperature can be retrieved simultaneously. This presentation will show our latest results on the water vapor, water-ice clouds seasonal and spatial distributions, as well as surface temperatures and dust distribution which may lend insight into where the water is going.

L K Tamppari↗
NASA NTRS1998

The Use of Correlated k-Distributions to Account for the Radiative Effect of Molecular Absorption Upon Satellite Measured Radiances

Establishing the radiative effect of molecular absorption (emission) in the atmosphere is critical to the proper interpretation of satellite retrieved radiances. Without an accurate accounting for molecular absorption, the assignment of radiative transfer processes to observed radiative effects could be fraught errors. Moreover, since the spectral characteristics of molecular absorption can change quickly with wavenumber, the adaptation of climate model parameterizations has the potential to lead to dubious results unless the chosen spectral range corresponds closely to the response function of the satellite instrument. Thus, an initiative has been undertaken to construct parameterizations that will account for the molecular absorption found in the spectral ranges of several satellite radiometers. Because of its efficiency and accuracy in calculating the molecular absorption for nonhomogeneous paths, the correlated k-distribution procedure has proven to be the most effective parameterization (Fu and Liou, 1992, and Kratz, 1995). A further advantage of the correlated k- distribution procedure is its ability to be incorporated directly into multiple scattering routines that consider scattering, as well as absorption, by clouds and aerosol particles.

Kratz, David P.↗
NASA NTRS1993

Mapping the Piute Mountains, CA with Thermal Infrared Multispectral Scanner (TIMS)

Thermal Infrared Multispectral Scanner (TIMS) data were acquired in 1990 over the PiuteMountains, California to evaluate their usefulness for lithologic mapping in an area ofmetamorphosed, structurally complex, igneous and sedimentary rocks. The data were calibrated,atmospherically corrected, and emissivity variations extracted from them. There was an excellentvisual correlation between the units revealed in the TIMS data and the recent mapping in the easternside of the area. It was also possible to correct, improve and extend the recent map. For example,several areas of amphibolite were identified in the TIMS data that had been incorrectly mapped asgranodioritic gneiss, and the presence of a swarm of mafic dikes, of which only a few had previouslybeen identified, was revealed...

Hook, S. J.↗