Showing papers on "Haze published in 1983"
TL;DR: In this paper, the average radius of the particles found in the upper few tenths of an optical depth exceeds 0.19 micron, if the widths of their diffraction peaks are close to those for equal-volume spheres.
Abstract: Limits on the physical properties of the scattering haze near the top of Titan's atmosphere are derived from data obtained from seven high-phase-angle images from Voyager 1 and 2. From the ratio of the intensities observed at two different high phase angles, an estimate can be made of the forward-scattering lobe of the single-scattering phase function. Comparing the forward-scattering estimate with diffraction lobes from particles of different radii, it is concluded that the average radius of the particles found in the upper few tenths of an optical depth exceeds 0.19 micron. Judging from data observed at four different phase angles, the haze particles probably have a refractive index near 1.6 and a mean size of about 0.5 micron, if the widths of their diffraction peaks are close to those for equal-volume spheres. However, the highly polarizing nature of the particles over a broad wavelength-bandpass (Tomasko and Smith, 1982; West et al, 1983) combined with their forward-scattering behavior makes it very unlikely that the particles are spherical. The nonsphericity contributes to the uncertainty about the radii of the particles, but it is thought that the average radius is several tenths of a micron.
103 citations
TL;DR: In this paper, the authors used the Aden and Kerker solution for spherical nuclei coated with a spherical shell to account for the observed sulphuric acid coating on Arctic aerosols.
Abstract: The optical parameters of Arctic haze, such as the scattering and the absorption coefficients and the asymmetry factor, have been estimated using a theoretical haze model. The Aden and Kerker solution for spherical nuclei coated with a spherical shell was employed to account for the observed sulphuric acid coating on Arctic aerosols. Six original aerosol materials are considered; four are natural and two are anthropogenic in origin (sulphuric acid and soot). The relative humidity is varied between 0 and 99% and the effects of anthropogenic substances are examined. Carbonaceous material can increase the absorption coefficient by up to a factor 5 in the visible range, while sulphuric acid significantly increases the growth of particles and affects all of the optical parameters. The haze model is found to be consistent with available measurements of aerosol characteristics and optical parameters. The haze model is then used to convert a vertical profile of the extinction coefficient to a profile of ...
60 citations
TL;DR: In this article, the authors made an assessment of the quantitative picture (i.e., models versus experiments and theory), upon which estimations for general radio path behavior can be based.
Abstract: Transparency of the four atmospheric extremely high frequency (EHF) window ranges located around 35, 90, 140, and 220 GHz is obscured by precipitation (rain, wet snow), by suspended particles (fog, cloud, haze, dust), and by water vapor An assessment is made of the quantitative picture (ie, models versus experiments and theory), upon which estimations for general radio path behavior can be based Useful models are provided for calculating attenuation based upon measurable meteorological variables: rain rate, liquid water content, humidity, temperature, and pressure Information currently available is not yet complete enough to provide accurate predictions under all climatological conditions Emphasis is on recent advances in formulating the physical basis for modeling transparency and on a discussion of some of the principal remaining uncertainties
56 citations
TL;DR: Voyager 2 photometric and polarimetric data are reduced and tabulated, with spatially resolved limb-to-terminator scans across Saturn's equatorial zone providing information on the altitude distribution of UV-absorbing hazes, together with the phase function and polarizing properties of stratospheric and tropospheric aerosols as discussed by the authors.
Abstract: Voyager 2 photometric and polarimetric data are reduced and tabulated, with spatially resolved limb-to-terminator scans across Saturn's equatorial zone providing information on the altitude distribution of UV-absorbing hazes, together with the phase function and polarizing properties of stratospheric and tropospheric aerosols. It is found that the UV photometry and polarimetry are best fit by Rayleigh's phase matrix. A stratospheric haze of small particles is allowed as long as the optical depth is near unity or less, and the center of the haze layer is in the 30 to 70 mbar region. The altitudes presently derived for three latitudes agree with those obtained by ground-based methane band studies and analyses from Pioneer 11. A high altitude absorber is abundant in the polar regions.
55 citations
TL;DR: During winter faster transport of polluted air to the Arctic is partly responsible for the occurrence of arctic haze as well as the observed excess concentrations of trace gases.
Abstract: At Pt. Barrow in the Arctic, winter concentrations of CHClF/sub 2/, CCl/sub 3/F, CCl/sub 2/F/sub 2/, CH/sub 3/CCl/sub 3/, C/sub 2/Cl/sub 4/, C/sub 2/HCl/sub 3/, CO, and CH/sub 3/Cl exceed their concentrations during other times of the year, similar to the seasonal pattern of arctic haze. The anthropogenic halocarbons and the combustion-derived CO and CH/sub 3/Cl are produced at the same midlatitude locations as the precursors of arctic haze and therefore serve as inert tracers of long-distance transport of pollution to the Arctic atmosphere. The best gaseous tracers of arctic haze are entirely man-made and have atmospheric lifetimes of less than about 5 years, or their concentrations are far from equilibrium with current yearly emissions. The presence of combustion-derived gaseous pollution in the arctic during winter agrees with independent studies showing a significant combustion-derived component in the arctic haze aerosol. During winter faster transport of polluted air to the Arctic is partly responsible for the occurrence of arctic haze as well as the observed excess concentrations of trace gases.
44 citations
TL;DR: In this article, a model for a spherical atmosphere with tangential viewing geometry was used to analyze the high altitude Venus haze and its variation over almost one half a Venusian year.
40 citations
TL;DR: In this article, an identifiable plume of contaminated air forms downwind of metropolitan St. Louis under certain conditions, and the contribution of this urban plume to tropospheric ozone and aerosol loadings is calculated from concentration and wind fields measured during Project MISTT.
Abstract: An identifiable plume of contaminated air forms downwind of metropolitan St. Louis under certain conditions. The contribution of this urban plume to tropospheric ozone and aerosol loadings is calculated from concentration and wind fields measured during Project MISTT. On all three summer days selected for study, net ozone exports reached 2–3×106 g mol/h, or about 3/2 mole per mole of emitted nitrogen, within hours of emission. Conversion of sulfur dioxide to sulfate aerosol was incomplete at the distances sampled; it is estimated that haze exports ultimately reached 500–600 km2/h, or 8–9 m2 per gram of emitted sulfur. Simple extrapolation of the yields observed at St. Louis indicates that anthropogenic inputs overwhelm natural contributions to ozone and aerosols over eastern North America.
33 citations
TL;DR: In this paper, the absorption of solar radiation by the Arctic haze was measured directly for the first time, and the measurements were used to calibrate a high resolution solar flux model, which was then used to compute atmospheric heating rates.
Abstract: During the recent Arctic Gas and Aerosols Sampling Project flight series, the absorption of solar radiation by the Arctic haze was measured directly for the first time. Absorpton was measured in three narrow band channels, and the measurements were used to calibrate a high resolution solar flux model, which was then used to compute atmospheric heating rates. Analyses of data from three flights with estimated optical depths of 0.26, 0.17, and 0.31 at 500 nm produced instantaneous solar heating rates of the order of 1.1 to 1.5 K/day. These rates are greater by a factor of 2 to 3 than heating in the absence of the haze. Possible climatic implications are briefly discussed.
31 citations
TL;DR: Aerosols in central Alaska's winter air mass system were classified according to size by diffusive separation and light-scattering spectrometry as mentioned in this paper, with particle number concentrations ranging from 300 to 2000 cm−3 and unimodal size spectra with maximum in number concentration near 1 × 10−6 cm radius.
Abstract: Aerosols in central Alaskan winter air mass system were classified according to size by diffusive separation and light-scattering spectrometry. Particles entering central Alaska from the Pacific Marine environment had number concentrations ranging from 300 to 2000 cm−3 (geometric mean 685 cm−3) and unimodal size spectra, with maximum in number concentration near 1 × 10−6 cm radius. Air masses entering Alaska from the Eurasian Arctic possessed a factor of two smaller aerosol number concentrations than Pacific Marine systems (e.g., 150–700 cm−3; geometric mean 386 cm−3) but contained a factor of two greater particle volume loading within the fine particle radius range ∼5 × 10−7 < r < 1 × 10−5 cm. The particles in Eurasian Arctic air masses were bimodally distributed, with maxima in the particle size spectra near r = 3 × 10−7 and 5 × 10−6 cm. Sulfur was the predominant element in all cases studied. A particle depleted region was present in the size spectra obtained for Eurasian Arctic air masses. Th...
27 citations
TL;DR: The rotational quantum number of the 6818.9-A feature was estimated using the relatively homogeneous atmosphere of Saturn, with only J = 0 and J = 1 fitting the observational constraints.
24 citations
Patent•
02 Feb 1983
TL;DR: In this paper, a method of measuring haze of an aircraft transparency is proposed, which produces a first reading representative of the level of light scattered by an area of a transparency under test while on the aircraft when it is illuminated by a known light source.
Abstract: A method of measuring haze of an aircraft transparency includes producing a first reading representative of the level of light scattered by an area of a transparency under test while on the aircraft when it is illuminated by a known light source, and producing a second reading representative of the level of light scattered by a predetermined, preferably worst haze condition, reference plate when it is illuminated by the light source in place of the transparency. Then, a ratio of the first and second readings is calculated to provide a quantitative measure proportional to the degree of haze in the transparency test area.
TL;DR: In this paper, the authors describe teleradiometer measurements in which the haze color and brightness were determined to estimate the relative importance of particle and NO 2 optical extinction to the appearance of winter haze in Denver.
Patent•
01 Mar 1983
TL;DR: In this paper, a system for image generation is presented which includes a device for controlling the sweep voltages of a CRT so that realistic views of the earth can be projected on a curved screen surface from a flat transparency and for generating a haze band between the earth and sky interface of the projected scene.
Abstract: A system for image generation is provided which includes a device for controlling the sweep voltages of a CRT so that realistic views of the earth can be projected on a curved screen surface from a flat transparency and for generating a haze band between the earth and sky interface of the projected scene. The preferred embodiment is an aircraft flight simulator in which real world scenes are projected and updated in accordance with simulated aircraft maneuvers. Various visual flight cures are or can be presented to an operator during training. These flight cues include a dynamic haze or cloud band along the projection of the earth and sky interface. The system permits image projection with six degrees of freedom (yaw, pitch, roll, altitude, north/south and east/west vector components) over simulated terrain. In the preferred embodiment, the haze or cloud band generation is accomplished so that it is compatible with a single projector technique.
TL;DR: Both passive and active remote sensing of atmospheric precipitation are studied with the vector radiative transfer equations by making use of the Mie scattering phase functions and incorporating the raindrop-size distributions.
Abstract: Both passive and active remote sensing of atmospheric precipitation are studied with the vector radiative transfer equations by making use of the Mie scattering phase functions and incorporating the raindrop-size distributions. For passive remote sensing, the Gaussian quadrature method is employed to solve for the brightness temperatures. For active remote sensing, an iterative approach carrying out to the second order in albedo is used to calculate for the bistatic coefficients, the backscattering cross sections/unit volume, and the interchannel cross talks. The calculated results are plotted as a function of rainfall rates and compared to various available experimental data. The theoretical model is easily applied to the remote sensing of aerosol particles, smoke, fog, and haze at infrared and visible frequencies.
TL;DR: In this article, four distinct types of particles are suggested to be present in the upper atmosphere of Venus and the lowest and densest haze may consist of a submicron sulfuric acid aerosol which extends above the cloud top, up to about 80 km.
TL;DR: In this paper, a comparison of reported measurements of the change in the direct and total hemispheric solar irradiances at Barrow, Alaska between days with and without visible haze with values computed from aerosol models with different imaginary parts of the refractive index leads to the conclusion that the haze is only weakly absorbing.
TL;DR: In this article, the geometric albedo of Uranus in and near prominent methane absorption bands between 05 and 09 μm was modeled and it was shown that the visible atmosphere probably consists of a thin aerosol haze layer ( τ scat ≅ 03−05; ω H ≅ 095) above an optically thick, semi-infinite Rayleigh scattering atmosphere.
TL;DR: The variation of potential gradient in mist, haze, and fog has been studied and during the formation of these hydrometers the potential gradients were found to increase.
Abstract: The variation of potential gradient in mist, haze, and fog has been studied. During the formation of these hydrometers the potential gradients were found to increase. Large positive potential gradients were observed during dense fog conditions. Possible charge generation mechanisms responsible for these potential gradients during fog formation are discussed.
TL;DR: The amount of Raman scattering in Saturn's equatorial zone and polar regions near the central meridian at the wavelengths of the H and K Ca II solar lines, 3934 A and 3969 A was measured.
TL;DR: In this article, solar, sky, and aureole radiance data from Australia and Nigeria were analyzed. But the results of the analysis were limited to two stations, Australia and Lagos, Nigeria.
Abstract: Solar, sky, and aureole radiance data from Kensington, Australia, and Lagos, Nigeria, are analysed. The values of the aerosol optical thickness at Lagos are comparable to measured values elsewhere in the subregion (Abidjan) under light haze. The values at Kensington are close to those of the “background aerosol.” Identical and anomalous values of aerosol optical thickness occurred at 1.67 µm at both stations as less than 15% of the values can be accounted for by aerosols. The high optical depths are therefore explained in terms of absorption, possibly mainly by CO2 (59–65%) and, to a lesser extent, by H2O (20–26%). Following correction for molecular multiple scattering, the aerosol scattering phase function increases substantially at 0.5 µm in Kensington and decreases considerably at 0.76 µm in Lagos when compared to the uncorrected function, confirming the relative fineness of the Kensington aerosol. The Lagos aerosol size distribution for moderately dusty air is reasonably bimodally log-normal with modal radiusr
m=0.49 µm (1.36 µm) for the moder≤1 µm (r>1 µm). The Kensington aerosol resembles one withr
m=0.05 µm forr<1 µm. There the Born approximation appears appropriate, and the weighted mean square radiusp
2=0.13 µm2. In the near forward direction the aerosol scattering phase funciton for Lagos resembles Deirmendjian’s simulations for a silicate-L haze and, for Kensington, a silicate-H haze.
22 Apr 1983
TL;DR: In this article, the authors provide a quantitative background for selecting criteria for automotive glazing materials, particularly for transmittance and haze, as these are affected by laboratory tests and road exposures.
Abstract: This study was performed to provide a quantitative background for selecting criteria for automotive glazing materials, particularly for transmittance and haze, as these are affected by laboratory tests and road exposures. Experimental designs and data collection protocols were prepared and followed which yielded objective descriptions of the response of new, in-use, and end-of-useful-life glazing materials to environmental exposures & simulations of exposures. Research subject areas included: (1) Transmittance & Haze of Automotive Glazing Presently in Use, (2) Tolerated Obscuration of Glazing in Use, (3) Environmental Effects on Glazing, (4) ANSI Z-26 Tests Effects on Glazing Transmittance & Haze, and (5) Production of a Motion Picture illustrating the Effects of Increasing Haze on Roadway & Roadside Visibility. The results indicated that drivers often operate vehicles with windshield haze levels exceeding 4%, largely attributable to dirty glazing. Tests based on environmental models indicate Securiflex glazing provides optical qualities equivalent to or exceeding on-road use requirements; Securiflex glazing meets ANSI Z-26 visibility and durability tests, (Tests 3, 4, 16, 17, 18, 19, and 24-17 modified to accept a 4% haze increase proposed for glass-plastic glazing) and retained adequate optical qualities (haze & transmittance) to meet present user requirements.
TL;DR: The average contribution of the coal-fired power plant plume alone to the IR extinction coefficient was 74% at the Four Corners plant; the background haze contributed 7-11% as discussed by the authors.
Abstract: Infrared measurements in the 8–14-μm spectral region were made of two coal-fired power plant plumes and area haze in the Four Corners region of New Mexico from 1 to 7 Nov. 1980. The layer transmittance, optical depth, and volume extinction coefficient derived from measurements on four nonconsecutive days show the effects of the plumes on the IR optical properties of the atmosphere. The average contribution of the plume alone to the IR extinction coefficient was 74% at the Four Corners plant; the background haze contributed 7–11%. More efficient particulate emission control at the San Juan power plant reduced the average contribution of its plume to 57% of the extinction coefficient. The haze contributed an average of 16%. The results show an increase with time of the haze bulk extinction coefficient during a persistent anticyclonic synoptic situation. Extinction coefficients of the haze showed a linearity with particulate loading, which led to estimates of IR volume extinctions of the free troposphere from aerosol measurements.
TL;DR: In this paper, a field monitoring program was undertaken to further characterize the particle size and chemical distribution of atmospheric aerosols in the area, and it was found that localized visibility correlated best with large-particle aerosol volume.
01 Oct 1983
TL;DR: In this paper, three transmissometers and five forward-scatter meters were evaluated for measuring fog, haze, rain, and snow in the large test chamber of the Eglin Air Force Base Climatic Laboratory.
Abstract: : Three transmissometers and five forward-scatter meters were evaluated for measuring fog, haze, rain, and snow in the large test chamber of the Eglin Air Force Base Climatic Laboratory. Methods were developed for generating moderately uniform and stable fog and haze conditions. Fog densities equivalent to Runway Visual Range (RVR) values of 100 to 600 feet were achieved; such fog densities are rare in nature and were the primary reason for undertaking the chamber tests. No unusual characteristics of the chamber fogs were noted. Laser transmissometers with 40- and 250 foot baselines served as standard sensors for the tests. Because of inhomogeneities in the chamber, only the 40-foot baseline gave good correlations with most of the test sensors. Consequently, one of the forward-scatter meters, the EG&G 207, was used as a secondary standard for high visibility (RVR above 1000 feet) conditions. With appropriate corrections, all the test sensors met the 15 percent root-mean-square error pass-fail criterion for measuring dense fog. (Author)
10 Jan 1983
TL;DR: The Arctic Gas and Aerosol Sampling Program (AGASP) was conducted across the Arctic in the spring of 1983 to study the large scale air pollution phenomenon known as Arctic haze as discussed by the authors.
Abstract: The Arctic Gas and Aerosol Sampling Program (AGASP) was conducted across the Arctic in the spring of 1983 to study the large scale air pollution phenomenon known as Arctic haze. A component of this program utilized a National Oceanic and Atmospheric Administration WP-3D Orion research aircraft to study the haze in situ. The program and aircraft instrumentation are described.