Haze on the Horizon

NASA Image and Video Library

2017-07-24

This false-color view from NASA's Cassini spacecraft gazes toward the rings beyond Saturn's sunlit horizon. Along the limb (the planet's edge) at left can be seen a thin, detached haze. This haze vanishes toward the left side of the scene. Cassini will pass through Saturn's upper atmosphere during the final five orbits of the mission, before making a fateful plunge into Saturn on Sept. 15, 2017. The region through which the spacecraft will fly on those last orbits is well above the haze seen here, which is in Saturn's stratosphere. In fact, even when Cassini plunges toward Saturn to meet its fate, contact with the spacecraft is expected to be lost before it reaches the depth of this haze. This view is a false-color composite made using images taken in red, green and ultraviolet spectral filters. The images were obtained using the Cassini spacecraft narrow-angle camera on July 16, 2017, at a distance of about 777,000 miles (1.25 million kilometers) from Saturn. Image scale is about 4 miles (7 kilometers) per pixel on Saturn. https://photojournal.jpl.nasa.gov/catalog/PIA21621

Vertical structure of foggy haze over the Beijing-Tianjin-Hebei area in January 2013

NASA Astrophysics Data System (ADS)

Han, Feng; Xu, Jun; He, Youjiang; Dang, Hongyan; Yang, Xuezhen; Meng, Fan

2016-08-01

In January 2013, frequent episodes of intense air pollution occurred in the Beijing-Tianjin-Hebei area (BTH), China. Besides the occurrence of region-wide dry haze pollution, foggy haze conditions also developed across the region on numerous days, lasting into the afternoon. Synergistic analysis, using multisatellite datasets, air sounding and surface meteorological observations, indicated that there was a vertical overlap of fog and aerosol layers during the foggy haze episodes in the region. Fog appeared at a low level of the atmosphere. The altitude of the upper boundary of the fog differed across the region, but it was always below 1 km. The aerosol layer that closely contacted with the top of the underlying fog was rather dense, having a high concentration comparable to that during severe pollution on the ground. Above the dense aerosol layer, aerosol with a concentration equivalent to that of moderate pollution stretched up to an altitude of 2 km. Beyond that, a tenuous aerosol layer extended 5 km into the atmosphere. This overlapping of fog and haze layers frequently occurred across the region in January 2013. The occurrence of a foggy haze over BTH could worsen the regional air quality, and its appearance across this region would have notable effects on the radiation balance.

Cassini limb images of hazes in Saturn’s northern hemisphere

NASA Astrophysics Data System (ADS)

Sanchez-Lavega, Agustin M.; Garcia, Daniel; del Rio-Gaztelurrutia, Teresa; Garcia-Muñoz, Antonio; Perez-Hoyos, Santiago; Hueso, Ricardo

2017-10-01

We have used high resolution Cassini ISS images of the limb of Saturn to study the vertical distribution, altitude location, thickness and optical properties of the haze layers in the northern hemisphere (1°S to 82°N) in 2013 and 2015. The images cover an ample spectral range from the ultraviolet (UV1 filter, 264 nm) to the near infrared (CB3 filter, 938 nm) including methane absorption bands at 619 nm, 724 nm and 890 nm. Spatial resolution ranges from 1.6 to 13 km/pixel depending on wavelength and latitude. Three latitude bands were selected for the analysis according to the background zonal wind profile measured at cloud level and known dynamical activity: (a) North Polar Region encompassing the Hexagon latitude (74°N) (b) Mid-latitudes (45°N-52°N), and (3) Equator (1°N-3°S). The best defined haze structures and most extended haze layers were found at the latitude of the Hexagon. Up to 6-8 haze layers extending up to 400 km in altitude above clouds (in the pressure range from about 0.7 bar to 0.1 mbar) were detected. The vertical thickness of the layers is in the range 3-15 km compared to the scale height which is about 40 km. The spectral reflectivity is relatively uniform between the layers in the blue and red continuum wavelengths coming from the backward light scattering from the haze particles, while the brightness in the methane bands (relative to red continuum) and in the ultraviolet shows the effects of methane absorption and Rayleigh scattering by the gas, respectively. At mid-latitudes 3-4 haze layers are found spanning up to altitudes 200 km above the clouds. At the Equator 5-6 layers are found extending up to altitudes 250 km above the clouds (up to 2 mbar in pressure level) in a region of great dynamical interest because of the particular structure of the zonal winds and their known oscillations. We comment on the possible nature of the haze layers on the basis of condensing species and photochemistry.

Process analysis of characteristics of the boundary layer during a heavy haze pollution episode in an inland megacity, China.

PubMed

Wang, Shan; Liao, Tingting; Wang, Lili; Sun, Yang

2016-02-01

Ground observation data from 8 meteorological stations in Xi'an, air mass concentration data from 13 environmental quality monitoring sites in Xi'an, as well as radiosonde observation and wind profile radar data, were used in this study. Thereby, the process, causes and boundary layer meteorological characteristics of a heavy haze episode occurring from 16 to 25 December 2013 in Xi'an were analyzed. Principal component analysis showed that this haze pollution was mainly caused by the high-intensity emission and formation of gaseous pollutants (NO2, CO and SO2) and atmospheric particles (PM2.5 (fine particles) and PM10 (respirable suspended particle). The second cause was the relative humidity and continuous low temperature. The third cause was the allocation of the surface pressure field. The presence of a near-surface temperature inversion at the boundary layer formed favorable stratification conditions for the formation and maintenance of heavy haze pollution. The persistent thick haze layer weakened the solar radiation. Meanwhile, a warming effect in the urban canopy layer and in the transition zone from the urban friction sublayer to the urban canopy was indicated. All these conditions facilitated the maintenance and reinforcement of temperature inversion. The stable atmospheric stratification finally acted on the wind field in the boundary layer, and further weakened the exchange capacity of vertical turbulence. The superposition of a wind field with the horizontal gentle wind induced the typical air stagnation and finally caused the deterioration of air quality during this haze event. Copyright © 2015. Published by Elsevier B.V.

About Jupiter's Reflectance Function in JunoCam Images

NASA Astrophysics Data System (ADS)

Eichstaedt, G.; Orton, G. S.; Momary, T.; Hansen, C. J.; Caplinger, M.

2017-09-01

NASA's Juno spacecraft has successfully completed several perijove passes. JunoCam is Juno's visible light and infrared camera. It was added to the instrument complement to investigate Jupiter's polar regions, and for education and public outreach purposes. Images of Jupiter taken by JunoCam have been revealing effects that can be interpreted as caused by a haze layer. This presumed haze layer appears to be structured, and it partially obscures Jupiter's cloud top. With empirical investigation of Jupiter's reflectance function we intend to separate light contributed by haze from light reflected off Jupiter's cloud tops, enabling both layers to be investigated separately.

Organic haze on Titan and the early Earth

PubMed Central

Trainer, Melissa G.; Pavlov, Alexander A.; DeWitt, H. Langley; Jimenez, Jose L.; McKay, Christopher P.; Toon, Owen B.; Tolbert, Margaret A.

2006-01-01

Recent exploration by the Cassini/Huygens mission has stimulated a great deal of interest in Saturn's moon, Titan. One of Titan's most captivating features is the thick organic haze layer surrounding the moon, believed to be formed from photochemistry high in the CH4/N2 atmosphere. It has been suggested that a similar haze layer may have formed on the early Earth. Here we report laboratory experiments that demonstrate the properties of haze likely to form through photochemistry on Titan and early Earth. We have used a deuterium lamp to initiate particle production in these simulated atmospheres from UV photolysis. Using a unique analysis technique, the aerosol mass spectrometer, we have studied the chemical composition, size, and shape of the particles produced as a function of initial trace gas composition. Our results show that the aerosols produced in the laboratory can serve as analogs for the observed haze in Titan's atmosphere. Experiments performed under possible conditions for early Earth suggest a significant optical depth of haze may have dominated the early Earth's atmosphere. Aerosol size measurements are presented, and implications for the haze layer properties are discussed. We estimate that aerosol production on the early Earth may have been on the order of 1014 g·year−1 and thus could have served as a primary source of organic material to the surface. PMID:17101962

Pluto Haze

NASA Image and Video Library

2015-09-10

Two different versions of an image of Pluto's haze layers, taken by New Horizons as it looked back at Pluto's dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto's north is at the top, and the sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto's haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto's disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth. http://photojournal.jpl.nasa.gov/catalog/PIA19880

Triton, Pluto, and Titan: A Comparison of Haze Photometry

NASA Astrophysics Data System (ADS)

Buratti, Bonnie J.; Hillier, John K.; Abgarian, Mary; Kutsop, Nicholas; Devins, Spencer; Mosher, Joel A.; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine; Young, Leslie; Ennico, Kimberly; New Horizons Science Team

2017-10-01

As Kuiper Belt Objects of similar size and albedo, Triton and Pluto were thought to be kindred bodies exhibiting like geologic histories and features, with possible seasonal volatile transport in their polar regions. During the flyby of Pluto in July 2015, active geological processes were observed on the planet (Stern et al., 2015), and a substantial haze layer that was more akin to Titan’s was observed (Gladstone et. al., 2016). Multiple haze layers were discovered surrounding the dwarf planet (Cheng et al. 2017).Using a radiative transfer model based on Chandrasekhar’s “Planetary Problem” of an optically thin atmosphere and a surface of arbitrary single scattering albedo and single particle phase function (Chandrasekhar, 1960; Hillier et al., 1990, 1991; Buratti et al., 2011), we have characterized the optical depth and surface properties of Pluto, Triton, and Titan. The forward-scattering properties of the haze can also be quantified by this model. Optical imaging data was analyzed for Triton and Pluto. For Titan we made use of published data on Titan (Tomasko and West, 2009) plus new Cassini Visual Infrared Mapping Spectrometer (VIMS) data, which spans the wavelength range between 0.35 and 5.2 microns, and which has several channels in the mid-infrared where both the haze opacity is relatively low and the atmosphere is optically thin. Pluto’s atmosphere is more optically thick than Triton’s but both are far thinner than Titan’s. The composition of Triton’s haze layer differs markedly from Titan’s. Observations of Pluto’s haze reveal a bluish color (Gladstone et al., 2016), but the reddish tint of possible haze deposits on the surface (Stern et al., 2015; Buratti et al., 2015) suggest Pluto’s haze composition is Titan-like. Institute of Technology. Government sponsorship acknowledged.

UV–Vis Light-induced Aging of Titan’s Haze and Ice

NASA Astrophysics Data System (ADS)

Couturier-Tamburelli, Isabelle; Piétri, Nathalie; Le Letty, Vincent; Chiavassa, Thierry; Gudipati, Murthy

2018-01-01

The study of the photochemical aging of aerosols is an important tool for understanding Titan’s stratosphere/troposphere composition and evolution, particularly the haze. Laboratory simulations of the photoreactivity of the haze aerosol analogs provide insight into the photochemical evolution of Titan’s atmosphere at and below the haze layers. Here we use experimental simulations to investigate the evolution of the laboratory analogs of these organic aerosols under ultraviolet (UV)–visible (Vis) photons, which make it through the haze layers during their sedimentation process. We present experimental results for the aging of Titan’s aerosol analogs obtained from two dominant nitrogen-containing organics, HC3N and HCN, under simulated Titan atmospheric conditions (photons and temperature). We report that volatile nitriles condensed on haze particles could be incorporated through photochemistry and provide one such sink mechanism for nitrile compounds. We provide laboratory evidence that the organic aerosols could photochemically evolve during their sedimentation through Titan’s atmosphere.

Individual Aerosol Particles from Biomass Burning in Southern Africa. 1; Compositions and Size Distributions of Carbonaceous Particles

NASA Technical Reports Server (NTRS)

Posfai, Mihaly; Simonics, Renata; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

2003-01-01

Individual aerosol particles in smoke plumes from biomass fires and in regional hazes in southern Africa were studied using analytical transmission electron microscopy (TEM), which allowed detailed characterization of carbonaceous particle types in smoke and determination of changes in particle properties and concentrations during smoke aging. Based on composition, morphology, and microstructure, three distinct types of carbonaceous particles were present in the smoke: organic particles with inorganic (K-salt) inclusions, tar ball particles, and soot. The relative number concentrations of organic particles were largest in young smoke, whereas tar balls were dominant in a slightly aged (1 hour) smoke from a smoldering fire. Flaming fires emitted relatively more soot particles than smoldering fires, but soot was a minor constituent of all studied plumes. Further aging caused the accumulation of sulfate on organic and soot particles, as indicated by the large number of internally mixed organic/sulfate and soot/sulfate particles in the regional haze. Externally mixed ammonium sulfate particles dominated in the boundary layer hazes, whereas organic/sulfate particles were the most abundant type in the upper hazes. Apparently, elevated haze layers were more strongly affected by biomass smoke than those within the boundary layer. Based on size distributions and the observed patterns of internal mixing, we hypothesize that organic and soot particles are the cloud-nucleating constituents of biomass smoke aerosols. Sea-salt particles dominated in the samples taken in stratus clouds over the Atlantic Ocean, off the coast of Namibia, whereas a distinct haze layer above the clouds consisted of aged biomass smoke particles.

Pluto Haze in Bands of Blue

NASA Image and Video Library

2016-01-14

This processed image is the highest-resolution color look yet at the haze layers in Pluto's atmosphere. Shown in approximate true color, the picture was constructed from a mosaic of four panchromatic images from the Long Range Reconnaissance Imager (LORRI) splashed with Ralph/Multispectral Visible Imaging Camera (MVIC) four-color filter data, all acquired by NASA's New Horizons spacecraft on July 14, 2015. The resolution is 1 kilometer (0.6 miles) per pixel; the sun illuminates the scene from the right. Scientists believe the haze is a photochemical smog resulting from the action of sunlight on methane and other molecules in Pluto's atmosphere, producing a complex mixture of hydrocarbons such as acetylene and ethylene. These hydrocarbons accumulate into small particles, a fraction of a micrometer in size, and scatter sunlight to make the bright blue haze seen in this image. As they settle down through the atmosphere, the haze particles form numerous intricate, horizontal layers, some extending for hundreds of miles around Pluto. The haze layers extend to altitudes of over 200 kilometers (120 miles). Adding to the stark beauty of this image are mountains on Pluto's limb (on the right, near the 4 o'clock position), surface features just within the limb to the right, and crepuscular rays (dark finger-like shadows to the left) extending from Pluto's topographic features. http://photojournal.jpl.nasa.gov/catalog/PIA20362

Matrix operator theory of radiative transfer. 2: scattering from maritime haze.

PubMed

Kattawar, G W; Plass, G N; Catchings, F E

1973-05-01

Matrix operator theory is used to calculate the reflected and transmitted radiance of photons that have interacted with plane-parallel maritime haze layers. The results are presented for three solar zenith angles, three values of the surface albedo, and a range of optical thicknesses from very thin to very thick. The diffuse flux at the lower boundary and the cloud albedo are tabulated. The forward peak and other features in the single scattered phase function cause the radiance in many cases to be very different from that for Rayleigh scattering. In particular the variation of the radiance with both the zenith or nadir angle and the azimuthal angle is more marked and the relative limb darkening under very thick layers is greater for haze M than for Rayleigh scattering. The downward diffuse flux at the lower boundary for A = 0 is always greater and the cloud albedo is always less for haze M than for Rayleigh layers.

Light Management in Flexible Glass by Wood Cellulose Coating

PubMed Central

Fang, Zhi-Qiang; Zhu, Hong-Li; Li, Yuan-Yuan; Liu, Zhen; Dai, Jia-Qi; Preston, Colin; Garner, Sean; Cimo, Pat; Chai, Xin-Sheng; Chen, Gang; Hu, Liang-Bing

2014-01-01

Ultra-thin flexible glass with high transparency is attractive for a broad range of display applications; however, substrates with low optical haze are not ideal for thin film solar cells, since most of the light will go through the semiconductor layer without scattering, and the length of light travelling path in the active layer is small. By simply depositing a layer of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-oxidized wood fibers (TOWFs), we are able to tailor the optical properties of flexible glass dramatically from exhibiting low haze (<1%) to high haze (~56%) without compromising the total forward transmittance (~90%). The influence of the TOWFs morphology on the optical properties of TOWFs-coated flexible glass is investigated. As the average fiber length decreases, the transmission haze of TOWF-coated flexible glass illustrates a decreasing trend. Earth-abundant natural materials for transparent, hazy, and flexible glass have tremendous applicability in the fabrication of flexible optoelectronics with tunable light scattering effects by enabling inexpensive and large-scale processes. PMID:25068486

Integrating models to predict regional haze from wildland fire.

Treesearch

D. McKenzie; S.M. O' Neill; N. Larkin; R.A. Norheim

2006-01-01

Visibility impairment from regional haze is a significant problem throughout the continental United States. A substantial portion of regional haze is produced by smoke from prescribed and wildland fires. Here we describe the integration of four simulation models, an array of GIS raster layers, and a set of algorithms for fire-danger calculations into a modeling...

Seeing High in the Sky

NASA Image and Video Library

2006-01-06

In this magnificent view, delicate haze layers high in the atmosphere encircle the oblate figure of Saturn. A special combination of spectral filters used for this image makes the high haze become visible

Detached-Eddy Simulations of Attached and Detached Boundary Layers

NASA Astrophysics Data System (ADS)

Caruelle, B.; Ducros, F.

2003-12-01

This article presents Detached-Eddy Simulations (DESs) of attached and detached turbulent boundary layers. This hybrid Reynolds Averaged Navier-Stokes (RANS) / Large Eddy Simulation (LES) model goes continuously from RANS to LES according to the mesh definition. We propose a parametric study of the model over two "academic" configurations, in order to get information on the influence of the mesh to correctly treat complex flow with attached and detached boundary layers.

Trade cumulus clouds embedded in a deep regional haze: Results from Indian Ocean CARDEX experiment

NASA Astrophysics Data System (ADS)

Wilcox, E. M.; Thomas, R. M.; Praveen, P. S.; Pistone, K.; Bender, F.; Feng, Y.; Ramanathan, V.

2013-12-01

During the winter monsoon, trade cumulus clouds over the North Indian Ocean are embedded within a deep regional haze described as an atmospheric brown cloud. While the trade-cu clouds are largely confined to the marine boundary layer, the sooty brown cloud extends from the boundary layer to as high as 3 km; well above the tops of the cumulus. The boundary layer pollution is persistent and limits drizzle in the cumulus over a period of greater than a month at the Maldives Climate Observatory located at Hanimaadhoo Island. The elevated haze from 1 to 3 km altitude is episodic and strongly modulated by synoptic variability in the 700 hPa flow. The elevated plume enhances heating above the marine boundary layer through daytime absorption of sunlight by the haze particles. The interplay between the microphysical modification of clouds by boundary layer pollution and the episodic elevated heating by the atmospheric brown cloud are explored in in-situ observations from UAVs and surface remote sensing during the CARDEX field campaign of winter 2012 and supported by multi-year analysis of satellite remote sensing observations. These observations document the variability in pollution at the surface and above the marine boundary layer and the effects of pollution on the microphysics of the trade-cu clouds, the depth of the marine boundary layer, the liquid water path of trade-cu clouds, and the profile of turbulent moisture flux through the boundary layer. The consequences of these effects for the radiative forcing of regional climate will be discussed.

Blue Rays: New Horizons High-Res Farewell to Pluto

NASA Image and Video Library

2017-03-24

This is the highest-resolution color departure shot of Pluto's receding crescent from NASA's New Horizons spacecraft, taken when the spacecraft was 120,000 miles (200,000 kilometers) away from Pluto. Shown in approximate true color, the picture was constructed from a mosaic of six black-and-white images from the Long Range Reconnaissance Imager (LORRI), with color added from a lower resolution Ralph/Multispectral Visible Imaging Camera (MVIC) color image, all acquired between 15:20 and 15:45 UT -- about 3.5 hours after closest approach to Pluto -- on July 14, 2015. The resolution of the LORRI images is about 0.6 miles (1 kilometer) per pixel; the sun illuminates the scene from the other side of Pluto and somewhat toward the top of this image. The image is dominated by spectacular layers of blue haze in Pluto's atmosphere. Scientists believe the haze is a photochemical smog resulting from the action of sunlight on methane and other molecules in Pluto's atmosphere, producing a complex mixture of hydrocarbons such as acetylene and ethylene. These hydrocarbons accumulate into small haze particles, a fraction of a micrometer in size, which preferentially scatter blue sunlight -- the same process that can make haze appear bluish on Earth. As they settle down through the atmosphere, the haze particles form numerous intricate, horizontal layers, some extending for hundreds of miles around large portions of the limb of Pluto. The haze layers extend to altitudes of over 120 miles (200 kilometers). Pluto's circumference is 4,667 miles (7,466 kilometers). Adding to the beauty of this picture are mountains and other topographic features on Pluto's surface that are silhouetted against the haze near the top of the image. Sunlight casts dramatic and beautiful finger-like shadows from many of these features onto the haze (especially on the left, near the 11 o'clock position), forming crepuscular rays like those often seen in Earth's atmosphere near sunrise or sunset. https://photojournal.jpl.nasa.gov/catalog/PIA21590

Multiple scattered radiation emerging from Rayleigh and continental haze layers. I - Radiance, polarization, and neutral points

NASA Technical Reports Server (NTRS)

Kattawar, G. W.; Plass, G. N.; Hitzfelder, S. J.

1976-01-01

The matrix operator method was used to calculate the polarization of radiation scattered on layers of various optical thicknesses, with results compared for Rayleigh scattering and for scattering from a continental haze. In both cases, there are neutral points arising from the zeros of the polarization of single scattered photons at scattering angles of zero and 180 degrees. The angular position of these Rayleigh-like neutral points (RNP) in the sky shows appreciable variation with the optical thickness of the scattering layer for a Rayleigh phase matrix, but only a small variation for haze L phase matrix. Another type of neutral point exists for non-Rayleigh phase functions that is associated with the zeros of the polarization for single scattering which occurs between the end points of the curve. A comparison of radiances calculated from the complete theory of radiative transfer using Stokes vectors with those obtained from the scalar theory shows that differences of the order of 23% may be obtained for Rayleigh scattering, while the largest difference found for a haze L phase function was of the order of 0.1%.

Titan Haze is Falling

NASA Image and Video Library

2011-05-05

The change in Titan haze layer is illustrated in this figure, derived from data obtained by NASA Cassini spacecraft. The picture of Titan in panel a was taken on May 3, 2006, panel b was taken on April 2, 2010.

Re-examination of the Possibility of Haze in Pluto's Atmosphere Based on Multi-Wavelength Observations of the Pluto Occultation of P131.1.

NASA Astrophysics Data System (ADS)

Thomas-Osip, J. E.; Elliot, J. L.; Clancy, K. B.

2002-12-01

Multi-wavelength observations of the occultation of P131.1 by Pluto (see Elliot et al., this conference) allow for a re-examination of the possibility of the existence of haze in Pluto's atmosphere. Models of the extinction efficiency of haze particles as a function of wavelength are being used investigate the potential for the existence of haze in the 2002 Pluto atmosphere. The existence of a haze layer in Pluto's atmosphere was postulated to explain the abrupt change in slope seen in the light curve of the 1988 stellar occultation by Pluto (Elliot and Young 1992, AJ, 103, 991). An alternative explanation (Hubbard et al. 1990, Icarus, 84, 1) includes a steep thermal gradient near the surface instead of, or in addition to, a haze layer. Modeling of the growth and sedimentation of photo-chemically produced spherical aerosols (Stansberry et al. 1989, Geophys. Res. Let., 16, 1221) suggested that an appropriate production rate is not sufficient to produce the opacity necessary to account for change in slope found in the 1988 light curve, if it were due solely to spherical particle haze extinction. Recent studies (see for example, Rannou et al. 1995, Icarus, 188, 355 and Thomas-Osip et al. 2002, Icarus, submitted) have shown that it is likely that photochemical hazes on Titan are aggregate in nature. Fractal aggregate particles can have larger extinction efficiencies than equivalent mass spheres of the same material (Rannou et al. 1999, Planet. Space Sci., 47,385). We are, therefore, also re-examining the effect of a haze with an aggregate morphology on modeling of the 1988 occultation observations. This research has been supported in part by NSF Grant AST-0073447 and NASA Grant NAG5-10444.

Multiple scattered radiation emerging from continental haze layers. 1: Radiance, polarization, and neutral points

NASA Technical Reports Server (NTRS)

Kattawar, G. W.; Plass, G. N.; Hitzfelder, S. J.

1975-01-01

The complete radiation field is calculated for scattering layers of various optical thicknesses. Results obtained for Rayleigh and haze scattering are compared. Calculated radiances show differences as large as 23% compared to the approximate scalar theory of radiative transfer, while the same differences are approximately 0.1% for a continental haze phase function. The polarization of reflected and transmitted radiation is given for various optical thicknesses, solar zenith angles, and surface albedos. Two types of neutral points occur for aerosol phase functions. Rayleigh-like neutral points arise from zero polarization that occurs at scattering angles of 0 deg and 180 deg. For Rayleigh phase functions, the position of these points varies with the optical thickness of the scattering layer. Non-Rayleigh neutral points are associated with the zeros of polarization which occur between the end points of the single scattering curve, and are found over a wide range of azimuthal angles.

Influence of plumes from biomass burning on atmospheric chemistry over the equatorial and tropical South Atlantic during CITE 3

NASA Technical Reports Server (NTRS)

Andreae, M. O.; Anderson, B. E.; Blake, D. R.; Bradshaw, J. D.; Collins, J. E.; Gregory, G. L.; Sachse, G. W.; Shipham, M. C.

1994-01-01

During all eight flights conducted over the equatorial and tropical South Atlantic in the course of the Chemical Instrumentation Test and Evaluation (CITE 3) experiment, we observed haze layers with elevated concentrations of aerosols, O3, CO, and other trace gases related to biomass burning emissions. They occurred at altitudes between 1000 and 5200 m and were usually only some 100-300 m thick. These layers extended horizontally over several 100 km and were marked by the presence of visible brownish haze. Air mass trajectories indicate that these layers originate in the biomass burning regions of Africa and South America and typically have aged at least 10 days since the time of emission. In the haze layers, O3 and CO concentrations up to 90 and 210 ppb were observed, respectively. The two species were highly correlated. The ratio concentrations in plume minus background concentrations of O3/CO is typically in the range 0.2-0.7, much higher than the ratios in the less aged plumes investigated previously in Amazonia. In most cases, aerosol (0.12-3 micrometer diameter) number concentrations were also elevated by up to 400/cu cm in the layers; aerosol enrichments were also strongly correlated with elevated CO levels. Clear correlations between CO and NO(x) enrichments were not apparent due to the age of the plumes, in which most NO(x) would have already reacted away within 1-2 days. Only in some of the plumes could clear correlations between NO(y) and CO be identified; the absence of a general correlation between NO(y) and CO may be due to instrumental limitations and to variable sinks for NO(y). The average enrichment of the ratio concentrations in plume minus background concentrations of NO(y)/CO was quite high, consistent with the efficient production of ozone observed in the plumes. The chemical characteristics of the haze layers, together with remote sensing information and trajectory calculations, suggest that fire emissions (in Africa and/or South America) are the primary source of the haze layer components.

Highlighting Titan's Hazes

NASA Image and Video Library

2017-08-11

NASA's Cassini spacecraft looks toward the night side of Saturn's moon Titan in a view that highlights the extended, hazy nature of the moon's atmosphere. During its long mission at Saturn, Cassini has frequently observed Titan at viewing angles like this, where the atmosphere is backlit by the Sun, in order to make visible the structure of the hazes. Titan's high-altitude haze layer appears blue here, whereas the main atmospheric haze is orange. The difference in color could be due to particle sizes in the haze. The blue haze likely consists of smaller particles than the orange haze. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The image was taken with the Cassini spacecraft narrow-angle camera on May 29, 2017. The view was acquired at a distance of approximately 1.2 million miles (2 million kilometers) from Titan. Image scale is 5 miles (9 kilometers) per pixel. https://photojournal.jpl.nasa.gov/catalog/PIA21625

Retrieval of Haze Properties in Pluto's Atmosphere from New Horizons Observations

NASA Astrophysics Data System (ADS)

Fan, S.; Gao, P.; Yung, Y. L.

2017-12-01

On July 14th, 2015, New Horizons performed its historic close approach of Pluto, giving humanity unprecedented observations of the dwarf planet's atmosphere. One of the amazing features seen was the multi-layered haze in its atmosphere. The haze was detected both at visible wavelengths by the Long Range Reconnaissance Imager (LORRI) from direct imaging and in the ultraviolet by the Alice spectrograph from solar occultations. Preliminary analysis using simplified models showed that neither spherical nor 2-dimensional aggregate particles could satisfy both sets of observations. In this work, we present a joint retrieval of haze particles using both LORRI and Alice data, which examines various size distributions and dimensions of aggregate particles. We map out the haze particles' phase function by the forward scattering and extinction properties by the occultation. With the combination of these two approaches, the Haze's properties of size and shape are constrained.

Ultraviolet observations of the Saturnian north aurora and polar haze distribution with the HST-FOC

NASA Technical Reports Server (NTRS)

Gerard, J. C.; Dols, V.; Grodent, D.; Waite, J. H.; Gladstone, G. R.; Prange, R.

1995-01-01

Near simultaneous observations of the Saturnian H2 north ultraviolet aurora and the polar haze were made at 153 nm and 210 nm respectively with the Faint Object Camera on board the Hubble Space Telescope. The auroral observations cover a complete rotation of the planet and, when co-added, reveal the presence of an auroral emission near 80 deg N with a peak brightness of about 150 kR of total H2 emission. The maximum optical depth of the polar haze layer is found to be located approximately 5 deg equatorward of the auroral emission zone. The haze particles are presumably formed by hydrocarbon aerosols initiated by H2+ auroral production. In this case, the observed haze optical depth requires an efficiency of aerosol formation of about 6 percent, indicating that auroral production of hydrocarbon aerosols is a viable source of high-latitude haze.

High Altitude, Wavelength-dependent Extinction in Titan's Atmosphere from the 2003 Nov. 14 Occultation

NASA Astrophysics Data System (ADS)

Zalucha, A.; Elliot, J. L.; Fitzsimmons, A.; Dhillon, V.; Marsh, T.; Hammel, H. B.; Irwin, P.; Thomas-Osip, J.; Taylor, F.

2005-08-01

A stellar occultation by Titan on 2003 Nov. 14 was observed from La Palma Observatory (Fitzsimmons et al., RAS Time Domain Astrophysics, 2004) using ULTRACAM with three Sloan filters: u', g', and i' (350, 480, and 770 nm, respectively; Dhillon and Marsh, NewAR, 25, 91, 2001). The latitudes probed during immersion and emersion were 1.1S and 1.8N, respectively. A central flash was seen in only the i' filter, indicating wavelength-dependent atmospheric extinction. The light curves were inverted to obtain six lower-limit temperature profiles between 360 and 500 km (30 and 2 microbar) altitude. The i' profiles agreed with the model of Yelle (ApJ, 383, 380, 1991) above 415 km (10 microbar). The temperature profiles are expected to be independent of wavelength; instead, it is found that the profiles obtained at different wavelengths diverged as altitude decreases, which implies significant extinction in the light curves. The onset of extinction occurred between 550 and 600 km (0.9 and 0.4 microbar) altitude with optical depth increasing below this height. This is ˜ 50-100 km higher than the detached haze layer seen by Cassini in 2004 (Porco et al., Nature, 434, 159, 2005). No discrete haze layers have yet been resolved in our data. Applying the model used by Elliot and Young (AJ, 103, 991,1992) gives the altitudes of optical depth equal to unity: 382 ± 5 km and 436 ± 5 km (u' immersion and emersion); 406 ± 4 km and 403 ± 10 km (g' immersion and emersion); and 345 ± 5 km and 326 ± 3 km (i' immersion and emersion). Another method shows that the optical depth behaved as a power law in wavelength, with exponent approximately -3. We gratefully acknowledge support from NSF grant AST-0073447 and NASA grant NNG04GF25G

Characteristics of Boundary Layer Structure during a Persistent Haze Event in the Central Liaoning City Cluster, Northeast China

NASA Astrophysics Data System (ADS)

Li, Xiaolan; Wang, Yangfeng; Shen, Lidu; Zhang, Hongsheng; Zhao, Hujia; Zhang, Yunhai; Ma, Yanjun

2018-04-01

The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements of particulate matter (PM) concentration and the meteorological data within the atmospheric boundary layer (ABL). During the observational period, the maximum hourly mean PM2.5 and PM10 concentrations in Shenyang, Anshan, Fushun, and Benxi ranged from 276 to 355 μg m-3 and from 378 to 442 μg m-3, respectively, and the lowest hourly mean atmospheric visibility (VIS) in different cities ranged from 0.14 to 0.64 km. The central Liaoning city cluster was located in the front of a slowly moving high pressure and was mainly controlled by southerly winds. Wind speed (WS) within the ABL (< 2 km) decreased significantly and WS at 10-m height mostly remained below 2 m s-1 during the hazy episodes, which was favorable for the accumulation of air pollutants. A potential temperature inversion layer existed throughout the entire ABL during the earlier hazy episode [from 0500 Local Time (LT) 18 December to 1100 LT 19 December], and then a potential temperature inversion layer developed with the bottom gradually decreased from 900 m to 300 m. Such a stable atmospheric stratification further weakened pollutant dispersion. The atmospheric boundary layer height (ABLH) estimated based on potential temperature profiles was mostly lower than 400 m and varied oppositely with PM2.5 in Shenyang. In summary, weak winds due to calm synoptic conditions, strong thermal inversion layer, and shallow atmospheric boundary layer contributed to the formation and development of this haze event. The backward trajectory analysis revealed the sources of air masses and explained the different characteristics of the haze episodes in the four cities.

Parameterization of Rocket Dust Storms on Mars in the LMD Martian GCM: Modeling Details and Validation

NASA Astrophysics Data System (ADS)

Wang, Chao; Forget, François; Bertrand, Tanguy; Spiga, Aymeric; Millour, Ehouarn; Navarro, Thomas

2018-04-01

The origin of the detached dust layers observed by the Mars Climate Sounder aboard the Mars Reconnaissance Orbiter is still debated. Spiga et al. (2013, https://doi.org/10.1002/jgre.20046) revealed that deep mesoscale convective "rocket dust storms" are likely to play an important role in forming these dust layers. To investigate how the detached dust layers are generated by this mesoscale phenomenon and subsequently evolve at larger scales, a parameterization of rocket dust storms to represent the mesoscale dust convection is designed and included into the Laboratoire de Météorologie Dynamique (LMD) Martian Global Climate Model (GCM). The new parameterization allows dust particles in the GCM to be transported to higher altitudes than in traditional GCMs. Combined with the horizontal transport by large-scale winds, the dust particles spread out and form detached dust layers. During the Martian dusty seasons, the LMD GCM with the new parameterization is able to form detached dust layers. The formation, evolution, and decay of the simulated dust layers are largely in agreement with the Mars Climate Sounder observations. This suggests that mesoscale rocket dust storms are among the key factors to explain the observed detached dust layers on Mars. However, the detached dust layers remain absent in the GCM during the clear seasons, even with the new parameterization. This implies that other relevant atmospheric processes, operating when no dust storms are occurring, are needed to explain the Martian detached dust layers. More observations of local dust storms could improve the ad hoc aspects of this parameterization, such as the trigger and timing of dust injection.

Airborne lidar observations of long-range transport in the free troposphere

NASA Technical Reports Server (NTRS)

Shipley, S. T.; Browell, E. V.; Mcdougal, D. S.; Orndorff, B. L.; Haagenson, P.

1984-01-01

Airborne lidar measurements of ozone and aerosols in the lower troposphere show the presence of pollutant layers above the mixed layer. Two case studies are analyzed to identify probable source regions and mechanisms for material injection into the free troposphere above local mixed layers. An elevated haze/oxidant layer observed over South Carolina on Aug. 2, 1980, was found to originate in cumulus convection over Georgia on Aug. 1, 1980. An extensive haze/oxidant layer observed over southeastern Virginia on July 31, 1981, is shown to have been in contact with the New England mixed layer on July 30, 1981. This transported air mass is estimated to contribute approximately 30 percent of the ozone maximum measured at the surface in the Norfolk, VA, area on July 31, 1981. Such elevated 'reservoir' layers are transported over long ranges and are not detected by sensors which are confined to the surface.

Cassini-Huygens makes first close approach to Titan

NASA Astrophysics Data System (ADS)

2004-10-01

Purple zaze hi-res Size hi-res: 88 kb Credits: NASA/JPL/Space Science Institute Purple haze around Titan This NASA/ESA/ASI Cassini-Huygens image of Titan was taken with the narrow-angle camera on 3 July 2004, from a distance of about 789 000 kilometres from Titan. The image scale is 4.7 kilometres per pixel. This image shows two thin haze layers. The outer haze layer is detached and appears to float high in the atmosphere. Because of its thinness, the high haze layer is best seen at the moon's limb. The image was taken using a spectral filter sensitive to wavelengths of ultraviolet light centred at 338 nanometres. The image has been falsely coloured, the globe of Titan retains the pale orange hue our eyes would usually see, but both the main atmospheric haze and the thin detached layer have been brightened and given a purple colour to enhance their visibility. At the time of the closest approach, which is scheduled for 18:44 CEST, the spacecraft will be travelling only 1200 kilometres above the surface of the moon, almost grazing the outer atmosphere, at a speed of six kilometres per second (21 800 kilometres per hour)! Confirmation that the fly-by was successful and that all the data were received will not take place until 03:30 CEST on 27 October. This fly-by not only allows important surface science to be performed, such as radar analysis at close quarters, but also it significantly changes the orbit of the spacecraft around Saturn. Currently Cassini-Huygens has an orbital period of four months, which will change to 48 days, thus setting the course for the next close Titan fly-by on 13 December 2004 and the Huygens probe release on 25 December. Several of the observations performed during this fly-by will provide important information for ESA’s Huygens team, who will be using the data gathered to double-check atmospheric models for entry and descent on 14 January 2005. The Huygens probe will need to perform reliably in some of the most challenging and remote environments ever attempted by a man-made object. On this pass, the Huygens touchdown site will be visible at around 167 degrees East and 10.7 degrees South on the sunlit face of Titan before reaching the point of closest approach. Data from the imaging and radar instrumentation on board Cassini-Huygens should provide a tantalising idea of what the surface of Titan could be like. A second view of the Huygens touchdown site will be possible on the second close fly-by in December. Jean-Pierre Lebreton, ESA’s Huygens Mission Manager and Project Scientist, said: “This first close-up look at Titan should enable us to find out just how precisely our atmospheric models fit with the real situation and of course we are excited about the prospect of discovering just what type of surface the Huygens probe could impact on early next year.” Today’s fly-by will also be looking at other aspects of Titan which, although it is the second largest moon in the Solar System after Jupiter’s Ganymede, we know relatively little about. The instruments on board the Cassini orbiter will be looking at the surface characteristics, atmospheric properties and interactions with Saturn’s magnetosphere. Huygens is dormant during the fly-by. The first images are expected at 03:30 CEST on 28 October. However, at the point of closest approach, Titan will have an apparent size far exceeding the field of view of the Cassini orbiter’s narrow-angle camera. Details below a 100-metre resolution may be seen if the camera can pierce the haze and fog. Spectacular multicolour images at 1-2 kilometre resolution are also anticipated from the Visual Infrared and Mapping Spectrometer and may reveal details about Titan surface structure and composition. However, the excitement does not stop after 26 October. On 28 October, at about 12:30 CEST, there is a close encounter with Tethys, another of the significant moons of Saturn. Tethys is a ball of solid ice about 1060 kilometres in diameter which orbits Saturn at a distance of 295 000 kilometres. The Cassini-Huygens spacecraft will pass within 246 000 kilometres of this moon at a speed of 13.8 kilometres per second. At this distance the narrow-angle camera should be able to resolve features down to about 1.4 kilometres in size. Note to Editors The Cassini-Huygens mission to Saturn is the most ambitious effort in planetary space exploration ever mounted. A cooperative endeavour of the European Space Agency (ESA), NASA and the Italian space agency, Agenzia Spaziale Italiana (ASI), Cassini-Huygens is sending a sophisticated robotic spacecraft to orbit the ringed planet and study the Saturnian system in detail over a four-year period. On board Cassini is a scientific probe called Huygens, provided by ESA, which will be released from the main spacecraft to parachute through the atmosphere to the surface of Saturn’s largest and most interesting moon, Titan. For more information about the Cassini-Huygens mission please see: http://saturn.esa.int

Titan's aerosol optical properties with VIMS observations at the limb

NASA Astrophysics Data System (ADS)

Rannou, Pascal; Seignovert, Benoit; Le Mouelic, Stephane; Sotin, Christophe

2016-06-01

The study of Titan properties with remote sensing relies on a good knowledge of the atmosphere properties. The in-situ observations made by Huygens combined with recent advances in the definition of methane properties enable to model and interpret observations with a very good accuracy. Thanks to these progresses, we can analyze in this work the observations made at the limb of Titan in order to retrieve information on the haze properties as its vertical profiles but also the spectral behaviour between 0.88 and 5.2 µm. To study the haze layer and more generally the source of opacities in the stratosphere, we use some observation made at the limb of Titan by the VIMS instrument onboard Cassini. We used a model in spherical geometry and in single scattering, and we accounted for the multiple scattering with a parallel plane model that evaluate the multiple scattering source function at the plane of the limb. Our scope is to retrieve informations about the vertical distribution of the haze, its spectral properties, but also to obtain details about the shape of the methane windows to desantangle the role of the methane and of the aerosols. We started our study at the latitude of 55°N, with a image taken in 2006 with a relatively high spatial resolution (for VIMS). Our preliminary results shows the spectral properties of the aerosols are the same whatever the altitude. This is a consequence of the large scale mixing. From limb profile between 0.9 and 5.2 µm, we can probe the haze layer from about 500 km (at 0.9 µm) to the ground (at 5.2 µm). We find that the vertical profile of the haze layer shows three distinct scale heights with transitions around 250 km and 350 km. We also clearly a transition around 70-90 km that may be due to the top of a condensation layer.

Titan's aerosol optical properties with VIMS observations at the limb of Titan

NASA Astrophysics Data System (ADS)

Rannou, Pascal; Seignovert, Benoit; Lavvas, Panayotis; Lemouelic, Stéphane; Sotin, Christophe

2015-11-01

The study of Titan properties with remote sensing relies on a good knowledge of the atmosphere properties. The in-situ observations made by Huygens combined with recent advances in the definition of methane properties enable to model and interpret observations with a very good accuracy. Thanks to these progresses, we can analyze in this work the observations made at the limb of Titan in order to retrieve information on the haze properties as its vertical profiles but also the spectral behaviour between 0.88 and 5.2 μm.To study the haze layer and more generally the source of opacities in the stratosphere, we use som observation made at the limbe of Titan by the VIMS instrument onboard Cassini. We used a model in spherical geometry and in single scattering, and we accounted for the multiple scattering with a parallel plane model that evaluate the multiple scattering source function at the plane of the limb.Our scope is to retrieve informations about the vertical distribution of the haze, its spectral properties, but also to obtain details about the shape of the methane windows to disantangle the role of the methane and of the aerosols.We started our study at the latitude of 55°N, with a image taken in 2006 with a relatively high spatial resolution (for VIMS). Our preliminary results shows the spectral properties of the aerosols are the same whatever the altitude. This is a consequence of the large scale mixing. From limb profile between 0.9 and 5.2 μm, we can probe the haze layer from about 500 km (at 0.9 μm) to the ground (at 5.2 μm). We find that the vertical profile of the haze layer shows three distinct scale heights with transitions around 250 km and 350 km. We also clearly a transition around 70-90 km that may be due to the top of a condensation layer.

Properties of arctic haze aerosol from lidar observations during iarea 2015 campaign on spitsbergen

NASA Astrophysics Data System (ADS)

Stachlewska, Iwona S.; Ritter, Christoph; Böckmann, Christine; Engelmann, Ronny

2018-04-01

Arctic Haze event was observed on 5-8 April 2015 using simultaneously Near-range Aerosol Raman Lidar of IGFUW and Koldewey Aerosol Raman Lidar of AWI, both based at AWIPEV German-French station in Ny-Ålesund, Spitsbergen. The alterations in particle abundance and altitude of the aerosol load observed on following days of the event is analyzed. The daytime profiles of particle optical properties were obtained for both lidars, and then served as input for microphysical parameters inversion. The results indicate aerosol composition typical for the Arctic Haze. However, in some layers, a likely abundance of aqueous aerosol or black carbon originating in biomass burning over Siberia, changes measurably the Arctic Haze properties.

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth

NASA Astrophysics Data System (ADS)

Arney, Giada; Domagal-Goldman, Shawn D.; Meadows, Victoria S.; Wolf, Eric T.; Schwieterman, Edward; Charnay, Benjamin; Claire, Mark; Hébrard, Eric; Trainer, Melissa G.

2016-11-01

Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8-2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ˜ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7-2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO2. Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets.

Boundary layer structure and scavenging effect during a typical winter haze-fog episode in a core city of BTH region, China

NASA Astrophysics Data System (ADS)

Han, Suqin; Liu, Jingle; Hao, Tianyi; Zhang, Yufen; Li, Peiyan; Yang, Jianbo; Wang, Qinliang; Cai, Ziying; Yao, Qing; Zhang, Min; Wang, Xiujun

2018-04-01

The vertical distribution of PM2.5 and meteorological parameters from ground to upper levels were observed simultaneously using meteorological tower, tethered balloons and aerosol laser radar in Dec of 2016 in the urban area of Tianjin and its southern district, Jinghai. The influence of the vertical structure of boundary layer on a typical haze-fog episode was analyzed. There existed long distance transport of PM in the high layers before the haze formed in Tianjin and the downward airflows brought the PM from the high layer to the ground. In the early stages of this episode, periodic temperature inversions occurred, leading to conspicuous diurnal variations in the vertical profile of the PM2.5. In the middle and late stages of this episode, strong inversion and thick humidity layer were sustained below 400 m, and there were no big daily changes in the vertical profiles of the PM2.5. During the rapid formation period of the fog, the inversion layer was damaged and turbulence was strengthened. During the stationary phase of the fog process, wind and turbulence in the boundary layer became weak again. Rime was the main weather-related, wet cleaning mechanism that lowered pollutants concentration during this fog episode. High concentrations of water soluble ions in the rime samples and the concentrations of those ions in ambient PM2.5 appeared significant decrease during the rime period, which illustrated the scavenging effect of rime.

Photochemistry, Ion Chemistry, and Haze Formation in Pluto’s Atmosphere

NASA Astrophysics Data System (ADS)

Summers, Michael E.; Stern, S. A.; Gladstone, G. Randal; Young, Leslie A.; Olkin, C. B.; Weaver, H. A.; Cheng, A. F.; Strobel, D. F.; Ennico, K. A.; Kammer, J. A.; Parker, A. H.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A. J.; Tsang, C. C.; Versteeg, M. H.; Greathouse, T. K.; Linscott, I. R.; Tyler, L. G.; Woods, W. W.; Hinson, D. P.; Parker, J. W.; Renaud, J. P.; Ewell, M.; Lisse, Cary M.

2015-11-01

The detection of ethylene (C2H4) and acetylene (C2H2) in Pluto’s atmosphere provides important ground-truth observations for validating photochemical models of Pluto’s atmosphere. Their detection also confirms the production of precursor chemical compounds involved in the formation of tholins, which are thought to give Pluto’s surface its reddish color. Photochemical models predict many other hydrocarbon and nitrile products, currently undetected, which may also be participants in tholin production on Pluto’s surface or on atmospheric haze particles. The observed atmospheric haze layer extending to altitudes of ~140 km above Pluto’s surface, suggests a global and very robust process of atmospheric particle nucleation, growth, and sedimentation onto Pluto’s surface. The high altitude extent of the haze layer suggests that the nucleation process begins above the expected altitude range where hydrocarbons become supersaturated (below ~30 km altitude). This situation may be analogous to that in Titan’s atmosphere, wherein nucleation and aerosol growth is directly related to large negative ion production. In the case of Pluto, this means that nucleation may occur at altitudes as high as 1200 km altitude where ionization in Pluto’s atmosphere peaks. In this paper we discuss these processes and their implications for haze formation in Pluto’s atmosphere and its deposition onto Pluto’s surface. This work was supported by NASA's New Horizons project.

Evolution of aerosol vertical distribution during particulate pollution events in Shanghai

NASA Astrophysics Data System (ADS)

Zhang, Yunwei; Zhang, Qun; Leng, Chunpeng; Zhang, Deqin; Cheng, Tiantao; Tao, Jun; Zhang, Renjian; He, Qianshan

2015-06-01

A set of micro pulse lidar (MPL) systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011. Three typical particulate pollution events (e.g., haze) were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer (PBL) during these pollution episodes. The aerosol vertical extinction coefficient (VEC) at any given measured altitude was prominently larger during haze periods than that before or after the associated event. Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering, leading to different aerosol vertical distribution structures. Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions. Several peaks in aerosol VECs were found at altitudes above 1 km during the dust- and bioburning-influenced haze events. Aerosol VECs decreased with increasing altitude during the local-polluted haze event, with a single maximum in the surface atmosphere. PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events; subsequently, PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages. The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.

High aerosol load over the Pearl River Delta, China, observed with Raman lidar and Sun photometer

NASA Astrophysics Data System (ADS)

Ansmann, Albert; Engelmann, Ronny; Althausen, Dietrich; Wandinger, Ulla; Hu, Min; Zhang, Yuanghang; He, Qianshan

2005-07-01

Height-resolved data of the particle optical properties, the vertical extend of the haze layer, aerosol stratification, and the diurnal cycle of vertical mixing over the Pearl River Delta in southern China are presented. The observations were performed with Raman lidar and Sun photometer at Xinken (22.6°N, 113.6°E) near the south coast of China throughout October 2004. The lidar run almost full time on 21 days. Sun photometer data were taken on 23 days, from about 0800 to 1700 local time. The particle optical depth (at about 533-nm wavelength) ranged from 0.3-1.7 and was, on average, 0.92. Ångström exponents varied from 0.65-1.35 (for wavelengths 380 to 502 nm) and from 0.75-1.6 (for 502 to 1044 nm), mean values were 0.97 and 1.22. The haze-layer mean extinction-to-backscatter ratio ranged from 35-59 sr, and was, on average, 46.7 sr. The top of the haze layer reached to heights of 1.5-3 km in most cases.

Pluto Blue Sky

NASA Image and Video Library

2015-10-08

Pluto's haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn's moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles (called tholins) that grow as they settle toward the surface. This image was generated by software that combines information from blue, red and near-infrared images to replicate the color a human eye would perceive as closely as possible. http://photojournal.jpl.nasa.gov/catalog/PIA19964

Influence of Haze on Molecular Lines Formed in the Atmosphere of Titan

NASA Astrophysics Data System (ADS)

Kim, Sang J.

2012-10-01

Radiative transfer calculations for the ro-vibrational lines of CH4, C2H2, C2H6, and HCN in atmosphere of Titan have been carried out without consideration of haze opacities (e.g., Yelle and Griffith, 2003), or only for very high (z > 500 km) atmospheric layers where haze influence is assumed to be negligible (e.g., Adriani et al. 2011; and García-Comas et al. 2011). Haze particles are found to exist in the high-altitude atmosphere of Titan, where the absorption lines of these molecules are modified by the haze opacities (Bellucci et al. 2009; Kim et al. 2011). We will present a discussion on the influence of the haze opacities on these molecular lines based on a preliminary result from updated radiative transfer calculations. References Adriani, A. et al. 2011. Icarus 214, 584-595. Bellucci, A. et al. 2009. Icarus 201, 198-216. García-Comas, M. et al. 2011. Icarus 214, 571-583. Kim, et al. 2011. 2011. Planetary and Space Science 59, 699-704. Yelle, R.V., Griffith, C.A., 2003. Icarus 166, 107-115.

Neptune False Color Image of Haze

NASA Technical Reports Server (NTRS)

1989-01-01

This false color photograph of Neptune was made from Voyager 2 images taken through three filters: blue, green, and a filter that passes light at a wavelength that is absorbed by methane gas. Thus, regions that appear white or bright red are those that reflect sunlight before it passes through a large quantity of methane. The image reveals the presence of a ubiquitous haze that covers Neptune in a semitransparent layer. Near the center of the disk, sunlight passes through the haze and deeper into the atmosphere, where some wavelengths are absorbed by methane gas, causing the center of the image to appear less red. Near the edge of the planet, the haze scatters sunlight at higher altitude, above most of the methane, causing the bright red edge around the planet. By measuring haze brightness at several wavelengths, scientists are able to estimate the thickness of the haze and its ability to scatter sunlight. The image is among the last full disk photos that Voyager 2 took before beginning its endless journey into interstellar space. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

Towards maximizing the haze effect of electrodes for high efficiency hybrid tandem solar cell

NASA Astrophysics Data System (ADS)

Vincent, Premkumar; Song, Dong-Seok; Kwon, Hyeok Bin; Kim, Do-Kyung; Jung, Ji-Hoon; Kwon, Jin-Hyuk; Choe, Eunji; Kim, Young-Rae; Kim, Hyeok; Bae, Jin-Hyuk

2018-02-01

In this study, we executed optical simulations to compute the optimum power conversion efficiency (PCE) of a-Si:H/organic photovoltaic (OPV) hybrid tandem solar cell. The maximum ideal short circuit current density (Jsc,max) of the tandem solar cell is initially obtained by optimizing the thickness of the active layer of the OPV subcell for varying thickness of the a-Si:H bottom subcell. To investigate the effect of Haze parameter on the ideal short-circuit current density (Jsc,ideal) of the solar cells, we have varied the haze ratio for the TCO electrode of the a-Si:H subcell in the tandem structure. The haze ratio was obtained for various root mean square (RMS) roughness of the TCO of the front cell. The effect of haze ratio on the Jsc,ideal on the tandem structured solar cell was studied, and the highest Jsc,ideal was obtained at a haze of 55.5% when the thickness of the OPV subcell was 150 nm and that of the a-Si:H subcell was 500 nm.

Does Pluto Have a Haze Layer?

NASA Technical Reports Server (NTRS)

Elliot, James L.

1997-01-01

The goal of this research was to determine whether Pluto has a haze layer through observations (with the Kuiper Airborne Observatory) of a stellar occultation by Pluto that was originally predicted to occur on 1993 October 3. As described in the attached material, our extensive astrometric measurements determined that this occultation would not be visible from Earth, and we canceled plans to observe it with the KAO. Efforts were then directed toward improving our astrometric techniques so that we could find future occultations with which we could satisfy the original goals of the research proposed for this grant.

Using high haze (> 90%) light-trapping film to enhance the efficiency of a-Si:H solar cells

NASA Astrophysics Data System (ADS)

Chu, Wei-Ping; Lin, Jian-Shian; Lin, Tien-Chai; Tsai, Yu-Sheng; Kuo, Chen-Wei; Chung, Ming-Hua; Hsieh, Tsung-Eong; Liu, Lung-Chang; Juang, Fuh-Shyang; Chen, Nien-Po

2012-07-01

The high haze light-trapping (LT) film offers enhanced scattering of light and is applied to a-Si:H solar cells. UV glue was spin coated on glass, and then the LT pattern was imprinted. Finally, a UV lamp was used to cure the UV glue on the glass. The LT film effectively increased the Haze ratio of glass and decreased the reflectance of a-Si:H solar cells. Therefore, the photon path length was increased to obtain maximum absorption by the absorber layer. High Haze LT film is able to enhance short circuit current density and efficiency of the device, as partial composite film generates broader scattering light, thereby causing shorter wave length light to be absorbed by the P layer so that the short circuit current density decreases. In case of lab-made a-Si:H thin film solar cells with v-shaped LT films, superior optoelectronic performances have been found (Voc = 0.74 V, Jsc = 15.62 mA/cm2, F.F. = 70%, and η = 8.09%). We observed ~ 35% enhancement of the short-circuit current density and ~ 31% enhancement of the conversion efficiency.

Quaternary low-angle slip on detachment faults in Death Valley, California

USGS Publications Warehouse

Hayman, N.W.; Knott, J.R.; Cowan, D.S.; Nemser, E.; Sarna-Wojcicki, A. M.

2003-01-01

Detachment faults on the west flank of the Black Mountains (Nevada and California) dip 29??-36?? and cut subhorizontal layers of the 0.77 Ma Bishop ash. Steeply dipping normal faults confined to the hanging walls of the detachments offset layers of the 0.64 Ma Lava Creek B tephra and the base of 0.12-0.18 Ma Lake Manly gravel. These faults sole into and do not cut the low-angle detachments. Therefore the detachments accrued any measurable slip across the kinematically linked hanging-wall faults. An analysis of the orientations of hundreds of the hanging-wall faults shows that extension occurred at modest slip rates (<1 mm/yr) under a steep to vertically oriented maximum principal stress. The Black Mountain detachments are appropriately described as the basal detachments of near-critical Coulomb wedges. We infer that the formation of late Pleistocene and Holocene range-front fault scarps accompanied seismogenic slip on the detachments.

The Effect of Oxygen on Organic Haze Properties

NASA Astrophysics Data System (ADS)

Ugelow, Melissa S.; De Haan, David O.; Hörst, Sarah M.; Tolbert, Margaret A.

2018-05-01

Atmospheric organic hazes are present on many planetary bodies, possibly including the ancient Earth and exoplanets, and can greatly influence surface and atmospheric properties. Here we examine the physical and optical properties of organic hazes produced with molecular nitrogen, methane, carbon dioxide, and increasing amounts of molecular oxygen, and compare them to hazes produced without added oxygen. As molecular oxygen is included in increasing amounts from 0 to 200 ppmv, the mass loading of haze produced decreases nonlinearly. With 200 ppmv molecular oxygen, the mass loading of particles produced is on the order of the amount of organic aerosol in modern Earth’s atmosphere, suggesting that while not a thick organic haze, haze particles produced with 200 ppmv molecular oxygen could still influence planetary climates. Additionally, the hazes produced with increasing amounts of oxygen become increasingly oxidized and the densities increase. For hazes produced with 0, 2 and 20 ppmv oxygen, the densities were found to be 0.94, 1.03 and 1.12 g cm‑3, respectively. Moreover, the hazes produced with 0, 2, and 20 ppmv oxygen are found to have real refractive indices of n = 1.58 ± 0.04, 1.53 ± 0.03 and 1.67 ± 0.03, respectively, and imaginary refractive indices of k={0.001}-0.001+0.002, 0.002 ± 0.002 and {0.002}-0.002+0.003, respectively. These k values demonstrate that the particles formed with oxygen have no absorption within our experimental error, and could result in a light scattering layer in an oxygen-containing atmosphere.

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth.

PubMed

Arney, Giada; Domagal-Goldman, Shawn D; Meadows, Victoria S; Wolf, Eric T; Schwieterman, Edward; Charnay, Benjamin; Claire, Mark; Hébrard, Eric; Trainer, Melissa G

2016-11-01

Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8-2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7-2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO 2 . Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets. Key Words: Haze-Archean Earth-Exoplanets-Spectra-Biosignatures-Planetary habitability. Astrobiology 16, 873-899.

Perceptual significance of colorimetric data for colors of plumes and haze

NASA Astrophysics Data System (ADS)

MacAdam, David L.

Colorimetric reduction of spectroradiometric and spectral absorption and scattering data, by use of C.I.E. (Commission Internationale de l'Eclairage) data is appropriate for assessment of the color appearances of plumes and haze and of vistas seen through haze. Chromatic adaptation needs to be taken into account, however, because a wide variety of chromaticities (e.g., color temperatures from 4000 K to at least 7000 K) can be perceived as white under various circumstances. The perceptions of all other colors shift correspondingly. Natural clouds or snow appear white: they have the chromaticity relative to which the perceived hues of all other objects in the same scene (including plumes and haze layers) are perceived. Those hues can be determined by drawing the straight line from that white point through the point representing the plume or haze. The wavelength at which that line intersects the spectrum locus is the dominant wavelength of the plume or haze, or other feature in the vista, for the state of chromatic adaptation of the observer. The dominant wavelength identifies the hue. The percentage of the distance from that white point to the spectrum locus is the purity of the plume, haze, or haze-veiled color. The perceived amount of coloration (saturation) can be evaluated as a multiple of the just-noticeable difference from the adaptation white.

Nitrous acid (HONO) measurements during winter haze events in Beijing

NASA Astrophysics Data System (ADS)

Bloss, W.; Kramer, L. J.; Crilley, L.; Lee, J. D.; Squires, F. A.; Tong, S.

2017-12-01

Daytime HONO levels can reach several parts per billion in megacities during winter haze events and hence act as the dominant (primary) precursor to OH radicals in the urban boundary layer, and affect NOx abundance. Understanding the sources of HONO is therefore important to quantify atmospheric oxidative capacity and secondary pollutant formation during such haze events. Despite decades of research, there are still large uncertainties in HONO formation mechanisms, and as a result models often substantially underestimate peak HONO levels. In this study, measurements of HONO were performed at the Institute of Atmospheric Physics (IAP) site located in central Beijing during Nov/Dec 2016, across both haze and non-haze events. Using a commercial long-path absorption photometer (LOPAP), vertical profiles of HONO concentrations up to a height of 260 m on the IAP Meteorological Tower were performed, as well as continuous near-surface measurements. Preliminary results showed that HONO levels near the ground were very high during the winter haze events with concentrations over 10 ppbV observed. Typically, during the vertical profiles a negative gradient was observed, indicating a large HONO source close to the surface. However, during some of the profiles elevated HONO concentrations were also observed at higher altitudes pointing to a strong source within the boundary layer. Co-located NOx and SO2 measurements are used to elucidate potential HONO sources from direct emissions, homogeneous gas phase reactions and heterogeneous conversion of NO2 on surfaces. Results from ground level HONO/NOx ratios show a midday peak during clean periods indicating a photo-enhanced process, which was not apparent during hazy days. The potential impact of these findings on the OH radical budget in wintertime Beijing will be discussed.

Comparison of physical and chemical properties of ambient aerosols during the 2009 haze and non-haze periods in Southeast Asia.

PubMed

Xu, Jingsha; Tai, Xuhong; Betha, Raghu; He, Jun; Balasubramanian, Rajasekhar

2015-10-01

Recurrent smoke-haze episodes that occur in Southeast Asia (SEA) are of much concern because of their environmental and health impacts. These haze episodes are mainly caused by uncontrolled biomass and peat burning in Indonesia. Airborne particulate matter (PM) samples were collected in the southwest coast of Singapore from 16 August to 9 November in 2009 to assess the impact of smoke-haze episodes on the air quality due to the long-range transport of biomass and peat burning emissions. The physical and chemical characteristics of PM were investigated during pre-haze, smoke-haze, and post-haze periods. Days with PM2.5 mass concentrations of ≥35 μg m(-3) were considered as smoke-haze events. Using this criterion, out of the total 82 sampling days, nine smoke-haze events were identified. The origin of air masses during smoke-haze episodes was studied on the basis of HYSPLIT backward air trajectory analysis for 4 days. In terms of the physical properties of PM, higher particle surface area concentrations and particle gravimetric mass concentrations were observed during the smoke-haze period, but there was no consistent pattern for particle number concentrations during the haze period as compared to the non-haze period except that there was a significant increase at about 08:00, which could be attributed to the entrainment of PM from aloft after the breakdown of the nocturnal inversion layer. As for the chemical characteristics of PM, among the six key inorganic water-soluble ions (Cl(-), NO3(-), nss-SO4(2-), Na(+), NH4(+), and nss-K(+)) measured in this study, NO3(-), nss-SO4(2-), and NH4(+) showed a significant increase in their concentrations during the smoke-haze period together with nss-K(+). These observations suggest that the increased atmospheric loading of PM with higher surface area and increased concentrations of optically active secondary inorganic aerosols [(NH4)2SO4 or NH4HSO4 and NH4NO3] resulted in the atmospheric visibility reduction in SEA due to the advection of biomass and peat burning emissions.

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth

PubMed Central

Domagal-Goldman, Shawn D.; Meadows, Victoria S.; Wolf, Eric T.; Schwieterman, Edward; Charnay, Benjamin; Claire, Mark; Hébrard, Eric; Trainer, Melissa G.

2016-01-01

Abstract Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8–2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7–2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO2. Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets. Key Words: Haze—Archean Earth—Exoplanets—Spectra—Biosignatures—Planetary habitability. Astrobiology 16, 873–899. PMID:27792417

Under an Orange Sky: The Many Implications of Organic Haze for Earthlike Planets

NASA Astrophysics Data System (ADS)

Arney, Giada; Domagal-Goldman, Shawn D.; Meadows, Victoria S.; Wolf, Eric; Schwieterman, Edward W.; Charnay, Benjamin; Claire, Mark; Hebrard, Eric

2015-11-01

Geochemical evidence suggests Archean Earth was intermittently enshrouded in an organic haze resulting from methane photolysis. Hazy exoplanets may be common, and hazes can significantly impact the environment of habitable planets. Earth is frequently studied as an analog for habitable exoplanets, and Archean Earth is the most alien planet we have geochemical data for. We have used 1D photochemical-climate and radiative transfer simulations to examine the climate, surface radiation environment, and spectra of Archean Earth with fractal hydrocarbon haze. We find that haze would have strongly impacted Earth’s climate, lowering the planetary surface temperature by 20-30 K. However, this cooling can be countered by concentrations of greenhouses gases consistent with geochemical constraints. For example, an atmosphere with 2% CO2, 0.37% CH4 and a self-consistent hydrocarbon haze has a globally averaged surface temperature of 274 K, which GCM models have shown is consistent with a large open ocean fraction (Charnay et al 2013). The cooling from haze means that there exists a “hazy habitable zone” closer to the star than the traditional habitable zone boundaries. Our results suggest that the hazy habitable zone can extend to the distance of Venus. An organic haze produces strong, remotely detectable spectral features, especially at wavelengths < 0.5 μm, reddening the planet’s color. The strong absorption of UV radiation by this haze means it could have provided a UV shield for the Archean Earth prior to the rise of oxygen when there was no ozone layer: we show that an organic haze can block 97% of the surface-incident UVC (λ < 0.28 μm) radiation compared to a haze-free planet. UVC radiation directly dissociates DNA, and it is blocked by ozone in the modern atmosphere. Organic hazes may therefore benefit surface biospheres on Earth and similar exoplanets. Finally, assuming geochemical constraints on the Archean atmospheric composition, we show that abiotic levels of methane flux to the atmosphere are insufficient to form an organic haze. For Earthlike exoplanets, organic haze may therefore be a novel type of spectral biosignature.

The greenhouse and antigreenhouse effects on Titan

NASA Technical Reports Server (NTRS)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1991-01-01

The parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the hypothesized terrestrial greenhouse effect can serve as bases for the evaluation of competing greenhouse theories. Attention is presently drawn to the similarity between the roles of H2 and CH4 on Titan and CO2 and H2O on earth. Titan also has an antigreenhouse effect due to a high-altitude haze layer which absorbs at solar wavelengths, while remaining transparent in the thermal IR; if this haze layer were removed, the antigreenhouse effect would be greatly reduced, exacerbating the greenhouse effect and raising surface temperature by over 20 K.

Characteristics and formation mechanism of continuous hazes in China: a case study during the autumn of 2014 in the North China Plain

NASA Astrophysics Data System (ADS)

Yang, Y. R.; Liu, X. G.; Qu, Y.; An, J. L.; Jiang, R.; Zhang, Y. H.; Sun, Y. L.; Wu, Z. J.; Zhang, F.; Xu, W. Q.; Ma, Q. X.

2015-07-01

Four extreme haze episodes occurred in October 2014 in the North China Plain (NCP). To clarify the formation mechanism of hazes in autumn, strengthened observations were conducted in Beijing from 5 October to 2 November. The meteorological parameters, satellite data, chemical compositions and optical properties of aerosols were obtained. The hazes originated from the NCP, developing in the southwest and northeast directions, with the highest concentration of PM2.5 of 469 μg m-3 in Beijing. The NCP was dominated by a weak high pressure system during the haze episode, which resulted in low surface wind speed and relatively stagnant weather. Moreover, the wind slowed down around Beijing city. The secondary aerosols NO3- was always higher than that of SO42-, which indicated the motor vehicles played a more important part in the hazes in October 2014, even though the oxidation rate from SO2 to SO42- was faster than that of NOx to NO3-. Sudden increases of the concentrations of organic matter, Cl- and BC (black carbon) before each haze episode implied that regional transport of pollutants by biomass burning was important for haze formation during autumn. A satellite map of fire points and the backward trajectories of the air masses also indicated this pollution source. The distinct decrease in the PBL (planetary boundary layer) height during four haze episodes restrained the vertical dispersion of the air pollutants. Water vapor also played a vital role in the formation of hazes by accelerating the chemical transformation of secondary pollutants, leading to hygroscopic growth of aerosols and altering the thermal balance of the atmosphere.

Characteristics and formation mechanism of continuous extreme hazes in China: a case study in autumn of 2014 in the North China Plain

NASA Astrophysics Data System (ADS)

Yang, Y. R.; Liu, X. G.; Qu, Y.; An, J. L.; Jiang, R.; Zhang, Y. H.; Sun, Y. L.; Wu, Z. J.; Zhang, F.; Xu, W. Q.; Ma, X. Q.

2015-04-01

Four extreme haze episodes occurred in October 2014 in the North China Plain (NCP). To clarify the formation mechanism of hazes in the autumn, strengthened observations were conducted in Beijing from 5 October to 2 November. The meteorological parameters, satellite data, chemical compositions and optical properties of aerosols were obtained. The hazes originated from NCP, developing in the southwest and northeast directions, with the highest concentration of PM2.5 of 469 μg m-3 in Beijing. NCP was dominated by a weak high pressure system during the haze episode, which resulted in low surface wind speed and relatively stagnant weather. Moreover, the wind slowed down around Beijing city. The secondary aerosols NO3- was always higher than that of SO42-, which indicated the motor vehicles played a more important part in the hazes in October 2014, even though the oxidation rate from SO2 to SO42- was faster than that of NOx to NO3-. Sudden increases of the concentrations of organic matter, Cl- and BC (Black carbon) before each haze episode implied that regional transport of pollutants by biomass burning was important for haze formation during the autumn. A satellite map of fire points and the backward trajectories of the air masses also indicated this pollution source. The distinct decrease in the PBL (planetary boundary layer) height during four haze episodes restrained the vertical dispersion of the air pollutants. Water vapor also played a vital role in the formation of hazes by accelerating the chemical transformation of secondary pollutants, leading to hygroscopic growth of aerosols and altering the thermal balance of the atmosphere.

Severe Pollution in China Amplified by Atmospheric Moisture.

PubMed

Tie, Xuexi; Huang, Ru-Jin; Cao, Junji; Zhang, Qiang; Cheng, Yafang; Su, Hang; Chang, Di; Pöschl, Ulrich; Hoffmann, Thorsten; Dusek, Uli; Li, Guohui; Worsnop, Douglas R; O'Dowd, Colin D

2017-11-17

In recent years, severe haze events often occurred in China, causing serious environmental problems. The mechanisms responsible for the haze formation, however, are still not well understood, hindering the forecast and mitigation of haze pollution. Our study of the 2012-13 winter haze events in Beijing shows that atmospheric water vapour plays a critical role in enhancing the heavy haze events. Under weak solar radiation and stagnant moist meteorological conditions in winter, air pollutants and water vapour accumulate in a shallow planetary boundary layer (PBL). A positive feedback cycle is triggered resulting in the formation of heavy haze: (1) the dispersal of water vapour is constrained by the shallow PBL, leading to an increase in relative humidity (RH); (2) the high RH induces an increase of aerosol particle size by enhanced hygroscopic growth and multiphase reactions to increase particle size and mass, which results in (3) further dimming and decrease of PBL height, and thus further depressing of aerosol and water vapour in a very shallow PBL. This positive feedback constitutes a self-amplification mechanism in which water vapour leads to a trapping and massive increase of particulate matter in the near-surface air to which people are exposed with severe health hazards.

New positive feedback mechanism between boundary layer meteorology and secondary aerosol formation during severe haze events.

PubMed

Liu, Quan; Jia, Xingcan; Quan, Jiannong; Li, Jiayun; Li, Xia; Wu, Yongxue; Chen, Dan; Wang, Zifa; Liu, Yangang

2018-04-17

Severe haze events during which particulate matter (PM) increases quickly from tens to hundreds of microgram per cubic meter in 1-2 days frequently occur in China. Although it has been known that PM is influenced by complex interplays among emissions, meteorology, and physical and chemical processes, specific mechanisms remain elusive. Here, a new positive feedback mechanism between planetary boundary layer (PBL), relative humidity (RH), and secondary PM (SPM) formation is proposed based on a comprehensive field experiment and model simulation. The decreased PBL associated with increased PM increases RH by weakening the vertical transport of water vapor; the increased RH in turn enhances the SPM formation through heterogeneous aqueous reactions, which further enhances PM, weakens solar radiation, and decreases PBL height. This positive feedback, together with the PM-Radiation-PBL feedback, constitutes a key mechanism that links PM, radiation, PBL properties (e.g. PBL height and RH), and SPM formation, This mechanism is self-amplifying, leading to faster PM production, accumulation, and more severe haze pollution.

Particulate matter in the Venus atmosphere

NASA Technical Reports Server (NTRS)

Ragent, B.; Esposito, L. W.; Tomasko, M. G.; Marov, M. IA.; Shari, V. P.

1985-01-01

The paper presents a summary of the data currently available (June 1984) describing the planet-enshrouding particulate matter in the Venus atmosphere. A description and discussion of the state of knowledge of the Venus clouds and hazes precedes the tables and plots. The tabular material includes a precis of upper haze and cloud-top properties, parameters for model-size distributions for particles and particulate layers, and columnar masses and mass loadings.

Photochemical Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes

NASA Technical Reports Server (NTRS)

He, Chao; Hoerst, Sarah M.; Lewis, Nikole K.; Yu, Xinting; Moses, Julianne I.; Kempton, Eliza M.- R.; Marley, Mark S.; McGuiggan, Patricia; Morley, Caroline V.; Valenti, Jeff A.;

Non-invasive NMR stratigraphy of a multi-layered artefact: an ancient detached mural painting.

PubMed

Di Tullio, Valeria; Capitani, Donatella; Presciutti, Federica; Gentile, Gennaro; Brunetti, Brunetto Giovanni; Proietti, Noemi

2013-10-01

NMR stratigraphy was used to investigate in situ, non-destructively and non-invasively, the stratigraphy of hydrogen-rich layers of an ancient Nubian detached mural painting. Because of the detachment procedure, a complex multi-layered artefact was obtained, where, besides layers of the original mural painting, also the materials used during the procedure all became constitutive parts of the artefact. NMR measurements in situ enabled monitoring of the state of conservation of the artefact and planning of minimum representative sampling to validate results obtained in situ by solid-state NMR analysis of the samples. This analysis enabled chemical characterization of all organic materials. Use of reference compounds and prepared specimens assisted data interpretation.

The Organic Aerosols of Titan's Atmosphere

NASA Technical Reports Server (NTRS)

Sotin, Christophe; Lawrence, Kenneth; Beauchamp, Patricia M.; Zimmerman, Wayne

2012-01-01

One of Titan's many characteristics is the presence of a haze that veils its surface. This haze is composed of heavy organic particles and determining the chemical composition of these particles is a primary objective for future probes that would conduct in situ analysis. Meanwhile, solar occultations provide constraints on the optical characteristics of the haze layer. This paper describes solar occultation observations obtained by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. These observations strongly constrain the optical characteristics of the haze layer. We detail the different steps involved in the processing of these data and apply them to two occultations that were observed at the South Pole and at the equator in order to investigate the latitudinal dependence of optical properties. The light curves obtained in seven atmospheric windows between 0.933-microns to 5-microns allow us to characterize atmospheric layers from 300 km to the surface. Very good fits of the light curves are obtained using a simple profile of number density of aerosols that is characterized by a scale height. The main difference between the South Pole and the equator is that the value of the scale height increases with altitude at the South Pole whereas it decreases at the equator. The vertically integrated amount of aerosols is similar at the two locations. The curve describing the cross-section versus wavelength is identical at the two locations suggesting that the aerosols have similar characteristics. Finally, we find that the two-way vertical transmission at 5-microns is as large as 80% at both locations.

Radiative Effects of Aerosols

NASA Technical Reports Server (NTRS)

Valero, Francisco P. J.

1996-01-01

During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

Characteristics and source apportionment of PM2.5 during persistent extreme haze events in Chengdu, southwest China

NASA Astrophysics Data System (ADS)

Li, L.; Liu, S.

2017-12-01

Based on detailed data from Chengdu Plain (CP) from 6 January to 16 January 2015 , two typical haze episodes were analyzed to clarify the haze formation mechanism in winter. Weather conditions, chemical compositions, secondary pollutant transformation, optical properties of aerosols, the potential source contribution function (PSCF) and source apportionment were studied. The planetary boundary layer (PBL) height decreased distinctly during the haze episodes and restrained air pollutant vertical dispersion. As the haze worsened, the value of PBL × PM2.5 increased notably. The [NO3-]/[SO42-] ratio was 0.61, 0.76 and 0.88 during a non-haze period, episode 1 and episode 2, respectively, indicating that the mobile source of the air pollution is increasingly predominant in Chengdu. Water vapor also played a vital role in the formation of haze by accelerating the chemical transformation of secondary pollutants, leading to the hygroscopic growth of aerosols. The PSCF and backward trajectories of the air masses indicated that the pollution mainly came from the south. The secondary inorganic aerosols, vehicle emissions, coal combustion, biomass burning, industry, and dust contributed 34.1%, 24.1%, 12.7%, 12.3%, 7.6%, and 7.2% to PM2.5 masses in episode 1 and 28.9%, 23.1%, 9.4%, 9.5%, 20.3% and 7.5% in episode 2.

Characteristics and source apportionment of PM2.5 during persistent extreme haze events in Chengdu, southwest China.

PubMed

Li, Lulu; Tan, Qinwen; Zhang, Yuanhang; Feng, Miao; Qu, Yu; An, Junling; Liu, Xingang

2017-11-01

Based on detailed data from Chengdu Plain (CP) from 6 January to 16 January, two typical haze episodes were analyzed to clarify the haze formation mechanism in winter. Weather conditions, chemical compositions, secondary pollutant transformation, optical properties of aerosols, the potential source contribution function (PSCF) and source apportionment were studied. The planetary boundary layer (PBL) height decreased distinctly during the haze episodes and restrained air pollutant vertical dispersion. As the haze worsened, the value of PBL × PM 2.5 increased notably. The [NO 3 - ]/[SO 4 2- ] ratio was 0.61, 0.76 and 0.88 during a non-haze period, episode 1 and episode 2, respectively, indicating that the mobile source of the air pollution is increasingly predominant in Chengdu. Water vapor also played a vital role in the formation of haze by accelerating the chemical transformation of secondary pollutants, leading to the hygroscopic growth of aerosols. The PSCF and backward trajectories of the air masses indicated that the pollution mainly came from the south. The secondary inorganic aerosols, vehicle emissions, coal combustion, biomass burning, industry, and dust contributed 34.1%, 24.1%, 12.7%, 12.3%, 7.6%, and 7.2% to PM 2.5 masses in episode 1 and 28.9%, 23.1%, 9.4%, 9.5%, 20.3% and 7.5% in episode 2. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pulling Back the Veil: The Characterization and Habitability of Enshrouded Worlds

NASA Astrophysics Data System (ADS)

Arney, Giada Nicole

This dissertation explores global atmospheric haze and cloud layers and shows that they are not impenetrable barriers to information about the lower atmosphere and surface environment of planets. In the first section of this dissertation, I discuss sub-cloud observations of the closest globally-enshrouded planet: Venus. Venus has near-infrared spectral windows observable on the planet's nightside that allow remote sensing of thermal radiation emanating from below the cloud and haze deck. We observed Venus with the Apache Point Observatory 3.5m telescope TripleSpec spectrograph (R = 3500, lambda=0.96-2.47 mum) on 1-3 March 2009 and on 25, 27, 30 November and 2-4 December 2010. With these observations and synthetic spectra generated with the Spectral Mapping and Atmospheric Radiative Transfer (SMART) model, I produced the first simultaneous maps of cloud opacity, acid concentration, water vapor (H2O), hydrogen chloride (HCl), carbon dioxide (CO), carbonyl sulfide (OCS), and sulfur dioxide (SO2 ) abundances in the Venusian sub-cloud atmosphere. My study of hazy early Earth presents simulations of a habitable, yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Using coupled climate-photochemical-microphysical simulations, I demonstrate that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (tau 5 at 200 nm) even with the fainter young sun. I find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding via their broad UV absorption signature, which can reduce surface UV flux by about 97% compared to a haze-free planet, and potentially allow for survival of land-based organisms at 2.6-2.7 billion years ago. To examine how organic haze may impact exoplanet habitability, I compared the production of fractal organic haze on Archean Earth-analog planets around several spectral types of stars: the sun at 2.7 billion years ago and at present day; the highly flaring M3.5V dwarf AD Leo; the M4V dwarf GJ 876; a modeled quiescent M dwarf; the K2V star epsilon Eridani; and the F2V star sigma Bootis. In my simulations, planets orbiting stars with the highest or lowest UV fluxes did not form haze. Low UV-stars are unable to drive the photochemistry needed for haze formation. High UV stars generate photochemical oxygen radicals that halt the buildup of this haze. Hazes can impact planetary habitability via UV shielding and surface cooling, but this cooling seems unimportant for hazy M dwarf planets because the bulk of the M dwarf spectral energy arrives at longer infrared wavelengths where organic hazes are relatively transparent. I simulated hazy planet spectra for these exoplanet-analogs in reflected light, thermal emission, and transit transmission and found that the spectral features of organic hazes should be detectable with future telescopes. For 10 transits of a hypothetical Archean-analog planet orbiting GJ 876 observed by the James Webb Space Telescope (JWST) over 0.8-14 mum, haze, methane and carbon dioxide are detectable assuming photon-limited noise levels. For direct imaging of a planet at 10 pc using a coronagraphic 10-meter class ultraviolet-visible-near infrared telescope, a shortwave haze absorption feature would be strongly detectable at >12 sigma in 200 hours. The impact of haze on planetary habitability and spectra are crucial to consider for future characterization of terrestrial exoplanets. Haze in the Archean could even have impacted the evolution of photosynthetic pigments because the spectrum of light reaching the planet's surface would have been reddened. I explore the consequences of this and show the spectrum of photons at the Earth's surface beneath a haze. In addition to haze, other types of UV shields would have been present in the Archean. I present spectra at several depths under water with and without dissolved Fe(II), a UV shielding compound that may have been in the Archean oceans. UV-tolerant phototrophs like Chloroflexus aurantiacus could have received a survivable level of UV irradiance under a haze and 10 cm of water containing 5 ppm dissolved Fe(II). Such organisms may have been protected even directly at the planet's surface. There are other ways that an Archean haze the evolving biosphere were connected. Any haze in Archean Earth's atmosphere would have been strongly dependent on biologically-produced methane, and hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO2. On planets with high levels of biogenic organic sulfur gases, photochemistry involving these gases can drive haze formation at lower CH 4/CO2 ratios than methane photochemistry alone, providing another means to argue for biological activity on a haze-rich planet. (Abstract shortened by ProQuest.).

DISCRIMINATING BETWEEN CLOUDY, HAZY, AND CLEAR SKY EXOPLANETS USING REFRACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misra, Amit K.; Meadows, Victoria S.

2014-11-01

We propose a method to distinguish between cloudy, hazy, and clear sky (free of clouds and hazes) exoplanet atmospheres that could be applicable to upcoming large aperture space- and ground-based telescopes such as the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT). These facilities will be powerful tools for characterizing transiting exoplanets, but only after a considerable amount of telescope time is devoted to a single planet. A technique that could provide a relatively rapid means of identifying haze-free targets (which may be more valuable targets for characterization) could potentially increase the science return for thesemore » telescopes. Our proposed method utilizes broadband observations of refracted light in the out-of-transit spectrum. Light refracted through an exoplanet atmosphere can lead to an increase of flux prior to ingress and subsequent to egress. Because this light is transmitted at pressures greater than those for typical cloud and haze layers, the detection of refracted light could indicate a cloud- or haze-free atmosphere. A detection of refracted light could be accomplished in <10 hr for Jovian exoplanets with JWST and <5 hr for super-Earths/mini-Neptunes with E-ELT. We find that this technique is most effective for planets with equilibrium temperatures between 200 and 500 K, which may include potentially habitable planets. A detection of refracted light for a potentially habitable planet would strongly suggest the planet was free of a global cloud or haze layer, and therefore a promising candidate for follow-up observations.« less

Study of Venus' cloud layers by polarimetry using SPICAV/VEx

NASA Astrophysics Data System (ADS)

Rossi, Loïc; Marcq, Emmanuel; Montmessin, Franck; Bertaux, Jean-Loup; Korablev, Oleg; Fedorova, Anna

2013-04-01

The study of Venus's cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. The main cloud layers between 50 and 70km are thought to consist in ~ 1μm radius droplets of a H2SO4-H2O solution. Nevertheless, the composition and the size distribution of the droplets are difficult to constrain more precisely. The polarization measurements have given great results in the determination of the constituents of the haze. In the early 1980s, Kawabata et al.(1980) used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the haze. They obtained a refractive index of 1.45 ± 0.04 at ? = 550nm and an effective radius of 0.23 ± 0.04μm, with a normalized size distribution variance of 0.18 ± 0.1. Our work aims to reproduce the method used by Kawabata et al. by writing a Lorentz-Mie scattering model and apply it to the so far unexploited polarization data of the SPICAV-IR instrument on-board ESA's Venus Express in order to better constrain haze and cloud particles at the top of Venus's clouds, as well as their spatial and temporal variability. We introduce here the model we developed, based on the BH-MIE scattering model. Taking into account the same size distribution of droplets as Kawabata et al., we obtained the polarization degree after a single Mie scattering by a haze at all phase angles given the effective radius and variance of the distribution and the refractive index of the droplets. Our model seems consistent as it reproduces the polarization degree modeled by Kawabata et al. We also present the first application of our model to the SPICAV-IR data under the single scattering assumption. Hence we can confirm the mean constraints on the size and refractive index of the haze and cloud droplets. In the near future, we then aim to extend our study of the polarization data by integrating our model into a radiative transfer model which will take into account the multiple scattering. Having more recent observations in wavelengths ranging from 650 to 1625nm, will put better constraints on the properties of both cloud and haze particles, with a primary focus on the cloud droplets characterization. Bibliography: BOHREN, C. F. AND HUMAN, D.R., in Absorption and Scattering of light by small particles, Wiley, 1983 KAWABATA, K. et al., Cloud and haze properties from Pioneer Venus Polarimetry, JGR, 1980

Photographer : JPL Range : 12 million km. ( 7.56 million miles) P-23057C & BW This Voyager 1

NASA Technical Reports Server (NTRS)

1980-01-01

Photographer : JPL Range : 12 million km. ( 7.56 million miles) P-23057C & BW This Voyager 1 photograph of Titan, the largest of Saturn's 14 known satellites, shows little more than the upper layers of clouds covering the moon. The orange colored haze, is believed to be composed of photochemically produced hydrocarbons, hides Titan's solid surface from Voyager's camera. Some weak shadings in the clouds are becoming visible. However, note that the satellite's southern, lower, hemisphere is brighter than the northern. It is not known whether these subtle shadings are on the surface or are due to clouds below a high haze layer.

Evolutionary processes and sources of high-nitrate haze episodes over Beijing, Spring.

PubMed

Yang, Ting; Sun, Yele; Zhang, Wei; Wang, Zifa; Liu, Xingang; Fu, Pingqing; Wang, Xiquan

2017-04-01

Rare and consecutive high-nitrate haze pollution episodes were observed in Beijing in spring 2012. We present detailed characterization of the sources and evolutionary mechanisms of this haze pollution, and focus on an episode that occurred between 15 and 26 April. Submicron aerosol species were found to be substantially elevated during haze episodes, and nitrates showed the largest increase and occupation (average: 32.2%) in non-refractory submicron particles (NR-PM 1 ), which did not occur in other seasons as previously reported. The haze episode (HE) was divided into three sub-episodes, HEa, HEb, and HEc. During HEa and HEc, a shallow boundary layer, stagnant meteorological conditions, and high humidity favored the formation of high-nitrate concentrations, which were mainly produced by three different processes - daytime photochemical production, gas-particle partitioning, and nighttime heterogeneous reactions - and the decline in visibility was mainly induced by NR-PM 1. However, unlike HEa and HEc, during HEb, the contribution of high nitrates was partly from the transport of haze from the southeast of Beijing - the transport pathway was observed at ~800-1000m by aerosol Lidar - and the decline in visibility during HEb was primarily caused by PM 2.5 . Our results provide useful information for air quality improvement strategies in Beijing during Spring. Copyright © 2016. Published by Elsevier B.V.

Duplex thrusting in the South Dabashan arcuate belt, central China

NASA Astrophysics Data System (ADS)

Li, Wangpeng; Liu, Shaofeng; Wang, Yi; Qian, Tao; Gao, Tangjun

2017-10-01

Due to later tectonic superpositioning and reworking, the South Dabashan arcuate belt extending NW to SE has experienced several episodes of deformation. The earlier deformational style and formation mechanism of this belt remain controversial. Seismic interpretations and fieldwork show that the curved orogen can be divided into three sub-belts perpendicular to the strike of the orogen, the imbricate thrust fault belt, the detachment fold belt and the frontal belt from NE to SW. The imbricate thrust fault belt is characterized by a series of SW-directed thrust faults and nappes. Two regional detachment layers at different depths have been recognized in the detachment fold and frontal belts, and these detachment layers divide the sub-belts into three structural layers: the lower, middle, and upper structural layers. The middle structural layer is characterized by a passive roof duplex structure, which is composed of a roof thrust at the top of the Sinian units, a floor thrust in the upper Lower Triassic units, and horses in between. Apatite fission track dating results and regional structural analyses indicate that the imbricate thrust fault belt may have formed during the latest Early Cretaceous to earliest Paleogene and that the detachment fold belt may have formed during the latest Late Cretaceous to earliest Neogene. Our findings provide important reference values for researching intra-continental orogenic and deformation mechanisms in foreland fold-thrust belts.

Multiple scattered radiation emerging from Rayleigh and continental haze layers. 1: Radiance, polarization, and neutral points.

PubMed

Kattawar, G W; Plass, G N; Hitzfelder, S J

1976-03-01

The complete radiation field including polarization is calculated by the matrix operator method for scattering layers of various optical thicknesses. Results obtained for Rayleigh scattering are compared with those for scattering from a continental haze. Radiances calculated using Stokes vectors show differences as large as 23% compared to the approximate scalar theory of radiative transfer, while the same differences are only of the order of 0.1% for a continental haze phase function. The polarization of the reflected and transmitted radiation is given for a wide range of optical thicknesses of the scattering layer, for various solar zenith angles, and various surface albedos. Two entirely different types of neutral points occur for aerosol phase functions. Rayleigh-like neutral points (RNP) arise from the zero polarization in single scattering that occurs for all phase functions at scattering angles of 0 degrees and 180 degrees . For Rayleigh phase functions, the position of the RNP varies appreciably with the optical thickness of the scattering layer. At low solar elevations there may be four RNP. For a continental haze phase function the position of the RNP in the reflected radiation shows only a small variation with the optical thickness, and the RNP exists in the transmitted radiation only for extremely small optical thicknesses. Another type of neutral point (NRNP) exists for aerosol phase functions. It is associated with the zeros of the single scattered polarization, which occur between the end points of the curve; these are called non-Rayleigh neutral points (NRNP). There may be from zero to four of these neutral points associated with each zero of the single scattering curve. They occur over a range of azimuthal angles, unlike the RNP that are in the principal plane only. The position of these neutral points is given as a function of solar angle and optical thickness.

New positive feedback mechanism between boundary layer meteorology and secondary aerosol formation during severe haze events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Quan; Jia, Xingcan; Quan, Jiannong

Severe haze events during which particulate matter (PM) increases quickly from tens to hundreds of microgram per cubic meter in 1-2 days frequently occur in China. Although it has been known that PM is influenced by complex interplays among emissions, meteorology, and physical and chemical processes, specific mechanisms remain elusive. In this paper, a new positive feedback mechanism between planetary boundary layer (PBL), relative humidity (RH), and secondary PM (SPM) formation is proposed based on a comprehensive field experiment and model simulation. The decreased PBL associated with increased PM increases RH by weakening the vertical transport of water vapor; themore » increased RH in turn enhances the SPM formation through heterogeneous aqueous reactions, which further enhances PM, weakens solar radiation, and decreases PBL height. This positive feedback, together with the PM-Radiation-PBL feedback, constitutes a key mechanism that links PM, radiation, PBL properties (e.g. PBL height and RH), and SPM formation, This mechanism is self-amplifying, leading to faster PM production, accumulation, and more severe haze pollution.« less

New positive feedback mechanism between boundary layer meteorology and secondary aerosol formation during severe haze events

DOE PAGES

Liu, Quan; Jia, Xingcan; Quan, Jiannong; ...

2018-04-17

Severe haze events during which particulate matter (PM) increases quickly from tens to hundreds of microgram per cubic meter in 1-2 days frequently occur in China. Although it has been known that PM is influenced by complex interplays among emissions, meteorology, and physical and chemical processes, specific mechanisms remain elusive. In this paper, a new positive feedback mechanism between planetary boundary layer (PBL), relative humidity (RH), and secondary PM (SPM) formation is proposed based on a comprehensive field experiment and model simulation. The decreased PBL associated with increased PM increases RH by weakening the vertical transport of water vapor; themore » increased RH in turn enhances the SPM formation through heterogeneous aqueous reactions, which further enhances PM, weakens solar radiation, and decreases PBL height. This positive feedback, together with the PM-Radiation-PBL feedback, constitutes a key mechanism that links PM, radiation, PBL properties (e.g. PBL height and RH), and SPM formation, This mechanism is self-amplifying, leading to faster PM production, accumulation, and more severe haze pollution.« less

The role of fog in haze episode in Tianjin, China: A case study for November 2015

NASA Astrophysics Data System (ADS)

Hao, Tianyi; Han, Suqin; Chen, Shucheng; Shan, Xiaolin; Zai, Ziying; Qiu, Xiaobin; Yao, Qing; Liu, Jingle; Chen, Jing; Meng, Lihong

2017-09-01

A severe haze episode that heavy fog appeared in its later stage emerged in Tianjin, east-central China, from November 27 to December 2, 2015. With meteorological data and pollutants monitoring data, the characteristics of this event and the role of fog in haze were investigated. During this process, the visibility was less than 600 m, especially in the haze and fog coexisting period (below 100 m). The peak value of PM2.5 mass concentration appeared in the haze only period was 446 μg/m3. The fog played a role in scavenging and removing PM2.5 during haze and fog coexisting period. The surface high humidity province can match well with the high PM2.5 concentration region in pollutants removal period. The fog top height was reduced to about 200 m by cold air. Although the cold air has arrived in Tianjin high altitude, the saturated layer below 200 m maintained for nearly 12 h. The heavy fog prevented the momentum in upper atmosphere from transmitting downward and caused the high altitude cold air difficult to reach the ground. The latent heat flux was transmitted upward ahead of sensible heat flux in pollutants removal period, indicating the increasing tendency of mechanical turbulence after fog dissipation. Turbulent kinetic energy (Etk) and the surface mean kinetic energy (E) also enhanced after fog dissipation. It demonstrates that the termination of haze was delayed by heavy fog.

In vivo laser confocal microscopy after non-Descemet's stripping automated endothelial keratoplasty.

PubMed

Kobayashi, Akira; Yokogawa, Hideaki; Sugiyama, Kazuhisa

2009-07-01

To investigate in vivo corneal changes in patients with bullous keratopathy who underwent non-Descemet's stripping automated endothelial keratoplasty (nDSAEK) with the use of laser confocal microscopy. Single-center, prospective clinical study. Ten eyes (10 patients; 3 men and 7 women; mean age, 73.5+/-6.6 years [mean+/-standard deviation]) with bullous keratopathy were evaluated in this study. In vivo laser confocal microscopy was performed before and 1, 3, and 6 months after nDSAEK. Selected confocal images of corneal layers were evaluated qualitatively and quantitatively for degree of haze and density of deposits. Before surgery, the following were observed in all patients: corneal epithelial edema, subepithelial haze, keratocytes in a honeycomb pattern, and tiny needle-shaped materials in the stroma. After nDSAEK, subepithelial haze, donor-recipient interface haze, and interface particles were observed in all measurable cases; postoperative haze, interface particles, and needle-shaped materials decreased statistically significantly (P<0.05) over the course of follow-up. In addition, hyperreflective giant interface particles were observed after nDSAEK in all patients. In vivo laser confocal microscopy can identify subclinical corneal abnormalities after nDSAEK such as subepithelial haze, host-recipient interface haze, host stromal needle-shaped materials, and host-recipient interface particles with characteristic giant particles. Further studies with this technology in a large number of patients and long-term follow-up are needed to understand fully the long-term corneal stromal changes after nDSAEK.

Ozone budget over the Amazon - Regional effects from biomass-burning emissions

NASA Technical Reports Server (NTRS)

Richardson, Jennifer L.; Fishman, Jack; Gregory, Gerald L.

1991-01-01

Data from the NASA dry-season Amazon boundary layer experiment (ABLE2A) is used with a 1D tropospheric photochemical model to analyze the atmospheric chemistry in the region and determine the impact of the long-range transport of biomass-burning emissions. Inputs of surface sources and the deposition of various species measured during ABLE2A are employed to simulate the background atmosphere, and haze characteristics are introduced for a 12-hr simulation. The in situ ozone production rate doubles during the period of haze when hydrocarbons are present. The model predicts that the production of ozone is enhanced during the dry season, and that increased ozone during the southern tropical burning season is related to the regional transport of haze.

Characteristics of aerosol pollution during heavy haze events in Suzhou, China

NASA Astrophysics Data System (ADS)

Tian, M.; Wang, H. B.; Chen, Y.; Yang, F. M.; Zhang, X. H.; Zou, Q.; Zhang, R. Q.; Ma, Y. L.; He, K. B.

2015-11-01

A comprehensive measurement was carried out to analyze the heavy haze events in Suzhou in January 2013 when extremely severe haze pollution occurred in many cities in China especially in the East. Hourly concentrations of PM2.5, chemical composition (including water-soluble inorganic ions, OC, and EC), and gas-phase precursors were obtained via on-line monitoring system. Based on these data, detailed aerosol composition, light extinction and gas-phase precursors were analyzed to understand the characteristics of the haze events, moreover, the formation mechanism of nitrate and sulfate in PM2.5 and the regional sources deduced from trajectory and PSCF were discussed to explore the origin of the heavy aerosol pollution. The results showed that frequent haze events were occurred on January 2013 and the concentrations of PM2.5 often exceeded 150 μg m-3 during the haze occurrence, with a maximum concentration of 324 μg m-3 on 14 January 2013. Unfavorable weather conditions (high RH, and low rainfall, wind speed and atmospheric pressure), high concentration of secondary aerosol species (including SO42-, NO3-, NH4+, and SOC) and precursors were observed during the haze events. Additionally, OM, (NH4)2SO4, NH4NO3 were demonstrated to be the major contributors to the visibility impairment but the share differed from haze events. This study also found that the high concentration of sulfate might be explained by the heterogeneous reactions in the aqueous surface layer of pre-existing particles or in cloud processes while nitrate might be mainly formed through homogeneous gas-phase reactions. The results of trajectory clustering and the PSCF method manifested that aerosol pollutions in the studied areas were mainly affected by local activities and surrounding sources transported from nearby cities.

Laboratory Simulations of Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes: Particle Color and Size Distribution

NASA Astrophysics Data System (ADS)

He, Chao; Hörst, Sarah M.; Lewis, Nikole K.; Yu, Xinting; Moses, Julianne I.; Kempton, Eliza M.-R.; McGuiggan, Patricia; Morley, Caroline V.; Valenti, Jeff A.; Vuitton, Véronique

2018-03-01

Super-Earths and mini-Neptunes are the most abundant types of planets among the ∼3500 confirmed exoplanets, and are expected to exhibit a wide variety of atmospheric compositions. Recent transmission spectra of super-Earths and mini-Neptunes have demonstrated the possibility that exoplanets have haze/cloud layers at high altitudes in their atmospheres. However, the compositions, size distributions, and optical properties of these particles in exoplanet atmospheres are poorly understood. Here, we present the results of experimental laboratory investigations of photochemical haze formation within a range of planetary atmospheric conditions, as well as observations of the color and size of produced haze particles. We find that atmospheric temperature and metallicity strongly affect particle color and size, thus altering the particles’ optical properties (e.g., absorptivity, scattering, etc.); on a larger scale, this affects the atmospheric and surface temperature of the exoplanets, and their potential habitability. Our results provide constraints on haze formation and particle properties that can serve as critical inputs for exoplanet atmosphere modeling, and guide future observations of super-Earths and mini-Neptunes with the Transiting Exoplanet Survey Satellite, the James Webb Space Telescope, and the Wide-Field Infrared Survey Telescope.

Earth observations taken by the Expedition 14 crew

NASA Image and Video Library

2006-11-10

ISS014-E-07738 (10 Nov. 2006) --- This image featuring a southeast-looking view of the Long Island Sound and New Jersey coast, with the lower Hudson River and New York Bay in the area of brightest sunglint was photographed by an Expedition 14 crewmember on the International Space Station. On the far right a gray haze can be seen streaming out to sea offshore of New Jersey, where it becomes harder to see. In fact haze covers most of the visible area offshore, partly obscuring the sea surface. By contrast, clouds look quite different from haze according to scientists. Clouds usually have sharp margins and are pure white, as clouds at the bottom show. Industrial haze is grayer and more diffuse, and is typical of the air over the Northeast. Flow lines show that winds are transporting the haze in clockwise fashion--i.e. bending south--which in turn signifies that a high pressure system was operating on that day, centered roughly over the coast. High pressure systems are notorious for promoting smog events because they bring clear skies, and sunlight promotes smog formation. Highs also concentrate polluted surface layers near the ground.

Constraining Dust Hazes at the L/T Transition via Variability

NASA Astrophysics Data System (ADS)

Radigan, Jacqueline; Apai, Daniel; Yang, Hao; Hiranaka, Kay; Cruz, Kelle; Buenzli, Esther; Marley, Mark

2014-12-01

The T2 dwarf SIMP 1629+03 is a variable L/T transition dwarf, with a normal near-infrared spectrum. However, it is remarkable in that the wavelength dependence of its variability differs markedly from that of other L/T transition brown dwarfs. In particular, the absence of a water absorption feature in its variability spectrum indicates that a patchy, high-altitude haze, rather than a deeper cloud layer is responsible for the observed variations. We propose to obtain Spitzer+HST observations of SIMP1629+02 over two consecutive rotations periods in order to simultaneously map it?s spectral variability across 1-5 um. The wide wavelength coverage will provide a suitable lever-arm for constraining the particle size distribution in the haze. A truly flat spectrum across this wavelength range would indicate large particle sizes in comparison to those inferred for red L-dwarf hazes, and would therefore provide direct evidence of grain growth with decreasing effective temperature and/or a grain-size dependence on surface gravity in brown dwarf atmospheres.

Accurate Spectral Fits of Jupiter's Great Red Spot: VIMS Visual Spectra Modelled with Chromophores Created by Photolyzed Ammonia Reacting with Acetyleneχ±

NASA Astrophysics Data System (ADS)

Baines, Kevin; Sromovsky, Lawrence A.; Fry, Patrick M.; Carlson, Robert W.; Momary, Thomas W.

2016-10-01

We report results incorporating the red-tinted photochemically-generated aerosols of Carlson et al (2016, Icarus 274, 106-115) in spectral models of Jupiter's Great Red Spot (GRS). Spectral models of the 0.35-1.0-micron spectrum show good agreement with Cassini/VIMS near-center-meridian and near-limb GRS spectra for model morphologies incorporating an optically-thin layer of Carlson (2016) aerosols at high altitudes, either at the top of the tropospheric GRS cloud, or in a distinct stratospheric haze layer. Specifically, a two-layer "crème brûlée" structure of the Mie-scattering Carlson et al (2016) chromophore attached to the top of a conservatively scattering (hereafter, "white") optically-thick cloud fits the spectra well. Currently, best agreement (reduced χ2 of 0.89 for the central-meridian spectrum) is found for a 0.195-0.217-bar, 0.19 ± 0.02 opacity layer of chromophores with mean particle radius of 0.14 ± 0.01 micron. As well, a structure with a detached stratospheric chromophore layer ~0.25 bar above a white tropospheric GRS cloud provides a good spectral match (reduced χ2 of 1.16). Alternatively, a cloud morphology with the chromophore coating white particles in a single optically- and physically-thick cloud (the "coated-shell model", initially explored by Carlson et al 2016) was found to give significantly inferior fits (best reduced χ2 of 2.9). Overall, we find that models accurately fit the GRS spectrum if (1) most of the optical depth of the chromophore is in a layer near the top of the main cloud or in a distinct separated layer above it, but is not uniformly distributed within the main cloud, (2) the chromophore consists of relatively small, 0.1-0.2-micron-radius particles, and (3) the chromophore layer optical depth is small, ~ 0.1-0.2. Thus, our analysis supports the exogenic origin of the red chromophore consistent with the Carlson et al (2016) photolytic production mechanism rather than an endogenic origin, such as upwelling of material from the depths of Jupiter.

The Dust Cycle Observed by Pathfinder

NASA Astrophysics Data System (ADS)

Smith, P. H.; Lemmon, M. T.; Tomasko, M. G.

1998-09-01

The Imager for Mars Pathfinder observed the Sun through special filters nearly every sol throughout the 83 sol mission; a total of 1733 images of the Sun have been obtained. Optical depths at four wavelengths (450, 670, 883, and 989 nm) steadily increased from 0.4 to 0.6 during the mission (Ls 145-185). Comparing observations taken in the morning to those from the afternoon shows a general variability with the morning haze being somewhat thicker by 0.1 optical depths. Typically, the trend is more pronounced in the blue wavelength band; we interpret this to be the influence of a high level haze of water ice crystals that forms in the early morning and evaporates during the day. Small, Rayleigh scattering crystals explains the spectral signature that we measure. It may be that this upper haze layer is associated with the small, ice crystals seen by Mariner 9, the Viking orbiters, and the Phobos orbiter. UV images taken by HST show strong limb brightening that can be explained by this high level ice. Calculations of the haze lifetimes given the sedimentation rates measured from the Rover's solar panels and the magnetic targets, suggest that the haze should completely deposit onto the surface within 120 days. A primary mechanism for replenishing the haze may be the dust devils that were observed during the sol 11 gallery pan.

The variation of characteristics and formation mechanisms of aerosols in dust, haze, and clear days in Beijing

NASA Astrophysics Data System (ADS)

Wang, Ying; Zhuang, Guoshun; Sun, Yele; An, Zhisheng

A 4-year campaign from 2001 to 2004 monitoring PM 2.5 and TSP in the spring season in urban Beijing, China was performed to study the variation of characteristics and the different formation mechanisms of aerosols in dust, haze, and clear days. A total of 315 aerosol samples were collected and used in this study. The aerosols were more basic in dust days and more acidic in haze days. The ions presented in the order of SO42->Ca 2+≫ NO3->Cl -> NH4+>Na + in dust days, and of SO42-> NO3-> NH4+≫Cl ->Ca 2+>K + in haze days. Ions has been classified into three groups, "Na +, Mg 2+, Ca 2+", "K +, SO42-, Cl -", and " NO3-, NH4+", representing crust, pollution-crust, and pollution species, respectively. Crust and pollution ions were the main ion fractions in dust and haze days, respectively. The variation of Ca 2+/Al showed that the increase of dust in dust and haze days was from soil and construction, respectively. "CaCO 3, CaSO 4, and (NH 4) 2SO 4" and "(NH 4) 2SO 4, NH 4NO 3, and Ca(NO 3) 2" were the major species in dust and haze days, respectively. The formation of CaSO 4 on airborne soil particles and the formation of (NH 4) 2SO 4 and NH 4NO 3 were the predominant pathways of sulfate and nitrate formations in dust and haze days, respectively. Sulfate might be mainly formed through heterogeneous reactions in the aqueous surface layer on the pre-existing particles, while nitrate mainly through homogeneous gas-phase reactions in the spring season in Beijing. The formation of sulfate and nitrate was accelerated in dust and haze days.

A campaign for investigating aerosol optical properties during winter hazes over Shijiazhuang, China

NASA Astrophysics Data System (ADS)

Qin, Kai; Wang, Luyao; Wu, Lixin; Xu, Jian; Rao, Lanlan; Letu, Husi; Shi, Tiewei; Wang, Runfeng

2017-12-01

As the capital of the most air-polluted Hebei province in China, Shijiazhuang has been suffering serious haze pollutions especially during wintertime. An integrated campaign for investigating aerosol optical properties under haze conditions over Shijiazhuang were carried out using a sunphotometer, an aethalometer and a lidar in the winter from late 2013 to early 2014. The results indicated that the haze episodes during the measurement period were severer and more frequent over Shijiazhuang than Beijing. Under heavy pollution conditions (PM2.5 > 150 μg/m3) over Shijiazhuang, fine-mode fractions of AOD500nm were larger than 0.80 with more dispersive angstrom exponent due to hygroscopic growth. The mean values of SSA over Shijiazhuang were smaller than those over Beijing both in this study and the severe haze episodes in January 2013, suggesting that there were more fine-mode absorbing particles over Shijiazhuang. More significant spectrally-dependence of imaginary part of refractive index over Shijiazhuang implies larger relative magnitude of brown carbon (BrC) as compared to Beijing. The black carbon (BC) measurement displayed extremely high records with a larger ratio of BC to PM2.5 (12.11% in average) comparing with other cities in China. The high carbonaceous aerosols (BC and BrC) should be attributed to large amounts of coal consumption. During the hazes with high BC concentrations, the daily maximal planetary boundary layer (PBL) heights were consistently lower than 500 m, implying the impacts of BC aerosols on the PBL development and hence enhance the surface haze pollution.

Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity

NASA Astrophysics Data System (ADS)

Hirtzig, M.; Bézard, B.; Coustenis, A.; Lellouch, E.; Drossart, P.; deBergh, C.; Campargue, A.; Boudon, V.; Tyuterev, V.; Rannou, P.; Cours, T.; Kassi, S.; Nikitin, A.; Wang, L.; Solomonidou, A.; Schmitt, B.; Rodriguez, S.

2012-04-01

In this paper we present an updated analysis of VIMS data in view of recent developments on the methane opacity in the 1.3-5.2 µm region, a very important parameter in simulating Titan's spectrum. We use a multi-stream radiative transfer model, benefitting from the latest methane absorption coefficients available [1], which allows us to determine more accurately the haze and surface contributions. This code is applied to Cassini/VIMS spectro-imaging data of various regions with very different spectral responses to extract information on the content of the lower atmosphere (0-200 km) as well as on the surface properties. In particular, we update the DISR aerosol model [2] for the Huygens landing site that we then adjust to fit the data for other locations on Titan's disk. Fitting VIMS data taken from 2004 to 2010 (TA to T70), around Titan's mid-latitudes (40°S-40°N), we determine the latitudinal and temporal evolution of the aerosol population, monitoring the North-South Asymmetry. While around the equinox [3] witnessed the collapse of the detached haze layer, we measure a continuous depletion of the aerosols throughout the atmosphere, although the NSA remains with a brighter northern hemisphere. Using this improved atmospheric model, we also retrieve surface albedos simultaneously for all the seven windows in the whole VIMS range for these regions, also recovering the shape of the surface albedo within each window. Eventually, we look for Titan's surface probable chemical composition, using mixtures of dark and complex hydrocarbons like bitumens and tholins, as well as bright CH4, CO2, NH3 and H2O ices of various grain sizes. [4] [1] Campargue, A. et al., (2012) Icarus, submitted. [2] Tomasko, M. et al., (2008) Planetary and Space Science, 56, 669. [3] West, R.A. et al., (2011) Geophysical Research Letters, 38, L06204. [4] Hirtzig, M. et al., (2012) Planetary and Space Science, submitted.

Delay of Turbulent Boundary Layer Detachment by Mechanical Excitation: Application to Rearward-facing Ramp

NASA Technical Reports Server (NTRS)

McKinzie, Daniel J., Jr.

1996-01-01

A vane oscillating about a fixed point at the inlet to a two-dimensional 20 deg rearward-facing ramp proved effective in delaying the detachment of a turbulent boundary layer. Flow-field, surface static pressure, and smoke-wire flow visualization measurements were made. Surface pressure coefficient distributions revealed that two different effects occurred with axial distance along the ramp surface. The surface pressure coefficient varied as a complex function of the vane oscillation frequency and its trailing edge displacement amplitude; that is, it varied as a function of the vane oscillation frequency throughout the entire range of frequencies covered during the test, but it varied over only a limited range of the trailing edge displacement amplitudes covered.The complexity of these findings prompted a detailed investigation, the results of which revealed a combination of phenomena that explain qualitatively how the mechanically generated, periodic, sinusoidal perturbing signal produced by the oscillating vane reacts with the fluid flow to delay the detachment of a turbulent boundary layer experiencing transitory detachment.

Lidar Measurements of Wind and Cloud Around Venus from an Orbiting or Floating/flying Platform

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Limaye, Sanjay; Emmitt, George D.; Refaat, Tamer F.; Kavaya, Michael J.; Yu, Jirong; Petros, Mulugeta

2015-01-01

Given the presence of clouds and haze in the upper portion of the Venus atmosphere, it is reasonable to consider a Doppler wind lidar (DWL) for making remote measurements of the 3-dimensional winds within the tops of clouds and the overlying haze layer. Assuming an orbit altitude of 250 kilometers and cloud tops at 60 kilometers (within the upper cloud layer), an initial performance assessment of an orbiting DWL was made using a numerical instrument and atmospheres model developed for both Earth and Mars. It is reasonable to expect vertical profiles of the 3-dimensional wind speed with 1 kilometer vertical resolution and horizontal spacing of 25 kilometers to several 100 kilometers depending upon the desired integration times. These profiles would begin somewhere just below the tops of the highest clouds and extend into the overlying haze layer to some to-be-determined height. Getting multiple layers of cloud returns is also possible with no negative impact on velocity measurement accuracy. The knowledge and expertise for developing coherent Doppler wind lidar technologies and techniques, for Earth related mission at NASA Langley Research Center is being leveraged to develop an appropriate system suitable for wind measurement around Venus. We are considering a fiber-laser-based lidar system of high efficiency and smaller size and advancing the technology level to meet the requirements for DWL system for Venus from an orbiting or floating/flying platform. This presentation will describe the concept, simulation and technology development plan for wind and cloud measurements on Venus.

Latitudinal variations in Titan's methane and haze from Cassini VIMS observations

USGS Publications Warehouse

Penteado, P.F.; Griffith, C.A.; Tomasko, M.G.; Engel, S.; See, C.; Doose, L.; Baines, K.H.; Brown, R.H.; Buratti, B.J.; Clark, R.; Nicholson, P.; Sotin, Christophe

2010-01-01

We analyze observations taken with Cassini's Visual and Infrared Mapping Spectrometer (VIMS), to determine the current methane and haze latitudinal distribution between 60??S and 40??N. The methane variation was measured primarily from its absorption band at 0.61 ??m, which is optically thin enough to be sensitive to the methane abundance at 20-50 km altitude. Haze characteristics were determined from Titan's 0.4-1.6 ??m spectra, which sample Titan's atmosphere from the surface to 200 km altitude. Radiative transfer models based on the haze properties and methane absorption profiles at the Huygens site reproduced the observed VIMS spectra and allowed us to retrieve latitude variations in the methane abundance and haze. We find the haze variations can be reproduced by varying only the density and single scattering albedo above 80 km altitude. There is an ambiguity between methane abundance and haze optical depth, because higher haze optical depth causes shallower methane bands; thus a family of solutions is allowed by the data. We find that haze variations alone, with a constant methane abundance, can reproduce the spatial variation in the methane bands if the haze density increases by 60% between 20??S and 10??S (roughly the sub-solar latitude) and single scattering absorption increases by 20% between 60??S and 40??N. On the other hand, a higher abundance of methane between 20 and 50 km in the summer hemisphere, as much as two times that of the winter hemisphere, is also possible, if the haze variations are minimized. The range of possible methane variations between 27??S and 19??N is consistent with condensation as a result of temperature variations of 0-1.5 K at 20-30 km. Our analysis indicates that the latitudinal variations in Titan's visible to near-IR albedo, the north/south asymmetry (NSA), result primarily from variations in the thickness of the darker haze layer, detected by Huygens DISR, above 80 km altitude. If we assume little to no latitudinal methane variations we can reproduce the NSA wavelength signatures with the derived haze characteristics. We calculate the solar heating rate as a function of latitude and derive variations of ???10-15% near the sub-solar latitude resulting from the NSA. Most of the latitudinal variations in the heating rate stem from changes in solar zenith angle rather than compositional variations. ?? 2009 Elsevier Inc. All rights reserved.

The influence of free-stream turbulence on separation of turbulent boundary layers in incompressible, two-dimensional flow

NASA Technical Reports Server (NTRS)

Potter, J. Leith; Barnett, R. Joel; Fisher, Carl E.; Koukousakis, Costas E.

1986-01-01

Experiments were conducted to determine if free-stream turbulence scale affects separation of turbulent boundary layers. In consideration of possible interrelation between scale and intensity of turbulence, the latter characteristic also was varied and its role was evaluated. Flow over a 2-dimensional airfoil in a subsonic wind tunnel was studied with the aid of hot-wire anemometry, liquid-film flow visualization, a Preston tube, and static pressure measurements. Profiles of velocity, relative turbulence intensity, and integral scale in the boundary layer were measured. Detachment boundary was determined for various angles of attack and free-stream turbulence. The free-stream turbulence intensity and scale were found to spread into the entire turbulent boundary layer, but the effect decreased as the airfoil surface was approached. When the changes in stream turbulence were such that the boundary layer velocity profiles were unchanged, detachment location was not significantly affected by the variations of intensity and scale. Pressure distribution remained the key factor in determining detachment location.

Characterizing Urban Turbulence Under Haze Pollution: Insights into Temperature-Humidity Dissimilarity

NASA Astrophysics Data System (ADS)

Guo, Xiaofeng; Sun, Yele; Miao, Shiguang

2016-03-01

We present a description of urban boundary-layer turbulence characteristics under conditions of severe haze pollution, an emerging issue of interest to air-pollution-relevant investigations. Comparative analysis between clean and hazy episodes reveals their remarkable difference in atmospheric stability. A stability signature is then identified in temperature-humidity de-correlation and dissimilarity. Such a signature is noteworthy, because the accuracy of a reliable parametrization of the heat-to-moisture transport efficiency is substantiated in unstable and stable conditions rather than in near-neutral conditions.

Clouds and Hazes in Saturn's Troposphere and Stratosphere

NASA Astrophysics Data System (ADS)

Merlet, Cecile; Irwin, P.; Fletcher, L.

2012-10-01

We present new results from the analysis of Saturn's near-infrared spectra measured with the Visual and Infrared Mapping Spectrometer (VIMS) instrument on the Cassini orbiter. VIMS near-infrared data are particularly relevant for the study of clouds and hazes in the troposphere and stratosphere of Saturn. Thermal emission in the 4.5-5.1 wavelength range is absorbed and scattered mainly by tropospheric clouds and radiatively active gases. The vertical structure as well as the optical and physical properties of tropospheric aerosols are obtained from Saturn's thermal emission spectra by using the retrieval algorithm Nemesis. The distribution of tropospheric phosphine and ammonia in gas phase will also be presented here. We managed to break the degeneracies inherent to the retrieval problem by analysing Saturn's thermal emission simultaneously at various viewing geometries. By using this method, we found that VIMS spectra at 4.5-5.1 microns are also sensitive to the hazes formed above the cloud layers. Saturn's reflected sunlight spectra at 0.8-3.5 microns measured with VIMS were also analysed in order to constrain the haze properties in the upper troposphere and lower stratosphere of the planet. Results from both the 0.8-3.5 and 4.5-5.1 wavelength ranges were combined to determine the cloud and haze model most consistent with VIMS spectroscopy over a wide range of viewing geometries and lighting conditions. An increase of temperature below the tropopause, often referred to as the temperature knee, was retrieved from Cassini/CIRS spectra. Seasonal variations of the knee and haze structure are compared, and as a result the assumption of local heating by the hazes to explain this feature will be discussed.

Effect of climate variability and change on winter haze over eastern China in recent decades

NASA Astrophysics Data System (ADS)

Liao, Hong; Yang, Yang

2017-04-01

In recent years, eastern China has frequently experienced persistent and severe winter haze pollution episodes with high aerosol concentrations, which have affected half of the 1.3 billion people in China. In this work, the increases in wintertime aerosol concentrations and severe haze events in eastern China over 1985-2015 were quantified by using observed atmospheric visibility from the National Climatic Data Center Global Summary of Day database, observed PM2.5 concentrations from the network of China National Environmental Monitoring Centre (CNEMC), and simulated PM2.5 concentrations from the Goddard Earth-Observing System (GEOS) chemical transport model (GEOS-Chem). Observed winter haze days (defined as days with atmospheric visibility less than 10 km and relative humidity less than 80%) averaged over eastern China (105-122.5°E, 20-45°N) increased from 21 days in 1980 to 42 days in 2014. Observed severe haze days (defined as days with PM2.5 >150 μg m-3) occurred mainly over Northern China. Considering variations in both anthropogenic emissions and meteorological parameters, the GEOS-Chem model simulated an increasing trend in wintertime surface-layer PM2.5 concentrations of 10.5 (±6.2) μg m-3 decade-1 over eastern China in the past decades. Sensitivity studies showed that changes in anthropogenic emissions and in climate contributed 87% and 17% to this increasing trend, respectively. Wintertime severe haze events over eastern China showed large interannual variations, driven by climate variability. Process analyses were performed to identify the key meteorological parameters that determined the interannual variations of wintertime severe haze events.

Jupiter Polar Haze in False Color

NASA Image and Video Library

2017-02-01

This false color view of Jupiter's polar haze was created by citizen scientist Gerald Eichstädt using data from the JunoCam instrument on NASA's Juno spacecraft. The image was taken on Dec. 11, 2016 at 2:30 p.m. PST (5:30 p.m. EST), when the spacecraft was 285,000 miles (459,000 kilometers) from Jupiter on the outbound leg of its third close flyby. This image is composited from four images taken through different filters: red, green, blue and methane. When the near-infrared methane image is processed with the others, the result is a false color product that highlights high clouds and high altitude hazes. The Great Red Spot and Oval BA (just below the Great Red Spot) are high in Jupiter's atmosphere, thus bright in this picture. The high-altitude haze layer over the south pole partially obscures our view of the storms below. By combining the methane data with the visible light images, we can learn about the vertical structure of Jupiter's atmosphere. http://photojournal.jpl.nasa.gov/catalog/PIA21379

Effect of liquid crystal birefringence on the opacity and off-axis haze of PDLC films

NASA Astrophysics Data System (ADS)

Pane, S.; Caporusso, M.

1998-02-01

PDLC systems are thin films consisting of a dispersion of liquid crystal micro-droplets in a continuous solid phase of polymer matrix. Application of an electric field on a thin layer of PDLC sandwiched between two transparent on-state. This effect make them useful for a wide variety of applications. Among them, smart windows for architectural is the most popular subject in literature. For this application, the key parameters of performance are the haze and the opacity. There are essentially two technologies used to prepare PDLC films, namely micro-encapsulation and phase separation.In the present work we will show the correlation between the opacity and the off-axis haze in PDLC films prepared with a phase separation technology. We will give the general rule in order to select the liquid crystal properties that allow the preparation of high opacity ad low haze PDLC films. Further study about the control of the parameters which influence the performances of PDLC films prepared with phase separation technology and the difference with the NCAP approach are in progress at our laboratory.

Results from the Mars global surveyor thermal emission spectrometer

USGS Publications Warehouse

Christensen, P.R.; Anderson, D.L.; Chase, S.C.; Clancy, R.T.; Clark, R.N.; Conrath, B.J.; Kieffer, H.H.; Kuzmin, R.O.; Malin, M.C.; Pearl, J.C.; Roush, T.L.; Smith, M.D.

1998-01-01

The Thermal Emission Spectrometer spectra of low albedo surface materials suggests that a four to one mixture of pyroxene to plagioclase, together with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentration of carbonates (<10 percent), olivine (<10 percent), clay minerals (<20 percent), and quartz (<5 percent) in the limited regions observed. Limb observations in the northern hemisphere reveal low-lying dust hazes and detached water-ice clouds at altitudes up to 55 kilometers. At an aerocentric longitude of 224??a major dust storm developed in the Noachis Terra region. The south polar cap retreat was similar to that observed by Viking.

The Halo

NASA Image and Video Library

2013-12-23

NASA's Cassini spacecraft looks towards the dark side of Saturn's largest moon, Titan, capturing the blue halo caused by a haze layer that hovers high in the moon's atmosphere. The haze that permeates Titan's atmosphere scatters sunlight and produces the orange color seen here. More on Titan's orange and blue hazes can be found at PIA14913. This view looks towards the side of Titan (3,200 miles or 5,150 kilometers across) that leads in its orbit around Saturn. North on Titan is up and rotated 40 degrees to the left. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The images were taken with the Cassini spacecraft narrow-angle camera on Nov. 3, 2013. The view was acquired at a distance of approximately 2.421 million miles (3.896 million kilometers) from Titan. Image scale is 14 miles (23 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA17180

Hot Jupiter with Hidden Water (Artist Concept)

NASA Image and Video Library

2016-06-08

Hot Jupiters, exoplanets around the same size as Jupiter that orbit very closely to their stars, often have cloud or haze layers in their atmospheres. This may prevent space telescopes from detecting atmospheric water that lies beneath the clouds, according to a study in the Astrophysical Journal. As much as half of the water in the atmospheres of these exoplanets may be blocked by these clouds or hazes, research suggests. The study, led by researchers at NASA's Jet Propulsion Laboratory, Pasadena, California, examined hot Jupiters that had been observed with the Hubble Space Telescope. http://photojournal.jpl.nasa.gov/catalog/PIA20687

Hydroxymethane sulfonate as a possible explanation for observed high levels of particulate sulfur during severe winter haze episodes in Beijing, China.

NASA Astrophysics Data System (ADS)

Moch, J.; Jacob, D.; Mickley, L. J.; Cheng, Y.; Li, M.; Munger, J. W.; Wang, Y.

2017-12-01

Observed PM2.5 during severe winter haze in Beijing, China, may reach levels as high as 880 μg m-3, with sulfur compounds contributing significantly to PM2.5 composition. Such sulfur has been traditionally assumed to be sulfate, even though models fail to generate such large sulfate enhancements under cold and hazy conditions. We show that particulate sulfur in wintertime Beijing possibly occurs as an S(IV)-HCHO adduct, hydroxymethane sulfonate (HMS), formed by reaction of aqueous-phase HCHO and S(IV) in cloud droplets. We use a 1-D chemistry model extending from the surface through the boundary layer to examine the potential role of HMS during the Beijing haze events of December 2011 and January 2013. Observed and assimilated meteorological fields including cloud liquid water were applied to the model, and we test the sensitivity of HMS formation to cloud pH and ambient SO2 and HCHO. Surface observations from the two haze events show excess ammonium in the aerosol, indicating cloud pH may be relatively high. Model results show that once cloud pH exceeds 4.5, HMS can accumulate rapidly, reaching a few hundred μg m-3 in a few hours. The timing of HMS formation is controlled by the presence of cloud liquid water, with eddy driven diffusion bringing HMS to the surface. The magnitude of HMS peaks is limited by the supply of HCHO. HMS episodes in the model end gradually over 1-3 days as fresh air is entrained into the boundary layer; in observations these episodes typically end when increasing wind speeds destabilize the boundary layer and disperses pollution. We find that consideration of HMS as a source of particulate sulfur significantly improves model match with observations. For example, assuming cloud pH of 5 and average surface SO2 and HCHO levels of 50 ppb and 5.5 ppb, we calculate mean HMS as 43.8 μg m-3 in January 2013, within 7 μg m-3 of observed particulate sulfur. Our 1-D model also captures the timing and magnitude of peak particulate sulfur in January 2013, with HMS approaching 100 μg m-3 during episodes. In contrast, a GEOS-Chem 3-D simulation without HMS chemistry yields peak particulate sulfur of 20 μg m-3. Our findings suggest that SO2 is not the limiting factor in winter haze events in Beijing and that, in order to reduce severe winter haze in this region, policymakers may need to address HCHO sources such as transportation.

Redefining the importance of nitrate during haze pollution to help optimize an emission control strategy

NASA Astrophysics Data System (ADS)

Pan, Yuepeng; Wang, Yuesi; Zhang, Junke; Liu, Zirui; Wang, Lili; Tian, Shili; Tang, Guiqian; Gao, Wenkang; Ji, Dongsheng; Song, Tao; Wang, Yonghong

2016-09-01

Nitrate salts represent a major component of fine mode aerosols, which play an important role in air pollution worldwide. Based on on-line and off-line aerosol measurements in urban Beijing for both clean and haze conditions, we demonstrate that the absolute and relative concentrations of nitrate increased with visibility degradation (relative humidity), whereas the variations of organics tracked the patterns of mixing-layer height and temperature. We propose that the increase in the relative contribution of nitrate to PM1 observed during the early stages of haze pollution was due to new particle formation, whereas the nitrate formed in PM1-2.5 during the latter stages was due to heterogeneous formation and hygroscopic growth. The increasing trend of nitrate (and also sulfate and ammonium) but decreasing trends of organics during haze development, together with the increase of the NO2/SO2 molar ratio with increasing proximity to downtown Beijing and with visibility degradation, provide further evidence that controlling NOx emissions should be a priority for improving air quality in mega cities. Additional large-scale investigation is required to adequately characterize the regional features of NOx-induced haze pollution in China. Such studies may provide insight into the formation of critical nuclei or the subsequent growth of freshly nucleated particles and advance our understanding of the role of nitrate in new particle formation.

Folding of a detachment and fault - Modified detachment folding along a lateral ramp, southwestern Montana, USA

NASA Astrophysics Data System (ADS)

Schmidt, Christopher; Whisner, S. Christopher; Whisner, Jennifer B.

2014-12-01

The inversion of the Middle Proterozoic Belt sedimentary basin during Late Cretaceous thrusting in Montana produced a large eastwardly-convex salient, the southern boundary of which is a 200 km-long oblique to lateral ramp subtended by a detachment between the Belt rocks and Archean basement. A 10 km-long lateral ramp segment exposes the upper levels of the detachment where hanging wall Belt rocks have moved out over the Paleozoic and Mesozoic section. The hanging wall structure consists of a train of high amplitude, faulted, asymmetrical detachment folds. Initial west-east shortening produced layer parallel shortening fabrics and dominantly strike slip faulting followed by symmetrical detachment folding. 'Lock-up' of movement on the detachment surface produced regional simple shear and caused the detachment folds to become asymmetrical and faulted. Folding of the detachment surface after lock-up modified the easternmost detachment folds further into a southeast-verging, overturned fold pair with a ramp-related fault along the base of the stretched mutual limb.

Development and characterization of high refractive index and high scattering acrylate polymer layers

NASA Astrophysics Data System (ADS)

Eiselt, Thomas; Gomard, Guillaume; Preinfalk, Jan; Gleissner, Uwe; Lemmer, Uli; Hanemann, Thomas

2016-04-01

The aim is to develop a polymer layer which has the ability to diffuse light homogeneously and exhibit a high refractive index. The mixtures are containing an acrylate casting resin, benzylmethacrylate, phenanthrene and other additives. Phenanthrene is employed to increase the refractive index. The mixtures are first rheologically characterized and then polymerized with heat and UV radiation. For the refractive index measurements the polymerized samples require a planar surface without air bubbles. To produce flat samples a special construction consisting of a glass plate, a teflon sheet, a silicone ring (PDMS mold), another teflon sheet and another glass plate is developed. Glue clamps are used to fix this construction together. Selected samples have a refractive index of 1.585 at 20°C at a wavelength of 589nm. A master mixture with a high refractive index is taken for further experiments. Nano scaled titanium dioxide is added and dispersed into the master mixture and then spin coated on a glass substrate. These layers are optically characterized. The specular transmission and the overall transmission are measured to investigate the degree of scattering, which is defined as the haze. Most of the presented layers express the expected haze of over 50%.

Flow Phenomena in the Very Near Wake of a Flat Plate with a Circular Trailing Edge

NASA Technical Reports Server (NTRS)

Rai, Man Mohan

2014-01-01

The very near wake of a flat plate with a circular trailing edge, exhibiting pronounced shedding of wake vortices, is investigated with data from a direct numerical simulation. The separating boundary layers are turbulent and statistically identical thus resulting in a wake that is symmetric in the mean. The focus here is on the instability of the detached shear layers, the evolution of rib-vortex induced localized regions of reverse flow that detach from the main body of reverse flow in the trailing edge region and convect downstream, and phaseaveraged velocity statistics in the very near wake. The detached shear layers are found to exhibit unstable behavior intermittently, including the development of shear layer vortices as in earlier cylinder flow investigations with laminar separating boundary layers. Only a small fraction of the separated turbulent boundary layers undergo this instability, and form the initial shed vortices. Pressure spectra within the shear layers show a broadband peak at a multiple of shedding frequency. Phase-averaged intensity and shear stress distributions of the randomly fluctuating component of velocity are compared with those obtained in the near wake. The distributions of the production terms in the transport equations for the turbulent stresses are also provided.

Looking Down on Lakes

NASA Image and Video Library

2014-04-07

NASA Cassini spacecraft peers down though layers of haze to glimpse the lakes of Titan northern regions. Titan has a hydrological cycle similar to Earth, but instead of water, Titan lakes and seas are filled with liquid methane and ethane.

Effect of the PTFE content in the gas diffusion layer on water transport in polymer electrolyte fuel cells (PEFCs)

NASA Astrophysics Data System (ADS)

Mortazavi, Mehdi; Tajiri, Kazuya

2014-01-01

The dynamic behavior of a liquid water droplet emerging and detaching from the surface of the gas diffusion layer (GDL) is investigated. The droplet growth and detachment are studied for different polytetrafluoroethylene (PTFE) contents within the GDL and for different superficial gas velocities flowing in the gas channel. To simulate the droplet behavior in the cathode and anode of an operating polymer electrolyte fuel cell, separate experiments are conducted with air and hydrogen being supplied in the gas channel, respectively. Both the superficial gas velocity and the PTFE content within the GDL are found to impact the droplet detachment diameter. Increasing the superficial gas velocity increases the drag force applied on the droplet sitting on the GDL surface. It is observed that the droplet detaches at a smaller diameter for higher superficial gas velocities. The droplets also detach at smaller diameters from GDLs with a higher amount of PTFE. Such observation is justified according to two different points of view: (1) heterogeneous through-plane PTFE distribution through the GDL and (2) reduced GDL surface roughness caused by PTFE loading.

Rat supraspinatus muscle atrophy after tendon detachment.

PubMed

Barton, Elisabeth R; Gimbel, Jonathan A; Williams, Gerald R; Soslowsky, Louis J

2005-03-01

Rotator cuff tears are one of the most common tendon disorders found in the healthy population. Tendon tears not only affect the biomechanical properties of the tendon, but can also lead to debilitation of the muscles attached to the damaged tendons. The changes that occur in the muscle after tendon detachment are not well understood. A rat rotator cuff model was utilized to determine the time course of changes that occur in the supraspinatus muscle after tendon detachment. It was hypothesized that the lack of load on the supraspinatus muscle would cause a significant decrease in muscle mass and a conversion of muscle fiber properties toward those of fast fiber types. Tendons were detached at the insertion on the humerus without repair. Muscle mass, morphology and fiber properties were measured at one, two, four, eight, and 16 weeks after detachment. Tendon detachment resulted in a rapid loss of muscle mass, an increase in the proportion of fast muscle fibers, and an increase in the fibrotic content of the muscle bed, concomitant with the appearance of adhesions of the tendon to surrounding surfaces. At 16 weeks post-detachment, muscle mass and the fiber properties in the deep muscle layers returned to normal levels. However, the fiber shifts observed in the superficial layers persisted throughout the experiment. These results suggest that load returned to the muscle via adhesions to surrounding surfaces, which may be sufficient to reverse changes in muscle mass.

THEORETICAL TRANSIT SPECTRA FOR GJ 1214b AND OTHER 'SUPER-EARTHS'

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howe, Alex R.; Burrows, Adam S., E-mail: arhowe@astro.princeton.edu, E-mail: burrows@astro.princeton.edu

2012-09-10

We present new calculations of transit spectra of super-Earths that allow for atmospheres with arbitrary proportions of common molecular species and haze. We test this method with generic spectra, reproducing the expected systematics and absorption features, then apply it to the nearby super-Earth GJ 1214b, which has produced conflicting observational data, leaving the questions of a hydrogen-rich versus hydrogen-poor atmosphere and the water content of the atmosphere ambiguous. We present representative transit spectra for a range of classes of atmosphere models for GJ 1214b. Our analysis supports a hydrogen-rich atmosphere with a cloud or haze layer, although a hydrogen-poor modelmore » with {approx}<10% water is not ruled out. Several classes of models are ruled out, however, including hydrogen-rich atmospheres with no haze, hydrogen-rich atmospheres with a haze of {approx}0.01 {mu}m tholin particles, and hydrogen-poor atmospheres with major sources of absorption other than water. We propose an observational test to distinguish hydrogen-rich from hydrogen-poor atmospheres. Finally, we provide a library of theoretical transit spectra for super-Earths with a broad range of parameters to facilitate future comparison with anticipated data.« less

Kink-style detachment folding in Bachu fold belt of central Tarim Basin, China: geometry and seismic interpretation

NASA Astrophysics Data System (ADS)

Bo, Zhang; Jinjiang, Zhang; Shuyu, Yan; Jiang, Liu; Jinhai, Zhang; Zhongpei, Zhang

2010-05-01

The phenomenon of Kink banding is well known throughout the engineering and geophysical sciences. Associated with layered structures compressed in a layer-parallel direction, it arises for example in stratified geological systems under tectonic compression. Our work documented it is also possible to develop super large-scale kink-bands in sedimentary sequences. We interpret the Bachu fold uplift belt of the central Tarim basin in western China to be composed of detachment folds flanked by megascopic-scale kink-bands. Those previous principal fold models for the Bachu uplift belt incorporated components of large-scale thrust faulting, such as the imbricate fault-related fold model and the high-angle, reverse-faulted detachment fold model. Based on our observations in the outcrops and on the two-dimension seismic profiles, we interpret that first-order structures in the region are kink-band style detachment folds to accommodate regional shortening, and thrust faulting can be a second-order deformation style occurring on the limb of the detachment folds or at the cores of some folds to accommodate the further strain of these folds. The belt mainly consists of detachment folds overlying a ductile decollement layer. The crests of the detachment folds are bounded by large-scale kink-bands, which are zones of angularly folded strata. These low-signal-tonoise, low-reflectivity zones observed on seismic profiles across the Bachu belt are poorly imaged sections, which resulted from steeply dipping bedding in the kink-bands. The substantial width (beyond 200m) of these low-reflectivity zones, their sub-parallel edges in cross section, and their orientations at a high angle to layering between 50 and 60 degrees, as well as their conjugate geometry, support a kink-band interpretation. The kink-band interpretation model is based on the Maximum Effective Moment Criteria for continuous deformation, rather than Mohr-Column Criteria for brittle fracture. Seismic modeling is done to identify the characteristics and natures of seismic waves within the kink-band and its fold structure, which supplies the further evidences for the kink-band interpretation in the region.

Numerical study of the effects of local atmospheric circulations on a pollution event over Beijing-Tianjin-Hebei, China.

PubMed

Miao, Yucong; Liu, Shuhua; Zheng, Yijia; Wang, Shu; Chen, Bicheng; Zheng, Hui; Zhao, Jingchuan

2015-04-01

Currently, the Chinese central government is considering plans to build a trilateral economic sphere in the Bohai Bay area, including Beijing, Tianjin and Hebei (BTH), where haze pollution frequently occurs. To achieve sustainable development, it is necessary to understand the physical mechanism of the haze pollution there. Therefore, the pollutant transport mechanisms of a haze event over the BTH region from 23 to 24 September 2011 were studied using the Weather Research and Forecasting model and the FLEXible-PARTicle dispersion model to understand the effects of the local atmospheric circulations and atmospheric boundary layer structure. Results suggested that the penetration by sea-breeze could strengthen the vertical dispersion by lifting up the planetary boundary layer height (PBLH) and carry the local pollutants to the downstream areas; in the early night, two elevated pollution layers (EPLs) may be generated over the mountain areas: the pollutants in the upper EPL at the altitude of 2-2.5 km were favored to disperse by long-range transport, while the lower EPL at the altitude of 1 km may serve as a reservoir, and the pollutants there could be transported downward and contribute to the surface air pollution. The intensity of the sea-land and mountain-valley breeze circulations played an important role in the vertical transport and distribution of pollutants. It was also found that the diurnal evolution of the PBLH is important for the vertical dispersion of the pollutants, which is strongly affected by the local atmospheric circulations and the distribution of urban areas. Copyright © 2015. Published by Elsevier B.V.

Simulation of the Aerosol-Atmosphere Interaction in the Dead Sea Area with COSMO-ART

NASA Astrophysics Data System (ADS)

Vogel, Bernhard; Bangert, Max; Kottmeier, Christoph; Rieger, Daniel; Schad, Tobias; Vogel, Heike

2014-05-01

The Dead Sea is a unique environment located in the Dead Sea Rift Valley. The fault system of the Dead Sea Rift Valley marks the political borders between Israel, Jordan, and Palestine. The Dead Sea region and the ambient Eastern Mediterranean coastal zone provide a natural laboratory for studying atmospheric processes ranging from the smallest scale of cloud processes to regional weather and climate. The virtual institute DESERVE is designed as a cross-disciplinary and cooperative international project of the Helmholtz Centers KIT, GFZ, and UFZ with well-established partners in Israel, Jordan and Palestine. One main focus of one of the work packages is the role of aerosols in modifying clouds and precipitation and in developing the Dead Sea haze layer as one of the most intriguing questions. The haze influences visibility, solar radiation, and evaporation and may even affect economy and health. We applied the online coupled model system COSMO-ART, which is able to treat the feedback processes between aerosol, radiation, and cloud formation, for a case study above the Dead Sea and adjacent regions. Natural aerosol like mineral dust and sea salt as well as anthropogenic primary and secondary aerosol is taken into account. Some of the observed features like the vertical double structure of the haze layer are already covered by the simulation. We found that absorbing aerosol like mineral dust causes a temperature increase in parts of the model domain. In other areas a decrease in temperature due to cirrus clouds modified by elevated dust layers is simulated.

JUPITER AS AN EXOPLANET: UV TO NIR TRANSMISSION SPECTRUM REVEALS HAZES, A Na LAYER, AND POSSIBLY STRATOSPHERIC H{sub 2}O-ICE CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montañés-Rodríguez, Pilar; González-Merino, B.; Pallé, E.

Currently, the analysis of transmission spectra is the most successful technique to probe the chemical composition of exoplanet atmospheres. However, the accuracy of these measurements is constrained by observational limitations and the diversity of possible atmospheric compositions. Here, we show the UV–VIS–IR transmission spectrum of Jupiter as if it were a transiting exoplanet, obtained by observing one of its satellites, Ganymede, while passing through Jupiter’s shadow, i.e., during a solar eclipse from Ganymede. The spectrum shows strong extinction due to the presence of clouds (aerosols) and haze in the atmosphere and strong absorption features from CH{sub 4}. More interestingly, themore » comparison with radiative transfer models reveals a spectral signature, which we attribute here to a Jupiter stratospheric layer of crystalline H{sub 2}O ice. The atomic transitions of Na are also present. These results are relevant for the modeling and interpretation of giant transiting exoplanets. They also open a new technique to explore the atmospheric composition of the upper layers of Jupiter’s atmosphere.« less

Clean Air Act Requirements and History

EPA Pesticide Factsheets

In 1970 congress designed the Clean Air Act to combat a variety of air pollution problems, and to tackle emerging pollution threats such as public health, national welfare, toxic air pollutants, acid rain, protection of the ozone layer, and regional haze.

An Analysis of Neptune's Stratospheric Haze Using High-Phase-Angle Voyager Images

NASA Technical Reports Server (NTRS)

Moses, Julianne I.; Rages, Kathy; Pollack, James B.

1995-01-01

We have inverted high-phase-angle Voyager images of Neptune to determine the atmospheric extinction coefficient as a function of altitude and the scattering phase function at a reference altitude. Comparisons between theoretical model and observations help separate the contributions from molecular Rayleigh and aerosol scattering and help determine the variation of the aerosol size, concentration, and scattering properties with altitude. Further comparisons between models and data allow us to place constraints on the location and composition of the hazes, the concentration and downward flux of certain condensible hydrocarbon gases, the eddy diffusion coefficient in the lower stratosphere, and the thermal profile in parts of Neptune's stratosphere. We find that a distinct stratospheric haze layer exists near 12(sub -1, sup +1) mbar in Neptune's lower stratosphere, most probably due to condensed ethane. The derived stratospheric haze production rate of 1.0(sub -0.3, sup +0.2) x 10(exp -15) g cm(exp -2) sec(exp -1) is substantially lower than photochemical model predictions. Evidence for hazes at higher altitudes also exists. Unlike the situation on Uranus, large particles (0.08-0.11 microns) may be present at high altitudes on Neptune (e.g., near 0.5 mbar), well above the region in which we expect the major hydrocarbon species to condense. Near 28 mbar, the mean particle size is about 0.13(sub -0.02, sup +0.02) microns with a concentration of 5(sub -3, sup +3) particles cm(exp -3). The cumulative haze extinction optical depth above 15 mbar in the clear filter is approx. 3 x 10(exp -3), and much of this extinction is due to scattering rather than absorption; thus, if our limb-scan sites are typical, the hazes cannot account for the stratospheric temperature inversion on Neptune and may not contribute significantly to atmospheric heating. We compare the imaging results with the results from other observations, including those of the Voyager Photopolarimeter Subsystem, and discuss differences between Neptune and Uranus.

Fasudil, a Clinically Used ROCK Inhibitor, Stabilizes Rod Photoreceptor Synapses after Retinal Detachment.

PubMed

Townes-Anderson, Ellen; Wang, Jianfeng; Halász, Éva; Sugino, Ilene; Pitler, Amy; Whitehead, Ian; Zarbin, Marco

2017-06-01

Retinal detachment disrupts the rod-bipolar synapse in the outer plexiform layer by retraction of rod axons. We showed that breakage is due to RhoA activation whereas inhibition of Rho kinase (ROCK), using Y27632, reduces synaptic damage. We test whether the ROCK inhibitor fasudil, used for other clinical applications, can prevent synaptic injury after detachment. Detachments were made in pigs by subretinal injection of balanced salt solution (BSS) or fasudil (1, 10 mM). In some animals, fasudil was injected intravitreally after BSS-induced detachment. After 2 to 4 hours, retinae were fixed for immunocytochemistry and confocal microscopy. Axon retraction was quantified by imaging synaptic vesicle label in the outer nuclear layer. Apoptosis was analyzed using propidium iodide staining. For biochemical analysis by Western blotting, retinal explants, detached from retinal pigmented epithelium, were cultured for 2 hours. Subretinal injection of fasudil (10 mM) reduced retraction of rod spherules by 51.3% compared to control detachments ( n = 3 pigs, P = 0.002). Intravitreal injection of 10 mM fasudil, a more clinically feasible route of administration, also reduced retraction (28.7%, n = 5, P < 0.05). Controls had no photoreceptor degeneration at 2 hours, but by 4 hours apoptosis was evident. Fasudil 10 mM reduced pyknotic nuclei by 55.7% ( n = 4, P < 0.001). Phosphorylation of cofilin and myosin light chain, downstream effectors of ROCK, was decreased with 30 μM fasudil ( n = 8-10 explants, P < 0.05). Inhibition of ROCK signaling with fasudil reduced photoreceptor degeneration and preserved the rod-bipolar synapse after retinal detachment. These results support the possibility, previously tested with Y27632, that ROCK inhibition may attenuate synaptic damage in iatrogenic detachments.

Descemet Membrane Endothelial Keratoplasty for Failed Deep Anterior Lamellar Keratoplasty: A Case Series.

PubMed

Einan-Lifshitz, Adi; Sorkin, Nir; Boutin, Tanguy; Mednick, Zale; Kreimei, Mohammad; Chan, Clara C; Rootman, David S

2018-06-01

To suggest a new surgical approach for posterior opacities or persistent Descemet membrane (DM) detachment in failed deep anterior lamellar keratoplasty (DALK) and to report the outcome of Descemet membrane endothelial keratoplasty (DMEK) in a series of patients with DALK failure. In this retrospective case series of patients who underwent DMEK for failed DALK at Toronto Western Hospital, 4 patients with failed DALK who underwent DMEK surgery were included. In all 4 cases, big bubble formation during initial DALK surgery had failed and the surgical technique was converted to manual dissection using the Melles technique. In 2 cases, the descemetorhexis in DMEK surgery was performed manually, and in 2 cases, the descemetorhexis was performed with the assistance of the femtosecond laser. Four eyes of 4 patients aged 70 ± 4 years were included. Average follow-up time was 9 ± 5 months. Indications for DALK surgery were corneal dystrophy in 2 patients and corneal scars in the other 2. DALK failure was due to persistent DM detachment that created a double chamber in 2 patients and due to posterior lamellar haze in the other 2. After DMEK surgery, 2 patients had graft detachment and required rebubbling. In 1 patient, the DMEK scroll was attached after 1 rebubble attempt, and in the other patient, a second rebubble attempt was needed. The final visual acuities were 20/40, 20/50, 20/70, and 20/200 (because of dense cataract). All procedures were uneventful. DMEK surgery may be effective in managing DALK failure.

Slab detachment under the Eastern Alps seen by seismic anisotropy

PubMed Central

Qorbani, Ehsan; Bianchi, Irene; Bokelmann, Götz

2015-01-01

We analyze seismic anisotropy for the Eastern Alpine region by inspecting shear-wave splitting from SKS and SKKS phases. The Eastern Alpine region is characterized by a breakdown of the clear mountain-chain-parallel fast orientation pattern that has been previously documented for the Western Alps and for the western part of the Eastern Alps. The main interest of this paper is a more detailed analysis of the anisotropic character of the Eastern Alps, and the transition to the Carpathian–Pannonian region. SK(K)S splitting measurements reveal a rather remarkable lateral change in the anisotropy pattern from the west to the east of the Eastern Alps with a transition area at about 12°E. We also model the backazimuthal variation of the measurements by a vertical change of anisotropy. We find that the eastern part of the study area is characterized by the presence of two layers of anisotropy, where the deeper layer has characteristics similar to those of the Central Alps, in particular SW–NE fast orientations of anisotropic axes. We attribute the deeper layer to a detached slab from the European plate. Comparison with tomographic studies of the area indicates that the detached slab might possibly connect with the lithosphere that is still in place to the west of our study area, and may also connect with the slab graveyard to the East, at the depth of the upper mantle transition zone. On the other hand, the upper layer has NW–SE fast orientations coinciding with a low-velocity layer which is found above a more-or-less eastward dipping high-velocity body. The anisotropy of the upper layer shows large-scale NW–SE fast orientation, which is consistent with the presence of asthenospheric flow above the detached slab foundering into the deeper mantle. PMID:25843968

Slab detachment under the Eastern Alps seen by seismic anisotropy

NASA Astrophysics Data System (ADS)

Qorbani, Ehsan; Bianchi, Irene; Bokelmann, Götz

2015-01-01

We analyze seismic anisotropy for the Eastern Alpine region by inspecting shear-wave splitting from SKS and SKKS phases. The Eastern Alpine region is characterized by a breakdown of the clear mountain-chain-parallel fast orientation pattern that has been previously documented for the Western Alps and for the western part of the Eastern Alps. The main interest of this paper is a more detailed analysis of the anisotropic character of the Eastern Alps, and the transition to the Carpathian-Pannonian region. SK(K)S splitting measurements reveal a rather remarkable lateral change in the anisotropy pattern from the west to the east of the Eastern Alps with a transition area at about 12°E. We also model the backazimuthal variation of the measurements by a vertical change of anisotropy. We find that the eastern part of the study area is characterized by the presence of two layers of anisotropy, where the deeper layer has characteristics similar to those of the Central Alps, in particular SW-NE fast orientations of anisotropic axes. We attribute the deeper layer to a detached slab from the European plate. Comparison with tomographic studies of the area indicates that the detached slab might possibly connect with the lithosphere that is still in place to the west of our study area, and may also connect with the slab graveyard to the East, at the depth of the upper mantle transition zone. On the other hand, the upper layer has NW-SE fast orientations coinciding with a low-velocity layer which is found above a more-or-less eastward dipping high-velocity body. The anisotropy of the upper layer shows large-scale NW-SE fast orientation, which is consistent with the presence of asthenospheric flow above the detached slab foundering into the deeper mantle.

Cell-Adhesive and Cell-Repulsive Zwitterionic Oligopeptides for Micropatterning and Rapid Electrochemical Detachment of Cells

PubMed Central

Kakegawa, Takahiro; Mochizuki, Naoto; Sadr, Nasser; Suzuki, Hiroaki

2013-01-01

In this study, we describe the development of oligopeptide-modified cell culture surfaces from which adherent cells can be rapidly detached by application of an electrical stimulus. An oligopeptide, CGGGKEKEKEK, was designed with a terminal cysteine residue to mediate binding to a gold surface via a gold–thiolate bond. The peptide forms a self-assembled monolayer through the electrostatic force between the sequence of alternating charged glutamic acid (E) and lysine (K) residues. The dense and electrically neutral oligopeptide zwitterionic layer of the modified surface was resistant to nonspecific adsorption of proteins and adhesion of cells, while the surface was altered to cell adhesive by the addition of a second oligopeptide (CGGGKEKEKEKGRGDSP) containing the RGD cell adhesion motif. Application of a negative electrical potential to this gold surface cleaved the gold–thiolate bond, leading to desorption of the oligopeptide layer, and rapid (within 2 min) detachment of virtually all cells. This approach was applicable not only to detachment of cell sheets but also for transfer of cell micropatterns to a hydrogel. This electrochemical approach of cell detachment may be a useful tool for tissue-engineering applications. PMID:22853640

UV spectroscopy of Titan's atmosphere, planetary organic chemistry and prebiological synthesis. II - Interpretation of new IUE observations in the 220-335 nm range

NASA Technical Reports Server (NTRS)

Courtin, Regis; Wagener, Richard; Mckay, Christopher P.; Caldwell, John; Fricke, Karl-Heinrich

1991-01-01

The theoretical model developed by McKay et al. (1989) to characterize the size distribution, thermal structure, and chemical composition of the stratospheric haze of Titan is applied to new 220-335-nm albedo measurements obtained with the long-wavelength prime camera of the IUE during August 1987. Data and model predictions are presented in extensive graphs and discussed in detail. It is shown that a simple model with particles of one size at a given altitude does not accurately reproduce the observed features in all spectral regions, but that good general agreement is obtained using a model with a uniformly mixed layer at 150-600 km and a bimodal distribution of small 'polymer' haze particles (radius less than 20 nm) and larger haze particles (radius 100-500 nm). The number densities implied by this model require, however, a mechanism such as electrostatic charging or reaction kinetics to inhibit coagulation of the smaller particles.

HUBBLE CAPTURES DETAILED IMAGE OF URANUS' ATMOSPHERE

NASA Technical Reports Server (NTRS)

2002-01-01

Hubble Space Telescope has peered deep into Uranus' atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus' atmosphere. Hubble's images are different from the ones taken by the Voyager 2 spacecraft, which flew by Uranus 10 years ago. Those images - not taken in infrared light - showed a greenish-blue disk with very little detail. The infrared image allows astronomers to probe the structure of Uranus' atmosphere, which consists of mostly hydrogen with traces of methane. The red around the planet's edge represents a very thin haze at a high altitude. The haze is so thin that it can only be seen by looking at the edges of the disk, and is similar to looking at the edge of a soap bubble. The yellow near the bottom of Uranus is another hazy layer. The deepest layer, the blue near the top of Uranus, shows a clearer atmosphere. Image processing has been used to brighten the rings around Uranus so that astronomers can study their structure. In reality, the rings are as dark as black lava or charcoal. This false color picture was assembled from several exposures taken July 3, 1995 by the Wide Field Planetary Camera-2. CREDIT: Erich Karkoschka (University of Arizona Lunar and Planetary Lab) and NASA

Detached Eddy Simulations of Hypersonic Transition

NASA Technical Reports Server (NTRS)

Yoon, S.; Barnhardt, M.; Candler, G.

2010-01-01

This slide presentation reviews the use of Detached Eddy Simulation (DES) of hypersonic transistion. The objective of the study was to investigate the feasibility of using CFD in general, DES in particular, for prediction of roughness-induced boundary layer transition to turbulence and the resulting increase in heat transfer.

Indian aerosols: present status.

PubMed

Mitra, A P; Sharma, C

2002-12-01

This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source regions along with wind trajectories. The loading of aerosols in the atmosphere is on rising due to energy intensive activities for developmental processes and other anthropogenic activities. One of the significant observation of INDOEX is the presence of high concentrations of carbonaceous aerosols in the near persistent winter time haze layer over tropical Indian Ocean which have probably been emitted from the burning of fossil-fuels and biofuels in the source region. These have significant bearing on the radiative forcing in the region and, therefore, have potential to alter monsoon and hydrological cycles. In general, the SPM concentrations have been found to be on higher sides in ambient atmosphere in many Indian cities but the NOx concentrations have been found to be on lower side. Even in the haze layer over Indian Ocean and surrounding areas, the NOx concentrations have been reported to be low which is not conducive of O3 formation in the haze/smog layer. The acid rain problem does not seem to exist at the moment in India because of the presence of neutralizing soil dust in the atmosphere. But the high particulate concentrations in most of the cities' atmosphere in India are of concern as it can cause deteriorated health conditions.

HST Rotational Spectral Mapping Of Two L-Type Brown Dwarfs: Variability In And Out Of Water Bands Indicates High-Altitude Haze Layers

DOE PAGES

Yang, Hao; Apai, Dániel; Marley, Mark S.; ...

2014-12-17

We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759-1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 μm and 1.7 μm. We find that the water absorption bands of the two L5 dwarfs at 1.15 μm and 1.4 μm vary at similar amplitudes as the adjacent continuum. This differs from the results of previous HST observations of L/T transition dwarfs, in which the water absorption at 1.4 μm displays variations of about half of the amplitude at othermore » wavelengths. We find that the relative amplitude of flux variability out of the water band with respect to that in the water band shows a increasing trend from the L5 dwarfs toward the early T dwarfs. We utilize the models of Saumon & Marley (2008) and find that the observed variability of the L5 dwarfs can be explained by the presence of spatially varying high-altitude haze layers above the condensate clouds. Therefore, our observations show that the heterogeneity of haze layers - the driver of the variability - must be located at very low pressures, where even the water opacity is negligible. In the near future, the rotational spectral mapping technique could be utilized for other atomic and molecular species to probe different pressure levels in the atmospheres of brown dwarfs and exoplanets and uncover both horizontal and vertical cloud structures.« less

Vertically resolved characteristics of air pollution during two severe winter haze episodes in urban Beijing, China

NASA Astrophysics Data System (ADS)

Wang, Qingqing; Sun, Yele; Xu, Weiqi; Du, Wei; Zhou, Libo; Tang, Guiqian; Chen, Chen; Cheng, Xueling; Zhao, Xiujuan; Ji, Dongsheng; Han, Tingting; Wang, Zhe; Li, Jie; Wang, Zifa

2018-02-01

We conducted the first real-time continuous vertical measurements of particle extinction (bext), gaseous NO2, and black carbon (BC) from ground level to 260 m during two severe winter haze episodes at an urban site in Beijing, China. Our results illustrated four distinct types of vertical profiles: (1) uniform vertical distributions (37 % of the time) with vertical differences less than 5 %, (2) higher values at lower altitudes (29 %), (3) higher values at higher altitudes (16 %), and (4) significant decreases at the heights of ˜ 100-150 m (14 %). Further analysis demonstrated that vertical convection as indicated by mixing layer height, temperature inversion, and local emissions are three major factors affecting the changes in vertical profiles. Particularly, the formation of type 4 was strongly associated with the stratified layer that was formed due to the interactions of different air masses and temperature inversions. Aerosol composition was substantially different below and above the transition heights with ˜ 20-30 % higher contributions of local sources (e.g., biomass burning and cooking) at lower altitudes. A more detailed evolution of vertical profiles and their relationship with the changes in source emissions, mixing layer height, and aerosol chemistry was illustrated by a case study. BC showed overall similar vertical profiles as those of bext (R2 = 0.92 and 0.69 in November and January, respectively). While NO2 was correlated with bext for most of the time, the vertical profiles of bext / NO2 varied differently for different profiles, indicating the impact of chemical transformation on vertical profiles. Our results also showed that more comprehensive vertical measurements (e.g., more aerosol and gaseous species) at higher altitudes in the megacities are needed for a better understanding of the formation mechanisms and evolution of severe haze episodes in China.

HST Rotational Spectral Mapping Of Two L-Type Brown Dwarfs: Variability In And Out Of Water Bands Indicates High-Altitude Haze Layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Hao; Apai, Dániel; Marley, Mark S.

We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759-1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 μm and 1.7 μm. We find that the water absorption bands of the two L5 dwarfs at 1.15 μm and 1.4 μm vary at similar amplitudes as the adjacent continuum. This differs from the results of previous HST observations of L/T transition dwarfs, in which the water absorption at 1.4 μm displays variations of about half of the amplitude at othermore » wavelengths. We find that the relative amplitude of flux variability out of the water band with respect to that in the water band shows a increasing trend from the L5 dwarfs toward the early T dwarfs. We utilize the models of Saumon & Marley (2008) and find that the observed variability of the L5 dwarfs can be explained by the presence of spatially varying high-altitude haze layers above the condensate clouds. Therefore, our observations show that the heterogeneity of haze layers - the driver of the variability - must be located at very low pressures, where even the water opacity is negligible. In the near future, the rotational spectral mapping technique could be utilized for other atomic and molecular species to probe different pressure levels in the atmospheres of brown dwarfs and exoplanets and uncover both horizontal and vertical cloud structures.« less

Measurement of cell adhesion force by vertical forcible detachment using an arrowhead nanoneedle and atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryu, Seunghwan; Hashizume, Yui; Mishima, Mari

Graphical abstract: - Highlights: • We developed a method to measure cell adhesion force by detaching cell using an arrowhead nanoneedle and AFM. • A nanofilm consisting of fibronectin and gelatin was formed on cell surface to reinforce the cell cortex. • By the nanofilm lamination, detachment efficiencies of strongly adherent cell lines were improved markedly. - Abstract: The properties of substrates and extracellular matrices (ECM) are important factors governing the functions and fates of mammalian adherent cells. For example, substrate stiffness often affects cell differentiation. At focal adhesions, clustered–integrin bindings link cells mechanically to the ECM. In order tomore » quantitate the affinity between cell and substrate, the cell adhesion force must be measured for single cells. In this study, forcible detachment of a single cell in the vertical direction using AFM was carried out, allowing breakage of the integrin–substrate bindings. An AFM tip was fabricated into an arrowhead shape to detach the cell from the substrate. Peak force observed in the recorded force curve during probe retraction was defined as the adhesion force, and was analyzed for various types of cells. Some of the cell types adhered so strongly that they could not be picked up because of plasma membrane breakage by the arrowhead probe. To address this problem, a technique to reinforce the cellular membrane with layer-by-layer nanofilms composed of fibronectin and gelatin helped to improve insertion efficiency and to prevent cell membrane rupture during the detachment process, allowing successful detachment of the cells. This method for detaching cells, involving cellular membrane reinforcement, may be beneficial for evaluating true cell adhesion forces in various cell types.« less

Spectral and Polarimetric Imagery Collection Experiment

DTIC Science & Technology

2011-12-01

Also melted snow liquid rate Optical rain gauge Rain rate Possibly snow rate Visibility meter Visibility Smoke, fog, haze Pyranometer Sun and sky...performance of the IR imagery due to thermal effect or possible inversion layer effects. Pyranometers measure total sun and sky radiation. If the direction

Twilight Haze

NASA Image and Video Library

2018-01-15

In this view, individual layers of haze can be distinguished in the upper atmosphere of Titan, Saturn's largest moon. Titan's atmosphere features a rich and complex chemistry originating from methane and nitrogen and evolving into complex molecules, eventually forming the smog that surrounds the moon. This natural color image was taken in visible light with the Cassini spacecraft wide-angle camera on March 31, 2005, at a distance of approximately 20,556 miles (33,083 kilometers) from Titan. The view looks toward the north polar region on the moon's night side. Part of Titan's sunlit crescent is visible at right. The Cassini spacecraft ended its mission on Sept. 15, 2017. https://photojournal.jpl.nasa.gov/catalog/PIA21902

The vertical structure of Arctic haze as determined from airborne net-flux radiometer measurements

NASA Technical Reports Server (NTRS)

Ackerman, T. P.; Valero, F. P. J.

1984-01-01

From net-flux radiometer measurements and model results, the vertical layer structure is deduced of the Arctic haze encountered during two of the AGASP flights. The total value of the absorption optical depth is found to be on the order of 0.065 for both flights, with the majority of the absorbing aerosol concentrated in the lowest 1.6 km of the atmosphere. A comparison of these results with measurements of the carbon concentration leads to a value of the specific absorption of carbon of 24 sq m g. While higher than expected, this value is shown to be consistent with an internally-mixed aerosol of carbon cores and sulfate shells.

The strengthening relationship between Eurasian snow cover and December haze days in central North China after the mid-1990s

NASA Astrophysics Data System (ADS)

Yin, Zhicong; Wang, Huijun

2018-04-01

The haze pollution in December has become increasingly serious over recent decades and imposes damage on society, ecosystems, and human health. In addition to anthropogenic emissions, climate change and variability were conducive to haze in China. In this study, the relationship between the snow cover over eastern Europe and western Siberia (SCES) and the number of haze days in December in central North China was analyzed. This relationship significantly strengthened after the mid-1990s, which is attributed to the effective connections between the SCES and the Eurasian atmospheric circulations. During 1998-2016, the SCES significantly influenced the soil moisture and land surface radiation, and then the combined underlying drivers of enhanced soil moisture and radiative cooling moved the the East Asia jet stream northward and induced anomalous, anti-cyclonic circulation over central North China. Modulated by such atmospheric circulations, the local lower boundary layer, the decreased surface wind, and the more humid air were conducive to the worsening dispersion conditions and frequent haze occurrences. In contrast, from 1979 to 1997, the linkage between the SCES and soil moisture was negligible. Furthermore, the correlated radiative cooling was distributed narrowly and far from the key area of snow cover. The associated atmospheric circulations with the SCES were not significantly linked with the ventilation conditions over central North China. Consequently, the relationship between the SCES and the number of hazy days in central North China was insignificant before the mid-1990s but has strengthened and has become significant since then.

Long-term effects of short-term retinal bleb detachments in rabbits.

PubMed

Ivert, Lena; Kjeldbye, Hild; Gouras, Peter

2002-03-01

To examine the effects of saline-induced bleb detachments in rabbit retina. Retinal bleb detachments were produced by the injection of 50 microl of balanced salt solution (BSS) into the subretinal space of one eye of each of six rabbits using a glass pipette with a flat tip, 50 microm in diameter. The retina was examined by biomicroscopy, scanning laser ophthalmoscopy (SLO), auto-fluorescence and simultaneous fluorescein and indocyanine green (ICG) angiography. Histological examination was carried out at 1, 2, 3 and 4 months after surgery. All rabbits showed leakage of fluorescein for at least a day after detachment, but within 1 month the leakage ceased. ICG staining developed gradually at the level of the RPE or Bruch's membrane near sites of previous staining. Lipofuscin fluorescence also developed gradually around areas of staining. Histology revealed the source of the excessive lipofuscin to be in the RPE layer, especially in cells migrating away from Bruch's membrane. Short-term bleb detachments cause a transient breakdown in the blood-retinal barrier, long-term ICG staining at or deep to the RPE layer, hyperlipofuscinosis and migration of the RPE. The abnormal lipofuscin accumulation is apparent on fluorescence ophthalmoscopy and can be confused with markers such as green fluorescent protein.

The Thermal Emission and Albedo of Super-Earths with Flat Transmission Spectra

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan; Marley, Mark

2014-11-01

Vast resources have been dedicated to characterizing the handful of planets with radii between Earth’s and Neptune’s that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain the atmospheric composition. Here, we present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can break these degeneracies and constrain the atmospheric composition. Of the ~four small planets studied to date, all have radii in the near-IR consistent with being constant in wavelength. This suggests either that these planets all have higher mean molecular weight atmospheres than expected for hydrogen-dominated bulk compositions, or that the atmospheres of small planets are consistently enshrouded in thick hazes and clouds. For the particularly well-studied planet GJ 1214b, the measurements made using HST/WFC3 can rule out atmospheres with high mean molecular weights, leaving clouds as the sole explanation for the flat transmission spectrum. We showed in Morley et al. 2013 that these clouds and hazes can be made of salts and sulfides, which condense in the upper atmosphere of a cool H-rich atmosphere like GJ 1214b, or made of photochemical hazes such as soots, which result from methane photodissociation and subsequent carbon chemistry. Here, we explore how clouds thick enough to obscure the transmission spectrum change both thermal emission spectra and albedo spectra. These observations are complementary to transmission spectra measurements. Thermal emission probes deeper layers of the atmosphere, potentially below the high haze layer obscuring the transmission spectra; albedo spectra probe reflected starlight largely from the cloud particles themselves. Crucially, these complementary observations of planets with flat transmission spectra may allow us to break the degeneracies between cloud materials, cloud height and longitude, and bulk composition of the atmosphere. We make predictions for the observability of known planets for current and future telescopes.

The Thermal Emission and Albedo of Super-Earths with Flat Transmission Spectra

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan J.; Marley, Mark

2015-01-01

Vast resources have been dedicated to characterizing the handful of planets with radii between Earth's and Neptune's that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain the atmospheric composition. Here, we present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can break these degeneracies and constrain the atmospheric composition.Of the ~five small planets studied to date, four have radii in the near-IR consistent with being constant in wavelength. This suggests either that these planets all have higher mean molecular weight atmospheres than expected for hydrogen-dominated bulk compositions, or that the atmospheres of small planets are consistently enshrouded in thick hazes and clouds. For the particularly well-studied planet GJ 1214b, the measurements made using HST/WFC3 can rule out atmospheres with high mean molecular weights, leaving clouds as the sole explanation for the flat transmission spectrum. We showed in Morley et al. 2013 that these clouds and hazes can be made of salts and sulfides, which condense in the upper atmosphere of a cool H-rich atmosphere like GJ 1214b, or made of photochemical hazes such as soots, which result from methane photodissociation and subsequent carbon chemistry. Here, we explore how clouds thick enough to obscure the transmission spectrum change both thermal emission spectra and albedo spectra. These observations are complementary to transmission spectra measurements. Thermal emission probes deeper layers of the atmosphere, potentially below the high haze layer obscuring the transmission spectra; albedo spectra probe reflected starlight largely from the cloud particles themselves. Crucially, these complementary observations of planets with flat transmission spectra may allow us to break the degeneracies between cloud materials, cloud height and longitude, and bulk composition of the atmosphere. We make predictions for the observability of known planets for current and future telescopes.

A Full View of Pluto Stunning Crescent

NASA Image and Video Library

2015-10-29

In September, NASA's New Horizons team released a stunning but incomplete image of Pluto's crescent. Thanks to new processing work by the science team, New Horizons is releasing the entire, breathtaking image of Pluto. This image was made just 15 minutes after New Horizons' closest approach to Pluto on July 14, 2015, as the spacecraft looked back at Pluto toward the sun. The wide-angle perspective of this view shows the deep haze layers of Pluto's atmosphere extending all the way around Pluto, revealing the silhouetted profiles of rugged plateaus on the night (left) side. The shadow of Pluto cast on its atmospheric hazes can also be seen at the uppermost part of the disk. On the sunlit side of Pluto (right), the smooth expanse of the informally named icy plain Sputnik Planum is flanked to the west (above, in this orientation) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. Below (east) of Sputnik, rougher terrain is cut by apparent glaciers. The backlighting highlights more than a dozen high-altitude layers of haze in Pluto's tenuous atmosphere. The horizontal streaks in the sky beyond Pluto are stars, smeared out by the motion of the camera as it tracked Pluto. The image was taken with New Horizons' Multi-spectral Visible Imaging Camera (MVIC) from a distance of 11,000 miles (18,000 kilometers) to Pluto. The resolution is 700 meters (0.4 miles).

Accelerated cell-sheet recovery from a surface successively grafted with polyacrylamide and poly(N-isopropylacrylamide).

PubMed

Akiyama, Yoshikatsu; Kikuchi, Akihiko; Yamato, Masayuki; Okano, Teruo

2014-08-01

A double polymeric nanolayer consisting of poly(N-isopropylacrylamide) (PIPAAm) and hydrophilic polyacrylamide (PAAm) was deposited on tissue culture polystyrene (TCPS) surfaces using electron beam irradiation to form a new temperature-responsive cell culture surface in which the basal hydrophilic PAAm component in the double polymeric layer promotes the hydration of the upper PIPAAm layer and induces rapid cell detachment compared to a conventional temperature-responsive cell culture surface, PIPAAm-grafted TCPS (PIPAAm-TCPS). Take-off angle-dependent X-ray photoelectron spectroscopy spectral analysis demonstrated that the grafted PIPAAm and PAAm components were located in the upper and basal regions of the double polymeric layer, respectively, suggesting that the double polymeric layer forms an inter-penetrating-network-like structure with PAAm at the basal portion of the PIPAAm grafted chains. The wettability of the temperature-responsive cell culture surfaces with the double polymeric layer tended to be more hydrophilic, with an increase in the basal PAAm graft density at a constant PIPAAm graft density. However, when the graft densities of the upper PIPAAm and basal PAAm were optimized, the resulting temperature-responsive cell culture surface with the double polymeric layer exhibited rapid cell detachment while maintaining cell adhesive character comparable to that of PIPAAm-TCPS. The cell adhesive character was altered from cell-adhesive to cell-repellent with increasing PAAm or PIPAAm graft density. The cell adhesive character of the temperature-responsive cell culture surfaces was relatively consistent with their contact angles. These results strongly suggest that the basal PAAm surface properties affect the degree of hydration and dehydration of the subsequently grafted PIPAAm. In addition, the roles of the hydrophilic component in accelerating cell detachment are further discussed in terms of the mobility of the grafted PIPAAm chains. Applications of this insight might be useful for designing temperature-responsive cell culture surfaces for achieving efficient cell culture and quick target cell detachment. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Photoreceptor layer map using spectral-domain optical coherence tomography.

PubMed

Lee, Ji Eun; Lim, Dae Won; Bae, Han Yong; Park, Hyun Jin

2009-12-01

To develop a novel method for analysis of the photoreceptor layer map (PLM) generated using spectral-domain optical coherence tomography (OCT). OCT scans were obtained from 20 eyes, 10 with macular holes (MH) and 10 with central serous chorioretinopathy (CSC) using the Macular Cube (512 x 128) protocol of the Cirrus HD-OCT (Carl Zeiss). The scanned data were processed using embedded tools of the advanced visualization. A partial thickness OCT fundus image of the photoreceptor layer was generated by setting the region of interest to a 50-microm thick layer that was parallel and adjacent to the retinal pigment epithelium. The resulting image depicted the photoreceptor layer as a map of the reflectivity in OCT. The PLM was compared with fundus photography, auto-fluorescence, tomography, and retinal thickness map. The signal from the photoreceptor layer of every OCT scan in each case was demonstrated as a single image of PLM in a fundus photograph fashion. In PLM images, detachment of the sensory retina is depicted as a hypo-reflective area, which represents the base of MH and serous detachment in CSC. Relative hypo-reflectivity, which was also noted at closed MH and at recently reattached retina in CSC, was associated with reduced signal from the junction between the inner and outer segments of photoreceptors in OCT images. Using PLM, changes in the area of detachment and reflectivity of the photoreceptor layer could be efficiently monitored. The photoreceptor layer can be analyzed as a map using spectral-domain OCT. In the treatment of both MH and CSC, PLM may provide new pathological information about the photoreceptor layer to expand our understanding of these diseases.

Towards an entropy-based detached-eddy simulation

NASA Astrophysics Data System (ADS)

Zhao, Rui; Yan, Chao; Li, XinLiang; Kong, WeiXuan

2013-10-01

A concept of entropy increment ratio ( s¯) is introduced for compressible turbulence simulation through a series of direct numerical simulations (DNS). s¯ represents the dissipation rate per unit mechanical energy with the benefit of independence of freestream Mach numbers. Based on this feature, we construct the shielding function f s to describe the boundary layer region and propose an entropy-based detached-eddy simulation method (SDES). This approach follows the spirit of delayed detached-eddy simulation (DDES) proposed by Spalart et al. in 2005, but it exhibits much better behavior after their performances are compared in the following flows, namely, pure attached flow with thick boundary layer (a supersonic flat-plate flow with high Reynolds number), fully separated flow (the supersonic base flow), and separated-reattached flow (the supersonic cavity-ramp flow). The Reynolds-averaged Navier-Stokes (RANS) resolved region is reliably preserved and the modeled stress depletion (MSD) phenomenon which is inherent in DES and DDES is partly alleviated. Moreover, this new hybrid strategy is simple and general, making it applicable to other models related to the boundary layer predictions.

The Role of an Electric Field in the Formation of a Detached Regime in Tokamak Plasma

NASA Astrophysics Data System (ADS)

Senichenkov, I.; Kaveeva, E.; Rozhansky, V.; Sytova, E.; Veselova, I.; Voskoboynikov, S.; Coster, D.

2018-03-01

Modeling of the transition to the detachment of ASDEX Upgrade tokamak plasma with increasing density is performed using the SOLPS-ITER numerical code with a self-consistent account of drifts and currents. Their role in plasma redistribution both in the confinement region and in the scrape-off layer (SOL) is investigated. The mechanism of high field side high-density formation in the SOL in the course of detachment is suggested. In the full detachment regime, when the cold plasma region expands above the X-point and reaches closed magnetic-flux surfaces, plasma perturbation in a confined region may lead to a change in the confinement regime.

Evidence that ganglion cells react to retinal detachment.

PubMed

Coblentz, Francie E; Radeke, Monte J; Lewis, Geoffrey P; Fisher, Steven K

2003-03-01

Growth associated protein 43 (GAP 43) is involved in synapse formation and it is expressed in the retina in a very specific pattern. Although GAP 43 is downregulated at the time of synapse formation, it can be re-expressed following injury such as axotomy or ischemia. Because of this we sought to characterize the expression of GAP 43 after retinal detachment (RD). Immunoblot, immunocytochemical and quantitative polymerase chain reaction (QPCR) techniques were used to assess the level of GAP 43 expression after experimental RD. GAP 43 was localized to three sublaminae of the inner plexiform layer of the normal retina. GAP 43 became upregulated in a subset of retinal ganglion cells following at least 7 days of RD. By immunoblot GAP 43 could be detected by 3 days. QPCR shows the upregulation of GAP 43 message by 6hr of detachment. To further characterize changes in ganglion cells, we used an antibody to neurofilament 70 and 200kDa (NF) proteins. Anti-NF labels horizontal cells, ganglion cell dendrites in the inner plexiform layer, and ganglion cell axons (fasicles) in the normal retina. Following detachment it is upregulated in horizontal cells and ganglion cells. When detached retina was double labelled with anti-GAP 43 and anti-NF, some cells were labelled with both markers, while others labelled with only one. We have previously shown that second order neurons respond to detachment; here we show that third order neurons are responding as well. Cellular remodelling of this type in response to detachment may explain the slow recovery of vision that often occurs after reattachment, or those changes that are often assumed to be permanent.

New Horizons Finds Blue Skies and Water Ice on Pluto

NASA Image and Video Library

2017-12-08

Pluto’s Blue Sky: Pluto’s haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn’s moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles (called tholins) that grow as they settle toward the surface. This image was generated by software that combines information from blue, red and near-infrared images to replicate the color a human eye would perceive as closely as possible. Credits: NASA/JHUAPL/SwRI Read more: www.nasa.gov/nh/nh-finds-blue-skies-and-water-ice-on-pluto NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The occultation of 28 Sgr by Titan

NASA Technical Reports Server (NTRS)

Hubbard, W. B.; Sicardy, Bruno; Miles, R.; Hollis, A. J.; Forrest, R. W.; Nicolson, I. K. M.; Appleby, G.; Beisker, W.; Bittner, C.; Bode, H.-J.

1993-01-01

We present a comprehensive analysis of data obtained during the 1989 July 3 occultation of 28 Sgr by Titan. The data set includes 23 lightcurves from 15 separate stations, spanning wavelengths from 0.36 to 0.89 micron. A detailed model of the structure of Titan's atmosphere in the altitude range 250 to 450 km is developed, giving the distribution of temperature, pressure, haze optical depth, and zonal wind velocity as a function of altitude and latitude. Haze layers detected in Titan's stratosphere are about one scale height higher than inferred from Voyager data, and show a wavelength dependence indicative of particle sizes on the order of 0.1 micron. A marked north-south dichotomy in haze density is observed with a transition to lower density south of about -20 deg latitude. Zonal wind speeds are inferred from global distortions from spherical symmetry and are of the order of 100 m/s with significant increase toward higher latitudes. Titan's high atmosphere shows substantial axial symmetry; the position angle of the symmetry axis is equal to the position angle of Saturn's spin axis to within about 1 deg.

Uranus' (3-0) H2 quadrupole line profiles

NASA Technical Reports Server (NTRS)

Trafton, L.

1987-01-01

Spectra of Uranus' S3(0) and S3(1) H2 quadrupole lines, obtained during the 1978-1980 apparitions, are analyzed, and are found to require the presence of a deep cloud. Modifications of the Baines and Bergstralh (1986) standard model, including an additional haze layer above the 16-km-am H2 level which contains strongly absorbing particles, are needed to fit the observations. For a Rayleigh phase function, such a haze (uniformly mixed with the gas above this level) would have an absorption optical depth of 0.16 and a single scattering particle albedo of 0.30. This modification would imply a fraction of normal H2 equal to 0.25 + or - 0.10, in agreement with the Baines and Bergstralh standard model.

Studies of humid continental haze during SPACE

NASA Technical Reports Server (NTRS)

Bowdle, D. A.; Greene, W. A.

1985-01-01

A concept for a solar radiometer network to provide supporting data during the Satellite Preciptiation and Cloud Experiment (SPACE) was developed. Each of the 9 prime and 10 supplementary SPACE ground sites will be equipped with an upward pointing global solar pyranometer. About half of the sites will also be equipped with upward pointing diffuse (shade ring) solar pyranometers, and a downward pointing global albedo pyranometer. These radiometers will be used to monitor the spatial and temporal variability of solar insolation and haze optical depth. The insolation data will ultimately be input to numerical models of the pre-storm and near-storm boundary layer. The optical depth data will be compared with simultaneous measurements from airborne and satellite-based passive visible radiometers and airborne lidars.

Increase in winter haze over eastern China in recent decades: Roles of variations in meteorological parameters and anthropogenic emissions: INCREASE IN WINTER HAZE IN EASTERN CHINA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yang; Liao, Hong; Lou, Sijia

The increase in winter haze over eastern China in recent decades due to variations in meteorological parameters and anthropogenic emissions was quantified using observed atmospheric visibility from the National Climatic Data Center Global Summary of Day database for 1980–2014 and simulated PM2.5 concentrations for 1985–2005 from the Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem). Observed winter haze days averaged over eastern China (105–122.5°E, 20–45°N) increased from 21 d in 1980 to 42 d in 2014, and from 22 to 30 d between 1985 and 2005. The GEOS-Chem model captured the increasing trend of winter PM2.5 concentrations for 1985–2005,more » with concentrations averaged over eastern China increasing from 16.1 μg m -3 in 1985 to 38.4 μg m -3 in 2005. Considering variations in both anthropogenic emissions and meteorological parameters, the model simulated an increase in winter surface-layer PM2.5 concentrations of 10.5 (±6.2) μg m -3 decade -1 over eastern China. The increasing trend was only 1.8 (±1.5) μg m -3 decade -1 when variations in meteorological parameters alone were considered. Among the meteorological parameters, the weakening of winds by -0.09 m s -1 decade -1 over 1985–2005 was found to be the dominant factor leading to the decadal increase in winter aerosol concentrations and haze days over eastern China during recent decades.« less

Characteristics of Turbulent Transfer during Episodes of Heavy Haze Pollution in Beijing in Winter 2016/17

NASA Astrophysics Data System (ADS)

Ren, Yan; Zheng, Shuwen; Wei, Wei; Wu, Bingui; Zhang, Hongsheng; Cai, Xuhui; Song, Yu

2018-02-01

We analyzed the structure and evolution of turbulent transfer and the wind profile in the atmospheric boundary layer in relation to aerosol concentrations during an episode of heavy haze pollution from 6 December 2016 to 9 January 2017. The turbulence data were recorded at Peking University's atmospheric science and environment observation station. The results showed a negative correlation between the wind speed and the PM2.5 concentration. The turbulence kinetic energy was large and showed obvious diurnal variations during unpolluted (clean) weather, but was small during episodes of heavy haze pollution. Under both clean and heavy haze conditions, the relation between the non-dimensional wind components and the stability parameter z/ L followed a 1/3 power law, but the normalized standard deviations of the wind speed were smaller during heavy pollution events than during clean periods under near-neutral conditions. Under unstable conditions, the normalized standard deviation of the potential temperature σ θ /| θ *| was related to z/ L, roughly following a -1/3 power law, and the ratio during pollution days was greater than that during clean days. The three-dimensional turbulence energy spectra satisfied a -2/3 power exponent rate in the high-frequency band. In the low-frequency band, the wind velocity spectrum curve was related to the stability parameters under clear conditions, but was not related to atmospheric stratification under polluted conditions. In the dissipation stage of the heavy pollution episode, the horizontal wind speed first started to increase at high altitudes and then gradually decreased at lower altitudes. The strong upward motion during this stage was an important dynamic factor in the dissipation of the heavy haze.

Detachment of CVD-grown graphene from single crystalline Ni films by a pure gas phase reaction

NASA Astrophysics Data System (ADS)

Zeller, Patrick; Henß, Ann-Kathrin; Weinl, Michael; Diehl, Leo; Keefer, Daniel; Lippmann, Judith; Schulz, Anne; Kraus, Jürgen; Schreck, Matthias; Wintterlin, Joost

2016-11-01

Despite great previous efforts there is still a high need for a simple, clean, and upscalable method for detaching epitaxial graphene from the metal support on which it was grown. We present a method based on a pure gas phase reaction that is free of solvents and polymer supports and avoids mechanical transfer steps. The graphene was grown on 150 nm thick, single crystalline Ni(111) films on Si(111) wafers with YSZ buffer layers. Its quality was monitored by using low energy electron diffraction and scanning tunneling microscopy. The gas phase etching uses a chemical transport reaction, the so-called Mond process, based on the formation of gaseous nickel tetracarbonyl in 1 bar of CO at 75 °C and by adding small amounts of sulfide catalysts. X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy were used to characterize the detached graphene. It was found that the method successfully removes the nickel from underneath the graphene layer, so that the graphene lies on the insulating oxide buffer layer. Small residual particles of nickel sulfide and cracks in the obtained graphene layer were identified. The defect concentrations were comparable to graphene samples obtained by wet chemical etching and by the bubbling transfer.

The oxidation of SO2 by NO2(g) at the air-water interface of aquated aerosol: implications for the rapid onset of haze-aerosol events in China

NASA Astrophysics Data System (ADS)

Li, L.; Colussi, A. J.; Hoffmann, M. R.

2017-12-01

Aqueous phase chemistry plays a vital role in the global atmosphere. The importance of heterogeneous chemistry has been recently underscored by the severe haze-fog pollution episodes experienced in Chinese megacities. A key finding is that despite reduced photochemistry during the wintertime haze events, the oxidation of S(IV) into sulfate aerosol occurs rapidly in spite of the low levels of ozone and H2O2. Field observations suggest that NO2 could serve as a suitable oxidant of S(IV) during the events under neutral pH conditions. However, the haze aerosols are mostly acidic. Furthermore, the air-water interface is more acidic than bulk-phase aquated system according to our recent findings. This work investigates the chemistry taking place as NO2(g) collides with the surface of aqueous S(IV) microdroplets as a function of pH to closely simulate actual haze aerosol events under atmospheric conditions. The reaction between NO2(g) and HSO3- (aq) is studied in situ under ambient temperature and pressure via online electrospray ionization mass spectrometry. The aqueous aerosols containing HSO3- is generated using a microjet which is exposed to NO2(g) alternatively, while the composition of the 1 nm interfacial liquid layer of the aerosol is instantaneously measured. The ratio of HSO3- to HSO4- is observed to decrease with the concomitant appearance of a strong m/z 62 signal upon NO2(g) exposure. The appearance of m/z 62 indicates the formation of NO3- via the disproportionation of NO2 (2NO2(g) + H2O (l) ⇌ H++NO3-(aq) + HONO(aq)) and thus impacts the ion-ion interactions of NO3- on the ratio of HSO3- to HSO4- in the outermost interfacial layers. Parallel experiments with NO3-(aq) additions are conducted to quantify the impact of NO3- on the the ratio, in order to unravel the contribution of NO2 to the oxidation of S(IV). After accounting for the HNO3 effect, it is concluded: (1) most NO2(g) is converted into NO3- via anion-catalyzed hydrolytic disproportionation; (2) the oxidation of HSO3- by NO2(g) is limited, with a maximum contribution of 10% at pH 4 6. The importance of transition metal catalyzed oxidation of S(IV) for aerosol formation at pH > 6 is also experimentally proved in this work. Overall, our research shows NO2 is not an important oxidant for sulfate aerosol formation during severe Chinese haze aerosol episodes.

Dust Ablation in Pluto's Atmosphere

NASA Astrophysics Data System (ADS)

Horanyi, M.; Poppe, A. R.; Sternovsky, Z.

2015-12-01

Based on measurements by in situ dust detectors onboard the Pioneer and New Horizon spacecraft the total production rate of dust particles born in the Kuiper belt can be estimated to be on the order of 5 x 10 ^3 kg/s in the approximate size range of 1 - 10 micron. These particles slowly migrate inward due to Poynting - Robertson drag and their spatial distribution is shaped by mean motion resonances with the gas giant planets in the outer solar system. The expected mass influx into Pluto's atmosphere is on the order of 50 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that, if the particles are rich in volatiles, they can fully sublimate due to drag heating and deposit their mass in a narrow layer. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles, as well as on our newly developed models of Pluto's atmosphere that can be learned by matching the altitude where haze layers could be formed.

Mud fossils

USGS Publications Warehouse

,

1997-01-01

At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas.

7 CFR 52.1842 - Product description of Layer or (Cluster) raisins with seeds.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Product description of Layer or (Cluster) raisins with... Raisins 1 § 52.1842 Product description of Layer or (Cluster) raisins with seeds. Raisins with Seeds that are referred to as Layer or Cluster raisins means that the raisins have not been detached from the...

INTERNAL LIMITING MEMBRANE PEELING-DEPENDENT RETINAL STRUCTURAL CHANGES AFTER VITRECTOMY IN RHEGMATOGENOUS RETINAL DETACHMENT.

PubMed

Hisatomi, Toshio; Tachibana, Takashi; Notomi, Shoji; Koyanagi, Yoshito; Murakami, Yusuke; Takeda, Atsunobu; Ikeda, Yasuhiro; Yoshida, Shigeo; Enaida, Hiroshi; Murata, Toshinori; Sakamoto, Taiji; Sonoda, Koh-Hei; Ishibashi, Tatsuro

2018-03-01

To examine retinal changes after vitrectomy with internal limiting membrane (ILM) peeling, we used 3-dimensional optical coherence tomography (3D-OCT) in rhegmatogenous retinal detachment cases. The 68 eyes from 67 patients with rhegmatogenous retinal detachment were studied, including 35 detached macula cases (51%) and 33 attached macula cases. Internal limiting membrane peeling was performed with fine forceps after brilliant blue G staining. The 3D-OCT images were obtained with volume-rendering technologies from cross-sectional OCT images. The 3D-OCT detected 45 eyes (66%) with ILM peeling-dependent retinal changes, including dissociated optic nerve fiber layer appearance, dimple sign, temporal macular thinning, ILM peeling area thinning, or forceps-related retinal thinning. The ILM peeled area was detectable in only 9 eyes with 3D-OCT, whereas it was undetectable in other 59 eyes. The dissociated optic nerve fiber layer appearance was detected in 8 of the total cases (12%), and dimple signs were observed in 14 cases (21%). Forceps-related thinning was also noted in eight cases (24%) of attached macula cases and in four cases (11%) of detached macula cases. No postoperative macular pucker was noted in the observational period. The 3D-OCT clearly revealed spatial and time-dependent retinal changes after ILM peeling. The changes occurred in 2 months and remained thereafter.

Organic chemistry in Titan's atmosphere

NASA Technical Reports Server (NTRS)

Scattergood, T.

1982-01-01

Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

Solar Spectral Radiative Forcing During the Southern African Regional Science Initiative

NASA Technical Reports Server (NTRS)

Pilewskie, P.; Pommier, J.; Bergstrom, R.; Gore, W.; Howard, S.; Rabbette, M.; Schmid, B.; Hobbs, P. V.; Tsay, S. C.

2003-01-01

During the dry season component of the Southern African Regional Science Initiative (SAFARI) in late winter 2000, the net solar spectral irradiance was measured at flight levels throughout biomass burning haze layers. From these measurements, the flux divergence, fractional absorption, instantaneous heating rate, and absorption efficiency were derived. Two cases are examined: on 24 August 2000 off the coast of Mozambique in the vicinity of Inhaca Island and on 6 September 2000 in a very thick continental haze layer over Mongu, Zambia. The measured absolute absorption was substantially higher for the case over Mongu where the measured midvisible optical depth exceeded unity. Instantaneous heating from aerosol absorption was 4 K d(sup -1) over Mongu, Zambia and 1.5 K d(sup -1) near Inhaca Island, Mozambique. However, the spectral absorption efficiency was nearly identical for both cases. Although the observations over Inhaca Island preceded the river of smoke from the southern African continent by nearly 2 weeks, the evidence here suggests a continental influence in the lower tropospheric aerosol far from source regions of burning.

Bevacizumab Therapy and Multimodal Ultra-widefield Imaging in Immunogammopathy Maculopathy Secondary to Waldenstrom’s Macroglobulinemia

PubMed Central

Xu, Lucy T.; Courtney, Robert J.; Ehlers, Justis P

2015-01-01

Waldenstrom’s macroglobulinemia (WM) is associated with retinal findings of hyperviscosity such as venous dilation, and findings of immunogammopathy maculopathy such as serous macular detachment. The report describes a case of bilateral serous macular detachment with intraretinal schisis-like fluid in a patient with WM. Enhanced depth imaging OCT revealed a thickened choroid with hyper-reflective accumulations in the RPE layer. The ultra-widefield fundus autofluorescence demonstrated a central area of hyperautofluorescence corresponding to the area of serous macular detachment. Ultra-widefield fluorescein angiography was characteristically silent. Intravitreal bevacizumab therapy resulted in significant reduction in intraretinal fluid, but minimal change in subretinal fluid. Long-term follow-up demonstrated alterations in retinal architecture and improved serous detachments. PMID:25707055

Molecular Dynamics Simulations of the Oil-Detachment from the Hydroxylated Silica Surface: Effects of Surfactants, Electrostatic Interactions, and Water Flows on the Water Molecular Channel Formation.

PubMed

Tang, Jian; Qu, Zhou; Luo, Jianhui; He, Lanyan; Wang, Pingmei; Zhang, Ping; Tang, Xianqiong; Pei, Yong; Ding, Bin; Peng, Baoliang; Huang, Yunqing

2018-02-15

The detachment process of an oil molecular layer situated above a horizontal substrate was often described by a three-stage process. In this mechanism, the penetration and diffusion of water molecules between the oil phase and the substrate was proposed to be a crucial step to aid in removal of oil layer/drops from substrate. In this work, the detachment process of a two-dimensional alkane molecule layer from a silica surface in aqueous surfactant solutions is studied by means of molecular dynamics (MD) simulations. By tuning the polarity of model silica surfaces, as well as considering the different types of surfactant molecules and the water flow effects, more details about the formation of water molecular channel and the expansion processes are elucidated. It is found that for both ionic and nonionic type surfactant solutions, the perturbation of surfactant molecules on the two-dimensional oil molecule layer facilitates the injection and diffusion of water molecules between the oil layer and silica substrate. However, the water channel formation and expansion speed is strongly affected by the substrate polarity and properties of surfactant molecules. First, only for the silica surface with relative stronger polarity, the formation of water molecular channel is observed. Second, the expansion speed of the water molecular channel upon the ionic surfactant (dodecyl trimethylammonium bromide, DTAB and sodium dodecyl benzenesulfonate, SDBS) flooding is more rapidly than the nonionic surfactant system (octylphenol polyoxyethylene(10) ether, OP-10). Third, the water flow speed may also affect the injection and diffusion of water molecules. These simulation results indicate that the water molecular channel formation process is affected by multiple factors. The synergistic effects of perturbation of surfactant molecules and the electrostatic interactions between silica substrate and water molecules are two key factors aiding in the injection and diffusion of water molecules and helpful for the oil detachment from silica substrate.

Atmospheric Prebiotic Chemistry and Organic Hazes

PubMed Central

Trainer, Melissa G.

2013-01-01

Earth’s atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of prebiotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer – if formed – would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere. PMID:24143126

Atmospheric Prebiotic Chemistry and Organic Hazes.

PubMed

Trainer, Melissa G

2013-08-01

Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of prebiotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

Atmospheric Prebiotic Chemistry and Organic Hazes

NASA Technical Reports Server (NTRS)

Trainer, Melissa G.

2012-01-01

Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of pre biotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

Haze over Eastern China

NASA Image and Video Library

2017-12-08

A thick layer of haze blanketed the North China Plain on October 9, 2014, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this natural-color image at 2:50 Coordinated Universal Time (10:50 a.m. local time). The haze obscured many features usually visible in MODIS imagery of the area, including China’s largest city, Beijing. On the day this image was acquired, measurements from ground-based sensors at the U.S. Consulate in Beijing reported PM2.5 measurements of 334 micrograms per cubic meter of air. Fine, airborne particulate matter (PM) that is smaller than 2.5 microns (about one thirtieth the width of a human hair) is considered dangerous because it is small enough to enter the passages of the human lungs. Most PM2.5 aerosol particles come from the burning of fossil fuels and biomass (wood fires and agricultural burning). The World Health Organization considers PM2.5 to be safe when it is below 25. Haze in this region tends to worsen in the fall and winter, when cold, heavy air traps pollutants near the surface. In this case, the haze was likely trapped by a temperature inversion. Normally, air is warmest near the surface of the Earth. Occasionally, a mass of warm air will move over cooler air so that the atmosphere actually warms with altitude. Since the cool air does not have the energy to rise through the warm air, vertical circulation slows and air becomes trapped near the surface. Any pollutant that enters the air gets trapped as well, and haze builds up over time. Daily satellite images of the North China Plain show that visible haze began to accumulate on October 7, 2014. NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Adam Voiland. Read more: earthobservatory.nasa.gov/NaturalHazards/view.php?id=8453... Credit: NASA Earth Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Dust ablation in Pluto's atmosphere

NASA Astrophysics Data System (ADS)

Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan

2016-04-01

Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

Possible influence of atmospheric circulations on winter haze pollution in Beijing-Tianjin-Hebei region, northern China

NASA Astrophysics Data System (ADS)

Zhang, Z. Y.

2016-12-01

Using the daily records derived from the synoptic weather stations and the NCEP/NCAR and ERA-Interim reanalysis data, the variability of the winter haze pollutions (indicated by the mean visibility and number of hazy days) in Beijing-Tianjin-Hebei (BTH) region during the period 1981 to 2015 and its relationship to the atmospheric circulations in middle-high latitude were analyzed in this study. The winter haze pollution in BTH had distinct inter-annual and inter-decadal variabilities without a significant long-term trend. According to the spatial distribution of correlation coefficients, six atmospheric circulation indices (I1 to I6) were defined from the key areas in sea level pressure (SLP), zonal and meridional winds at 850 hPa (U850, V850), geopotential height field at 500 hPa (H500), zonal wind at 200 hPa (U200), and air temperature at 200 hPa (T200), respectively. All of the six indices have significant and stable correlations with the winter visibility and number of hazy days in BTH. The six circulation indices together can explain 77.7% (78.7%) and 61.7% (69.1%) variances of the winter visibility and number of hazy days in the year-to-year (inter-annual) variability, srespectively. The increase of Ic(a comprehensive index derived from the six individual circulation indices) can cause a shallowing of the East Asian trough at the middle troposphere and a weakening of the Siberian high pressure field at sea level, and then accompanied by a reduction (increase) of horizontal advection and vertical convection (relative humidity) in the lowest troposphere and a reduced boundary layer height in BTH and its neighboring areas, which are favorable for the formation of haze pollutions in BTH winter, and vice versa. The high level of the prediction statistics and the reasonable mechanism suggested that the winter haze pollutions in BTH can be forecasted or estimated credibly based on the optimized atmospheric circulation indices. Thus it is helpful for government decision-making departments to take actions in advance in dealing with probably severe haze pollutions in BTH indicated by the atmospheric circulation conditions.

Strain localisation in mechanically layered rocks beneath detachment zones: insights from numerical modelling

NASA Astrophysics Data System (ADS)

Le Pourhiet, L.; Huet, B.; Labrousse, L.; Yao, K.; Agard, P.; Jolivet, L.

2013-04-01

We have designed a series of fully dynamic numerical simulations aimed at assessing how the orientation of mechanical layering in rocks controls the orientation of shear bands and the depth of penetration of strain in the footwall of detachment zones. Two parametric studies are presented. In the first one, the influence of stratification orientation on the occurrence and mode of strain localisation is tested by varying initial dip of inherited layering in the footwall with regard to the orientation of simple shear applied at the rigid boundary simulating a rigid hanging wall, all scaling and rheological parameter kept constant. It appears that when Mohr-Coulomb plasticity is being used, shear bands are found to localise only when the layering is being stretched. This corresponds to early deformational stages for inital layering dipping in the same direction as the shear is applied, and to later stages for intial layering dipping towards the opposite direction of shear. In all the cases, localisation of the strain after only γ=1 requires plastic yielding to be activated in the strong layer. The second parametric study shows that results are length-scale independent and that orientation of shear bands is not sensitive to the viscosity contrast or the strain rate. However, decreasing or increasing strain rate is shown to reduce the capacity of the shear zone to localise strain. In the later case, the strain pattern resembles a mylonitic band but the rheology is shown to be effectively linear. Based on the results, a conceptual model for strain localisation under detachment faults is presented. In the early stages, strain localisation occurs at slow rates by viscous shear instabilities but as the layered media is exhumed, the temperature drops and the strong layers start yielding plastically, forming shear bands and localising strain at the top of the shear zone. Once strain localisation has occured, the deformation in the shear band becomes extremely penetrative but the strength cannot drop since the shear zone has a finite thickness.

A study of X-divertor in NSTX-U with SOLPS simulations

NASA Astrophysics Data System (ADS)

Chen, Zhong-Ping; Kotschenreuther, Mike; Mahajan, Swadesh; Gerhardt, Stefan

2018-03-01

The X-divertor (XD) geometry in NSTX-U is demonstrated, via SOLPS simulations, to perform better than the standard divertor (SD); in particular, it allows detachment at a lower upstream density and stabilizes the detachment front near the target, away from the main X-point. Consequently a stable detached operation becomes possible—the localization near the plate allows a vast reduction of heat fluxes without degrading the core plasma. Indeed, it is confirmed by our simulation that at similar states of detachment the XD outperforms the SD by reducing the heat fluxes to the target and maintaining higher upstream temperatures, resulting in scrape-off layers that are more favorable for advanced tokamak operation. These advantages are attributed to the unique geometric characteristics of XD—poloidal flaring near the target.

Interior radiances in optically deep absorbing media. 3: Scattering from Haze L

NASA Technical Reports Server (NTRS)

Kattawar, G. W.; Plass, G. N.

1974-01-01

The interior radiances are calculated within an optically deep absorbing medium scattering according to the Haze L phase function. The dependence on the solar zenith angle, the single scattering albedo, and the optical depth within the medium is calculated by the matrix operator method. The development of the asymptotic angular distribution of the radiance in the diffusion region is illustrated through a number of examples; it depends only on the single scattering albedo and on the phase function for single scattering. The exact values of the radiance in the diffusion region are compared with values calculated from the approximate equations proposed by Van de Hulst. The variation of the radiance near the lower boundary of an optically thick medium is illustrated with examples. The attenuation length is calculated for various single scattering albedos and compared with the corresponding values for Rayleigh scattering. The ratio of the upward to the downward flux is found to be remarkably constant within the medium. The heating rate is calculated and found to have a maximum value at an optical depth of two within a Haze L layer when the sun is at the zenith.

Bacterial desorption from food container and food processing surfaces.

PubMed

McEldowney, S; Fletcher, M

1988-03-01

The desorption ofStaphylococcus aureus, Acinetobacter calcoaceticus, and a coryneform from the surfaces of materials used for manufacturing food containers (glass, tin plate, and polypropylene) or postprocess canning factory conveyor belts (stainless steel and nylon) was investigated. The effect of time, pH, temperature, and adsorbed organic layers on desorption was studied.S. aureus did not detach from the substrata at any pH investigated (between pH 5 and 9).A. calcoaceticus and the coryneform in some cases detached, depending upon pH and substratum composition. The degree of bacterial detachment from the substrata was not related to bacterial respiration at experimental pH values. Bacterial desorption was not affected by temperature (4-30°C) nor by an adsorbed layer of peptone and yeast extract on the substrata. The results indicate that bacterial desorption, hence bacterial removal during cleaning or their transfer via liquids flowing over colonized surfaces, is likely to vary with the surface composition and the bacterial species colonizing the surfaces.

Unprecedented Fires in Southern Africa

NASA Technical Reports Server (NTRS)

2002-01-01

The fires that raged across southern Africa this August and September produced a thick 'river of smoke' over the region. NASA-supported studies currently underway on the event will contribute to improved air pollution policies in the region and a better understanding of its impact on climate change. This year the southern African fire season peaked in early September. The region is subject to some of the highest levels of biomass burning in the world. The heaviest burning was in western Zambia, southern Angola, northern Namibia, and northern Botswana. Some of the blazes had fire fronts 20 miles long that lasted for days. In this animation, multiple fires are burning across the southern part of the African continent in September 2000. The fires, indicated in red, were observed by the Advanced Very High Resolution Radiometer (AVHRR) instrument on board the NOAA-14 satellite. The fires generated large amounts of heat-absorbing aerosols (the dark haze), which were observed with the Earth Probe Total Ozone Mapping Spectrometer (TOMS) instrument. These observations were collected as part of a NASA-supported field campaign called SAFARI 2000 (Southern African Regional Science Initiative). The recent six-week 'dry-season' portion of this experiment was planned to coincide with the annual fires. SAFARI 2000 planners tracked the changing location of fires with daily satellite maps provided by researchers at NASA's Goddard Space Flight Center. 'Every year African biomass burning greatly exceeds the scale of the fires seen this year in the western United States,' says Robert Swap of the University of Virginia, one of the campaign organizers. 'But the southern African fire season we just observed may turn out to be an extreme one even by African standards. It was amazing how quickly this region went up in flames.' The thick haze layer from these fires was heavier than campaign participants had seen in previous field studies in the Amazon Basin and during the Kuwati oil fires. The haze aerosols sampled were more heat-absorbing than expected, which means the haze layer may have a significant warming influence on the region's atmosphere. For more information, see the press release Image courtesy NASA Goddard Space Flight Center, Science Visualization Studio

Haze variation in valley region its affecting factors

NASA Astrophysics Data System (ADS)

Liu, Yinge; Zhao, Aling; Wang, Yan; Wang, Shaoxiong; Dang, Caoni

2018-02-01

The haze has a great harm on the environment and human health. Based on the daily meteorological observation data including visibility, relative humidity, wind speed, temperature, air pollution index and weather record of Baoji region in China, and using least squares method, wavelet and correlation analysis method, the temporal and spatial characteristics of haze were analyzed. While the factors affecting the haze change were discussed. The results showed that the haze mainly occurs in plain areas, and in hilly areas and mountain the haze frequency is relatively small. Overall the annual average haze is decreasing, especially in winter and spring the reduction trend of haze is most obvious, however, in summer haze is increasing. The haze has a 5-year short period and 10-year and 15-year long-term cycles change. Moreover, there was a significant negative correlation between temperature and wind speed with haze, while the relative humidity was significantly positively correlated with haze. These studies provide the basis for atmospheric environmental monitor and management.

Variations of polycyclic aromatic hydrocarbons in ambient air during haze and non-haze episodes in warm seasons in Hangzhou, China.

PubMed

Lu, Hao; Wang, Shengsheng; Wu, Zuliang; Yao, Shuiliang; Han, Jingyi; Tang, Xiujuan; Jiang, Boqiong

2017-01-01

To investigate the characteristics of polycyclic aromatic hydrocarbons (PAHs) during haze episodes in warm seasons, daily PM 2.5 and gaseous samples were collected from March to September 2015 in Hangzhou, China. Daily samples were further divided into four groups by the definition of haze according to visibility and relative humidity (RH), including non-haze (visibility, >10 km), light haze (visibility, 8-10 km, RH <90 %), medium haze (visibility, 5-8 km, RH <90 %), and heavy haze (visibility, <5 km, RH <90 %). Significantly higher concentrations of PM 2.5 -bound PAHs were found in haze days, but the mean PM 2.5 -bound PAH concentrations obviously decreased with the aggravation of haze pollution from light to heavy. The gas/particle partitioning coefficients of PAHs decreased from light-haze to heavy-haze episodes, which indicated that PM 2.5 -bound PAHs were restricted to adhere to the particulate phase with the aggravation of haze pollution. Absorption was considered the main mechanism of gas/particle partitioning of PAHs from gaseous to particulate phase. Analysis of air mass transport indicated that the PM 2.5 -bound PAH pollution in haze days was largely from regional sources but also significantly affected by long-range air mass transport. The inhalation cancer risk associated with PAHs exceeded the acceptable risk level markedly in both haze and non-haze days.

Enhanced capture rate for haze defects in production wafer inspection

NASA Astrophysics Data System (ADS)

Auerbach, Ditza; Shulman, Adi; Rozentsvige, Moshe

2010-03-01

Photomask degradation via haze defect formation is an increasing troublesome yield problem in the semiconductor fab. Wafer inspection is often utilized to detect haze defects due to the fact that it can be a bi-product of process control wafer inspection; furthermore, the detection of the haze on the wafer is effectively enhanced due to the multitude of distinct fields being scanned. In this paper, we demonstrate a novel application for enhancing the wafer inspection tool's sensitivity to haze defects even further. In particular, we present results of bright field wafer inspection using the on several photo layers suffering from haze defects. One way in which the enhanced sensitivity can be achieved in inspection tools is by using a double scan of the wafer: one regular scan with the normal recipe and another high sensitivity scan from which only the repeater defects are extracted (the non-repeater defects consist largely of noise which is difficult to filter). Our solution essentially combines the double scan into a single high sensitivity scan whose processing is carried out along two parallel routes (see Fig. 1). Along one route, potential defects follow the standard recipe thresholds to produce a defect map at the nominal sensitivity. Along the alternate route, potential defects are used to extract only field repeater defects which are identified using an optimal repeater algorithm that eliminates "false repeaters". At the end of the scan, the two defect maps are merged into one with optical scan images available for all the merged defects. It is important to note, that there is no throughput hit; in addition, the repeater sensitivity is increased relative to a double scan, due to a novel runtime algorithm implementation whose memory requirements are minimized, thus enabling to search a much larger number of potential defects for repeaters. We evaluated the new application on photo wafers which consisted of both random and haze defects. The evaluation procedure involved scanning with three different recipe types: Standard Inspection: Nominal recipe with a low false alarm rate was used to scan the wafer and repeaters were extracted from the final defect map. Haze Monitoring Application: Recipe sensitivity was enhanced and run on a single field column from which on repeating defects were extracted. Enhanced Repeater Extractor: Defect processing included the two parallel routes: a nominal recipe for the random defects and the new high sensitive repeater extractor algorithm. The results showed that the new application (recipe #3) had the highest capture rate on haze defects and detected new repeater defects not found in the first two recipes. In addition, the recipe was much simpler to setup since repeaters are filtered separately from random defects. We expect that in the future, with the advent of mask-less lithography and EUV lithography, the monitoring of field and die repeating defects on the wafer will become a necessity for process control in the semiconductor fab.

Toxic epidermal necrolysis: an update

PubMed Central

Tiwari, Prashant; Panik, Rajnikant; Bhattacharya, Arin; Ahirwar, Dheeraj; Chandy, Anish

2013-01-01

Toxic epidermal necrolysis (TEN), also known as Lyell's syndrome, is a rare, life-threatening dermatological condition that is usually induced by reaction to medications. It is characterized by the detachment of the top layer of skin (the epidermis) from the lower layers of the skin (the dermis) all over the body. There is broad agreement in medical literature that TEN can be considered a more severe form of Stevens Johnson syndrome, and debate whether it falls on a spectrum of disease that includes erythema multiforme. Some authors consider that there is an overlap between the two syndromes (usually between 10% and 30% of skin detachment). This article deals with history, epidemiology, diagnosis, pathophysiology treatment and management of TEN.

Broken Pledges: The Deadly Rite of Hazing.

ERIC Educational Resources Information Center

Nuwer, Hank

The practice of hazing in college fraternities, sororities, high school clubs, professional societies, business, the military, and secret societies is investigated. Through the retelling of actual stories involving hazing, the book addresses the questions of why men and women haze and allow themselves to be hazed, how the problems of hazing can be…

76 FR 12651 - Approval and Promulgation of Implementation Plans; State of Oregon; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-08

... reasonable progress goals and the long term strategy. A. Definition of Regional Haze Regional haze is... Addressing Regional Haze Successful implementation of the Regional Haze Program will require long-term...'s long term strategy for addressing regional haze. The reasonable progress goals in the draft and...

Salt geometry influence on present-day stress orientations in the Nile Delta: Insights from numerical modeling

NASA Astrophysics Data System (ADS)

Eckert, Andreas; Zhang, Weicheng

2016-02-01

The offshore Nile Delta displays sharply contrasting orientations of the maximum horizontal stress, SH, in regions above Messinian evaporites (suprasalt) and regions below Messinian evaporites (subsalt). Published stress orientation data predominantly show margin-normal suprasalt SH orientations but a margin-parallel subsalt SH orientation. While these data sets provide the first major evidence that evaporite sequences can act as mechanical detachment horizons, the cause for the stress orientation contrast remains unclear. In this study, 3D finite element analysis is used to investigate the causes for stress re-orientation based on two different hypotheses. The modeling study evaluates the influence of different likely salt geometries and whether stress reorientations are the result of basal drag forces induced by gravitational gliding or whether they represent localized variations due to mechanical property contrasts. The modeling results show that when salt is present as a continuous layer, gravitational gliding occurs and basal drag forces induced in the suprasalt layers result in the margin-normal principal stress becoming the maximum horizontal stress. With the margin-normal stress increase being confined to the suprasalt layers, the salt acts as a mechanical detachment horizon, resulting in different SH orientations in the suprasalt compared to the subsalt layers. When salt is present as isolated bodies localized stress variations occur due to the mechanical property contrasts imposed by the salt, also resulting in different SH orientations in the suprasalt compared to the subsalt layers. The modeling results provide additional quantitative evidence to confirm the role of evaporite sequences as mechanical detachment horizons.

Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney

The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further themore » similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.« less

HST ROTATIONAL SPECTRAL MAPPING OF TWO L-TYPE BROWN DWARFS: VARIABILITY IN AND OUT OF WATER BANDS INDICATES HIGH-ALTITUDE HAZE LAYERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Hao; Apai, Dániel; Karalidi, Theodora

We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759–1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 μm and 1.7 μm. We find that the water absorption bands of the two L5 dwarfs at 1.15 μm and 1.4 μm vary at similar amplitudes as the adjacent continuum. This differs from the results of previous HST observations of L/T transition dwarfs, in which the water absorption at 1.4 μm displays variations of about half of the amplitude at othermore » wavelengths. We find that the relative amplitude of flux variability out of the water band with respect to that in the water band shows a increasing trend from the L5 dwarfs toward the early T dwarfs. We utilize the models of Saumon and Marley and find that the observed variability of the L5 dwarfs can be explained by the presence of spatially varying high-altitude haze layers above the condensate clouds. Therefore, our observations show that the heterogeneity of haze layers—the driver of the variability—must be located at very low pressures, where even the water opacity is negligible. In the near future, the rotational spectral mapping technique could be utilized for other atomic and molecular species to probe different pressure levels in the atmospheres of brown dwarfs and exoplanets and uncover both horizontal and vertical cloud structures.« less

Interplay between magmatic accretion, spreading asymmetry and detachment faulting at a segment end: Crustal structure south of the Ascension Fracture Zone

NASA Astrophysics Data System (ADS)

Bialas, Jörg; Dannowski, Anke; Reston, Timothy J.

2015-12-01

A wide-angle seismic section across the Mid-Atlantic Ridge just south of the Ascension transform system reveals laterally varying crustal thickness, and to the east a strongly distorted Moho that appears to result from slip along a large-offset normal fault, termed an oceanic detachment fault. Gravity modelling supports the inferred crustal structure. We investigate the interplay between magmatism, detachment faulting and the changing asymmetry of crustal accretion, and consider several possible scenarios. The one that appears most likely is remarkably simple: an episode of detachment faulting which accommodates all plate divergence and results in the westward migration of the ridge axis, is interspersed with dominantly magmatic and moderately asymmetric (most on the western side) spreading which moves the spreading axis back towards the east. Following the runaway weakening of a normal fault and its development into an oceanic detachment fault, magma both intrudes the footwall to the fault, producing a layer of gabbro (subsequently partially exhumed).

Surface-properties relationship in sputtered Ag thin films: Influence of the thickness and the annealing temperature in nitrogen

NASA Astrophysics Data System (ADS)

Guillén, C.; Herrero, J.

2015-01-01

Metal layers with high roughness and electrical conductivity are required as back-reflector electrodes in several optoelectronic devices. The metal layer thickness and the process temperature should be adjusted to reduce the material and energetic costs for the electrode preparation. Here, Ag thin films with thickness ranging from 30 to 200 nm have been deposited by sputtering at room temperature on glass substrates. The structure, morphology, optical and electrical properties of the films have been analyzed in the as-grown conditions and after thermal treatment in flowing nitrogen at various temperatures in the 150-550 °C range. The surface texture has been characterized by the root-mean-square roughness and the correlation length coefficients, which are directly related to the electrical resistivity and the light-scattering parameter (reflectance haze) for the various samples. The increment in the reflectance haze has been used to detect surface agglomeration processes that are found dependent on both the film thickness and the annealing temperature. A good compromise between light-scattering and electrical conductivity has been achieved with 70 nm-thick Ag films after 350 °C heating.

An Analysis of Cassini Observations Regarding the Structure of Jupiter's Equatorial Atmosphere

NASA Technical Reports Server (NTRS)

Choi, David S.; Simon-Miller, Amy A.

2012-01-01

A variety of intriguing atmospheric phenomena reside on both sides of Jupiter's equator. 5-micron bright hot spots and opaque plumes prominently exhibit dynamic behavior to the north, whereas compact, dark chevron-shaped features and isolated anticyclonic disturbances periodically occupy the southern equatorial latitudes. All of these phenomena are associated with the vertical and meridional perturbations of Rossby waves disturbing the mean atmospheric state. As previous observational analysis and numerical simulations have investigated the dynamics of the region, an examination of the atmosphere's vertical structure though radiative transfer analysis is necessary for improved understanding of this unique environment. Here we present preliminary analysis of a multispectral Cassini imaging data set acquired during the spacecraft's flyby of Jupiter in 2000. We evaluated multiple methane and continuum spectral channels at available viewing angles to improve constraints on the vertical structure of the haze and cloud layers comprising these interesting features. Our preliminary results indicate distinct differences in the structure for both hemispheres. Upper troposphere hazes and cloud layers are prevalent in the northern equatorial latitudes, but are not present in corresponding southern latitudes. Continued analysis will further constrain the precise structure present in these phenomena and the differences between them.

Detached eddy simulation for turbulent fluid-structure interaction of moving bodies using the constraint-based immersed boundary method

NASA Astrophysics Data System (ADS)

Nangia, Nishant; Bhalla, Amneet P. S.; Griffith, Boyce E.; Patankar, Neelesh A.

2016-11-01

Flows over bodies of industrial importance often contain both an attached boundary layer region near the structure and a region of massively separated flow near its trailing edge. When simulating these flows with turbulence modeling, the Reynolds-averaged Navier-Stokes (RANS) approach is more efficient in the former, whereas large-eddy simulation (LES) is more accurate in the latter. Detached-eddy simulation (DES), based on the Spalart-Allmaras model, is a hybrid method that switches from RANS mode of solution in attached boundary layers to LES in detached flow regions. Simulations of turbulent flows over moving structures on a body-fitted mesh incur an enormous remeshing cost every time step. The constraint-based immersed boundary (cIB) method eliminates this operation by placing the structure on a Cartesian mesh and enforcing a rigidity constraint as an additional forcing in the Navier-Stokes momentum equation. We outline the formulation and development of a parallel DES-cIB method using adaptive mesh refinement. We show preliminary validation results for flows past stationary bodies with both attached and separated boundary layers along with results for turbulent flows past moving bodies. This work is supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1324585.

Long-term damage to glass in Paris in a changing environment.

PubMed

Ionescu, Anda; Lefèvre, Roger-Alexandre; Brimblecombe, Peter; Grossi, Carlota M

2012-08-01

Glass weathering depends mainly on its chemical composition: Si-Ca-K mediaeval glass is low durable, while Si-Ca-Na Roman as well as modern glass are very durable. Mediaeval glass is subject to the superficial leaching of K and Ca ions leading to the formation of a hydrated silica-gel layer. Both types of glass develop a superficial stratum of deposited atmospheric particles cemented by crystals of gypsum (and syngenite in the case of Si-Ca-K glass), leading to an impairment of the optical properties: decrease of transparency and increase of haze. Dose-response functions established for the two types of glass reveal that haze depends only on pollution parameters (PM, SO(2), NO(2)), while leaching depends both on pollution and climate parameters (RH, T, SO(2), NO(2)). Instrumental records are available for temperature in Paris from 1800. Air pollution in Paris was estimated from statistics of fuel use from 1875 to 1943, measurements that started in the 1950s and projections across the 21st century. The estimated annual rate of haze development indicates a gradual rise from the 16th century. The increasing importance of coal as a fuel through the 19th century and enhanced sulphur dioxide concentration make a rapid increase in haze formation, which reaches a peak about 1950. The likely damage to mediaeval glass follows a rather similar pattern. The period of damage from aggressive pollutants looks later and for a briefer time in Paris than in London. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of meteorology and secondary particle formation on visibility during heavy haze events in Beijing, China.

PubMed

Zhang, Qiang; Quan, Jiannong; Tie, Xuexi; Li, Xia; Liu, Quan; Gao, Yang; Zhao, Delong

2015-01-01

The causes of haze formation in Beijing, China were analyzed based on a comprehensive measurement, including PBL (planetary boundary layer), aerosol composition and concentrations, and several important meteorological parameters such as visibility, RH (relative humidity), and wind speed/direction. The measurement was conducted in an urban location from Nov. 16, 2012 to Jan. 15, 2013. During the period, the visibility varied from >20 km to less than a kilometer, with a minimum visibility of 667 m, causing 16 haze occurrences. During the haze occurrences, the wind speeds were less than 1m/s, and the concentrations of PM2.5 (particle matter with radius less than 2.5 μm) were often exceeded 200 μg/m(3). The correlation between PM2.5 concentration and visibility under different RH values shows that visibility was exponentially decreased with the increase of PM2.5 concentrations when RH was less than 80%. However, when RH was higher than 80%, the relationship was no longer to follow the exponentially decreasing trend, and the visibility maintained in very low values, even with low PM2.5 concentrations. Under this condition, the hygroscopic growth of particles played important roles, and a large amount of water vapor acted as particle matter (PM) for the reduction of visibility. The variations of meteorological parameters (RH, PBL heights, and WS (wind speed)), chemical species in gas-phase (CO, O3, SO2, and NOx), and gas-phase to particle-phase conversions under different visibility ranges were analyzed. The results show that from high visibility (>20 km) to low visibility (<2 km), the averaged PBL decreased from 1.24 km to 0.53 km; wind speeds reduced from 1m/s to 0.5m/s; and CO increased from 0.5 ppmv to 4.0 ppmv, suggesting that weaker transport/diffusion caused the haze occurrences. This study also found that the formation of SPM (secondary particle matter) was accelerated in the haze events. The conversions between SO2 and SO4 as well as NOx to NO3(-) increased, especially under high humidity conditions. When the averaged RH was 70%, the conversions between SO2 and SO4 accounted for about 20% concentration of PM2.5, indicating that formation of secondary particle matter had important contribution for the haze occurrences in Beijing. Copyright © 2014 Elsevier B.V. All rights reserved.

Arctic Haze Analysis

NASA Astrophysics Data System (ADS)

Mei, Linlu; Xue, Yong

2013-04-01

The Arctic atmosphere is perturbed by nature/anthropogenic aerosol sources known as the Arctic haze, was firstly observed in 1956 by J. Murray Mitchell in Alaska (Mitchell, 1956). Pacyna and Shaw (1992) summarized that Arctic haze is a mixture of anthropogenic and natural pollutants from a variety of sources in different geographical areas at altitudes from 2 to 4 or 5 km while the source for layers of polluted air at altitudes below 2.5 km mainly comes from episodic transportation of anthropogenic sources situated closer to the Arctic. Arctic haze of low troposphere was found to be of a very strong seasonal variation characterized by a summer minimum and a winter maximum in Alaskan (Barrie, 1986; Shaw, 1995) and other Arctic region (Xie and Hopke, 1999). An anthropogenic factor dominated by together with metallic species like Pb, Zn, V, As, Sb, In, etc. and nature source such as sea salt factor consisting mainly of Cl, Na, and K (Xie and Hopke, 1999), dust containing Fe, Al and so on (Rahn et al.,1977). Black carbon and soot can also be included during summer time because of the mix of smoke from wildfires. The Arctic air mass is a unique meteorological feature of the troposphere characterized by sub-zero temperatures, little precipitation, stable stratification that prevents strong vertical mixing and low levels of solar radiations (Barrie, 1986), causing less pollutants was scavenged, the major revival pathway for particulates from the atmosphere in Arctic (Shaw, 1981, 1995; Heintzenberg and Larssen, 1983). Due to the special meteorological condition mentioned above, we can conclude that Eurasian is the main contributor of the Arctic pollutants and the strong transport into the Arctic from Eurasia during winter caused by the high pressure of the climatologically persistent Siberian high pressure region (Barrie, 1986). The paper intends to address the atmospheric characteristics of Arctic haze by comparing the clear day and haze day using different dataset, including satellite remote sensing, ground-based observations and modelling. The key question is which information should be used for analysis and how to integrate the source information. The behavior of different atmospheric parameters as described in the paper is consistent and the analysis using satellite atmospheric parameters is in line with synoptic charts. Hence the different data sources are complementary and the results support each other (Mei et al., 2011). In the paper, Aerosol Optical Depth (AOD) from both satellite retrieval data and ground-based measurements were analyzed the characteristic, especially the absorption. We also discuss the effect of Arctic haze to the Arctic temperature, snow albedo and arctic flux in details.

The Lavrion Pb-Zn-Fe-Cu-Ag detachment-related district (Attica, Greece): Structural control on hydrothermal flow and element transfer-deposition

NASA Astrophysics Data System (ADS)

Scheffer, Christophe; Tarantola, Alexandre; Vanderhaeghe, Olivier; Voudouris, Panagiotis; Rigaudier, Thomas; Photiades, Adonis; Morin, Denis; Alloucherie, Alison

2017-10-01

The impact of lithological heterogeneities on deformation, fluid flow and ore deposition is discussed based on the example of the Lavrion low-angle detachment partly accommodating gravitational collapse of the Hellenides orogenic belt in Greece. The Lavrion peninsula is characterised by a multiphase Pb-Zn-Fe-Cu-Ag ore system with a probable pre-concentration before subduction followed by progressive remobilisation and deposition coeval with the development of a low-angle ductile to brittle shear zone. The mylonitic marble below the detachment shear zone is composed of white layers of pure marble alternating with blue layers containing impurities (SiO2, Al2O3, carbonaceous material). Ductile mylonitic deformation is more pervasive in the less competent impure blue marble. We propose that localised deformation in the impure marble is associated with fluid circulation and dolomitisation, which in turn causes an increase in competence of these layers. Mineralised cataclastic zones, crosscutting the mylonitic fabric, are preferentially localised in the more competent dolomitic layers. Oxygen and carbon isotopic signatures of marble invaded by carbonate replacement deposits during ductile to ductile-brittle deformation are consistent with decarbonation coeval with the invasion of magmatic fluids. Mineralised cataclastic zones reflecting brittle deformation evolve from low 13C to low 18O signatures, interpreted as local interaction with carbonaceous material that trends toward the contribution of a surface-derived fluid. These features indicate that the Lavrion area records a complex deposition history influenced by the evolution of fluid reservoirs induced by the thermal and mechanical evolution of the marble nappe stack. Ore remobilisation and deposition associated with the activity of the low-angle detachment is (i) firstly related to the intrusion of the Plaka granodiorite leading to porphyry-type and carbonate replacement mineralisation during ductile-brittle deformation and (ii) then marked by progressive penetration of surface-derived fluids guided by strain localisation in the more competent levels leading to epithermal mineralisation associated with brittle deformation.

Corneal haze following PRK with mitomycin C as a retreatment versus prophylactic use in the contralateral eye.

PubMed

Netto, Marcelo V; Chalita, Maria Regina; Krueger, Ronald R

2007-01-01

To report photorefractive keratectomy (PRK) treated with mitomycin C (MMC) for previous corneal haze in one eye and PRK with MMC to prevent corneal haze formation in the fellow eye. A 40-year-old woman underwent PRK with MMC to treat previous corneal haze (secondary to previous PRK without MMC) for residual refractive error of +0.50 +0.25 x 165 in the left eye and PRK with MMC to prevent corneal haze in the right eye. Postoperative slit-lamp examination revealed no haze in the right eye, but continued mild haze in the left eye. Treatment with PRK and MMC for previous corneal haze is not as effective as primary PRK with MMC in preventing postoperative corneal haze formation.

Geodynamic models of terrane accretion: Testing the fate of island arcs, oceanic plateaus, and continental fragments in subduction zones

NASA Astrophysics Data System (ADS)

Tetreault, J. L.; Buiter, S. J. H.

2012-08-01

Crustal growth at convergent margins can occur by the accretion of future allochthonous terranes (FATs), such as island arcs, oceanic plateaus, submarine ridges, and continental fragments. Using geodynamic numerical experiments, we demonstrate how crustal properties of FATs impact the amount of FAT crust that is accreted or subducted, the type of accretionary process, and the style of deformation on the overriding plate. Our results show that (1) accretion of crustal units occurs when there is a weak detachment layer within the FAT, (2) the depth of detachment controls the amount of crust accreted onto the overriding plate, and (3) lithospheric buoyancy does not prevent FAT subduction during constant convergence. Island arcs, oceanic plateaus, and continental fragments will completely subduct, despite having buoyant lithospheric densities, if they have rheologically strong crusts. Weak basal layers, representing pre-existing weaknesses or detachment layers, will either lead to underplating of faulted blocks of FAT crust to the overriding plate or collision and suturing of an unbroken FAT crust. Our experiments show that the weak, ultramafic layer found at the base of island arcs and oceanic plateaus plays a significant role in terrane accretion. The different types of accretionary processes also affect deformation and uplift patterns in the overriding plate, trench migration and jumping, and the dip of the plate interface. The resulting accreted terranes produced from our numerical experiments resemble observed accreted terranes, such as the Wrangellia Terrane and Klamath Mountain terranes in the North American Cordilleran Belt.

Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arney, Giada N.; Meadows, Victoria S.; Tovar, Guadalupe

Hazes are common in known planetary atmospheres, and geochemical evidence suggests that early Earth occasionally supported an organic haze with significant environmental and spectral consequences. The UV spectrum of the parent star drives organic haze formation through methane photochemistry. We use a 1D photochemical-climate model to examine production of fractal organic haze on Archean Earth-analogs in the habitable zones of several stellar types: the modern and early Sun, AD Leo (M3.5V), GJ 876 (M4V), ϵ Eridani (K2V), and σ Boötis (F2V). For Archean-like atmospheres, planets orbiting stars with the highest UV fluxes do not form haze because of the formationmore » of photochemical oxygen radicals that destroy haze precursors. Organic hazes impact planetary habitability via UV shielding and surface cooling, but this cooling is minimized around M dwarfs, whose energy is emitted at wavelengths where organic hazes are relatively transparent. We generate spectra to test the detectability of haze. For 10 transits of a planet orbiting GJ 876 observed by the James Webb Space Telescope , haze makes gaseous absorption features at wavelengths < 2.5 μ m 2–10 σ shallower than a haze-free planet, and methane and carbon dioxide are detectable at >5 σ . A haze absorption feature can be detected at 5 σ near 6.3 μ m, but a higher signal-to-noise ratio is needed to distinguish haze from adjacent absorbers. For direct imaging of a planet at 10 pc using a coronagraphic 10 m class ultraviolet–visible–near-infrared telescope, a UV–blue haze absorption feature would be strongly detectable at >12 σ in 200 hr.« less

Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets

NASA Astrophysics Data System (ADS)

Arney, Giada N.; Meadows, Victoria S.; Domagal-Goldman, Shawn D.; Deming, Drake; Robinson, Tyler D.; Tovar, Guadalupe; Wolf, Eric T.; Schwieterman, Edward

2017-02-01

Hazes are common in known planetary atmospheres, and geochemical evidence suggests that early Earth occasionally supported an organic haze with significant environmental and spectral consequences. The UV spectrum of the parent star drives organic haze formation through methane photochemistry. We use a 1D photochemical-climate model to examine production of fractal organic haze on Archean Earth-analogs in the habitable zones of several stellar types: the modern and early Sun, AD Leo (M3.5V), GJ 876 (M4V), ɛ Eridani (K2V), and σ Boötis (F2V). For Archean-like atmospheres, planets orbiting stars with the highest UV fluxes do not form haze because of the formation of photochemical oxygen radicals that destroy haze precursors. Organic hazes impact planetary habitability via UV shielding and surface cooling, but this cooling is minimized around M dwarfs, whose energy is emitted at wavelengths where organic hazes are relatively transparent. We generate spectra to test the detectability of haze. For 10 transits of a planet orbiting GJ 876 observed by the James Webb Space Telescope, haze makes gaseous absorption features at wavelengths < 2.5 μm 2-10σ shallower than a haze-free planet, and methane and carbon dioxide are detectable at >5σ. A haze absorption feature can be detected at 5σ near 6.3 μm, but a higher signal-to-noise ratio is needed to distinguish haze from adjacent absorbers. For direct imaging of a planet at 10 pc using a coronagraphic 10 m class ultraviolet-visible-near-infrared telescope, a UV-blue haze absorption feature would be strongly detectable at >12σ in 200 hr.

Urbanization and industrialization effects on haze in China: take Jinagsu for example

NASA Astrophysics Data System (ADS)

Liu, Duanyang; Wei, Jiansu; Kang, Zhiming; Yan, Wenlian; Cao, Lu; Chen, Hao

2017-04-01

Since the policy of ''Reform and Open to the Outside World'' was implemented from 1978, urbanization and industrialization have been rapid in China, leading to the expansion of urban areas, industrial district and population synchronous with swift advances in economy. With urban industrialization development underway, the urban heat island (UHI) and air pollution are being enhanced, together with vegetation coverage and relative humidity on the decrease. Based on the surface meteorological data of Jiangsu Province during 1980-2012, the climatic characteristics and the trends of haze were analyzed. The results indicated that during 1980-2012 haze days increased; in particular, severe and moderate haze days significantly increased. In the northern and coastal cities of Jiangsu Province China, haze days showed a significant increase. Haze often appeared in fall and winter, and rare in summer in the study area. It also occurred more often inland, and less along the coast. Haze occurred more often in June due to straw burning in the harvest time. The haze day increased during the 1990's over southern and southwestern Jiangsu Province; in central and northern Jiangsu, haze day increased after 2000. The continuous, regional and regional continuous haze days all showed increasing trends. As the urban area expanded each year, industrial emissions, coal consumption and car ownership increased accordingly, resulting in regional temperature increase and relative humidity decrease, which formed the urban heat island and dry island effects. Hence, haze formation and maintenance conditions became more favorable for more haze days, which led to the increase of haze days, and the significant increases of continuous, regional and regional continuous haze days.

The characteristics of premature infants with transient corneal haze.

PubMed

Lai, Yu-Hung; Chen, Hsiu-Lin; Yang, San-Nan; Chang, Shun-Jen; Chuang, Lea-Yea; Wu, Wen-Chuan

2018-01-01

The etiology of transient corneal haze in premature infants is not known and how it relates to clinical outcomes in premature infants is not clear. To study associated factors of transient corneal haze in premature infants. We performed a retrospective study of 261 premature infants from retinopathy of prematurity (ROP) screening in the neonatal intensive care unit at a tertiary referral hospital. Characteristics of premature infants with and without corneal haze were analyzed by correlation tests, Chi-square tests, and logistic regressions were used for statistical analyses. Associations between corneal haze and birth weight (BW), gestational age at birth (GA), central corneal thickness, intraocular pressure, and other systemic and ophthalmic data were evaluated. The incidence of corneal haze was 13.4%. Lower BW, lower GA, packed red blood cells (RBC) transfusion, more days on oxygen, older maternal age, bronchopulmonary disease, and stage 3 ROP are associated with corneal haze. The severity of corneal haze decreased with infants' postmenstrual age. Multivariate logistic regression analyses revealed that BW and maternal age are the most important predictors of corneal haze. Low BW and older maternal age are the most important predictors of corneal haze in premature infants. Premature infants with corneal haze could carry more systemic and ocular morbidities. Hence they may require more clinical attention. Corneal haze is unlikely to hinder the treatment of ROP. However, it is possible that corneal haze could hinder the examination of ROP in some infants. If corneal haze does interfere with ROP screening, a closer, more conservative follow-up schedule with a senior ophthalmologist experienced in managing ROP is recommended.

BILATERAL SEROUS MACULAR DETACHMENT IN A PATIENT WITH NEPHROTIC SYNDROME.

PubMed

Bilge, Ayse D; Yaylali, Sevil A; Yavuz, Sara; Simsek, İlke B

2018-01-01

The purpose of this study was to report a case of a woman with nephrotic syndrome who presented with blurred vision because of bilateral serous macular detachment. Case report and literature review. A 55-year-old woman with a history of essential hypertension, diabetes, and nephrotic syndrome was presented with blurred vision in both eyes. Her fluorescein angiography revealed dye leakage in the early and subretinal pooling in the late phases, and optical coherence tomography scans confirmed the presence of subretinal fluid in the subfovel area. In nephrotic syndrome cases especially with accompaniment of high blood pressure, fluid accumulation in the retina layer may occur. Serous macular detachment must be kept in mind when treating these patients.

Carbonate pseudotachylite? from a Miocene extensional detachment, W. Cyclades, Greece.

NASA Astrophysics Data System (ADS)

Rice, A. Hugh N.; Grasemann, Bernhard

2016-04-01

Most pseudotachylites, both impact- and fault-related, occur in silicate-rich rocks, typically with 'granitoid' compositions. Examples of melting in carbonate rocks, excluding magmatic sources, are restricted to impact-events, except for a carbonate pseudotachylite in the Canalone Fault, S. Italy (Viganò et al. 2011). Another potential example of carbonate pseudotachylite, shown here, comes from the Miocene-aged W. Cycladic Detachment System, in Greece. Top-SSE ductile to brittle movement on this detachment, with a maximum displacement estimated at tens of kilometers, exhumed of HP-rocks. The carbonate pseudotachylite occurs within an <200 mm thick zone of cataclasites developed between footwall carbonate ultramylonites, containing thin layers and cm-scale boudins of quartzite, and hanging wall breccias; no contacts with the footwall ultramylonites or hanging wall breccias has been found (yet). The cataclasite zone, which can be traced along-strike for at least 90 m, over ~20 m elevation, comprises several distinct layers. In the sample described, five layers occur. The lowest (A; >43 mm thick), consists of dark (hematitic) red, ultra-fine grained unlayered carbonate with up to 40x10 mm rather rounded clasts of earlier generations of cataclasite, many with a quartzite composition. These clasts are fractured and partially separated, with a fine red carbonate matrix. No layering of the matrix or clasts is apparent. The clasts become finer and more abundant towards the boundary with Layer B. Layers B and D (~57 & ~20 mm thick) dominantly comprises protocataclasite with greyish quartz fragments separated by a carbonate matrix along narrow fractures. Zone C and E (~23 m & >15 mm thick) comprise pale pink carbonate-dominated rocks with abundant <30x5 mm-sized red carbonate clasts (+/- quartz fragments) of earlier cataclasite generations. These elongate clasts lie parallel to the overall banding, which is parallel to the ultramylonitic foliation (detachment surface). Smaller clasts are markedly more rounded and comprise carbonate and quartzite material and may have darker (?reaction) rims. No layering is seen in the pale pink groundmass although this is present in some elongate clasts. All layer boundaries are irregular and no principle slip surfaces have been seen. Injection veins from 1 to 9 mm wide and up to at least 100 mm long derive from the central layer (C), cutting the overall layering at a high angle and branching in several places. These veins contain clasts comparable to those in Layer C. Both thick and thin injection-veins are rimmed by impersistent white calcite suggesting that injection was associated with precipitation of calcite. Whether Layer C (and perhaps E also) is a carbonate pseudotachylite is unknown. Although the injection veins are suggestive of this, these also occur in conjunction with ultracataclasites (Craddock et al. 2012). The irregular boundaries between the layers and the lack of any principal slip surfaces might indicate decarbonation and/or fluidization of gouge layer (Rowe and Griffith, 2015). Finally, abundant tubules, with rounded profiles and mostly sub-circular shapes up to 1.2 mm across, occur in Layers C and E, and less so D; these could be interpreted to reflect vents formed by partial carbonate degassing during melting.

Some effects of oscillation waveform and amplitude on unsteady turbulent shear flows

NASA Technical Reports Server (NTRS)

Agarwal, Naval K.; Simpson, Roger L.; Shivaprasad, B. G.

1992-01-01

Some physical features of several unsteady separating turbulent boundary layers are presented for practical Reynolds numbers and reduced frequencies such as for helicopter and turbomachinery flows. The effects of unsteadiness amplitude and waveform are examined for flows along the floor of a converging and diverging wind tunnel test section. At the end of the converging portion, the mean skin friction coefficient normalized on the mean dynamic pressure is independent of the waveform and amplitude within low experimental uncertainties. In the detaching and detached portions of the flow, wall values of the fraction of time that the flow moves downstream of gamma sub pu, which is a separated flow state variable, shows that oscillation waveform and amplitude strongly influence the detached flow behavior. Distributions of gamma sub pu during a cycle indicate hysteresis within the detached flow and the effects of the higher harmonics of pressure gradient and velocity.

77 FR 43205 - Notice of Data Availability for Approval, Disapproval and Promulgation of Implementation Plans...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-24

... Haze State Implementation Plan; Federal Implementation Plan for Regional Haze AGENCY: Environmental... (SIP) revision submitted by the State of Wyoming on January 12, 2011, that addresses regional haze...; Regional Haze State Implementation Plan; Federal Implementation Plan for Regional Haze; Proposed Rule (77...

Haze in Apple-Based Beverages: Detailed Polyphenol, Polysaccharide, Protein, and Mineral Compositions.

PubMed

Millet, Melanie; Poupard, Pascal; Le Quéré, Jean-Michel; Bauduin, Remi; Guyot, Sylvain

2017-08-09

Producers of apple-based beverages are confronted with colloidal instability. Haze is caused by interactions between molecules that lead to the formation of aggregates. Haze composition in three apple-based beverages, namely, French sparkling cider, apple juice, and pommeau, was studied. Phenolic compounds, proteins, polysaccharides, and minerals were analyzed using global and detailed analytical methods. The results explained <75% (w/w) of haze dry mass. Polyphenols, represented mainly by procyanidins, were the main compounds identified and accounted for 10-31% of haze. However, oxidized phenolic compounds were probably underestimated and may represent a high proportion of haze. Proteins were present in all of the samples in proportions of <6% of haze except in two apple juice hazes, where they were the main constituents (18 and 24%). Polysaccharides accounted for 0-30% of haze. Potassium and calcium were the main minerals.

The Progression of Haze Formation in Rabbit Corneas Following Phototherapeutic Keratectomy

PubMed Central

Gibson, Daniel J.; Tuli, Sonal S.; Schultz, Gregory S.

2013-01-01

Purpose. To determine the topographical location and time course of development of corneal haze in a phototherapeutic keratectomy model using slit lamp examination, macrophotography, quantitative image analysis, and immunofluorescence staining of corneal sections. Methods. Rabbit corneas were ablated with an excimer laser and were observed and graded for haze via slit lamp, imaged, and graded by macrophotography. Corneal sections were stained for α-smooth muscle actin (α-SMA) and tenascin-C (TNC). The distribution of haze imaged in the macrophotographs and density of α-SMA and TNC staining were compared. A daily image time course of haze formation was generated using macrophotography. Results. The first signs of corneal haze were apparent shortly after reepithelialization. The haze was distributed as a ring at the wound margin in all cases, while nearly all corneas also had some central islands of haze initiation. With time, the haze spread within the ablated zone and intensified. The pattern of immunofluorescent staining for α-SMA and TNC at the wound margin mirrored the haze distribution, spread, and intensification with time. Conclusions. The initiation and spread of subepithelial haze begins shortly after reepithelialization. The haze then spreads from the loci of initiation and becomes more dense with time, maturing as early as 14 days after wounding. The improved temporal and spatial resolution provided by these data improve the current model of light-scattering haze formation in wounded corneas, which will improve the design of studies aimed at maintaining corneal clarity following acute injury or surgery. PMID:23800768

Tauroursodeoxycholic Acid (TUDCA) Protects Photoreceptors from Cell Death after Experimental Retinal Detachment

PubMed Central

Mantopoulos, Dimosthenis; Murakami, Yusuke; Comander, Jason; Thanos, Aristomenis; Roh, Miin; Miller, Joan W.; Vavvas, Demetrios G.

2011-01-01

Background Detachment of photoreceptors from the underlying retinal pigment epithelium is seen in various retinal disorders such as retinal detachment and age-related macular degeneration and leads to loss of photoreceptors and vision. Pharmacologic inhibition of photoreceptor cell death may prevent this outcome. This study tests whether systemic administration of tauroursodeoxycholic acid (TUDCA) can protect photoreceptors from cell death after experimental retinal detachment in rodents. Methodology/Principal Findings Retinal detachment was created in rats by subretinal injection of hyaluronic acid. The animals were treated daily with vehicle or TUDCA (500 mg/kg). TUNEL staining was used to evaluate cell death. Photoreceptor loss was evaluated by measuring the relative thickness of the outer nuclear layer (ONL). Macrophage recruitment, oxidative stress, cytokine levels, and caspase levels were also quantified. Three days after detachment, TUDCA decreased the number of TUNEL-positive cells compared to vehicle (651±68/mm2 vs. 1314±68/mm2, P = 0.001) and prevented the reduction of ONL thickness ratio (0.84±0.03 vs. 0.65±0.03, P = 0.002). Similar results were obtained after 5 days of retinal detachment. Macrophage recruitment and expression levels of TNF-a and MCP-1 after retinal detachment were not affected by TUDCA treatment, whereas increases in activity of caspases 3 and 9 as well as carbonyl-protein adducts were almost completely inhibited by TUDCA treatment. Conclusions/Significance Systemic administration of TUDCA preserved photoreceptors after retinal detachment, and was associated with decreased oxidative stress and caspase activity. TUDCA may be used as a novel therapeutic agent for preventing vision loss in diseases that are characterized by photoreceptor detachment. PMID:21961034

Improving biomass burning pollution predictions in Singapore using AERONET and Lidar observations.

NASA Astrophysics Data System (ADS)

Hardacre, Catherine; Chew, Boon Ning; Gan, Christopher; Burgin, Laura; Hort, Matthew; Lee, Shao Yi; Shaw, Felicia; Witham, Claire

2016-04-01

Every year millions of people are affected by poor air quality from trans-boundary smoke haze emitted from large scale biomass burning in Asia. These fires are a particular problem in the Indonesian regions of Sumatra and Kalimantan where peat fires, lit to clear land for oil palm plantations and agriculture, typically result in high levels of particulate matter (PM) emissions. In June 2013 and from August-October 2015 the combination of widespread burning, meteorological and climatological conditions resulted in severe air pollution throughout Southeast Asia. The Met Office of the United Kingdom (UKMO) and the Hazard and Risk Impact Assessment Unit of the Meteorological Service of Singapore (MSS) have developed a quantitative haze forecast to provide a reliable, routine warning of haze events in the Singapore region. The forecast system uses the UKMO's Lagrangian particle dispersion model NAME (Numerical Atmosphere-dispersion Modelling Environment) in combination with high resolution, satellite based emission data from the Global Fire Emissions System (GFAS). The buoyancy of biomass burning smoke and it's rise through the atmosphere has a large impact on the amount of air pollution at the Earth's surface. This is important in Singapore, which is affected by pollution that has travelled long distances and that will have a vertical distribution influenced by meteorology. The vertical distribution of atmospheric aerosol can be observed by Lidar which provides information about haze plume structure. NAME output from two severe haze periods that occurred in June 2013 and from August-October 2015 was compared with observations of total column aerosol optical depth (AOD) from AERONET stations in Singapore and the surrounding region, as well as vertically resolved Lidar data from a station maintained by MSS and from MPLNET. Comparing total column and vertically resolved AOD observations with NAME output indicates that the model underestimates PM concentrations throughout the column. This discrepancy may arise from i) too low emissions of PM, ii) uncertainties in the long range transport of PM or iii) the role of the boundary layer in NWP, all of which are being explored at UKMO and MSS. This study gives a more comprehensive evaluation of the model's performance and indicates that vertically resolved AOD data may be useful as a model input for the haze forecast system.

Predicting the soiling of modern glass in urban environments: A new physically-based model

NASA Astrophysics Data System (ADS)

Alfaro, S. C.; Chabas, A.; Lombardo, T.; Verney-Carron, A.; Ausset, P.

2012-12-01

This study revisits the measurements of the MULTI-ASSESS and Long Term Soiling programs for understanding physically, and modeling, the processes controlling the soiling of modern glass in polluted conditions. The results show a strong correlation between the size distribution of particles and the evolution of the mass deposited at the surface of the glass. Over observation periods covering more than 2 years, the mass deposition on glass panels sheltered from the rain is observed to accelerate regularly with time at the sites closest to the sources of particulate matter (Roadside sites). At these sites the deposit is also richer in coarse (supermicron) mineral particles than at more distant (Urban Background and Suburban) sites, where the contribution of submicron particles (among which a significant fraction of particulate organic matter) is larger. This size and compositional segregation probably explains that the mass accumulation tends to slow down with time and finally saturate after an estimated duration of more than 10 years at the Suburban sites. The analysis of the correlation between the measured accumulated mass and haze shows that the haze-creating mass efficiency of the deposit decreases progressively as the density of particles increases on the glass panels. This is interpreted as being a consequence of the increasing influence of multiple scattering. A steady-state is eventually obtained when layers of closely packed particles are formed, which occurs for surface masses of the order of a few tens of μg cm-2. After this stage is reached, the haze increases linearly with further mass deposition at a pace conditioned by the size-distribution of the deposit. The parameterization of the evolution of the deposited mass with time, and of the correlation linking this mass to the haze allows proposing a new physically-based model able to predict the development of the haze on sheltered glass. Finally, a comparison of the model predictions with the independent measurements performed at the experimental sites of the AERO program shows that the model is able to simulate correctly the development of the haze at a variety of urban sites ranging from the Suburban to Roadside categories. This predictive tool should help developing conservation strategies adapted to the real environmental conditions of the historical and modern buildings.

Dusk in the South

NASA Image and Video Library

2013-12-23

Slipping into shadow, the south polar vortex at Saturn's moon Titan still stands out against the orange and blue haze layers that are characteristic of Titan's atmosphere. Images like this, from NASA's Cassini spacecraft, lead scientists to conclude that the polar vortex clouds form at a much higher altitude -- where sunlight can still reach -- than the lower-altitude surrounding haze. This view looks towards the trailing hemisphere of Titan (3,200 miles or 5,150 kilometers across). North on Titan is up and rotated 17 degrees to the left. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The image was taken with the Cassini spacecraft narrow-angle camera on July 30, 2013. The view was acquired at a distance of approximately 895,000 miles (1.441 million kilometers) from Titan. Image scale is 5 miles (9 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA17177

Pluto Majestic Mountains, Frozen Plains and Foggy Hazes

NASA Image and Video Library

2015-09-17

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA's New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto's horizon. The smooth expanse of the informally named icy plain Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. To the right, east of Sputnik, rougher terrain is cut by apparent glaciers. The backlighting highlights more than a dozen layers of haze in Pluto's tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 780 miles (1,250 kilometers) wide. http://photojournal.jpl.nasa.gov/catalog/PIA19948

Source apportionment and health risk assessment among specific age groups during haze and non-haze episodes in Kuala Lumpur, Malaysia.

PubMed

Sulong, Nor Azura; Latif, Mohd Talib; Khan, Md Firoz; Amil, Norhaniza; Ashfold, Matthew J; Wahab, Muhammad Ikram Abdul; Chan, Kok Meng; Sahani, Mazrura

2017-12-01

This study aims to determine PM 2.5 concentrations and their composition during haze and non-haze episodes in Kuala Lumpur. In order to investigate the origin of the measured air masses, the Numerical Atmospheric-dispersion Modelling Environment (NAME) and Global Fire Assimilation System (GFAS) were applied. Source apportionment of PM 2.5 was determined using Positive Matrix Factorization (PMF). The carcinogenic and non-carcinogenic health risks were estimated using the United State Environmental Protection Agency (USEPA) method. PM 2.5 samples were collected from the centre of the city using a high-volume air sampler (HVS). The results showed that the mean PM 2.5 concentrations collected during pre-haze, haze and post-haze periods were 24.5±12.0μgm -3 , 72.3±38.0μgm -3 and 14.3±3.58μgm -3 , respectively. The highest concentration of PM 2.5 during haze episode was five times higher than World Health Organisation (WHO) guidelines. Inorganic compositions of PM 2.5 , including trace elements and water soluble ions were determined using inductively coupled plasma-mass spectrometry (ICP-MS) and ion chromatography (IC), respectively. The major trace elements identified were K, Al, Ca, Mg and Fe which accounted for approximately 93%, 91% and 92% of the overall metals' portions recorded during pre-haze, haze and post-haze periods, respectively. For water-soluble ions, secondary inorganic aerosols (SO 4 2- , NO 3 - and NH 4 + ) contributed around 12%, 43% and 16% of the overall PM 2.5 mass during pre-haze, haze and post-haze periods, respectively. During haze periods, the predominant source identified using PMF was secondary inorganic aerosol (SIA) and biomass burning where the NAME simulations indicate the importance of fires in Sumatra, Indonesia. The main source during pre-haze and post-haze were mix SIA and road dust as well as mineral dust, respectively. The highest non-carcinogenic health risk during haze episode was estimated among the infant group (HI=1.06) while the highest carcinogenic health risk was estimated among the adult group (2.27×10 -5 ). Copyright © 2017 Elsevier B.V. All rights reserved.

Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets

NASA Astrophysics Data System (ADS)

Arney, Giada; Meadows, Victoria; Domagal-Goldman, Shawn; Deming, Drake; Robinson, Tyler D.; Tovar, Guadalupe; Wolf, Eric; Schwieterman, Edward

2016-10-01

Hazes are common in planetary atmospheres, and geochemical evidence suggests early Earth occasionally supported an organic haze. The formation of organic hazes is initiated by methane photochemistry sensitive to the host star UV spectrum. Because methane can be produced by a variety of biological and geological processes, organic-rich terrestrial planets with hazes may be common in the galaxy. We use a 1D photochemical-climate model to examine the production of fractal organic haze on Archean Earthlike planets orbiting several different stars: the modern and early Sun, AD Leo (M3.5V), GJ 876 (M4V), a modeled quiescent M dwarf (M3.5V), ɛ Eridani (K2V), and σ Boötis (F2V). For the planetary atmospheric compositions used, planets orbiting stars with the highest or lowest UV fluxes do not form haze. Low UV-stars are unable to drive the photochemistry needed for haze formation. High UV stars generate photochemical oxygen radicals that halt haze production. Organic hazes can impact planetary habitability via UV shielding and surface cooling, but this cooling is minimized for hazy M dwarf planets whose incident stellar radiation arrives at wavelengths where organic hazes are largely transparent. We generate synthetic planetary spectra to test the detectability of haze. For 10 transits of an Archean-analog planet orbiting GJ 876 observed by the James Webb Space Telescope, gaseous absorption features at wavelengths < 2.5μm are 2-10σ shallower in the presence of a haze compared to a clear-sky planet, and methane and carbon dioxide are detectable at >5σ assuming photon-limited noise levels. An absorption feature from the haze can be detected at the 5σ level near 6.3μm, but higher signal-to-noise would be needed to uniquely distinguish haze from other absorbers in this spectral region. For direct imaging of a planet at 10 parsecs using a coronagraphic 10-meter class ultraviolet-visible-near infrared telescope, a UV-blue haze absorption feature would be strongly detectable at >12σ in 200 hours. Although haze is often considered a feature that conceals planetary features, organic haze can indicate a geologically active planet - and therefore a potentially habitable one - and possibly even reveal the presence of life.

Titan-Like Exoplanets: Variations in Geometric Albedo and Effective Transit Height with Haze Production Rate

NASA Technical Reports Server (NTRS)

Checlair, Jade; McKay, Christopher P.; Imanaka, Hiroshi

2016-01-01

Extensive studies characterizing Titan present an opportunity to study the atmospheric properties of Titan-like exoplanets. Using an existing model of Titan's atmospheric haze, we computed geometric albedo spectra and effective transit height spectra for six values of the haze production rate (zero haze to twice present) over a wide range of wavelengths (0.2-2 microns). In the geometric albedo spectra, the slope in the UV-visible changes from blue to red when varying the haze production rate values from zero to twice the current Titan value. This spectral feature is the most effective way to characterize the haze production rates. Methane absorption bands in the visible-NIR compete with the absorbing haze, being more prominent for smaller haze production rates. The effective transit heights probe a region of the atmosphere where the haze and gas are optically thin and that is thus not effectively probed by the geometric albedo. The effective transit height decreases smoothly with increasing wavelength, from 376 km to 123 km at 0.2 and 2 microns, respectively. When decreasing the haze production rate, the methane absorption bands become more prominent, and the effective transit height decreases with a steeper slope with increasing wavelength. The slope of the geometric albedo in the UV-visible increases smoothly with increasing haze production rate, while the slope of the effective transit height spectra is not sensitive to the haze production rate other than showing a sharp rise when the haze production rate increases from zero. We conclude that geometric albedo spectra provide the most sensitive indicator of the haze production rate and the background Rayleigh gas. Our results suggest that important and complementary information can be obtained from the geometric albedo and motivates improvements in the technology for direct imaging of nearby exoplanets.

The nature and extent of college student hazing.

PubMed

Allan, Elizabeth J; Madden, Mary

2012-01-01

This study explored the nature and extent of college student hazing in the USA. Hazing, a form of interpersonal violence, can jeopardize the health and safety of students. Using a web-based survey, data were collected from 11,482 undergraduate students, aged 18-25 years, who attended one of 53 colleges and universities. Additionally, researchers interviewed 300 students and staff at 18 of the campuses. Results reveal hazing among USA college students is widespread and involves a range of student organizations and athletic teams. Alcohol consumption, humiliation, isolation, sleep-deprivation and sex acts are hazing practices common across student groups. Furthermore, there is a large gap between the number of students who report experience with hazing behaviors and those that label their experience as hazing. To date, hazing prevention efforts in post-secondary education have focused largely on students in fraternities/sororities and intercollegiate athletes. Findings from this study can inform development of more comprehensive and research-based hazing prevention efforts that target a wider range of student groups. Further, data can serve as a baseline from which to measure changes in college student hazing over time.

Haze formation in model beer systems.

PubMed

Miedl, Michaela; Garcia, Marco A; Bamforth, Charles W

2005-12-28

The interaction of a haze-active protein (gliadin) and a haze-active polyphenol (tannic acid) was studied in a model beer system in order to investigate the principle mechanisms of haze formation at low temperatures. Low concentrations (g/L) of tannic acid, high concentrations of gliadin, and comparatively high temperatures lead to maximum haze values. When considered on a molar basis, the greatest haze levels are displayed at an approximate 1:1 equivalence of polyphenol and protein. The greater part of haze formation was completed within 0.5 h, irrespective of the concentration of gliadin, the concentration of tannic acid, and the temperature of the model solution.

Timing and conditions of clay fault gouge formation on the Naxos detachment (Cyclades, Greece)

NASA Astrophysics Data System (ADS)

Mancktelow, N.; Zwingmann, H.; Mulch, A.

2016-10-01

Clay fault gouge from the Naxos detachment (locally up to 1.0-1.5 m thick) is reported and dated for the first time. K-Ar ages on eight clay size fractions from the detachment and a minor fault in the immediate footwall have a narrow range, from 10.3 to 9.0 Ma, with an average of 9.7 ± 0.5 Ma (±1σ). These results are in excellent accord with regional and local age constraints, independently demonstrating the reliability of the method. Hydrogen δD values fall in the range -89 to -95‰, indicating interaction with infiltrating meteoric water during gouge formation, which is consistent with deposition of freshwater sediments in the hanging wall at the same time. Clay mineralogy in the detachment gouge is predominantly mixed layer illite-smectite with subordinate 1 M illite and kaolinite but without higher-temperature 2 M1 illite/mica. Clay fault gouge predominantly formed over a limited time and temperature range, potentially acting as a weak lubricant promoting movement on the Naxos detachment, with correspondingly rapid exhumation and cooling of the underlying footwall.

E4 True and False Color Hot Spot Mosaic

NASA Image and Video Library

1998-03-06

True and false color views of Jupiter from NASA's Galileo spacecraft show an equatorial "hotspot" on Jupiter. These images cover an area 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles). The top mosaic combines the violet and near infrared continuum filter images to create an image similar to how Jupiter would appear to human eyes. Differences in coloration are due to the composition and abundances of trace chemicals in Jupiter's atmosphere. The bottom mosaic uses Galileo's three near-infrared wavelengths displayed in red, green, and blue) to show variations in cloud height and thickness. Bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the deep cloud with an overlying thin haze. The light blue region to the left is covered by a very high haze layer. The multicolored region to the right has overlapping cloud layers of different heights. Galileo is the first spacecraft to distinguish cloud layers on Jupiter. North is at the top. The mosaic covers latitudes 1 to 10 degrees and is centered at longitude 336 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers (about 930,000 miles) by the Solid State Imaging camera system aboard Galileo. http://photojournal.jpl.nasa.gov/catalog/PIA00602

"Wetting enhancer" pullulan coating for antifog packaging applications.

PubMed

Introzzi, Laura; Fuentes-Alventosa, José María; Cozzolino, Carlo A; Trabattoni, Silvia; Tavazzi, Silvia; Bianchi, Claudia L; Schiraldi, Alberto; Piergiovanni, Luciano; Farris, Stefano

2012-07-25

A new antifog coating made of pullulan is described in this work. The antifog properties are discussed in terms of wettability, surface chemistry/morphology, and by quantitative assessment of the optical properties (haze and transparency) before and after fog formation. The work also presents the results of antifog tests simulating the typical storage conditions of fresh foods. In these tests, the antifog efficiency of the pullulan coating was compared with that of two commercial antifog films, whereas an untreated low-density polyethylene (LDPE) film was used as a reference. The obtained results revealed that the pullulan coating behaved as a "wetting enhancer", mainly due to the low water contact angle (∼24°), which in turn can be ascribed to the inherent hydrophilic nature of this polysaccharide, as also suggested by the X-ray photoelectron spectroscopy experiments. Unlike the case of untreated LDPE and commercial antifog samples, no discrete water formations (i.e., droplets or stains) were observed on the antifog pullulan coating on refrigeration during testing. Rather, an invisible, continuous and thin layer of water occurred on the biopolymer surface, which was the reason for the unaltered haze and increased transparency, with the layer of water possibly behaving as an antireflection layer. As confirmed by atomic force microscopy analysis, the even deposition of the coating on the plastic substrate compared to the patchy surfacing of the antifog additives in the commercial films is another important factor dictating the best performance of the antifog pullulan coating.

Hazy Archean Earth as an Analog for Hazy Earthlike Exoplanets

NASA Astrophysics Data System (ADS)

Arney, Giada; Meadows, Victoria; Domagal-Goldman, Shawn; Claire, Mark; Schwieterman, Edward

2015-01-01

Hazy exoplanets may be common (Bean et al. 2010, Sing et al. 2011, Kreidberg et al 2014), and in our solar system, Venus and Titan have photochemically-produced hazes. There is evidence that Earth itself had a hydrocarbon haze in the Archean (Zerkle et al. 2012, Domagal-Goldman et al. 2008) with important climatic effects (Pavlov et al. 2001, Trainer et al. 2006, Haqq-Misra et al. 2008, Wolf and Toon 2012). We use a 1D coupled photochemical-climate model and a line-by-line radiative transfer model to investigate the climactic and spectral impacts of a fractal hydrocarbon haze on Archean Earth. The haze absorbs significantly at shorter wavelengths and can strongly suppress the Rayleigh scattering tail, a broadband effect that would be remotely detectable at low spectral resolution at wavelengths less than 0.5 μm. Hazes may have a more significant impact on transit transmission spectra. Using the transit transmission radiative transfer model developed by Misra et al. (2014) to generate hazy Archean spectra, we find that even a thin hydrocarbon haze masks the lower atmosphere from the visible into the near infrared where the haze optical depth exceeds unity. The transit transmission spectra we generate for hazy Archean Earth are steeply sloped like the Titan solar occultation spectrum observed by Robinson et al. (2014). Thick hazes can also cool the planet significantly: for example, the thick fractal haze generated around Archean Earth with 0.3% CH4, 1% CO2 and 1 ppm C2H6 cools the planet from roughly 290 K without the haze to below freezing with the haze. Finally, we investigate the impact of host star spectral type on haze formation, comparing the hazes generated around a solar-type star to those generated at an Earth analog planet around the M dwarf AD Leo. Our results indicate hazes around M dwarfs for the same initial atmospheric composition may be thinner due to decreased UV photolysis of methane and other hydrocarbons needed for haze formation. Earthlike planets around M dwarfs may therefore be more likely to remain haze-free than those around G dwarfs; therefore, they may be easier to examine spectrally.

Forecasting the Occurrence of Severe Haze Events in Asia using Machine Learning Algorithms

NASA Astrophysics Data System (ADS)

Walton, A. L.

2016-12-01

Particulate pollution has become a serious environmental issue of many Asian countries in recent decades, threatening human health and frequently causing low visibility or haze days that interrupt from working, outdoor, and school activities to air, road, and sea transportation. To ultimately prevent such severe haze to occur requires many difficult tasks to be accomplished, dealing with trade and negotiation, emission control, energy consumption, transportation, land and plantation management, among other, of all involved countries or parties. Whereas, before these difficult measures could finally take place, it would be more practical to reduce the economic loss by developing skills to predict the occurrence of such events in reasonable accuracy so that effective mitigation or adaptation measures could be implemented ahead of time. The "traditional" numerical models developed based on fluid dynamics and explicit or parameterized representations of physiochemical processes can be certainly used for this task. However, the significant and sophisticated spatiotemporal variabilities associated with these events, the propagation of numerical or parameterization errors through model integration, and the computational demand all pose serious challenges to the practice of using these models to accomplish this interdisciplinary task. On the other hand, large quantity of meteorological, hydrological, atmospheric aerosol and composition, and surface visibility data from in-situ observation, reanalysis, or satellite retrievals, have become available to the community. These data might still not sufficient for evaluating and improving certain important aspects of the "traditional" models. Nevertheless, it is likely that these data can already support the effort to develop alternative "task-oriented" and computationally efficient forecasting skill using deep machine learning technique to avoid directly dealing with the sophisticated interplays across multiple process layers. I will present an experiential case of applying machine learning technique to predict the occurrence of severe haze events in Asia.

Forecasting the Occurrence of Severe Haze Events in Asia using Machine Learning Algorithms

NASA Astrophysics Data System (ADS)

Wang, C.

2017-12-01

Particulate pollution has become a serious environmental issue of many Asian countries in recent decades, threatening human health and frequently causing low visibility or haze days that interrupt from working, outdoor, and school activities to air, road, and sea transportation. To ultimately prevent such severe haze to occur requires many difficult tasks to be accomplished, dealing with trade and negotiation, emission control, energy consumption, transportation, land and plantation management, among other, of all involved countries or parties. Whereas, before these difficult measures could finally take place, it would be more practical to reduce the economic loss by developing skills to predict the occurrence of such events in reasonable accuracy so that effective mitigation or adaptation measures could be implemented ahead of time. The "traditional" numerical models developed based on fluid dynamics and explicit or parameterized representations of physiochemical processes can be certainly used for this task. However, the significant and sophisticated spatiotemporal variabilities associated with these events, the propagation of numerical or parameterization errors through model integration, and the computational demand all pose serious challenges to the practice of using these models to accomplish this interdisciplinary task. On the other hand, large quantity of meteorological, hydrological, atmospheric aerosol and composition, and surface visibility data from in-situ observation, reanalysis, or satellite retrievals, have become available to the community. These data might still not sufficient for evaluating and improving certain important aspects of the "traditional" models. Nevertheless, it is likely that these data can already support the effort to develop alternative "task-oriented" and computationally efficient forecasting skill using deep machine learning technique to avoid directly dealing with the sophisticated interplays across multiple process layers. I will present an experiential case of applying machine learning technique to predict the occurrence of severe haze events in Asia.

Microscopic Behavior Of Colloidal Particles Under The Effect Of Acoustic Stimulations In The Ultrasonic To Megasonic Range

NASA Astrophysics Data System (ADS)

Abdel-Fattah, Amr I.; Roberts, Peter M.

2006-05-01

It is well known that colloid attachment and detachment at solid surfaces are influenced strongly by physico-chemical conditions controlling electric double layer (EDL) and solvation-layer effects. We present experimental observations demonstrating that, in addition, acoustic waves can produce strong effects on colloid/surface interactions that can alter the behavior of colloid and fluid transport in porous media. Microscopic colloid visualization experiments were performed with polystyrene micro-spheres suspended in water in a parallel-plate glass flow cell. When acoustic energy was applied to the cell at frequencies from 500 kHz to 5 MHz, changes in colloid attachment to and detachment from the glass cell surfaces were observed. Quantitative measurements of acoustically-induced detachment of 300-nm microspheres in 0.1M NaCl solution demonstrated that roughly 30% of the colloids that were attached to the glass cell wall during flow alone could be detached rapidly by applying acoustics at frequencies in the range of 0.7 to 1.2 MHz. The remaining attached colloids could not be detached by acoustics. This implies the existence of both "strong" and "weak" attachment sites at the cell surface. Subsequent re-attachment of colloids with acoustics turned off occurred only at new, previously unoccupied sites. Thus, acoustics appears to accelerate simultaneously both the deactivation of existing weak sites where colloids are already attached, and the activation of new weak sites where future attachments can occur. Our observations indicate that acoustics (and, in general, dynamic stress) can influence colloid-colloid and colloid-surface interactions in ways that could cause significant changes in porous-media permeability and mass transport. This would occur due to either buildup or release of colloids present in the porous matrix.

Typical Types and Formation Mechanisms of Haze in an Eastern Asia Megacity, Shanghai

NASA Technical Reports Server (NTRS)

Huang, K.; Zhuang, G.; Lin, Y.; Fu, J. S.; Wang, Q.; Liu, T.; Zhang, R.; Jiang, Y.; Deng, C.; Fu, Q.;

Developments in signal processing and interpretation in laser tapping

NASA Astrophysics Data System (ADS)

Perton, M.; Neron, C.; Blouin, A.; Monchalin, J.-P.

2013-01-01

A novel technique, called laser-tapping, based on the thermoelastic excitation by laser like laser-ultrasonics has been previously introduced for inspecting honeycomb and foam core structures. If the top skin is delaminated or detached from the substrate, the detached layer is driven into vibration. The interpretation of the vibrations in terms of Lamb wave resonances is first discussed for a flat bottom hole configuration and then used to determine appropriate signal processing for samples such as honeycomb structures.

Effect of 3D magnetic perturbations on divertor conditions and detachment in tokamak and stellarator

DOE PAGES

Ahn, J. -W.; Briesemester, A. R.; Kobayashi, M.; ...

2017-06-22

Enhanced perpendicular heat and momentum transport induces parallel pressure loss leading to divertor detachment, which can be produced by the increase of density in 2D tokamaks. However, in the 3D configurations such as tokamaks with 3D fields and stellarators, the fraction of perpendicular transport can be higher even in a lower density regime, which could lead to the early transition to detachment without passing through the high-recycling regime. 3D fields applied to the limiter tokamak plasmas produce edge stochastic layers close to the last closed flux surface (LCFS), which can allow for enhanced perpendicular transport and indeed the absence ofmore » high recycling regime and early detachment have been observed in TEXTOR and Tore Supra. However, in the X-point divertor tokamaks with the applied 3D fields, the parallel transport is still dominant and the detachment facilitation has not been observed yet. Rather, 3D fields affected detachment adversely under certain conditions, either by preventing detachment onset as seen in DIII-D or by re-attaching the existing detached plasma as shown in NSTX. The possible way for strong 3D effects to induce access to the early detachment in divertor tokamaks appears to be via significant perpendicular loss of parallel momentum by frictional force for the counter-streaming flows between neighboring flow channels in the divertor. In principle, the adjacent lobes in the 3D divertor tokamak may generate the counter-streaming flow channels. However, an EMC3-EIRENE simulation for ITER H-mode plasmas demonstrated that screened RMP leads to significantly reduced counter-flows near the divertor target, therefore the momentum loss effect leading to detachment facilitation is expected to be small. This is consistent with the observation in LHD, which showed screening (amplification) of RMP fields in the attachment (stable detachment) case. In conclusion, work for optimal parameter window for best divertor operation scenario is needed particularly for the 3D divertor tokamak configuration.« less

Effect of 3D magnetic perturbations on divertor conditions and detachment in tokamak and stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, J. -W.; Briesemester, A. R.; Kobayashi, M.

Enhanced perpendicular heat and momentum transport induces parallel pressure loss leading to divertor detachment, which can be produced by the increase of density in 2D tokamaks. However, in the 3D configurations such as tokamaks with 3D fields and stellarators, the fraction of perpendicular transport can be higher even in a lower density regime, which could lead to the early transition to detachment without passing through the high-recycling regime. 3D fields applied to the limiter tokamak plasmas produce edge stochastic layers close to the last closed flux surface (LCFS), which can allow for enhanced perpendicular transport and indeed the absence ofmore » high recycling regime and early detachment have been observed in TEXTOR and Tore Supra. However, in the X-point divertor tokamaks with the applied 3D fields, the parallel transport is still dominant and the detachment facilitation has not been observed yet. Rather, 3D fields affected detachment adversely under certain conditions, either by preventing detachment onset as seen in DIII-D or by re-attaching the existing detached plasma as shown in NSTX. The possible way for strong 3D effects to induce access to the early detachment in divertor tokamaks appears to be via significant perpendicular loss of parallel momentum by frictional force for the counter-streaming flows between neighboring flow channels in the divertor. In principle, the adjacent lobes in the 3D divertor tokamak may generate the counter-streaming flow channels. However, an EMC3-EIRENE simulation for ITER H-mode plasmas demonstrated that screened RMP leads to significantly reduced counter-flows near the divertor target, therefore the momentum loss effect leading to detachment facilitation is expected to be small. This is consistent with the observation in LHD, which showed screening (amplification) of RMP fields in the attachment (stable detachment) case. In conclusion, work for optimal parameter window for best divertor operation scenario is needed particularly for the 3D divertor tokamak configuration.« less

Hubble Captures Detailed Image of Uranus' Atmosphere

NASA Technical Reports Server (NTRS)

1996-01-01

Hubble Space Telescope has peered deep into Uranus' atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus' atmosphere.

Hubble's images are different from the ones taken by the Voyager 2 spacecraft, which flew by Uranus 10 years ago. Those images - not taken in infrared light - showed a greenish-blue disk with very little detail.

The infrared image allows astronomers to probe the structure of Uranus' atmosphere, which consists of mostly hydrogen with traces of methane. The red around the planet's edge represents a very thin haze at a high altitude. The haze is so thin that it can only be seen by looking at the edges of the disk, and is similar to looking at the edge of a soap bubble. The yellow near the bottom of Uranus is another hazy layer. The deepest layer, the blue near the top of Uranus, shows a clearer atmosphere.

Image processing has been used to brighten the rings around Uranus so that astronomers can study their structure. In reality, the rings are as dark as black lava or charcoal.

This false color picture was assembled from several exposures taken July 3, 1995 by the Wide Field Planetary Camera-2.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Modeling the feedback between aerosol and boundary layer processes: a case study in Beijing, China.

PubMed

Miao, Yucong; Liu, Shuhua; Zheng, Yijia; Wang, Shu

2016-02-01

Rapid development has led to frequent haze in Beijing. With mountains and sea surrounding Beijing, the pollution is found to be influenced by the mountain-plain breeze and sea-land breeze in complex ways. Meanwhile, the presence of aerosols may affect the surface energy balance and impact these boundary layer (BL) processes. The effects of BL processes on aerosol pollution and the feedback between aerosol and BL processes are not yet clearly understood. Thus, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is used to investigate the possible effects and feedbacks during a haze episode on 23 September 2011. Influenced by the onshore prevailing wind, sea-breeze, and upslope breeze, about 45% of surface particulate matter (PM)2.5 in Beijing are found to be contributed by its neighbor cities through regional transport. In the afternoon, the development of upslope breeze suppresses the growth of BL in Beijing by imposing a relatively low thermal stable layer above the BL, which exacerbates the pollution. Two kinds of feedback during the daytime are revealed as follows: (1) as the aerosols absorb and scatter the solar radiation, the surface net radiation and sensible heat flux are decreased, while BL temperature is increased, resulting in a more stable and shallower BL, which leads to a higher surface PM2.5 concentration in the morning and (2) in the afternoon, as the presence of aerosols increases the BL temperature over plains, the upslope breeze is weakened, and the boundary layer height (BLH) over Beijing is heightened, resulting in the decrease of the surface PM2.5 concentration there.

Aerothermodynamic environment for a Titan probe with deployable decelerator

NASA Technical Reports Server (NTRS)

Green, M. J.; Swenson, B. L.; Balakrishnan, A.

1985-01-01

It is pointed out that further exploration of Titan, Saturn's largest moon, is of current interest to the scientific community, particularly from the standpoint of the organic chemical evolution of its atmosphere. For a suitable study of this Saturnian satellite, a mission involving a Titan atmospheric entry probe is to be conducted. The probe is to employ a deployable decelerator with the aim to allow scientific measurements in the haze layer. The present investigation is concerned with an assessment of the aerothermodynamic environment for the considered probe during its hypervelocity, low-Reynolds-number entry. Attention is given to the employed computational method, the Titan probe configuration, the Titan probe trajectory, the viscous-layer regime of the aerothermodynamic environment, and the incipient merged-layer regime.

Three dimensional Visualization of Jupiter's Equatorial Region

NASA Technical Reports Server (NTRS)

1997-01-01

Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

This frame is a view from the southwest looking northeast, from an altitude just above the high haze layer. The streaks in the lower cloud leading towards the hotspot are visible. The upper haze layer is mostly flat, with notable small peaks that can be matched with features in the lower cloud. In reality, these areas may represent a continuous vertical cloud column.

Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on more sophisticated studies of Jupiter's cloud structure. The upper and lower clouds are separated in the rendering by an arbitrary amount, and the height variations are exaggerated by a factor of 25.

The lower cloud is colored using the same false color scheme used in previously released image products, assigning red, green, and blue to the 756, 727, and 889 nanometer mosaics, respectively. Light bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the lower cloud with an overlying thin haze.

The images used cover latitudes 1 to 10 degrees and are centered at longitude 336 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers (about 930,000 miles) by the Solid State Imaging (CCD) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

The effect of ambient exposure to PM2.5 on the transfusion usage of blood components and adverse transfusion reactions in the haze weather.

PubMed

Chang, Chih-Chun; Lin, Hui-Jung; Sun, Jen-Tang; Li, Pei-Yu; Lee, Tai-Chen; Su, Ming-Jang; Yen, Tzung-Hai; Chu, Fang-Yeh

2016-10-01

Accumulating evidence has shown that ambient exposure to PM 2.5 , especially in the haze weather, increased the risk of various diseases. However, the association of air pollution status with blood transfusion utilization and the prevalence and severity of adverse transfusion reactions remain to be clarified. The data of monthly transfusion usage of blood components, adverse transfusion reactions, as well as PM 2.5 and PM 10 levels from 2013 to 2015 were obtained. During the study interval, both PM 2.5 and PM 10 levels were significantly increased in the haze weather when compared with the non-haze weather. The utilization of total blood components per patient-month in the haze weather was prone to be increased when compared with that in the non-haze weather (13.28 ± 1.66 vs. 12.33 ± 1.30, p = 0.068). The usage of RBC products per patient-month in the haze weather was significantly increased when compared with that in the non-haze weather (4.39 ± 0.39 vs. 4.07 ± 0.30, p = 0.009). There was no obvious difference between the haze and non-haze weathers for the usage of platelet and plasma products per patient-month. Besides, no definite differences of the prevalence and severity of transfusion-associated adverse reaction were observed between the haze and non-haze weathers. Our study first indicated that transfusion utilization, particularly the RBC products, was significantly increased in the haze weather when compared with that in the non-haze weather. There was no obvious association of air pollution with the prevalence and severity of adverse transfusion reactions and further research is required. Copyright © 2016 Elsevier Ltd. All rights reserved.

Izu detachment hypothesis: A proposal of a unified cause for the Miyake-Kozu event and the Tokai slow event

NASA Astrophysics Data System (ADS)

Seno, Tetsuzo

2005-10-01

Based on the fact that interseismic deformation of collision zones is generally described by slip along a detachment at depth, I attempt to interpret the deformation of the Izu collision zone in terms of a detachment model. The systematic deviation of the GPS velocities of the Izu Peninsula (Nov. 1998-June 2000) from the Philippine Sea-Eurasian relative plate motions is fitted by the slip on the detachment at a depth of 15-20 km with a rate of 3 cm/yr. On June 26, 2000, seismo-magmatic activity that started near Miyakejima expanded NW by 20 km close to Kozushima in association with dike intrusion over a few months. The horizontal movements associated with this event, however, spread over wide areas in central Honshu. Simple dike intrusion models cannot explain these movements. To explain these, I hypothesize that a 20 cm of rapid slip occurred on the detachment at the time of this event. The abnormal crustal movements in the Tokai-central Honshu-Kanto region then started after the event. I propose that they represent delayed diffusive transfer of the slip on the detachment over surrounding low viscosity layers, such as nearby rupture zones of great earthquakes.

Characteristics of bacterial and fungal aerosols during the autumn haze days in Xi'an, China

NASA Astrophysics Data System (ADS)

Li, Yanpeng; Fu, Honglei; Wang, Wei; Liu, Jun; Meng, Qinglong; Wang, Wenke

2015-12-01

In recent years, haze pollution has become one of the most critical environmental issues in Xi'an, China, with particular matter (PM) being one of the top pollutants. As an important fraction of PM, bioaerosols may have adverse effects on air quality and human health. In this study, to better understand the characteristics of such biological aerosols, airborne microbial samples were collected by using an Andersen six-stage sampler in Xi'an from October 8th to 22nd, 2014. The concentration, size distribution and genera of airborne viable bacteria and fungi were comparably investigated during the haze days and non-haze days. Correlations of bioaerosol levels with meteorological parameters and PM concentrations were also examined. The results showed that the daily average concentrations of airborne viable bacteria and fungi during the haze days, 1102.4-1736.5 and 1466.2-1703.9 CFU/m3, respectively, were not only much higher than those during the non-haze days, but also exceeded the recommended permissible limit values. Comparing to size distributions during the non-haze days, slightly different patterns for bacterial aerosols and similar single-peak distribution pattern for fungal aerosols were observed during the haze days. Moreover, more allergic and infectious genera (e.g. Neisseria, Aspergillus, and Paecilomyces) in bioaerosols were identified during the haze days than during non-haze days. The present results reveal that bioaerosols may have more significant effects on public health and urban air quality during the haze days than during non-haze days.

Quantitative evaluation of haze formation of koji and progression of internal haze by drying of koji during koji making.

PubMed

Ito, Kazunari; Gomi, Katsuya; Kariyama, Masahiro; Miyake, Tsuyoshi

2017-07-01

The construction of an experimental system that can mimic koji making in the manufacturing setting of a sake brewery is initially required for the quantitative evaluation of mycelia grown on/in koji pellets (haze formation). Koji making with rice was investigated with a solid-state fermentation (SSF) system using a non-airflow box (NAB), which produced uniform conditions in the culture substrate with high reproducibility and allowed for the control of favorable conditions in the substrate during culture. The SSF system using NAB accurately reproduced koji making in a manufacturing setting. To evaluate haze formation during koji making, surfaces and cross sections of koji pellets obtained from koji making tests were observed using a digital microscope. Image analysis was used to distinguish between haze and non-haze sections of koji pellets, enabling the evaluation of haze formation in a batch by measuring the haze rate of a specific number of koji pellets. This method allowed us to obtain continuous and quantitative data on the time course of haze formation. Moreover, drying koji during the late stage of koji making was revealed to cause further penetration of mycelia into koji pellets (internal haze). The koji making test with the SSF system using NAB and quantitative evaluation of haze formation in a batch by image analysis is a useful method for understanding the relations between haze formation and koji making conditions. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Pollutional haze as a potential cause of lung cancer.

PubMed

Shi, Xuefei; Liu, Hongbing; Song, Yong

2015-10-01

Along with fast economic growth over the past few decades, the world is faced with cumulatively serious environmental pollution and now is paying increased attention to pollutional haze. In the last few years, multiple epidemiological studies and animal models have provided compelling evidences that inhalation of pollutional haze could be linked to several adverse health effects. Since the respiratory tract is the crucial passageway of entry of pollutional haze, the lung is the main affected organ. Therefore, here, we reviewed some of the important information around long-term exposure to pollutional haze and lung cancer, as well as highlight important roles of pollutional haze in human lung carcinogenesis, providing evidence for pollutional haze acting as another risk factor for lung cancer.

Mechanism for the formation and microphysical characteristics of submicron aerosol during heavy haze pollution episode in the Yangtze River Delta, China.

PubMed

Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Pan, Chen; Liu, Zirui; Liu, Xiaohui; Duan, Qing; Liu, Xuan; Wang, Yuesi

2014-08-15

In this paper we investigate a severe pollution episode that occurred in the Yangtze River Delta (YRD) region in January 2013. The episode was caused by the combination of anthropogenic emissions and unusual atmospheric circulation, the depression of strong cold air activities and the very unfavorable dispersion. The episode contained three haze events (haze1: Jan. 4-9, haze2: Jan. 10-13, and haze3: Jan. 14-16). In Nanjing, aerosol size distributions from 10nm to 10 μm and chemical components of single particles from 0.2 to 2 μm were measured with a Wide Range Particle Spectrometer (WPS) and a Single Particle Aerosol Mass Spectrometer (SPAMS), respectively. The results indicate that the mean PM2.5 concentrations in the YRD region were greater than 110 μg·m(-3). The highest PM2.5 concentration of 175.6 μg·m(-3) occurred in Nanjing; the other cities had values in the range of 110.8-147.3 μg·m(-3). The average PM2.5 concentrations were 58.3, 122.7, 145.4 and 154.7 μg·m(-3) on clean and haze1, haze2 and haze3 days, respectively. The highest PM2.5 values of 416.5, 415.5 and 300.5 μg·m(-3) in Nanjing occurred during the three haze events. The spectra of the aerosol number concentrations had unimodal distributions on clean and haze days. The maximum surface area peaks were located at 0.5-0.7 μm and had values of 419, 1397, 1309 and 1378 μm(2)·cm(-3)·nm(-1) on clean and haze1, haze2 and haze3 days, respectively. The number concentrations of biomass/biofuel burning-containing particles (biomass), organic carbon-containing particles (OC), elemental carbon-containing particles (EC), nitrate-containing particles (nitrate) and sulfate-containing particles (sulfate) increased significantly during the haze events. The chemical components of the aerosols during the haze1 and haze2 events were similar to those on clean days, and variations were caused by local particle accumulations under poor diffusion conditions. The high EC particle concentration of 24.76% during the haze3 event was impacted by the pollutants transported from surrounding cities. In addition, the different chemical components showed distinct size distributions. Copyright © 2014 Elsevier B.V. All rights reserved.

Numerical simulation of diurnally varying thermal environment in a street canyon under haze-fog conditions

NASA Astrophysics Data System (ADS)

Tan, Zijing; Dong, Jingliang; Xiao, Yimin; Tu, Jiyuan

2015-10-01

The impact of haze-fog on surface temperature, flow pattern, pollutant dispersion and pedestrian thermal comfort are investigated using computational fluid dynamics (CFD) approach based on a three-dimensional street canyon model under different haze-fog conditions. In this study, light extinction coefficient (Kex) is adopted to represent haze-fog pollution level. Numerical simulations are performed for different Kex values at four representative time events (1000 LST, 1300 LST, 1600 LST and 2000 LST). The numerical results suggest that the surface temperature is strongly affected by the haze-fog condition. Surface heating induced by the solar radiation is enhanced by haze-fog, as higher surface temperature is observed under thicker haze-fog condition. Moreover, the temperature difference between sunlit and shadow surfaces is reduced, while that for the two shadow surfaces is slightly increased. Therefore, the surface temperature among street canyon facets becomes more evenly distributed under heavy haze-fog conditions. In addition, flow patterns are considerably altered by different haze-fog conditions, especially for the afternoon (1600 LST) case, in which thermal-driven flow has opposite direction as that of the wind-driven flow direction. Consequently, pollutants such as vehicular emissions will accumulate at pedestrian level, and pedestrian thermal comfort may lower under thicker haze-fog condition.

Characteristics of atmospheric particulate mercury in size-fractionated particles during haze days in Shanghai

NASA Astrophysics Data System (ADS)

Chen, Xiaojia; Balasubramanian, Rajasekhar; Zhu, Qiongyu; Behera, Sailesh N.; Bo, Dandan; Huang, Xian; Xie, Haiyun; Cheng, Jinping

2016-04-01

Atmospheric particulate mercury (PHg) is recognized as a global pollutant that requires regulation because of its significant impacts on both human health and wildlife. The haze episodes that occur frequently in China could influence the transport and fate of PHg. To examine the characteristics of PHg during haze and non-haze days, size-fractioned particles were collected using thirteen-stage Nano-MOUDI samplers (10 nm-18 μm) during a severe haze episode (from December 2013 to January 2014) in Shanghai. The PHg concentration on haze days (4.11 ± 0.53 ng m-3) was three times higher than on non-haze days (1.34 ± 0.15 ng m-3). The ratio of the PHg concentration to total gaseous mercury (TGM) ranged from 0.42 during haze days to 0.21 during non-haze days, which was possibly due to the elevated concentration of particles for gaseous elemental mercury (GEM) adsorption, elevated sulfate and nitrate contributing to GEM oxidation, and the catalytic effect of elevated water-soluble inorganic metal ions. PHg/PM10 during haze days (0.019 ± 0.004 ng/μg) was lower than during non-haze days (0.024 ± 0.002 ng/μg), and PHg/PM10 was significantly reduced with an increasing concentration of PM10, which implied a relatively lower growth velocity of mercury than other compositions on particles during haze days, especially in the diameter range of 0.018-0.032 μm. During haze days, each size-fractioned PHg concentration was higher than the corresponding fraction on non-haze days, and the dominant particle size was in the accumulation mode, with constant accumulation to a particle size of 0.56-1.0 μm. The mass size distribution of PHg was bimodal with peaks at 0.32-0.56 μm and 3.1-6.2 μm on non-haze days, and 0.56-1.0 μm and 3.1-6.2 μm on haze days. There was a clear trend that the dominant size for PHg in the fine modes shifted from 0.32-0.56 μm during non-haze days to 0.56-1.0 μm on haze days, which revealed the higher growth velocity of PHg on haze days due to the condensation and accumulation of Hg in particles. Traffic emissions and coal combustion may contribute to the high concentrations of Hg, because PHg of every size was found to correlate positively with SO2, NO2, and CO. A correlation was found between every mode of PHg and relative humidity, which affected the gas-particle partitioning of semi-volatile organic compounds, resulting in effective partitioning into aerosols. The strong correlations between Hg and water-soluble ions implied the oxidation of elemental Hg was the main gas-to-particle chemical transformation process.

Removing Boundary Layer by Suction

NASA Technical Reports Server (NTRS)

Ackeret, J

1927-01-01

Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface.

Electron pressure balance in the SOL through the transition to detachment

DOE PAGES

McLean, A. G.; Leonard, A. W.; Makowski, M. A.; ...

2015-02-07

Upgrades to core and divertor Thomson scattering (DTS) diagnostics at DIII-D have provided measurements of electron pressure profiles in the lower divertor from attached- to fully-detached divertor plasma conditions. Detailed, multistep sequences of discharges with increasing line-averaged density were run at several levels of P inj. Strike point sweeping allowed 2D divertor characterization using DTS optimized to measure T e down to 0.5 eV. The ionization front at the onset of detachment is found to move upwards in a controlled manner consistent with the indication that scrape-off layer parallel power flux is converted from conducted to convective heat transport. Measurementsmore » of n e, T e and p e in the divertor versus Lparallel demonstrate a rapid transition from Te ≥ 15 eV to ≤3 eV occurring both at the outer strike point and upstream of the X-point. Furthermore, these observations provide a strong benchmark for ongoing modeling of divertor detachment for existing and future tokamak devices.« less

Electron pressure balance in the SOL through the transition to detachment

NASA Astrophysics Data System (ADS)

McLean, A. G.; Leonard, A. W.; Makowski, M. A.; Groth, M.; Allen, S. L.; Boedo, J. A.; Bray, B. D.; Briesemeister, A. R.; Carlstrom, T. N.; Eldon, D.; Fenstermacher, M. E.; Hill, D. N.; Lasnier, C. J.; Liu, C.; Osborne, T. H.; Petrie, T. W.; Soukhanovskii, V. A.; Stangeby, P. C.; Tsui, C.; Unterberg, E. A.; Watkins, J. G.

2015-08-01

Upgrades to core and divertor Thomson scattering (DTS) diagnostics at DIII-D have provided measurements of electron pressure profiles in the lower divertor from attached- to fully-detached divertor plasma conditions. Detailed, multistep sequences of discharges with increasing line-averaged density were run at several levels of Pinj. Strike point sweeping allowed 2D divertor characterization using DTS optimized to measure Te down to 0.5 eV. The ionization front at the onset of detachment is found to move upwards in a controlled manner consistent with the indication that scrape-off layer parallel power flux is converted from conducted to convective heat transport. Measurements of ne, Te and pe in the divertor versus Lparallel demonstrate a rapid transition from Te ⩾ 15 eV to ⩽3 eV occurring both at the outer strike point and upstream of the X-point. These observations provide a strong benchmark for ongoing modeling of divertor detachment for existing and future tokamak devices.

Characterization of the seismically imaged Tuscarora fold system and implications for layer parallel shortening in the Pennsylvania salient

NASA Astrophysics Data System (ADS)

Mount, Van S.; Wilkins, Scott; Comiskey, Cody S.

2017-12-01

The Tuscarora fold system (TFS) is located in the Pennsylvania salient in the foreland of the Valley and Ridge province. The TFS is imaged in high quality 3D seismic data and comprises a system of small-scale folds within relatively flat-lying Lower Silurian Tuscarora Formation strata. We characterize the TFS structures and infer layer parallel shortening (LPS) directions and magnitudes associated with deformation during the Alleghany Orogeny. Previously reported LPS data in our study area are from shallow Devonian and Carboniferous strata (based on outcrop and core analyses) above the shallowest of three major detachments recognized in the region. Seismic data allows us to characterize LPS at depth in strata beneath the shallow detachment. Our LPS data (orientations and inferred magnitudes) are consistent with the shallow data leading us to surmise that LPS during Alleghanian deformation fanned around the salient and was distributed throughout the stratigraphic section - and not isolated to strata above the shallow detachment. We propose that a NW-SE oriented Alleghanian maximum principal stress was perturbed by deep structure associated with the non-linear margin of Laurentia resulting in fanning of shortening directions within the salient.

Hazing in the Military: A Pilot Study

DTIC Science & Technology

2013-05-14

while an education program to reduce workplace bullying will not likely transfer to decrease hazing. HAZING IN THE MILITARY: A PILOT STUDY 3...different. It is important not to assume they are the same in policy or treatment. A policy covering hazing may enable workplace bullying to go unnoticed...however, it is also found in the adult workplace . Bullying behaviors, like hazing, may be psychological or physical in nature, vary in severity, and

Spatiotemporal influence of temperature, air quality, and urban environment on cause-specific mortality during hazy days.

PubMed

Ho, Hung Chak; Wong, Man Sing; Yang, Lin; Shi, Wenzhong; Yang, Jinxin; Bilal, Muhammad; Chan, Ta-Chien

2018-03-01

Haze is an extreme weather event that can severely increase air pollution exposure, resulting in higher burdens on human health. Few studies have explored the health effects of haze, and none have investigated the spatiotemporal interaction between temperature, air quality and urban environment that may exacerbate the adverse health effects of haze. We investigated the spatiotemporal pattern of haze effects and explored the additional effects of temperature, air pollution and urban environment on the short-term mortality risk during hazy days. We applied a Poisson regression model to daily mortality data from 2007 through 2014, to analyze the short-term mortality risk during haze events in Hong Kong. We evaluated the adverse effect on five types of cause-specific mortality after four types of haze event. We also analyzed the additional effect contributed by the spatial variability of urban environment on each type of cause-specific mortality during a specific haze event. A regular hazy day (lag 0) has higher all-cause mortality risk than a day without haze (odds ratio: 1.029 [1.009, 1.049]). We have also observed high mortality risks associated with mental disorders and diseases of the nervous system during hazy days. In addition, extreme weather and air quality contributed to haze-related mortality, while cold weather and higher ground-level ozone had stronger influences on mortality risk. Areas with a high-density environment, lower vegetation, higher anthropogenic heat, and higher PM 2.5 featured stronger effects of haze on mortality than the others. A combined influence of haze, extreme weather/air quality, and urban environment can result in extremely high mortality due to mental/behavioral disorders or diseases of the nervous system. In conclusion, we developed a data-driven technique to analyze the effects of haze on mortality. Our results target the specific dates and areas with higher mortality during haze events, which can be used for development of health warning protocols/systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, J. -W.; Briesemester, A. R.; Kobayashi, M.

Enhanced perpendicular heat and momentum transport induces parallel pressure loss leading to divertor detachment, which can be produced by the increase of density in 2D tokamaks. However, in the 3D configurations such as tokamaks with 3D fields and stellarators, the fraction of perpendicular transport can be higher even in a lower density regime, which could lead to the early transition to detachment without passing through the high-recycling regime. 3D fields applied to the limiter tokamak plasmas produce edge stochastic layers close to the last closed flux surface (LCFS), which can allow for enhanced perpendicular transport and indeed the absence ofmore » high recycling regime and early detachment have been observed in TEXTOR and Tore Supra. However, in the X-point divertor tokamaks with the applied 3D fields, the parallel transport is still dominant and the detachment facilitation has not been observed yet. Rather, 3D fields affected detachment adversely under certain conditions, either by preventing detachment onset as seen in DIII-D or by re-attaching the existing detached plasma as shown in NSTX. The possible way for strong 3D effects to induce access to the early detachment in divertor tokamaks appears to be via significant perpendicular loss of parallel momentum by frictional force for the counter-streaming flows between neighboring flow channels in the divertor. In principle, the adjacent lobes in the 3D divertor tokamak may generate the counter-streaming flow channels. However, an EMC3-EIRENE simulation for ITER H-mode plasmas demonstrated that screened RMP leads to significantly reduced counter-flows near the divertor target, therefore the momentum loss effect leading to detachment facilitation is expected to be small. This is consistent with the observation in LHD, which showed screening (amplification) of RMP fields in the attachment (stable detachment) case. In conclusion, work for optimal parameter window for best divertor operation scenario is needed particularly for the 3D divertor tokamak configuration.« less

Microtopographic Evidence of Hillslope Susceptibility to Active Layer Detachments and Rapid Soil Erosion in Permafrost-dominated Watersheds

NASA Astrophysics Data System (ADS)

Rowland, J. C.; Shelef, E.; Sutfin, N. A.; Piliouras, A.; Andresen, C. G.; Wilson, C. J.

2017-12-01

Movement and storage rates of soil and carbon along permafrost-dominated hillslopes may vary dramatically from long-term steady creeping, at centimeters per year, to rapid gullying, land sliding, and active layer detachments of meter to decimeter sized portions of hillslopes. The rate and drivers of hillslope soil processes may have strong feedbacks on microtopography and hydrology that in turn strongly influence vegetation dynamics and biogeochemistry within watersheds. We observed evidence of both steady soil creep and more catastrophic soil erosion processes occurring across three small watersheds in the southern Seward Peninsula, AK. In these watersheds, we inferred active soil creep processes from the occurrence of solifluction lobes with partially buried shrubs and tilted survey benchmarks on slopes lacking lobes. More dramatic and rapid erosion of soils was evidenced by active layer detachments, extensional cracks in the tundra vegetation, gullying, and both small- and large-scale soil failure scarps. The margins and heads of valley hollows exhibited failure scars up to 4m in height. The spatial distribution of actively eroding areas suggests that some portions of hilllslopes may be more susceptible to rapid erosion. Coring of hillslope soils suggests a possible association between more actively eroding areas and the presence of an ice-rich layer (> 50%) at depths of approximately 90 cm down to the inferred top of bedrock at depths at 170 to 200 cm. We observed that the surface of these hillslope regions appears to have greater microtopographic roughness with a more chaotic and "lumpy" surface than portions of the hillslope were no massive ice layers were encountered. We hypothesize that the extensional cracking and chaotic surface roughness may arise from small-scale soil failures triggered when the seasonal thaw depth intersects the ice-rich layer. It may be possible to identify hillslope regions underlain by ice-rich layers with greater susceptibility for localized erosion and deformation based on a quantitative characterization of the hillslope microtopography. Using drone-based LiDAR topographic data to be acquired in late summer of 2017, we will quantitatively explore the relationship between microtopography and hillslope ice-content.

Clouds, hazes, and the stratospheric methane abundance in Neptune

NASA Technical Reports Server (NTRS)

Baines, Kevin H.; Hammel, Heidi B.

1994-01-01

Analysis of high-spatial-resolution (approximately 0.8 arcsec) methane band and continuum imagery of Neptune's relatively homogeneous Equatorial Region yields significant constraints on (1) the stratospheric gaseous methane mixing ratio (f(sub CH4, S)), (2) the column abundances and optical properties of stratospheric and tropospheric hydrocarbon hazes, and (3) the wavelength-dependent single-scattering albedo of the 3-bar opaque cloud. From the center-to-limb behavior of the 7270-A and 8900-A CH4 bands, the stratospheric methane mixing ratios is limited to f(sub CH4, S) less than 1.7 x 10(exp -3), with a nominal value of f(sub CH4, S) = 3.5 x 10(exp -4), one to two orders of magnitude less than pre-Voyager estimates, but in agreement with a number of recent ultraviolet and thermal infrared measurements, and largely in agreement with the tropopause mixing ratio implied by Voyager temperature measurements. Upper limits to the stratospheric haze mass column abundance and 6190-A and 8900-A haze opacities are 0.61 micrograms/sq cm and 0.075 and 0.042, respectively, with nominal values of 0.20 micrograms/sq cm and 0.025 and 0.014 for the 0.2 micrometers radius particles preferred by the recent Voyager PPS analysis of Pryor et al. (1992). The tropospheric CH4 haze opacities are comparable to that found in the stratosphere, i.e., upper limits of 0.104 and 0.065 at 6190 A and 8900 A, respectively, with nominal values of 0.085 and 0.058. This indicates a column abundance less than 11.0 micrograms/sq cm, corresponding to the methane gas content within a well-mixed 3% methane tropospheric layer only 0.1 cm thick near the 1.5-bar CH4 condensation level. Conservative scattering is ruled out for the opaque cloud near 3 bars marking the bottom of the visible atmosphere. Specifically, we find cloud single-scattering albedos of 0.915 +/- 0.006 at 6340 A, 0.775 +/- 0.012 at 7490 A, and 0.803 +/- 0.010 at 8260 A. Global models utilizing a complete global spectrum confirm the red-absorbing character of the 3-bar cloud. The global-mean model has approximately 7.7 times greater stratospheric aerosol content than the Equatorial Region. An analysis of stratospheric haze precipitation rates indicates a steady-state haze production rate of 0.185-1.5 x 10(exp -14) g/sq cm/s, in agreement with recent theoretical photochemical estimates. Finally, reanalysis of the Voyager PPS 7500-A phase angle data utilizing the f(sub CH4, S) value derived here confirms the Pryor et al. result of a tropospheric CH4 haze opacity of a few tenths in the 22-30 degs S latitude region, several times that of the Equatorial Region or of the globe. The factor-of-10 reduction in f(sub CH4, S) below that assumed by Pryor et al. implies decreased gas absorption and consequently a decrease in the forward-scattering component of tropospheric aerosols.

77 FR 48061 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... Promulgation of Air Quality Implementation Plans; Pennsylvania; Regional Haze State Implementation Plan...'s limited approval of Pennsylvania's Regional Haze State Implementation Plan (SIP). DATES: Effective... announcing our limited approval of Pennsylvania's Regional Haze SIP. In this document, we inadvertently...

Detachment and diffusive-convective transport in an evolving heterogeneous two-dimensional biofilm hybrid model.

PubMed

Luna, E; Domínguez-Zacarias, G; Ferreira, C Pio; Velasco-Hernandez, J X

2004-12-01

Under the hypothesis of correlation between biofilm survival and nutrient availability, by considering fluid drag forces and mortality due to nutrient depletion, a biofilm detachment/breaking condition is derived. The mechanisms leading to biofilm detachment/breaking are discussed. We construct and describe a hybrid model for a heterogeneous biofilm attached to walls in a channel where liquid is flowing. The model is called hybrid because it couples conservation equations with a cellular automaton. The biofilm layer is viewed as a porous medium with variable porosity, tortuosity, and permeability. The model is solved using asymptotic and finite differences methods. Results for porosity, nutrient distribution, and average surface location are presented. The model is capable of reproducing biofilm heterogeneity as well as the typical surface fingering (mushroomlike structure).

Dual effects of the winter monsoon on haze-fog variations in eastern China

NASA Astrophysics Data System (ADS)

Liu, Qian; Sheng, Lifang; Cao, Ziqi; Diao, Yina; Wang, Wencai; Zhou, Yang

2017-06-01

Previous studies have revealed a negative correlation between the East Asian winter monsoon and wintertime haze-fog events in China. The winter monsoon reduces haze-fog by advecting away aerosol particles and supplying clean air through cold waves. However, it is found that the frequency of haze-fog events on subseasonal time scales displays no correlation with typical winter monsoon indices. The results show that the accumulating and maintaining effects of calm weather related to the Siberian High, which is also a part of the monsoon circulation system, are equally important for the development of haze-fog events during winter. Correlation analysis indicates that subseasonal variations in haze-fog are closely related to the intensity of the Siberian High (r = 0.49). The Siberian High may increase the occurrence of haze-fog events by reducing the near surface wind speed and enhancing the stratification stability. To quantify the contribution of these diverse effects of the winter monsoon on the variations in haze-fog events, we analyzed haze-fog events during periods of cold wave activity and calm weather separately and contrasted the relative contributions of these two effects on different time scales. On the subseasonal scale, the effect of the Siberian High was 2.0 times that of cold waves; on the interannual scale, the effect of cold waves was 2.4 times that of the Siberian High. This study reveals the dual effects of the East Asian winter monsoon on wintertime haze-fog variations in eastern China and provides a more comprehensive understanding of the relationship between the monsoon and haze-fog events.

Effects of surface roughness on an adverse-pressure-gradient separating turbulent boundary layer

NASA Astrophysics Data System (ADS)

Wu, Wen; Piomelli, Ugo; Turbulence Simulation; Modelling Laboratory Team

2017-11-01

Separating turbulent boundary layers over smooth and rough flat plates are investigated by large-eddy simulations. A suction-blowing velocity distribution is imposed at the top boundary to produce an adverse-to-favourable pressure gradient and a closed separation bubble. Sandgrain roughness in the fully-rough regime is modelled by an immersed boundary method. In the rough-wall case, streamline detachment occurs earlier and the separation region is substantially larger due to the momentum deficit caused by the roughness. The adverse pressure gradient decreases the form drag and causes a thin reversed-flow region below the roughness crest, so that Cf = 0 does not coincide with the detachment of the flow from the surface. The wake regions behind roughness elements affect the intermittency of the near-wall flow, so that upstream of the detachment point the flow can be reversed half of the time, but its average is positive. The separated shear layer exhibits higher turbulent kinetic energy (TKE); the growth of the TKE there begins earlier relative to the separation point, and the peak TKE occurs close to the separation point. The momentum deficit caused by the roughness, again, plays a critical role in these changes. The authors acknowledge the support from Hydro-Québec and the NSERC Collaborative Research & Development program (CRDPJ 418786-11). The simulations were performed at CAC Queen't site. UP also thanks the support of Canada Research Chair Program.

77 FR 30212 - Approval and Promulgation of Air Quality Implementation Plans; Vermont; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-22

... Promulgation of Air Quality Implementation Plans; Vermont; Regional Haze AGENCY: Environmental Protection... Implementation Plan (SIP) that addresses regional haze for the first planning period from 2008 through 2018. The... numerous sources located over a wide geographic area (also referred to as the ``regional haze program...

78 FR 40654 - Approval, Disapproval and Promulgation of Implementation Plans; State of Wyoming; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-08

..., Disapproval and Promulgation of Implementation Plans; State of Wyoming; Regional Haze State Implementation Plan; Federal Implementation Plan for Regional Haze; Notice of Public Hearings AGENCY: Environmental...) addressing regional haze under. We are making this change in response to letters submitted by the Governor of...

77 FR 30932 - Approval and Promulgation of Air Quality Implementation Plans; Massachusetts; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-24

... background for EPA's proposed action? A. The Regional Haze Problem B. Background Information C. Roles of... the background for EPA's proposed action? A. The Regional Haze Problem Regional haze is visibility... distances, even hundreds of kilometers. Therefore, to effectively address the problem of visibility...

[Bilateral macular retinoschisis associated with unilateral peripheral retinoschisis].

PubMed

Oummad, Hanane; Elkaddoumi, Maryama; Maré, Josiane; Lezrek, Mounir; Cherkaoui, Ouafae

2017-01-01

X-linked juvenile retinoschisis is a hereditary disorder which usually occurs in boys rather than in girls, who are rarely affected. First clinical manifestations usually appear during the first decade. It is responsible for variable severity and slowly progressive vision loss. This progression can be characterized by vitreous hemorrhages and recurrent retinal detachments. We report the case of a 17-year old patient with stellar bilateral microcistic macular rearrangement of the eye-ground, centered on the foveola, associated with peripheral schisis with retinal detachment and unilateral tearing of internal and external layers.

Haze in beverages.

PubMed

Siebert, Karl J

2009-01-01

Beverages such as beer, wine, clear fruit juices, teas, and formulated products with similar ingredients are generally expected by consumers to be clear (free of turbidity) and to remain so during the normal shelf life of the product. Hazy products are often regarded as defective and perhaps even potentially harmful. Since consumers are usually more certain of what they perceive visually than of what they taste or smell, the development of haze in a clear product can reduce the likelihood of repeat purchasing of a product and can have serious economic consequences to a producer. Hazes are caused by suspended insoluble particles of colloidal or larger size that can be perceived visually or by instruments. Hazes in clear beverages can arise from a number of causes, but are most often due to protein-polyphenol interaction. The nature of protein-polyphenol interaction and its effect on haze particles, analysis of haze constituents, and stabilization of beverages against haze formation are reviewed.

77 FR 30214 - Approval and Promulgation of Air Quality Implementation Plans; Rhode Island; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-22

... Promulgation of Air Quality Implementation Plans; Rhode Island; Regional Haze AGENCY: Environmental Protection... Implementation Plan (SIP) that addresses regional haze for the first planning period from 2008 through 2018. The... geographic area (also referred to as the ``regional haze program''). DATES: Effective Date: This rule is...

77 FR 22550 - Approval and Promulgation of Air Quality Implementation Plans; New Hampshire; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-16

... and Promulgation of Air Quality Implementation Plans; New Hampshire; Regional Haze; Reopening of... regional haze for the first planning period from 2008 through 2018. Two commentors requested an extension... supplemental submittals on January 14, 2011, and August 26, 2011, that addresses regional haze for the first...

77 FR 16937 - Approval and Promulgation of Air Quality Implementation Plans; West Virginia; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-23

... Promulgation of Air Quality Implementation Plans; West Virginia; Regional Haze State Implementation Plan AGENCY... limited disapproval of West Virginia's Regional Haze State Implementation Plan (SIP) revision. EPA is... mandatory Class I areas through a regional haze program. EPA is also approving this revision as meeting the...

76 FR 42557 - Approval and Promulgation of Air Quality Implementation Plans; Delaware; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-19

... Promulgation of Air Quality Implementation Plans; Delaware; Regional Haze State Implementation Plan AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA is approving the Delaware Regional Haze... visibility in mandatory Class I areas through a regional haze program. EPA is also approving this revision...

77 FR 30454 - Approval and Promulgation of Implementation Plans; State of Oregon; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-23

.... Determination of Reasonable Progress Goals F. Long Term Strategy G. Coordinating Regional Haze and Reasonably... Reasonable Progress Goals (RPGs) and the Long Term Strategy (LTS). A. Definition of Regional Haze Regional... implementation of the regional haze program will require long-term regional coordination among states, tribal...

76 FR 73955 - Approval and Promulgation of Air Quality Implementation Plans; Maine; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

...: Table of Contents I. What is the background for EPA's proposed action? A. The Regional Haze Problem B... the background for EPA's proposed action? A. The Regional Haze Problem Regional haze is visibility... hundreds of kilometers. Therefore, to effectively address the problem of visibility impairment in Class I...

77 FR 3975 - Approval and Promulgation of Air Quality Implementation Plans; Indiana; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-26

.... What is the background for EPA's proposed action? A. The Regional Haze Problem B. Requirements of the... is the background for EPA's proposed action? A. The Regional Haze Problem Regional haze is visibility..., to effectively address the problem of visibility impairment in Class I areas, states need to develop...

The first close-up images of Jupiter's polar regions: Results from the Juno mission JunoCam instrument

NASA Astrophysics Data System (ADS)

Orton, Glenn S.; Hansen, Candice; Caplinger, Michael; Ravine, Michael; Atreya, Sushil; Ingersoll, Andrew P.; Jensen, Elsa; Momary, Thomas; Lipkaman, Leslie; Krysak, Daniel; Zimdar, Robert; Bolton, Scott

2017-05-01

During Juno's first perijove encounter, the JunoCam instrument acquired the first images of Jupiter's polar regions at 50-70 km spatial scale at low emission angles. Poleward of 64-68° planetocentric latitude, where Jupiter's east-west banded structure breaks down, several types of discrete features appear on a darker background. Cyclonic oval features are clustered near both poles. Other oval-shaped features are also present, ranging in size from 2000 km down to JunoCam's resolution limits. The largest and brightest features often have chaotic shapes. Two narrow linear features in the north, associated with an overlying haze feature, traverse tens of degrees of longitude. JunoCam also detected an optically thin cloud or haze layer past the northern nightside terminator estimated to be 58 ± 21 km (approximately three scale heights) above the main cloud deck. JunoCam will acquire polar images on every perijove, allowing us to track the state and evolution of longer-lived features.

Trace Gases and Aerosol Optical Properties Over the US Mid-Atlantic During Summer 2001

NASA Astrophysics Data System (ADS)

Doddridge, B. G.; Piety, C. A.

2001-12-01

Anthropogenic emissions from rapid urban sprawl, commuter/commercial traffic and industrialization along the East Coast of the United States have a profound effect on urban and regional air quality. During summer 2001 we used a light aircraft research platform operated from North Carolina northward through Pennsylvania measuring meteorological scalars, selected trace gases and aerosol optical properties on selected pollution episode days. The goal of this research is to gain an improved understanding of the sources, sinks, transport and photochemical transformations controlling the observed abundance of photochemical oxidants and fine particulate haze over the U.S. Mid-Atlantic region. The aircraft research capabilities will be described, over 60 research flights totaling in excess of 160 flight hours summarized, and key findings presented. Although westerly transport of remnant ozone and haze along with precursors can make substantial contributions to observed urban corridor air quality aloft, significant production downwind of the urban center often can occur within the planetary boundary layer during the afternoon hours.

A short review on the effects of aerosols on visibility impairment

NASA Astrophysics Data System (ADS)

Emetere Moses, E.; Akinyemi, ML

2017-05-01

Ozone in the lower planetary boundary layer of the earth atmosphere is dangerous to people and vegetation, since it oxidizes natural tissue. The diminished in visibility is because of dispersing of sun based radiation by high convergences of anthropogenic aerosols. Visibility impairment is most prominent at high relative mugginess when the aerosols swell by the take-up of water to expand the cross sectional area for dispersing; this is the wonder known as haze. Haze has become a major air pollution challenge the aviation industry has to cope with in recent time. In this review, two major problems were spotted to be responsible for air disaster in any region of the world. While some developed countries had almost resolved the challenge of visibility impairment by seeking relevant solutions, most developing countries do not have a recovery plan. Therefore, the resolution of this major challenge may be the leverage for most developing nations to draw out a recovery plan.

Retrieval of haze properties and HCN concentrations from the three-micron spectrum of Titan

NASA Astrophysics Data System (ADS)

Kim, Sang J.; Lee, D. W.; Sim, C. K.; Seon, K. I.; Courtin, R.; Geballe, T. R.

2018-05-01

The 3 μm spectrum of Titan contains line emission and absorption as well as a significant haze continuum. The line emission has been previously analyzed in the literature, but that analysis has not properly included the influence of haze on the line emission. We report a new analysis of the 3 μm HCN emission spectrum using radiative transfer equations that include scattering and absorption by molecules and haze particles at altitudes lower than 500 km, where the influence of haze on the emergent spectrum becomes significant. Taking advantage of the dominance of resonant single scattering in the HCN ν3 fundamental and of the moderate haze optical thickness of the atmosphere around 3 μm, we adopt single dust and molecular scattering and present a formulation for the radiative transfer process. We evaluate the quantitative influence of haze scattering on the emission line intensities, and derive vertically-resolved single scattering albedos of the haze from model fits. We also present the resulting concentrations of HCN for altitudes below 500 km, where we find that the haze scattering significantly influences the retrieval of the concentrations of HCN. We conclude that the formulation we present is useful for the analysis of the HCN line emission from Titan and other similar hazy planetary or celestial objects.

Chemical Composition Characteristics of Atmospheric Aerosols in Relation to Haze, Asian Dust and Mixed Haze-Asian Dust Episodes at Background Site of Korea in 2013

NASA Astrophysics Data System (ADS)

KO, H.; Song, J. M.; Cha, J. W.; Kang, C. H.; Kim, J.; Ryoo, S. B.

2016-12-01

The PM10 and PM2.5 aerosols were collected at the Gosan site of Jeju Island, Korea in 2013 and analyzed, in order to examine the variation characteristics of chemical compositions in relation to haze, Asian dust, and mixed haze-Asian dust episodes. For the haze event, nitrate concentrations increased highly as 8.8 and 25.1 times for PM10 and PM2.5, respectively, possibly caused by the inflow of air mass stagnated in eastern parts of China into Jeju area. For the Asian dust event, the concentrations of nss-Ca2+, NO3- and nss-SO42- increased 6.0, 1.5, 1.8 times for PM10, and 2.3, 1.3, 1.6 times for PM2.5, respectively. Meanwhile, for the mixed haze-Asian dust event, the concentrations of nss-Ca2+ and NO3- increased 13.4 and 3.2 times for PM10, and 1.8 and 3.4 times for PM2.5, respectively. The NH4NO3 content was higher than that of (NH4)2SO4 during the haze event, however it was relatively low during the mixed haze-Asian dust event. NO3-/nss-SO42- concentration ratios of Asian Dust in PM10 and PM2.5 were 0.4 and 0.2, showing less significant effect from automobile and local pollution sources. The aerosols were acidified mostly by inorganic acids, especially the nitric acid contributed highly to the acidification during both haze and mixed haze-Asian dust events. Meanwhile, the neutralization by ammonia was noticeably high during haze event when the stagnated air mass moved from China.

Constraints on the microphysics of Pluto's photochemical haze from New Horizons observations

NASA Astrophysics Data System (ADS)

Gao, Peter; Fan, Siteng; Wong, Michael L.; Liang, Mao-Chang; Shia, Run-Lie; Kammer, Joshua A.; Yung, Yuk L.; Summers, Michael E.; Gladstone, G. Randall; Young, Leslie A.; Olkin, Catherine B.; Ennico, Kimberly; Weaver, Harold A.; Stern, S. Alan; New Horizons Science Team

2017-05-01

The New Horizons flyby of Pluto confirmed the existence of hazes in its atmosphere. Observations of a large high- to low- phase brightness ratio, combined with the blue color of the haze (indicative of Rayleigh scattering), suggest that the haze particles are fractal aggregates, perhaps analogous to the photochemical hazes on Titan. Therefore, studying the Pluto hazes can shed light on the similarities and differences between the Pluto and Titan atmospheres. We model the haze distribution using the Community Aerosol and Radiation Model for Atmospheres assuming that the distribution is shaped by downward transport and coagulation of particles originating from photochemistry. Hazes composed of both purely spherical and purely fractal aggregate particles are considered. General agreement between model results and solar occultation observations is obtained with aggregate particles when the downward mass flux of photochemical products is equal to the column-integrated methane destruction rate ∼1.2 × 10-14 g cm-2 s-1, while for spherical particles the mass flux must be 2-3 times greater. This flux is nearly identical to the haze production flux of Titan previously obtained by comparing microphysical model results to Cassini observations. The aggregate particle radius is sensitive to particle charging effects, and a particle charge to radius ratio of 30 e-/μm is necessary to produce ∼0.1-0.2 μm aggregates near Pluto's surface, in accordance with forward scattering measurements. Such a particle charge to radius ratio is 2-4 times higher than those previously obtained for Titan. Hazes composed of spheres with the same particle charge to radius ratio have particles that are 4 times smaller at Pluto's surface. These results further suggest that the haze particles are fractal aggregates. We also consider the effect of condensation of HCN, C2H2, C2H4, and C2H6 on the haze particles, which may play an important role in shaping their altitude and size distributions.

Satellite view of the extreme haze clouds over China

NASA Astrophysics Data System (ADS)

Minghui, T.; Chen, L.; Wang, Z.

2013-12-01

Minghui Tao*, Liangfu Chen, Zifeng Wang State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China *Email: tmh1985@163.com ABSTRACT: In the past decades, great increases in anthropogenic emissions have caused dramatic changes in air quality and regional climate in China, which are further complicated by the natural processes such as dust events and atmospheric dynamics such as variations in intensity of the Asian monsoon. The common urban photochemistry smog, haze, and fog-haze pollution lead to poor air quality in major cities in eastern and middle parts of China. On the other hand, the heavy aerosol loading exerts marked influences on radiation, clouds, and precipitation over China. Satellites usually observed widespread haze clouds over eastern China. In most of previous studies, the dense haze clouds were directly connected with accumulation of anthropogenic emissions. However, satellite observations show that formation processes of haze clouds and local pollution near surface were different. Understanding the connections and interactions between haze clouds and local anthropogenic emissions is essential in chemistry and climate modeling of the aerosols over China. In January 2013, durative haze clouds covered most parts of eastern China, leading to extreme pollution events in many cities. With integrated A-train satellite observations and ground measurements, we investigated variations, optical properties, vertical structures as well as formation process of the extreme haze clouds over eastern China. Satellite-surface results were compared to analyze relations between the haze clouds and surface pollution. Different from traditional views, our results reveal that variation and formation of the haze clouds were driven by large-scale natural processes rather than local anthropogenic emissions. Figure 1. Aqua MODIS true color images of the haze clouds over eastern China on Jan 10, 2013.

Impact of regional haze towards air quality in Malaysia: A review

NASA Astrophysics Data System (ADS)

Latif, Mohd Talib; Othman, Murnira; Idris, Nurfathehah; Juneng, Liew; Abdullah, Ahmad Makmom; Hamzah, Wan Portia; Khan, Md Firoz; Nik Sulaiman, Nik Meriam; Jewaratnam, Jegalakshimi; Aghamohammadi, Nasrin; Sahani, Mazrura; Xiang, Chung Jing; Ahamad, Fatimah; Amil, Norhaniza; Darus, Mashitah; Varkkey, Helena; Tangang, Fredolin; Jaafar, Abu Bakar

2018-03-01

Haze is a common phenomenon afflicting Southeast Asia (SEA), including Malaysia, and has occurred almost every year within the last few decades. Haze is associated with high level of air pollutants; it reduces visibility and affects human health in the affected SEA countries. This manuscript aims to review the potential origin, chemical compositions, impacts and mitigation strategies of haze in Malaysia. "Slash and burn" agricultural activities, deforestation and oil palm plantations on peat areas, particularly in Sumatra and Kalimantan, Indonesia were identified as the contributing factors to high intensity combustions that results in transboundary haze in Malaysia. During the southwest monsoon (June to September), the equatorial SEA region experiences a dry season and thus an elevated number of fire events. The prevailing southerly and south-westerly winds allow the cross-boundary transportation of pollutants from the burning areas in Sumatra and Kalimantan in Indonesia, to Peninsular Malaysia and Malaysian Borneo, respectively. The dry periods caused by the El Niño - Southern Oscillation (ENSO) prolong the duration of poor air quality. The size range of particulate matter (PM) in haze samples indicates that haze is dominated by fine particles. Secondary inorganic aerosols (SIA, such as SO42- and NH4+) and organic substances (such as levoglucosan, LG) were the main composition of PM during haze episodes. Local vehicular emissions and industrial activities also contribute to the amount of pollutants and can introduce toxic material such as polyaromatic hydrocarbons (PAHs). Haze episodes have contributed to increasing hospital visits for treatments related to chronic obstructive pulmonary diseases, upper respiratory infections, asthma and rhinitis. Respiratory mortality increased 19% due to haze episodes. Children and senior citizens are more likely to suffer the health impacts of haze. The inpatient cost alone from haze episodes was estimated at around USD 91,000 per year in Malaysia. Almost all economic sectors also experienced losses, with the heaviest losses in the agriculture and tourism sectors. This review suggests several ways forward to reduce haze episodes in SEA and Malaysia. These include economic approaches, research collaborations and science-policy interface. Improving forecasting capabilities can help reduce response time to burning events and subsequently reduce its impacts. Lastly, commitment and involvement by individuals, government agencies, and the entrepreneurial private sectors are crucial to reduce biomass burning (BB) and haze episodes in SEA.

Hazing in Public Schools: A Liability Challenge for School Leaders

ERIC Educational Resources Information Center

Essex, Nathan L.

2014-01-01

Hazing in public schools is a significant problem that may result in serious physical or emotional harm to students who are victims. According to experts in the field, each year more than 1,500,000 American students become new hazing victims. Hazing also results in legal challenges for school personnel. The courts consider public schools to be…

77 FR 11452 - Approval and Promulgation of Air Quality Implementation Plans; State of Georgia; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-27

... Problem B. Requirements of the CAA and EPA's Regional Haze Rule (RHR) C. Roles of Agencies in Addressing.... The Regional Haze Problem Regional haze is visibility impairment that is produced by a multitude of... of kilometers. Therefore, to effectively address the problem of visibility impairment in Class I...

A Case of High School Hazing: Applying Restorative Justice to Promote Organizational Learning

ERIC Educational Resources Information Center

DeWitt, Douglas M.; DeWitt, Lori J.

2012-01-01

While collegiate fraternity and sorority hazing are well documented problems that receive prominent attention, hazing at the high school level is also a serious issue. Across the nation, media headlines offer a continual reminder that high school hazing is not a phenomenon of the past. As high school principals seek ways to discourage and…

Spatiotemporal variations of severe haze episodes in China

NASA Astrophysics Data System (ADS)

Li, J.; Liao, H.

2017-12-01

Rapid economic growth and associated emissions increase in China have led to severe air pollution in recent decades. This study presents the spatial and temporal variations of severe haze episodes in China obtained from monitoring sites and the global chemical transport model GEOS-Chem. Cities in the Beijing-Tianjin-Hebei (BTH) and Yangtze River Delta (YRD) regions suffered from severe haze, with highest numbers of severe haze episodes in winter and the lowest numbers of episodes in summer. Backward trajectory analysis by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated the origins of air mass during severe haze episodes for BTH and YRD. The principal component analysis was applied for different regions to classify synoptic conditions associated with the severe haze episodes.

Nucleophilic addition of nitrogen to aryl cations: mimicking Titan chemistry.

PubMed

Li, Anyin; Jjunju, Fred P M; Cooks, R Graham

2013-11-01

The reactivity of aryl cations toward molecular nitrogen is studied systematically in an ion trap mass spectrometer at 10(2) Pascal of nitrogen, the pressure of the Titan main haze layer. Nucleophilic addition of dinitrogen occurs and the nature of aryl group has a significant influence on the reactivity, through inductive effects and by changing the ground state spin multiplicity. The products of nitrogen activation, aryldiazonium ions, react with typical nitriles, aromatic amines, and alkynes (compounds that are relevant as possible Titan atmosphere constituents) to form covalently bonded heterocyclic products. Theoretical calculations at the level [DFT(B3LYP)/6-311++G(d,p)] indicate that the N2 addition reaction is exothermic for the singlet aryl cations but endothermic for their triplet spin isomers. The -OH and -NH2 substituted aryl ions are calculated to have triplet ground states, which is consistent with their decreased nitrogen addition reactivity. The energy needed for the generation of the aryl cations from their protonated precursors (ca. 340 kJ/mol starting with protonated aniline) is far less than that required to directly activate the nitrogen triple bond (the lowest energy excited state of N2 lies ca. 600 kJ/mol above the ground state). The formation of aza-aromatics via arene ionization and subsequent reactions provide a conceivable route to the genesis of nitrogen-containing organic molecules in the interstellar medium and Titan haze layers.

Saturn's secrets revealed - A special report

NASA Astrophysics Data System (ADS)

Sutton, C.

1980-11-01

Scientific results of the encounter of Voyager 1 with Saturn are reported. Instruments on the Voyager spacecraft, which was launched on September 5, 1977 and flew within 124,200 km of the Saturn cloud tops on November 12, 1980, revealed the presence of several hundred rings within the six visible from earth, as well as eccentric rings, braiding and clumps within the narrow F ring, and spoke-like structures in the B ring. During its flight beneath the ring plane, Voyager 1 also discovered that the rings extend toward the visible surface of the cloud tops, and are composed of ice chunks or silicate with an icy coating about a meter in diameter. Observations of Titan revealed the satellite to have a dense atmosphere, composed primarily of molecular nitrogen, with as many as three layers of haze above the cloud tops. Three additional moons of Saturn were discovered apparently focusing ring particles, and the moon Janus, discovered from earth in 1966, was shown to be actually two moons. Close approaches to other Saturn satellites show Mimas, Tethys, Dione and Rhea to be heavily cratered, icy bodies, some with features indicating they had been struck by objects almost large enough to shatter them. Surface features on Saturn, which is covered by a deep layer of haze, and the details of the Saturn magnetosphere have also been observed.

Slab detachment during continental collision: Influence of crustal rheology and interaction with lithospheric delamination

NASA Astrophysics Data System (ADS)

Duretz, T.; Gerya, T. V.

2013-08-01

Collision between continents can lead to the subduction of continental material. If the crust remains coupled to the downgoing slab, a large buoyancy force is generated. This force slows down convergence and promotes slab detachment. If the crust resists to subduction, it may decouple from the downgoing slab and be subjected to buoyant extrusion. We employ two-dimensional thermo-mechanical modelling to study the importance of crustal rheology on the evolution of subduction-collision systems. We propose simple quantifications of the mechanical decoupling between lithospheric levels (σ*) and the potential for buoyant extrusion of the crust (ξ*). The modelling results indicate that a variable crustal rheological structure results in slab detachment, delamination, or the combination of both mechanisms. A strong crust provides coupling at the Moho (low σ*) and remains coherent during subduction (low ξ). It promotes deep subduction of the crust (180 km) and slab detachment. Exhumation occurs in coherent manners via eduction and thrusting. Slab detachment triggers the development of topography (> 4.5 km) close to the suture. A contrasting style of collision occurs using a weak crustal rheology. Mechanical decoupling at the Moho (high σ*) promotes the extrusion of the crust (high ξ), disabling slab detachment. Ongoing shortening leads to buckling of the crust and development of topography on the lower plate. Collisions involving rheologically layered crust allow decoupling at mid-crustal depths. This structure favours both the extrusion of upper crust and the subduction of the lower crust. Such collisions are successively affected by delamination and slab detachment. Topography develops together with the buoyant extrusion of crust onto the foreland and is further amplified by slab detachment. Our results suggest that the occurrence of both delamination (Apennines) and slab detachment (Himalayas) in orogens may indicate differences in the initial crustal structure of subducting continental plates in these regions.

Application of tethered balloon for studying vertical distribution of air pollutants within lower tropsphere of Shanghai

NASA Astrophysics Data System (ADS)

Zhang, K.; Wang, D.; Fu, Q.; Xiu, G.; Duan, Y.

2016-12-01

Tethered balloon-based measurement campaign of particle number concentration (PNC) and particle number size distribution (PNSD) in the range of 15.7-661.2 nm was conducted within the lower troposphere of 1000 m in Shanghai, a Chinses megacity, in December 2015. The meteorological condition, PNC, and PNSD were synchronous measured at ground-based station as well as on the tethered balloon. Overall, the mixing layer height (MLH) showed a peak at about LST 14:00-15:00. On ground level, the 88.2 nm particles had the highest number concentration. The Pearson correlation analysis based on the ground level data shows the Pearson correlation coefficient between PNC and NO2was 0.774. The synchronous measurement of PNC and PNSD on ground level and on the tethered balloon showed the 15.7-200 nm particles had higher PNC on ground level, but the PNC of 200-661.2 nm particles are higher at 400 m. And the wind condition showed a strong influence on PNC.The vertical profiles of meteorological parameters and air pollutants was observed. The particle mass concentration, ozone concentration, temperature, and humidity all showed a quick change when the balloon across the atmosphere boundary layer. One episodic haze event (Dec 22nd-Dec 23rd) was selected with specific focus on the variation of PNSD and PNC vertical profiles. Before the haze, the PNC at ground was 9281 cm-3. The MaxDm (the particle diameter with the highest number concentration) was 53.3 nm at that time. Due to the shallow MLH, the MaxDm changed rapidly to 126.3 nm at 321 m. During the haze, the MaxDm and the PNC on ground level was 126.3 nm and 18515 cm-3 respectively. And a quick drop of PNC was observed at 553 m. This may due to the change of wind direction, temperature, and relative humidity. At the end of haze, the MaxDm and the PNC on ground level was 126.3 nm and 10711 cm-3 respectively. The highest MaxDm during those three launches all appeared at a high altitude, usually above 300 m. This result is consisted with the synchronous measurement on December 21st to some degree. This study provides a first insight of PNSD vertical profiles over Eastern China, which will greatly improve the kownledge of the characteristics of particles within the lower tropsphere.

Secrets Revealed from Pluto Twilight Zone

NASA Image and Video Library

2016-06-02

NASA's New Horizons spacecraft took this stunning image of Pluto only a few minutes after closest approach on July 14, 2015. The image was obtained at a high phase angle -- that is, with the sun on the other side of Pluto, as viewed by New Horizons. Seen here, sunlight filters through and illuminates Pluto's complex atmospheric haze layers. The southern portions of the nitrogen ice plains informally named Sputnik Planum, as well as mountains of the informally named Norgay Montes, can also be seen across Pluto's crescent at the top of the image. Looking back at Pluto with images like this gives New Horizons scientists information about Pluto's hazes and surface properties that they can't get from images taken on approach. The image was obtained by New Horizons' Ralph/Multispectral Visual Imaging Camera (MVIC) approximately 13,400 miles (21,550 kilometers) from Pluto, about 19 minutes after New Horizons' closest approach. The image has a resolution of 1,400 feet (430 meters) per pixel. Pluto's diameter is 1,475 miles (2,374 kilometers). The inset at top right in the annotated version shows a detail of Pluto's crescent, including an intriguing bright wisp (near the center) measuring tens of miles across that may be a discreet, low-lying cloud in Pluto's atmosphere; if so, it would be the only one yet identified in New Horizons imagery. This cloud -- if that's what it is -- is visible for the same reason the haze layers are so bright: illumination from the sunlight grazing Pluto's surface at a low angle. Atmospheric models suggest that methane clouds can occasionally form in Pluto's atmosphere. The scene in this inset is 140 miles (230 kilometers) across. The inset at bottom right shows more detail on the night side of Pluto. This terrain can be seen because it is illuminated from behind by hazes that silhouette the of the annotated version limb. The topography here appears quite rugged, and broad valleys and sharp peaks with relief totaling 3 miles (5 kilometers) are apparent. This image, made from closer range, is much better than the lower-resolution images of this same terrain taken several days before closest approach. These silhouetted terrains therefore act as a useful "anchor point," giving New Horizons scientists a rare, detailed glimpse at the lay of the land in this mysterious part of Pluto seen at high resolution only in twilight. The scene in this inset is 460 miles (750 kilometers) wide. http://photojournal.jpl.nasa.gov/catalog/PIA20727

Possible connection between the East Asian summer monsoon and a swing of the haze-fog-prone area in eastern China

NASA Astrophysics Data System (ADS)

Liu, Qian; Cao, Ziqi; Sheng, Lifang; Diao, Yina; Wang, Wencai; Zhou, Yang; Qiu, Jingyi

2018-05-01

The summer monsoon has recently been hypothesized to influence haze-fog events over China, but the detailed processes involved have yet to be determined. In the present study, we found that the haze-fog-prone area swings over eastern China during boreal summer (May to September), coinciding with the movement of the subtropical monsoon convergence belt (hereinafter referred to simply as the "convergence belt"). Further investigation showed that the convergence belt modulates the spatial distribution of the haze-fog-prone area by altering the regional atmospheric conditions. When the warm and wet summer monsoon air mass pushes northwards and meets with cold air, a frontal zone (namely, the convergence belt) forms. The ascent of warm and wet air along the front strengthens the atmospheric stability ahead of the frontal zone, while the descent of cold and dry air weakens the vertical diffusion at the same place. These processes result in an asymmetric distribution of haze-fog along the convergence belt. Based on the criterion of absolute stability and downdraft, these atmospheric conditions favorable for haze-fog are able to identify 57-79% of haze-fog-prone stations, and the anticipation accuracy is 61-71%. After considering the influence of air pollutants on haze-fog occurrence, the anticipation accuracy rises to 78-79%. Our study reveals a connection between local haze-fog weather phenomena and regional atmospheric conditions and large-scale circulation, and demonstrates one possible mechanism for how the summer monsoon influences the distribution of haze-fog in eastern China.

Analytical solution for haze values of aluminium-induced texture (AIT) glass superstrates for a-Si:H solar cells.

PubMed

Sahraei, Nasim; Forberich, Karen; Venkataraj, Selvaraj; Aberle, Armin G; Peters, Marius

2014-01-13

Light scattering at randomly textured interfaces is essential to improve the absorption of thin-film silicon solar cells. Aluminium-induced texture (AIT) glass provides suitable scattering for amorphous silicon (a-Si:H) solar cells. The scattering properties of textured surfaces are usually characterised by two properties: the angularly resolved intensity distribution and the haze. However, we find that the commonly used haze equations cannot accurately describe the experimentally observed spectral dependence of the haze of AIT glass. This is particularly the case for surface morphologies with a large rms roughness and small lateral feature sizes. In this paper we present an improved method for haze calculation, based on the power spectral density (PSD) function of the randomly textured surface. To better reproduce the measured haze characteristics, we suggest two improvements: i) inclusion of the average lateral feature size of the textured surface into the haze calculation, and ii) considering the opening angle of the haze measurement. We show that with these two improvements an accurate prediction of the haze of AIT glass is possible. Furthermore, we use the new equation to define optimum morphology parameters for AIT glass to be used for a-Si:H solar cell applications. The autocorrelation length is identified as the critical parameter. For the investigated a-Si:H solar cells, the optimum autocorrelation length is shown to be 320 nm.

Haze detection by using modified normalized difference haze index in Beijing, Tianjin, and Hebei province

NASA Astrophysics Data System (ADS)

Han, Xinlei; Yao, Fengmei; Zhang, Jiahua; Waqar, Mirza Muhammad; Zha, Yong; He, Junliang

2016-04-01

This paper presents the development of index to detect haze from moderate resolution imaging spectroradiometer remote sensing data. Detection of haze over a large area has always been a problem. This study focuses on Beijing, Tianjin, and Shijiazhuang cities in China. These cities have suffered the worst hazy weather in recent years. The spectral influence of haze on surface features was determined through analysis of the spectral variations of surface covers between hazy and haze-free days. A spectral index known as modified normalized difference haze index (m-NDHI) is developed that can be used to monitor haze distribution and intensity. Correlation analysis of the derived m-NDHI and previously developed NDHI with in situ PM2.5 (particulate matter with diameter <2.5 μm) data reveals that m-NDHI over water bodies has a coefficient of 0.7096, 0.5864, and 0.4857 and NDHI has coefficient of 0.5625, 0.5321, and 0.4618 with PM2.5 for Beijing, Tianjin, and Shijiazhuang, respectively, in winter. Moreover, the correlation of m-NDHI with PM2.5 is 0.4097, 0.8092, and 0.5546 during the spring, summer, and autumn, respectively, in Beijing. This developed index can be a much easier and more effective method to detect haze in large scales from remotely sensing data and characterize the situation of urban atmospheric pollution.

Retinal Layers Measurements following Silicone Oil Tamponade for Retinal Detachment Surgery.

PubMed

Jurišić, Darija; Geber, Mia Zorić; Ćavar, Ivan; Utrobičić, Dobrila Karlica

2017-12-19

This study aimed to investigate the influence of silicone oil on the retinal nerve fiber layer (RNFL) thickness in patients with primary rhegmatogenous retinal detachment who underwent vitreoretinal surgery. The study included 47 patients (eyes), who underwent a pars plana vitrectomy with the silicone oil tamponade. The control group included unoperated eye of all participants. Spectral-domain optical coherence tomography (SD-OCT) was used for the measurements of peripapilar and macular RNFL thickness. The average peripapillary RNFL thickness was significantly higher in the silicone oil filled eyes during endotamponade and after its removal. The eyes with elevated IOP had less thickening of the RNFL in comparison to the eyes with normal IOP. Central macular thickness and macular volume were decreased in the silicone oil filled eyes in comparison to the control eyes. In conclusion, silicone oil caused peripapilar RNFL thickening in the vitrectomized eyes during endotamponade and after silicone oil removal.

A study on sonoporation of cells cultured on a soft collagen gel scaffold

NASA Astrophysics Data System (ADS)

Kudo, Nobuki; Kinoshita, Yuto

2012-11-01

Efficiencies of sonoporation were investigated using four types of monolayer-cell samples: cells cultured directly on a cover slip, cells cultured on a cover slip coated with collagen gel of several μm in thickness, and cells cultured on collagen gel scaffolds of 0.4 and 1.0 mm in thicknesses. Cell samples attached with Levovist microbubbles were irradiated by one shot of a three- or 10,000-cycle ultrasound pulse, and cell detachment and membrane perforation were investigated. Experimental results showed that rates of cell detachment and membrane damage were markedly decreased in the presence of soft gel layer of 0.4 and 1.0 mm in thicknesses under the cells and that these rates were inversely proportional to the thickness of the gel layer. These results indicate that optimum conditions of sonoporation in vitro should be carefully translated into those in vivo.

Visibility and Haze

EPA Pesticide Factsheets

Haze forms when sunlight encounters particle pollution. It reduces visibility in cities and scenic areas. This web area provides regulatory information and progress towards improving visibility through EPA’s regional haze program.

DOD Service Academies: More Changes Needed To Eliminate Hazing. Report to Congressional Requesters.

ERIC Educational Resources Information Center

General Accounting Office, Washington, DC. Div. of National Security and International Affairs.

This study sought to review the extent of hazing at the three Department of Defense (DOD) service academies, the actions taken by the academies to control and eliminate hazing, and the impact of hazing on cadets and midshipmen. The three academies studied were the Naval Academy (Annapolis, Maryland), the Air Force Academy (Colorado Springs,…

Salix polaris growth responses to active layer detachment and solifluction processes in High Arctic.

NASA Astrophysics Data System (ADS)

Siekacz, Liliana

2015-04-01

The work is dedicated to demonstrate the potential of Salix polaris grow properties in the dendrogemorphologic image, analyzing periglacially induced slope processes in the high Arctic.. Observed anatomical and morphological plants responses to solifluction and active layer detachment processes are presented qualitatively and quantitatively as a summary of presented features frequency. The results are discussed against the background of the other research results in this field. The investigations was performed in Ebba valley, in the vicinity of Petunia Bay, northernmost part of Billefjorden in central Spitsbergen (Svalbard). Environmental conditions are characterized by annual precipitation sum lower than 200 mm (Hagen et al.,1993) and average summer temperature of about 5°C, with maximum daily temperatures rarely exceeding 10°C (Rachlewicz, 2009). Collected shrub material was prepared according to the methods presented by Schweingruber and Poschlod (2005). Thin (approx. 15-20μm) sections of the whole cross-section were prepared with a sledge microtome, stained with Safranine and Astra blue and finally permanently fixed on microslides with Canada balsam and dried. Snapshots were taken partially for each cross-section with digital camera (ColorView III, Olympus) connected to a microscope (Olympus BX41) and merged into one, high resolution image. After all, ring widths were measured in 3-4 radii in every single cross-section using ImageJ software. Analyzed plants revealed extremely harsh environmental conditions of their growth. Buchwał et al. (2013) provided quantitative data concerning missing rings and partially missing rings in shrubs growing on Ebba valley floor. Mean ring width at the level of 79μm represents one of the smallest values of yearly growth ever noted. The share of missing rings and partially missing rings was 11,2% and 13,6% respectively. Plants growing on Ebba valley slope indicate almost twice smaller values of ring width (41μm), and higher participation of missing and partially missing rings. Share of missing rings in shrubs growing within an active layer detachment on the valley slope reached 16,22% and 15,36%. Even higher variation is observed in partially missing rings which account for 31,07% within detachment and 23,39% on surrounding slope. Those values are more than twice higher comparing to the valley floor. There is also noticeable difference between detachment and surrounding slope indicating that wedging rings are an effect of mechanical stress that is higher within the detachment. Comparing growth patterns in aboveground and belowground plant parts different growth allocation is noticed. Years of detachment event growth rings were present only in aboveground parts. It is supposed that mechanical stress delays the onset of the growing season similarly to low temperatures (Buchwał et al., 2013), resulting in not enough time to fully allocate resources for growth in the belowground parts. Growth pattern is extremely irregular, indicating that the slope is in constant movement, which disrupts growth conditions. Analyzed shrubs showed two possible event years: 2006 and 2008, with the highest participation of missing and partially missing rings. Air and ground temperature data were also analyzed and confirmed that active layer detachment happened in 2006. REFERENCES Buchwał A, Rachlewicz G, Fonti P, Cherubini P, Gärtner H, (2013) Temperature modulates intra-plant growth of Salix Polaris from a high Arctic site (Svalbard). Polar Biol 36:1305-1318. Hagen J O, Liestøl O, Roland E, Jørgensen T, (1993) Glacier atlas of Svalbard and Jan Mayen. Norsk Polarinstitutt Meddelelser 129: 160. Rachlewicz G, (2009) Contemporary sediment fluxes and relief changes in high Arctic glacierized valley systems (Billefjorden, Central Spitsbergen). Wyd. Nauk. UAM Poznań, seria Geografia 87:204. Schweingruber FH, Poschlod P, (2005) Growth rings in herbs and shrubs: life span, age determination and stem anatomy. For Snow Landsc Res 79:195-415

Wine protein haze: mechanisms of formation and advances in prevention.

PubMed

Van Sluyter, Steven C; McRae, Jacqui M; Falconer, Robert J; Smith, Paul A; Bacic, Antony; Waters, Elizabeth J; Marangon, Matteo

2015-04-29

Protein haze is an aesthetic problem in white wines that can be prevented by removing the grape proteins that have survived the winemaking process. The haze-forming proteins are grape pathogenesis-related proteins that are highly stable during winemaking, but some of them precipitate over time and with elevated temperatures. Protein removal is currently achieved by bentonite addition, an inefficient process that can lead to higher costs and quality losses in winemaking. The development of more efficient processes for protein removal and haze prevention requires understanding the mechanisms such as the main drivers of protein instability and the impacts of various wine matrix components on haze formation. This review covers recent developments in wine protein instability and removal and proposes a revised mechanism of protein haze formation.

Coherent and turbulent process analysis of the effects of a longitudinal vortex on boundary layer detachment on a NACA0015 foil

NASA Astrophysics Data System (ADS)

Prothin, Sebastien; Djeridi, Henda; Billard, Jean-Yves

2014-05-01

In this paper, the influence of a single tip vortex on boundary layer detachment is studied. This study offers a preliminary approach in order to better understand the interaction between a propeller hub vortex and the rudder installed in its wake. This configuration belongs to the field of marine propulsion and encompasses such specific problem as cavitation inception, modification of propulsive performances and induced vibrations. To better understand the complex mechanisms due to propeller-rudder interactions it was decided to emphasize configurations where the hub vortex is generated by an elliptical 3-D foil and is located upstream of a 2-D NACA0015 foil at high incidences for a Reynolds number of 5×105. The physical mechanisms were studied using Time Resolved Stereoscopic Particle Image Velocimetry (TR-SPIV) techniques. Particular attention was paid to the detachment at 25° incidence and a detailed cartography of the mean and turbulent properties of the wake is presented. Proper Orthogonal Decomposition (POD) analysis was applied in order to highlight the unsteady nature of the flow using phase averaging based on the first POD coefficients to characterize the turbulent and coherent process in the near wake of the rudder.

A numerical study of defect detection in a plaster dome ceiling using structural acoustics.

PubMed

Bucaro, J A; Romano, A J; Valdivia, N; Houston, B H; Dey, S

2009-07-01

A numerical study is carried out to evaluate the effectiveness of using measured surface displacements resulting from acoustic speaker excitation to detect and localize flaws in a domed, plaster ceiling. The response of the structure to an incident acoustic pressure is obtained at four frequencies between 100 and 400 Hz using a parallel h-p structural acoustic finite element-based code. Three ceiling conditions are modeled: the pristine ceiling considered rigidly attached to the domed-shape support, partial detachment of a segment of the plaster layer from the support, and an interior pocket of plaster deconsolidation modeled as a heavy fluid. Spatial maps of the normal displacement resulting from speaker excitation are interpreted with the help of predictions based on static analysis. It is found that acoustic speaker excitation can provide displacement levels readily detected by commercially available laser Doppler vibrometer systems. Further, it is concluded that for 1 in. thick plaster layers, detachment sizes as small as 4 cm are detectable by direct observation of the measured displacement maps. Finally, spatial structure differences are observed in the displacement maps beneath the two defect types, which may provide a wavenumber-based feature useful for distinguishing plaster detachment from other defects such as deconsolidation.

Impact of crop field burning and mountains on heavy haze in the North China Plain: a case study

NASA Astrophysics Data System (ADS)

Long, Xin; Tie, Xuexi; Cao, Junji; Huang, Rujin; Feng, Tian; Li, Nan; Zhao, Suyu; Tian, Jie; Li, Guohui; Zhang, Qiang

2016-08-01

With the provincial statistical data and crop field burning (CFB) activities captured by Moderate Resolution Imaging Spectroradiometer (MODIS), we extracted a detailed CFB emission inventory in the North China Plain (NCP). The WRF-CHEM model was applied to investigate the impact of CFB on air pollution during the period from 6 to 12 October 2014, corresponding to a heavy haze incident with high concentrations of PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm). The WRF-CHEM model generally performed well in simulating the surface species concentrations of PM2.5, O3 and NO2 compared to the observations; in addition, it reasonably reproduced the observed temporal variations of wind speed, wind direction and planetary boundary layer height (PBLH). It was found that the CFB that occurred in southern NCP (SNCP) had a significant effect on PM2.5 concentrations locally, causing a maximum of 34 % PM2.5 increase. Under continuous southerly wind conditions, the CFB pollution plume went through a long-range transport to northern NCP (NNCP; with several mega cities, including Beijing, the capital city of China), where few CFBs occurred, resulting in a maximum of 32 % PM2.5 increase. As a result, the heavy haze in Beijing was enhanced by the CFB, which occurred in SNCP. Mountains also play significant roles in enhancing the PM2.5 pollution in NNCP through the blocking effect. The mountains blocked and redirected the airflows, causing the pollutant accumulations along the foothills of mountains. This study suggests that the prohibition of CFB should be strict not only in or around Beijing, but also on the ulterior crop growth areas of SNCP. PM2.5 emissions in SNCP should be significantly limited in order to reduce the occurrences of heavy haze events in the NNCP region.

A low-angle detachment fault revealed: Three-dimensional images of the S-reflector fault zone along the Galicia passive margin

NASA Astrophysics Data System (ADS)

Schuba, C. Nur; Gray, Gary G.; Morgan, Julia K.; Sawyer, Dale S.; Shillington, Donna J.; Reston, Tim J.; Bull, Jonathan M.; Jordan, Brian E.

2018-06-01

A new 3-D seismic reflection volume over the Galicia margin continent-ocean transition zone provides an unprecedented view of the prominent S-reflector detachment fault that underlies the outer part of the margin. This volume images the fault's structure from breakaway to termination. The filtered time-structure map of the S-reflector shows coherent corrugations parallel to the expected paleo-extension directions with an average azimuth of 107°. These corrugations maintain their orientations, wavelengths and amplitudes where overlying faults sole into the S-reflector, suggesting that the parts of the detachment fault containing multiple crustal blocks may have slipped as discrete units during its late stages. Another interface above the S-reflector, here named S‧, is identified and interpreted as the upper boundary of the fault zone associated with the detachment fault. This layer, named the S-interval, thickens by tens of meters from SE to NW in the direction of transport. Localized thick accumulations also occur near overlying fault intersections, suggesting either non-uniform fault rock production, or redistribution of fault rock during slip. These observations have important implications for understanding how detachment faults form and evolve over time. 3-D seismic reflection imaging has enabled unique insights into fault slip history, fault rock production and redistribution.

A review of radiative detachment studies in tokamak advanced magnetic divertor configurations

DOE PAGES

Soukhanovskii, V. A.

2017-04-28

The present vision for a plasma–material interface in the tokamak is an axisymmetric poloidal magnetic X-point divertor. Four tasks are accomplished by the standard poloidal X-point divertor: plasma power exhaust; particle control (D/T and He pumping); reduction of impurity production (source); and impurity screening by the divertor scrape-off layer. A low-temperature, low heat flux divertor operating regime called radiative detachment is viewed as the main option that addresses these tasks for present and future tokamaks. Advanced magnetic divertor configuration has the capability to modify divertor parallel and cross-field transport, radiative and dissipative losses, and detachment front stability. Advanced magnetic divertormore » configurations are divided into four categories based on their salient qualitative features: (1) multiple standard X-point divertors; (2) divertors with higher order nulls; (3) divertors with multiple X-points; and (4) long poloidal leg divertors (and also with multiple X-points). As a result, this paper reviews experiments and modeling in the area of radiative detachment in the advanced magnetic divertor configurations.« less

A review of radiative detachment studies in tokamak advanced magnetic divertor configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soukhanovskii, V. A.

The present vision for a plasma–material interface in the tokamak is an axisymmetric poloidal magnetic X-point divertor. Four tasks are accomplished by the standard poloidal X-point divertor: plasma power exhaust; particle control (D/T and He pumping); reduction of impurity production (source); and impurity screening by the divertor scrape-off layer. A low-temperature, low heat flux divertor operating regime called radiative detachment is viewed as the main option that addresses these tasks for present and future tokamaks. Advanced magnetic divertor configuration has the capability to modify divertor parallel and cross-field transport, radiative and dissipative losses, and detachment front stability. Advanced magnetic divertormore » configurations are divided into four categories based on their salient qualitative features: (1) multiple standard X-point divertors; (2) divertors with higher order nulls; (3) divertors with multiple X-points; and (4) long poloidal leg divertors (and also with multiple X-points). As a result, this paper reviews experiments and modeling in the area of radiative detachment in the advanced magnetic divertor configurations.« less

Polarimetry Of Planetary Atmospheres: From The Solar System Gas Giants To Extrasolar Planets

NASA Astrophysics Data System (ADS)

Buenzli, Esther; Bazzon, A.; Schmid, H. M.

2011-09-01

The polarization of light reflected from a planet provides unique information on the atmosphere structure and scattering properties of particles in the upper atmosphere. The solar system planets show a large variety of atmospheric polarization properties, from the thick, highly polarizing haze on Titan and the poles of Jupiter, Rayleigh scattering by molecules on Uranus and Neptune, to clouds in the equatorial region of Jupiter or on Venus. Polarimetry is also a promising differential technique to search for and characterize extra-solar planets, e.g. with the future VLT planet finder instrument SPHERE. For the preparation of the SPHERE planet search program we have made a suite of polarimetric observations and models for the solar system gas giants. The phase angles for the outer planets are small for Earth bound observations and the integrated polarization is essentially zero due to the symmetric backscattering situation. However, a second order scattering effect produces a measurable limb polarization for resolved planetary disks. We have made a detailed model for the spectropolarimetric signal of the limb polarization of Uranus between 520 and 935 nm to derive scattering properties of haze and cloud particles and to predict the polarization signal from an extra-solar point of view. We are also investigating imaging polarimetry of the thick haze layers on Titan and the poles of Jupiter. Additionally, we have calculated a large grid of intensity and polarization phase curves for simpler atmosphere models of extrasolar planets.

Impact of Sulfur Hazes on the Reflected Light Spectra of Giant Exoplanets

NASA Astrophysics Data System (ADS)

Gao, Peter; Marley, Mark S.; Zahnle, Kevin; Robinson, Tyler D.; Lewis, Nikole K.

2017-01-01

Recent work has shown that photochemical hazes composed of elemental sulfur and its allotropes may arise in the atmospheres of warm and temperate giant exoplanets due to the photolysis of H2S. We investigate the impact such a haze would have on an exoplanet's geometric albedo spectrum using a suite of established radiative-convective, cloud, and albedo models, and how this may impact future direct imaging missions, such as WFIRST. For Jupiter-massed planets, photochemical destruction of H2S results in the production of ~1 ppmv of S8 between 100 and 0.1 mbar. The S8 mixing ratio is largely independent of the stellar UV flux, vertical mixing rates, and atmospheric temperature for expected ranges of those values, such that the S8 haze mass is dependent only on the S8 supersaturation, controlled by the local temperature. Nominal haze masses are found to drastically alter a planet's geometric albedo spectrum: whereas a clear atmosphere is dark at wavelengths between 0.5 and 1 μm due to molecular absorption, the addition of a sulfur haze boosts the albedo there to ~0.7 due to its purely scattering nature. Strong absorption by the haze shortward of 0.4 μm results in albedos <0.1, contrasting the high albedos produced by Rayleigh scattering in a clear atmosphere. These dramatic alteration in the geometric albedo spectra will lead to substantial color changes for hazy planets away from that expected for more Jupiter-like planets. For this reason colors are unlikely to provide definitive identification of warm Jupiter-like planets. The albedo change due to a sulfur haze is largely independent of the location of the haze in the atmosphere, but is a strong function of the haze optical depth as controlled by its column number density and mean particle size, though the absorption feature at short wavelengths remains robust. Detection of such a haze by future direct imaging missions like WFIRST is possible, though discriminating between a sulfur haze and any other reflective material, such as water ice, will require observations shortward of 0.4 μm, which is currently beyond WFIRST's grasp.

Molecular composition and size distribution of sugars, sugar-alcohols and carboxylic acids in airborne particles during a severe urban haze event caused by wheat straw burning

NASA Astrophysics Data System (ADS)

Wang, Gehui; Chen, Chunlei; Li, Jianjun; Zhou, Bianhong; Xie, Mingjie; Hu, Shuyuan; Kawamura, Kimitaka; Chen, Yan

2011-05-01

Molecular compositions and size distributions of water-soluble organic compounds (WSOC, i.e., sugars, sugar-alcohols and carboxylic acids) in particles from urban air of Nanjing, China during a severe haze event caused by field burning of wheat straw were characterized and compared with those in the summer and autumn non-haze periods. During the haze event levoglucosan (4030 ng m -3) was the most abundant compound among the measured WSOC, followed by succinic acid, malic acid, glycerol, arabitol and glucose, being different from those in the non-haze samples, in which sucrose or azelaic acid showed a second highest concentration, although levoglucosan was the highest. The measured WSOC in the haze event were 2-20 times more than those in the non-hazy days. Size distribution results showed that there was no significant change in the compound peaks in coarse mode (>2.1 μm) with respect to the haze and non-haze samples, but a large difference in the fine fraction (<2.1 μm) was found with a sharp increase during the hazy days mostly due to the increased emissions of wheat straw burning. Molecular compositions of organic compounds in the fresh smoke particles from wheat straw burning demonstrate that sharply increased concentrations of glycerol and succinic and malic acids in the fine particles during the haze event were mainly derived from the field burning of wheat straw, although the sources of glucose and related sugar-alcohols whose concentrations significantly increased in the fine haze samples are unclear. Compared to that in the fresh smoke particles of wheat straw burning an increase in relative abundance of succinic acid to levoglucosan during the haze event suggests a significant production of secondary organic aerosols during transport of the smoke plumes.

Volatile organic compounds (VOCs) during non-haze and haze days in Shanghai: characterization and secondary organic aerosol (SOA) formation.

PubMed

Han, Deming; Wang, Zhen; Cheng, Jinping; Wang, Qian; Chen, Xiaojia; Wang, Heling

2017-08-01

To better understand the characterization and secondary organic aerosol (SOA) formation of volatile organic compounds (VOCs) during non-haze and haze days, ambient VOCs were continuously measured by a vehicle-mounted online thermal desorption system coupled with a gas chromatography-mass spectrometry (TD-GC/MS) system in Shanghai, China. The average concentrations of VOCs in haze episodes (193.2 μg m -3 ) were almost 50% higher than in non-haze periods (130.8 μg m -3 ). VOC concentrations exhibited a bi-modal pattern in the morning and evening rush hour periods on both non-haze and haze days. The ratios of toluene to benzene (T/B) and m,p-xylene to ethylbenzene (X/E) indicated that VOCs were aged air mass transported from nearby areas. The estimated SOA yields were 12.6 ± 5.3 and 16.7 ± 6.7 μg m -3 for non-haze and haze days, respectively, accounting for 9.6 and 8.7% of the corresponding PM 2.5 concentrations, which were slightly underestimated. VOCs-sensitivity (VOCs-S) based on a PM 2.5 -dependent model was used to investigate the variation between VOCs and PM 2.5 concentrations in the morning rush hour. It was found that VOCs were more sensitive to PM 2.5 on clean days than during periods of heavy particulate pollution. VOCs-sensitivity was significantly correlated with the ratio of specific PM 2.5 to background PM 2.5 , with a simulated equation of y = 0.84x -0.62 (r 2  = 0.93, p < 0.001). Our findings suggest that strategies to mitigate VOC emissions and further alleviate haze episodes in Shanghai based on reducing gasoline vehicle-related sources would be very efficient.

Chemical composition, source, and process of urban aerosols during winter haze formation in Northeast China.

PubMed

Zhang, Jian; Liu, Lei; Wang, Yuanyuan; Ren, Yong; Wang, Xin; Shi, Zongbo; Zhang, Daizhou; Che, Huizheng; Zhao, Hujia; Liu, Yanfei; Niu, Hongya; Chen, Jianmin; Zhang, Xiaoye; Lingaswamy, A P; Wang, Zifa; Li, Weijun

2017-12-01

The characteristics of aerosol particles have been poorly evaluated even though haze episodes frequently occur in winter in Northeast China. OC/EC analysis, ion chromatography, and transmission electron microscopy (TEM) were used to investigate the organic carbon (OC) and elemental carbon (EC), and soluble ions in PM 2.5 and the mixing state of individual particles during a severe wintertime haze episode in Northeast China. The organic matter (OM), NH 4 + , SO 4 2- , and NO 3 - concentrations in PM 2.5 were 89.5 μg/m 3 , 24.2 μg/m 3 , 28.1 μg/m 3 , and 32.8 μg/m 3 on the haze days, respectively. TEM observations further showed that over 80% of the haze particles contained primary organic aerosols (POAs). Based on a comparison of the data obtained during the haze formation, we generate the following synthetic model of the process: (1) Stable synoptic meteorological conditions drove the haze formation. (2) The early stage of haze formation (light or moderate haze) was mainly caused by the enrichment of POAs from coal burning for household heating and cooking. (3) High levels of secondary organic aerosols (SOAs), sulfates, and nitrates formation via heterogeneous reactions together with POAs accumulation promoted to the evolution from light or moderate to severe haze. Compared to the severe haze episodes over the North China Plain, the PM 2.5 in Northeast China analyzed in the present study contained similar sulfate, higher SOA, and lower nitrate contents. Our results suggest that most of the POAs and secondary particles were likely related to emissions from coal-burning residential stoves in rural outskirts and small boilers in urban areas. The inefficient burning of coal for household heating and cooking should be monitored during wintertime in Northeast China. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of haze pollution on water-soluble chemical species in PM2.5 and size-resolved particles at an urban site during fall.

PubMed

Yu, Geun-Hye; Zhang, Yan; Cho, Sung-Yong; Park, Seungshik

2017-07-01

To investigate the influence of haze on the chemical composition and formation processes of ambient aerosol particles, PM 2.5 and size-segregated aerosol particles were collected daily during fall at an urban site of Gwangju, Korea. During the study period, the total concentration of secondary ionic species (SIS) contributed an average of 43.9% to the PM 2.5 , whereas the contribution of SIS to the PM 2.5 during the haze period was 62.3%. The NO 3 - and SO 4 2- concentrations in PM 2.5 during the haze period were highly elevated, being 13.4 and 5.0 times higher than those during non-haze period, respectively. The PM, NO 3 - , SO 4 2- , oxalate, water-soluble organic carbon (WSOC), and humic-like substances (HULIS) had tri-modal size distributions peaks at 0.32, 1.0, and 5.2μm during the non-haze and haze periods. However, during the non-haze period they exhibited dominant size distributions at the condensation mode peaking at 0.32μm, while on October 21 when the heaviest haze event occurred, they had predominant droplet mode size distributions peaking at 1.00μm. Moreover, strong correlations of WSOC and HULIS with SO 4 2- , oxalate, and K + at particle sizes of <1.8μm indicate that secondary processes and emissions from biomass burning could be responsible for WSOC and HULIS formations. It was found that the factors affecting haze formation could be the local stable synoptic conditions, including the weak surface winds and high surface pressures, the long-range transportation of haze from eastern China and upwind regions of the Korean peninsula, as well as the locally emitted and produced aerosol particles. Copyright © 2016. Published by Elsevier B.V.

Schneiderian membrane detachment using transcrestal hydrodynamic ultrasonic cavitational sinus lift: a human cadaver head study and histologic analysis.

PubMed

Troedhan, Angelo; Kurrek, Andreas; Wainwright, Marcel; Jank, Siegfried

2014-08-01

Recent studies have suggested the osteogenic layer of the periosteum at the base of the sinus membrane to play a key role in bone regeneration after sinus lift procedures. Thus, atraumatic detachment of the sinus membrane with an intact periosteum seems mandatory. The present histologic study of fresh human cadaver heads investigated the detachment behavior and histologic integrity of the detached periosteum after application of the transcrestal hydrodynamic ultrasonic cavitational sinus lift (tHUCSL-INTRALIFT). A total of 15 sinuses in 8 fresh human cadaver heads were treated using tHUCSL-INTRALIFT. After surgery, they were checked macroscopically for damage to the sinus membrane and then processed for histologic inspection under light microscopy. A total of 150 histologic specimens, randomly selected from the core surgical sites, were investigated using hematoxylin-eosin (HE), Azan, and trichrome staining. None of the 150 inspected specimens showed any perforation or dissection of the periosteum from the subepithelial connective tissue and respiratory epithelium and were fully detached from the bony antrum floor. The connecting Sharpey fibers revealed to be cleanly separated from the sinus floor in all specimens. The results of the present study suggest tHUCSL-INTRALIFT should be used to perform predictable and safe detachment of the periosteum from the bony sinus floor as a prerequisite for undisturbed and successful physiologic subantral bone regeneration. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Peter; Marley, Mark S.; Zahnle, Kevin

Recent work has shown that sulfur hazes may arise in the atmospheres of some giant exoplanets, due to the photolysis of H{sub 2}S. We investigate the impact such a haze would have on an exoplanet’s geometric albedo spectrum and how it may affect the direct imaging results of the Wide Field Infrared Survey Telescope ( WFIRST ), a planned NASA space telescope. For temperate (250 K <  T {sub eq} < 700 K) Jupiter-mass planets, photochemical destruction of H{sub 2}S results in the production of ∼1 ppmv of S{sub 8} between 100 and 0.1 mbar, which, if cool enough, will condense to formmore » a haze. Nominal haze masses are found to drastically alter a planet’s geometric albedo spectrum: whereas a clear atmosphere is dark at wavelengths between 0.5 and 1 μ m, due to molecular absorption, the addition of a sulfur haze boosts the albedo there to ∼0.7, due to scattering. Strong absorption by the haze shortward of 0.4 μ m results in albedos <0.1, in contrast to the high albedos produced by Rayleigh scattering in a clear atmosphere. As a result, the color of the planet shifts from blue to orange. The existence of a sulfur haze masks the molecular signatures of methane and water, thereby complicating the characterization of atmospheric composition. Detection of such a haze by WFIRST is possible, though discriminating between a sulfur haze and any other highly reflective, high-altitude scatterer will require observations shortward of 0.4 μ m, which is currently beyond WFIRST ’s design.« less

Biological regulation of atmospheric chemistry en route to planetary oxygenation.

PubMed

Izon, Gareth; Zerkle, Aubrey L; Williford, Kenneth H; Farquhar, James; Poulton, Simon W; Claire, Mark W

2017-03-28

Emerging evidence suggests that atmospheric oxygen may have varied before rising irreversibly ∼2.4 billion years ago, during the Great Oxidation Event (GOE). Significantly, however, pre-GOE atmospheric aberrations toward more reducing conditions-featuring a methane-derived organic-haze-have recently been suggested, yet their occurrence, causes, and significance remain underexplored. To examine the role of haze formation in Earth's history, we targeted an episode of inferred haze development. Our redox-controlled (Fe-speciation) carbon- and sulfur-isotope record reveals sustained systematic stratigraphic covariance, precluding nonatmospheric explanations. Photochemical models corroborate this inference, showing Δ 36 S/Δ 33 S ratios are sensitive to the presence of haze. Exploiting existing age constraints, we estimate that organic haze developed rapidly, stabilizing within ∼0.3 ± 0.1 million years (Myr), and persisted for upward of ∼1.4 ± 0.4 Myr. Given these temporal constraints, and the elevated atmospheric CO 2 concentrations in the Archean, the sustained methane fluxes necessary for haze formation can only be reconciled with a biological source. Correlative δ 13 C Org and total organic carbon measurements support the interpretation that atmospheric haze was a transient response of the biosphere to increased nutrient availability, with methane fluxes controlled by the relative availability of organic carbon and sulfate. Elevated atmospheric methane concentrations during haze episodes would have expedited planetary hydrogen loss, with a single episode of haze development providing up to 2.6-18 × 10 18 moles of O 2 equivalents to the Earth system. Our findings suggest the Neoarchean likely represented a unique state of the Earth system where haze development played a pivotal role in planetary oxidation, hastening the contingent biological innovations that followed.

Qualitative review of hazing in collegiate and school sports: consequences from a lack of culture, knowledge and responsiveness.

PubMed

Diamond, Alex B; Callahan, S Todd; Chain, Kelly F; Solomon, Gary S

2016-02-01

As with most mental health disorders, the topic of hazing is not exclusive to the student athlete. However, it is also clear that the unique set of situations faced by athletes create a set of additional and difficult challenges to their mental and physical well-being. A deep-rooted culture, a lack of knowledge about hazing and its causal relationships, and a failure to act by teammates and adults all play a role in the propagation of this danger. Also, in an era where the popular press similarly celebrates and chastises episodes of hazing, it is increasingly crucial to turn to the scientific literature for guidance. To provide a comprehensive review of the scientific research on hazing in sports and to make recommendations for enhancing the approach and assistance to those in need on an individual and societal level. Qualitative literature review of hazing in collegiate and school sports. Databases including PubMed, Google Scholar, SPORTDiscus, EMBASE and MEDLINE were searched using standardised terms, alone and in combination, including 'hazing', 'bullying', 'sport', 'athlete', 'college', 'school' and 'youth'. Despite increased attention to its dangers, hazing remains pervasive throughout the sports world. However, many do not recognise those actions as consistent with hazing. A change in culture, increased education and awareness, along with methodologically sound strategies for action must occur in order to reduce the ill effects and cycle of hazing. To date, current information and efforts are lacking. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

APMP Pilot Study on Transmittance Haze

NASA Astrophysics Data System (ADS)

Liu, Wen-Chun; Hwang, Jisoo; Koo, Annette; Wu, Houping; Leecharoen, Rojana; Yu, Hsueh-Ling

2018-02-01

Five NMIs within APMP, including CMS/ITRI, MSL, NIM, NIMT and KRISS from TCPR applied to the APMP technical committee initiative project for funding to carry out a pilot comparison of transmittance haze in 2012. The project started in 2014 and the final report was completed at the end of 2016. In this pilot comparison, three different haze standards were adopted, and transmittance haze for each standard was measured according to ASTM D1003 or ISO 14782. This paper presents the first results of an APMP pilot study of transmittance haze and the analysis of the variation among different haze measurement systems which are commonly used. The study shows that the variables such as sphere multiplier, transmittance distribution, fluorescence of samples and optical path of the incident beam cause discrepancies among NMIs and highlight deficiencies in current documentary standards.

Fabrication of Simple Indoor Air Haze Purifier using Domestic Discarded Substances and Its Haze Removal Performance

NASA Astrophysics Data System (ADS)

Wang, Zhou; Cao, Haoshu; Zhao, Shuang

2018-01-01

Based on the concept of circular economy, discarded plastic bottles stuffed with discarded cotton, clothing and sofa cushion were used as pre-filter to remove big particles (dust and coal dust) in air and 4 L tap water in discarded plastic bottle was worked as an absorbing medium to dissolve the water soluble ions in air (SO4 2-, NO3-, NH4+, Cl- and Ca2+). Moreover, the internet control design was used in this homemade indoor air haze purifier to achieve the performance of remote control and intelligent management. The experimental results showed that this indoor air haze purifier can effectively reduce the level of indoor air haze and the air quality after 20 minutes treatment is higher than that of two commercial well-known air haze purifier

E4 True and false color hot spot mosaic

NASA Technical Reports Server (NTRS)

1997-01-01

True and false color views of Jupiter from NASA's Galileo spacecraft show an equatorial 'hotspot' on Jupiter. These images cover an area 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles). The top mosaic combines the violet and near infrared continuum filter images to create an image similar to how Jupiter would appear to human eyes. Differences in coloration are due to the composition and abundances of trace chemicals in Jupiter's atmosphere. The bottom mosaic uses Galileo's three near-infrared wavelengths displayed in red, green, and blue) to show variations in cloud height and thickness. Bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the deep cloud with an overlying thin haze. The light blue region to the left is covered by a very high haze layer. The multicolored region to the right has overlapping cloud layers of different heights. Galileo is the first spacecraft to distinguish cloud layers on Jupiter.

North is at the top. The mosaic covers latitudes 1 to 10 degrees and is centered at longitude 336 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers (about 930,000 miles) by the Solid State Imaging camera system aboard Galileo. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

Dome effect of black carbon and its key influencing factors: a one-dimensional modelling study

NASA Astrophysics Data System (ADS)

Wang, Zilin; Huang, Xin; Ding, Aijun

2018-02-01

Black carbon (BC) has been identified to play a critical role in aerosol-planetary boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been referred to as the dome effect. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, as well as the underlying land surface, have not been quantitatively explored yet. Here, based on available in situ measurements of meteorology and atmospheric aerosols together with the meteorology-chemistry online coupled model WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC dome effect and surface haze pollution. Furthermore, we discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on the PBL is very sensitive to the altitude of aerosol layer. The upper-level BC, especially that near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulent mixing. The dome effect of BC tends to be significantly intensified as BC mixed with scattering aerosols during winter haze events, resulting in a decrease in PBL height by more than 15 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such an effect to air quality in countryside. This study indicates that China's regional air pollution would greatly benefit from BC emission reductions, especially those from elevated sources from chimneys and also domestic combustion in rural areas, through weakening the aerosol-boundary layer interactions that are triggered by BC.

The Shift from Acceptance to Prevention: Hazing Behaviors in the U.S. Military

DTIC Science & Technology

2016-10-31

Service Members’ (SMs) identification of hazing behaviors. Data were collected from a survey administered during various human relations specialists...Fleet, and Wing. Methods: A total of 152 students participated in this survey across three human relations specialists training courses. The... survey consisted of the following: All students were told to write their own definitions of hazing before receiving any introduction to hazing material

A Combined CFD/Characteristic Method for Prediction and Design of Hypersonic Inlet with Nose Bluntness

NASA Astrophysics Data System (ADS)

Gao, Wenzhi; Li, Zhufei; Yang, Jiming

Leading edge bluntness is widely used in hypersonic inlet design for thermal protection[1]. Detailed research of leading edge bluntness on hypersonic inlet has been concentrated on shock shape correlation[2], boundary layer flow[3], inlet performance[4], etc. It is well known that blunted noses cause detached bow shocks which generate subsonic regions around the noses and entropy layers in the flowfield.

Combining light-harvesting with detachability in high-efficiency thin-film silicon solar cells.

PubMed

Ram, Sanjay K; Desta, Derese; Rizzoli, Rita; Bellettato, Michele; Lyckegaard, Folmer; Jensen, Pia B; Jeppesen, Bjarke R; Chevallier, Jacques; Summonte, Caterina; Larsen, Arne Nylandsted; Balling, Peter

2017-06-01

Efforts to realize thin-film solar cells on unconventional substrates face several obstacles in achieving good energy-conversion efficiency and integrating light-management into the solar cell design. In this report a technique to circumvent these obstacles is presented: transferability and an efficient light-harvesting scheme are combined for thin-film silicon solar cells by the incorporation of a NaCl layer. Amorphous silicon solar cells in p-i-n configuration are fabricated on reusable glass substrates coated with an interlayer of NaCl. Subsequently, the solar cells are detached from the substrate by dissolution of the sacrificial NaCl layer in water and then transferred onto a plastic sheet, with a resultant post-transfer efficiency of 9%. The light-trapping effect of the surface nanotextures originating from the NaCl layer on the overlying solar cell is studied theoretically and experimentally. The enhanced light absorption in the solar cells on NaCl-coated substrates leads to significant improvement in the photocurrent and energy-conversion efficiency in solar cells with both 350 and 100 nm thick absorber layers, compared to flat-substrate solar cells. Efficient transferable thin-film solar cells hold a vast potential for widespread deployment of off-grid photovoltaics and cost reduction.

Hazing DEOCS 4.1 Construct Validity Summary

DTIC Science & Technology

2017-08-01

Hazing DEOCS 4.1 Construct Validity Summary DEFENSE EQUAL OPPORTUNITY MANAGEMENT INSTITUTE DIRECTORATE OF...the analysis. Tables 4 – 6 provide additional information regarding the descriptive statistics and reliability of the Hazing items. Table 7 provides

Comparison of Personal PM2.5 Exposure in Various Micro-Environments during Haze and Clean Days in Nanjing

NASA Astrophysics Data System (ADS)

Zhang, T.

2015-12-01

There is a long term trend of haze in East China. As a main component of haze, fine particle (PM2.5) in various micro-environments (MEs) is a cause for concern regarding the environment and public health. To estimate individual PM2.5 exposures in distinct, non-residential MEs and to determine exposure characteristics during haze and clean days, we conducted personal PM2.5 monitoring with portable PM2.5 personal environment monitors (MicroPEM) in 19 indoor/outdoor MEs in Nanjing, and compared personal exposure data with ambient PM2.5 levels. Personal PM2.5 exposure patterns displayed notable spatial variance, peaking in snack streets and restaurants and dipping in subways and labs. Under both haze and non-haze conditions, different characteristics of MEs and the background PM2.5 level jointly determine the spatial variance of individual exposure. Indoor MEs with better ventilation systems led to lower personal PM2.5 exposure levels. During haze days, impact from high ambient PM2.5 overwhelms influence from other factors and dominates personal exposure trends.

Regional Haze Evolved from Peat Fires - an Overview

NASA Astrophysics Data System (ADS)

Hu, Yuqi; Rein, Guillermo

2016-04-01

This work provides an overview of haze episodes, their cause, emissions and health effects found in the scientific literature. Peatlands, the terrestrial ecosystems resulting from the accumulation of partially decayed vegetation, become susceptible to smouldering fires because of natural droughts or anthropogenic-induced drainages. Once ignited, smouldering peat fires persistently consume large amounts of soil carbon in a flameless form. It is estimated that the average annual carbon gas emissions (mainly CO2 and CO) from peat fires are equivalent to 15% of manmade emissions, representing influential perturbation of global carbon circle. In addition to carbon emissions, smouldering peat fires emit substantial quantities of heterogeneous smoke, which is responsible for haze phenomena, has not yet been fully studied. Peat-fire-derived smoke is characterized by high concentration of particulate matter (PM), ranging from nano-scale ultrafine fraction (PM1, particle diameter < 1 μm) to micro-scale fine (PM2.5, particle diameter < 2.5 μm) and coarse fraction (PM10, particle diameter < 10 μm). The dispersal of the smoke could be blocked due to the stagnant weather condition, and then low buoyant smoke plume could accumulate and migrate long distances, leading to regional haze. Apart from air quality deterioration, haze leads to severe reduction in visibility, which strongly affects local transportation, construction, tourism and agriculture-based industries. For example, an unprecedented peatland mega-fire burst on the Indonesian islands Kalimantan and Sumatra during the 1997 El-Niño event, resulting in transboundary smoke-haze disaster. Severe haze events continue to appear in Southeast Asia every few years due to periodical peat fires in this region. In addition, smouldering peat fires have been frequently reported in tropical, temperate and boreal regions (Botswana in 2000, North America in 2004, Scotland in 2006 and Central Russia in 2010 et al.), peat-fire-induced haze has become a regional seasonal phenomenon. Exposure to smoky haze results in deleterious physiologic responses, predominantly to the respiratory and cardiovascular systems. In 1997, an estimation of 100 million people in 5 countries in Southeast Asia were affected by Indonesia haze episode while 20 million people suffered from respiratory problems in Indonesia alone. Fine PM fraction generated from peat fires could penetrate into lower respiratory tracks and exacerbate respiratory diseases including chronic bronchitis, emphysema and asthma. Epidemiological studies show that direct exposure to haze pollution is associated with decreased pulmonary function and increased morbidity and mortality among individuals with pre-existent cardiovascular diseases. Reported cases of acute respiratory infection increased 3.8 times during the 1997 Indonesia haze episode (1,446,120 cases in total with 527 haze-related deaths). Collectively, peat fire and the resultant haze considerably affect the local society in many aspects, and more thorough research need to be carried out for further haze mitigation and governance. Corresponding author: Dr. Guillermo Rein: g.rein@imperial.ac.uk

A computer vision approach for solar radiation nowcasting using MSG images

NASA Astrophysics Data System (ADS)

Álvarez, L.; Castaño Moraga, C. A.; Martín, J.

2010-09-01

Cloud structures and haze are the two main atmospheric phenomena that reduce the performance of solar power plants, since they absorb solar energy reaching terrestrial surface. Thus, accurate forecasting of solar radiation is a challenging research area that involves both a precise localization of cloud structures and haze, as well as the attenuation introduced by these artifacts. Our work presents a novel approach for nowcasting services based on image processing techniques applied to MSG satellite images provided by the EUMETSAT Rapid Scan Service (RSS) service. These data are an interesting source of information for our purposes since every 5 minutes we obtain actual information of the atmospheric state in nearly real time. However, a workaround must be given in order to forecast solar radiation. To that end, we synthetically forecast MSG images forecasts from past images applying computer vision techniques adapted to fluid flows in order to evolve atmospheric state. First, we classify cloud structures on two different layers, corresponding to top and bottom clouds, which includes haze. This two-level classification responds to the dominant climate conditions found in our region of interest, the Canary Islands archipelago, regulated by the Gulf Stream and Trade Winds. Vertical structure of Trade Winds consists of two layers, the bottom one, which is fresh and humid, and the top one, which is warm and dry. Between these two layers a thermal inversion appears that does not allow bottom clouds to go up and naturally divides clouds in these two layers. Top clouds can be directly obtained from satellite images by means of a segmentation algorithm on histogram heights. However, bottom clouds are usually overlapped by the former, so an inpainting algorithm is used to recover overlapped areas of bottom clouds. For each layer, cloud motion is estimated through a correlation based optic flow algorithm that provides a vector field that describes the displacement field in each layer between two consecutive images in a sequence. Since RSS service from EUMETSAT provides images every 5 minutes (Δt), the cloud motion vector field between images at time t0 and (t0 - Δt) is quite similar to that between (t0 - Δt) and (t0 - 2Δt). Under this assumption, we infer the motion vector field for the next image in order to build a synthetic version of the image at time (t0 + Δt). The computation of this future motion vector field takes into account terrain orography in order to produce more realistic forecasts. In this sense, we are currently working on the integration of information from NWP outputs in order to introduce other atmospheric phenomena. Applying this algorithm several times we are able to produce short-term forecasts up to 6 hours with encouraging performance. To validate our results, we use both, comparison of synthetically generated images with the corresponding images at a given time, and direct solar radiation measurement with the set of meteorological stations located at several points of the canarian archipelago.

Advanced light-scattering materials: Double-textured ZnO:B films grown by LP-MOCVD

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Spadoni, A.; Antonaia, A.

2013-12-01

Double-textured ZnO:B layers with enhanced optical scattering in both short and long wavelength regions have been successfully fabricated using MOCVD technique through a three step process. Growth of double-textured structures has been induced by wet etching on polycrystalline ZnO surface. Our double-layer structure consists of a first ZnO:B layer wet etched and subsequently used as substrate for a second ZnO:B layer deposition. Polycrystalline ZnO:B layers were etched by utilizing diluted solutions of fluoridic acid (HF), chloridric acid (HCl) and phosphoric acid (H3PO4) and their effect on surface morphology modification was systematically investigated. The morphology of the second deposited ZnO layer strongly depended on the surface properties of the etched ZnO first layer. Growth of cauliflower-like texture was induced by protrusions presence on the HCl etched surface. Optimized double-layer structure shows a cauliflower-like double texture with higher RMS roughness and increased spectral haze values in both short and long wavelength regions, compared to conventional pyramidal-like single texture. Furthermore, this highly scattering structure preserves excellent optical and electrical properties.

Correction of Atmospheric Haze in RESOURCESAT-1 LISS-4 MX Data for Urban Analysis: AN Improved Dark Object Subtraction Approach

NASA Astrophysics Data System (ADS)

Mustak, S.

2013-09-01

The correction of atmospheric effects is very essential because visible bands of shorter wavelength are highly affected by atmospheric scattering especially of Rayleigh scattering. The objectives of the paper is to find out the haze values present in the all spectral bands and to correct the haze values for urban analysis. In this paper, Improved Dark Object Subtraction method of P. Chavez (1988) is applied for the correction of atmospheric haze in the Resoucesat-1 LISS-4 multispectral satellite image. Dark object Subtraction is a very simple image-based method of atmospheric haze which assumes that there are at least a few pixels within an image which should be black (% reflectance) and such black reflectance termed as dark object which are clear water body and shadows whose DN values zero (0) or Close to zero in the image. Simple Dark Object Subtraction method is a first order atmospheric correction but Improved Dark Object Subtraction method which tends to correct the Haze in terms of atmospheric scattering and path radiance based on the power law of relative scattering effect of atmosphere. The haze values extracted using Simple Dark Object Subtraction method for Green band (Band2), Red band (Band3) and NIR band (band4) are 40, 34 and 18 but the haze values extracted using Improved Dark Object Subtraction method are 40, 18.02 and 11.80 for aforesaid bands. Here it is concluded that the haze values extracted by Improved Dark Object Subtraction method provides more realistic results than Simple Dark Object Subtraction method.

An analysis of chemical and meteorological characteristics of haze events in the Seoul metropolitan area during January 12-18, 2013

NASA Astrophysics Data System (ADS)

Koo, Youn-Seo; Yun, Hui-Young; Choi, Dae-Ryun; Han, Jin-Seok; Lee, Jae-Bum; Lim, Yong-Jae

2018-04-01

The chemical characteristics of secondary inorganic and carbonaceous aerosols as well as their formation mechanisms during the haze event of January 12-18, 2013, in the Seoul Metropolitan Area (SMA) were investigated using measurements at the Baengnyeong and Seoul supersites with data available from LIDAR, meteorology, and modeling. An extraordinary haze event that occurred in northern China during that period extended to the Korean Peninsula and initiated the haze event in the SMA. Local emissions of primary aerosol and gaseous precursors in the SMA then made the situation worse under adverse meteorological conditions. OM (Organic Matter) and SO42- were the major long-range transport (LRT) aerosols from the Beijing, Tianjin and Hebei province (BTH) area to the SMA during the initial stage of the haze event. The LRT of SO42- from the BTH area, which was detected at Baengnyeong Island, was mostly acidic, while in Seoul, it was fully neutralized to (NH4)2SO4. The SIAs (Secondary Inorganic Aerosols) consisting of 56.5% PM2.5 during the haze period were the major chemical species causing haze problems in the SMA. NO3- was the most dominant chemical species among the SIAs and was locally formed by a heavy burden of NOx emissions from mobile sources in the SMA. Carbonaceous aerosols of OM and EC (Elemental Carbon) in the SMA during the haze period consisted of 18.9% PM2.5, but secondary organic carbon (SOC) was not the key species inducing the haze event during the January episode in the SMA.

Load sharing in bioinspired fibrillar adhesives with backing layer interactions and interfacial misalignment

NASA Astrophysics Data System (ADS)

Bacca, Mattia; Booth, Jamie A.; Turner, Kimberly L.; McMeeking, Robert M.

2016-11-01

Bio-inspired fibrillar adhesives rely on the utilization of short-range intermolecular forces harnessed by intimate contact at fibril tips. The combined adhesive strength of multiple fibrils can only be utilized if equal load sharing (ELS) is obtained at detachment. Previous investigations have highlighted that mechanical coupling of fibrils through a compliant backing layer gives rise to load concentration and the nucleation and propagation of interfacial flaws. However, misalignment of the adhesive and contacting surface has not been considered in theoretical treatments of load sharing with backing layer interactions. Alignment imperfections are difficult to avoid for a flat-on-flat interfacial configuration. In this work we demonstrate that interfacial misalignment can significantly alter load sharing and the kinematics of detachment in a model adhesive system. Load sharing regimes dominated by backing layer interactions and misalignment are revealed, the transition between which is controlled by the misalignment angle, fibril separation, and fibril compliance. In the regime dominated by misalignment, backing layer deformation can counteract misalignment giving rise to improved load sharing when compared to an identical fibrillar array with a rigid backing layer. This result challenges the conventional belief that stiffer (and thinner) backing layers consistently reduce load concentration among fibrils. Finally, we obtain analytically the fibril compliance distribution required to harness backing layer interactions to obtain ELS. Through fibril compliance optimization, ELS can be obtained even with misalignment. However, since misalignment is typically not deterministic, it is of greater practical significance that the array optimized for perfect alignment exhibits load sharing superior to that of a homogeneous array subject to misalignment. These results inform the design of fibrillar arrays with graded compliance capable of exhibiting improved load sharing over large areas.

Formation mechanism of the photomask blanks material related haze

NASA Astrophysics Data System (ADS)

Kim, Jung-Jin; Choi, Junyoul; Koh, Soowan; Kim, Minho; Lee, Jiyoung; Lee, Han-Shin; Kim, Byung Gook; Jeon, Chan-uk

2016-05-01

We have observed a new type haze of which formation deviates from the generally accepted models with respect to the size, shape, and removability by chemicals. It has very small size of 50~100nm and are crowded around the cell boundary, while the typical haze doesn't prefer a special region on mask in the majority of cases. It is hard to remove by general cleaning, while the typical haze is easily removed by general cleaning process and even de-ionized water. It is confirmed that the source of the haze is blank material related ions which are formed by chemical etching of blanks during mask cleaning process or the photomask blanks itself.

Deformation of Fold-and-Thrust Belts above a Viscous Detachment: New Insights from Analogue Modelling Experiments

NASA Astrophysics Data System (ADS)

Nogueira, Carlos R.; Marques, Fernando O.

2015-04-01

Theoretical and experimental studies on fold-and-thrusts belts (FTB) have shown that, under Coulomb conditions, deformation of brittle thrust wedges above a dry frictional basal contact is characterized by dominant frontward vergent thrusts (forethrusts) with thrust spacing and taper angle being directly influenced by the basal strength (increase in basal strength leading to narrower thrust spacing and higher taper angles); whereas thrust wedges deformed above a weak viscous detachment, such as salt, show a more symmetric thrust style (no prevailing vergence of thrusting) with wider thrust spacing and shallower wedges. However, different deformation patterns can be found on this last group of thrust wedges both in nature and experimentally. Therefore we focused on the strength (friction) of the wedge basal contact, the basal detachment. We used a parallelepiped box with four fixed walls and one mobile that worked as a vertical piston drove by a computer controlled stepping motor. Fine dry sand was used as the analogue of brittle rocks and silicone putty (PDMS) with Newtonian behaviour as analogue of the weak viscous detachment. To investigate the strength of basal contact on thrust wedge deformation, two configurations were used: 1) a horizontal sand pack with a dry frictional basal contact; and 2) a horizontal sand pack above a horizontal PDMS layer, acting as a basal weak viscous contact. Results of the experiments show that: the model with a dry frictional basal detachment support the predictions for the Coulomb wedges, showing a narrow wedge with dominant frontward vergence of thrusting, close spacing between FTs and high taper angle. The model with a weak viscous frictional basal detachment show that: 1) forethrusts (FT) are dominant showing clearly an imbricate asymmetric geometry, with wider spaced thrusts than the dry frictional basal model; 2) after FT initiation, the movement on the thrust can last up to 15% model shortening, leading to great amount of displacement along the FT; 3) intermittent reactivation of FTs also occurs despite the steepening of the FT plane and existence of new FT ahead, creating a high critical taper angle; 4) injection of PDMS from the basal weak layer into the FTs planes also favours to the long living of FTs and to the high critical taper angle; 5) vertical sand thickening in the hanging block also added to the taper angle.

Formation of an ultramafic seafloor at the Southwest Indian Ridge 62°-65°E : internal structure of detachment faults and sparse volcanism documented by sidescan sonar and dredges

NASA Astrophysics Data System (ADS)

Cannat, M.; Sauter, D.; Rouméjon, S.

2012-12-01

In october 2010, the Smoothseafloor cruise (RV Marion Dufresne ) documented the continuous exposure, for the past 10 myrs, of mantle-derived ultramafic rocks in the seafloor of the ultra-slow Southwest Indian Ridge in two 50 to 100 km-wide magma-poor corridors centered respectively at 62°30'E and 64°35'E. The proposed interpretation (Sauter et al., AGU abstract 2011) involves successive large offset normal faults (or detachments) that expose ultramafic rocks alternatively in the southern (Antarctic), then in the northern (African) plates. In this presentation we focus on the most recent, near axis regions in these two ultramafic seafloor corridors. We show details of the sidescan sonar images with smooth, non-corrugated exposed detachment surfaces, and an intriguing pattern of pluridecameter-thick and locally anastomozing reflective and less reflective layers in the detachments footwall. Based on preliminary microstructural observations made on samples dredged in the same region, we tentatively interpret these layers as due to contrasted patterns of deformation in the ultramafics next to the fault. Testing this interpretation would be an attractive goal for future submersible and drilling cruises. Deformation types documented in the dredge samples range from heterogeneous plastic to semi-brittle deformation of the primary peridotite mineralogy, to brittle deformation of serpentinized ultramafic rocks. Magmatic rocks make less than 5% of the overal volume of our near axis dredges. These include variably sheared metagabbros, and unmetamorphosed balsalts. Sidescan sonar images show that these basalts form a thin (<200 m) highly discontinuous carapace over the exposed detachments. We show that these basalts are preferentially located along moderate offset normal faults that cut the detachments, or next to inferred breakaways. This observation leads us to propose a link between axial faulting and volcanism in these magma-poor sections of the ultra-slow spreading Southwest Indian Ridge. The SmoothSeafloor Scientific Party : Daniel Sauter, Mathilde Cannat, Muriel Andreani, Dominique Birot, Adrien Bronner, Daniele Brunelli, Julie Carlut, Adelie Delacour, Vivien Guyader, Veronique Mendel, Bénédicte Ménez, Christopher MacLeod, Valerio Pasini, Stéphane Rouméjon, Etienne Ruellan and Roger Searle

Observations of the global haze redistribution on Titan from 2006 to 2015 with OSIRIS at Keck

NASA Astrophysics Data System (ADS)

Ádámkovics, Máté; de Pater, Imke

2017-07-01

We observed Titan with the OH Suppressing InfraRed Imaging Spectrograph (OSIRIS) at the W. M. Keck observatory from 2006 through 2015 using adaptive optics. The sunlight scattered by atmospheric haze was spatially resolved in the 2.0 μm (K) band window, and the spectra were analyzed with a radiative transfer model to determine the vertical (altitude) and meridional (latitudinal) variation in the haze distribution over this time period. This study complements recent work by Karkoschka (2016) in the season of observations, in the time span and sampling interval, in wavelength coverage and spectral resolution, as well as in the radiative transfer methodology and analysis. We observe the largest meridional gradient in haze opacity above 20 km toward the northern hemisphere in January 2010. Individual observations can show significant deviations from a relatively smooth linear gradient in haze across the entire disk. The variation in haze below 20 km is rarely well-described by a simple model and there is a systematically smaller amount of haze opacity retrieved from the equator to 10° S when observing the disk with a sub-observer longitude near 150° W. This correlation with longitude suggests one of the following; a localized decrease in haze scattering, a localized increase in gas opacity, or a systematic over-estimate of the surface albedo in this region.

Role of atmospheric circulations in haze pollution in December 2016

NASA Astrophysics Data System (ADS)

Yin, Zhicong; Wang, Huijun

2017-09-01

In the east of China, recent haze pollution has been severe and damaging. In addition to anthropogenic emissions, atmospheric circulations and local meteorological conditions were conducive factors. The number of December haze days over North China and the Huanghuai area has increased sharply since 2010 and was greatest in 2016. During 2016, the most aggressive control measures for anthropogenic emissions were implemented from 16 to 21 December, but the most severe haze pollution still occurred, covering approximately 25 % of the land area of China and lasting for 6 days. The atmospheric circulations must play critical roles in the sub-seasonal haze events. Actually, the positive phase of the East Atlantic-West Russia pattern in the middle troposphere strengthened the anomalous anti-cyclone over the NH area that confined vertical motion below. The associated southerly anomalies made the cold air and surface wind speed weaker, but enhanced the humid flow. Thus, the horizontal and vertical dispersion of atmospheric particulates was suppressed and the pollutants gathered within a narrow space. In December 2016, these key indices were strongly beneficial for haze occurrence and combined to result in the severest haze pollution. The influences of the preceding autumn sea surface temperature near the Gulf of Alaska and the subtropical eastern Pacific, October-November snow cover in western Siberia, and associated physical processes on haze pollution are also discussed.

Local and transboundary factors' impacts on trace gases and aerosol during haze episode in 2015 El Niño in Malaysia.

PubMed

Samsuddin, Nur Adilla Che; Khan, Md Firoz; Maulud, Khairul Nizam Abdul; Hamid, Ahmad Hazuwan; Munna, Fahia Tarannum; Rahim, Muhammad Aizat Ab; Latif, Mohd Talib; Akhtaruzzaman, Md

2018-07-15

Southeast Asian haze is a semi-natural phenomenon that chokes the region each year during the dry monsoon season. Smoke-haze episodes caused by the vegetation and peat fires in Indonesia severely affected large parts of Malaysia during the 2015 El Niño phenomenon. This study aimed to evaluate the factors that influenced the concentrations of aerosol and trace gases during the 2015 haze and non-haze period on a semi-urban site in the southern part of Malaysian peninsula that facing Sumatra (Muar, Site A), and on an urban site near to Kuala Lumpur, influenced by the city centre (Cheras, Site B). Local land use data and the cluster of air mass weighted backward trajectory were used to identify the potential factors from local sources and the transboundary region, respectively. The annual median concentrations of PM 10 for semi-urban and urban sites were 45.0μg/m 3 and 47.0μg/m 3 , respectively for the study period (Jan-Dec 2015) from the hourly observation dataset. The highest PM 10 concentrations during the haze were 358μg/m 3 and 415μg/m 3 for the two sites, respectively, representing absolutely unhealthy air. However, the trace gases were within the safe threshold. The average concentrations of PM 10 and carbon monoxide were two fold higher during the haze than the non-haze episodes on both sites. Nitrogen dioxide was more influenced by haze compared with sulphur dioxide and ozone. The results of the land use change suggest that the local factor can also partially affect the air pollution on the urban area (Site B) but more visible in 2015. The results of the backward trajectory and the wildfire radiative power showed that the smoke-haze episodes that affected Malaysia in 2015 were mainly initiated in the Indonesian Sumatra and Kalimantan regions. This study provides a very useful information towards the impacted region during El Niño haze episode. Copyright © 2017 Elsevier B.V. All rights reserved.

Attribution of the Main Sources of Biomass Burning in South East Asia that Impact on Air Quality in Singapore

NASA Astrophysics Data System (ADS)

Hansen, A. B.; Kendall, E.; Chew, B. N.; Chong, W. M.; Gan, C.; Hort, M. C.; Shaw, F.; Witham, C. S.

2017-12-01

Biomass burning in South East Asia causes intense haze episodes in Singapore, these are of major concern to the local government and the population exposed to the haze. Using a Lagrangian dispersion model we have studied haze in the seven most recent years (2010 - 2016) to gain a deeper understanding of intense haze in Singapore. In this study, modelled haze time-series at one eastern and one western monitoring station in Singapore are compared to local observed PM10 and PM2.5 air concentrations. The haze time-series are broken down by season or month, source region, and monitoring location.The analysis, presented as time series and pie charts, illustrates the relative contribution to haze in Singapore from different regions, variations between seasons and the correlation of impact to the combined timing of burning activity and meteorological patterns. Air history maps, showing where air arriving in Singapore originates from and/or has travelled through, are used to isolate the meteorological dependence of impacts. These show a strong monsoonal variation and help explain the inter-annual differences between sources and actual concentrations of biomass burning PM in Singapore. For example, there is a strong correlation in 2013 between burning in Riau and haze in Singapore, but a weak correlation in other years when a significant part of haze originates from, e.g., Peninsula Malaysia, but emissions are seemingly negligible. We see that, in spite of the size of Singapore, there is significant difference in concentrations and major contributing source regions between the two monitoring stations, annually and seasonally. The differences at the two monitoring stations are seen in varying degrees in the years 2011, 2012, 2014, and 2015, throughout different seasons. Although only biomass burning is considered in the simulations, our modelled results are in good agreement with local observations. We have identified the source regions with the biggest contributions to haze in Singapore as Riau and Peninsula Malaysia, with secondary contributions from South Sumatra, Jambi, Central and West Kalimantan, Riau Islands, and Bangka-Belitung. We show that both regional burning and regional weather has significant impact on local haze conditions in Singapore.

Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres.

PubMed

Arney, Giada; Domagal-Goldman, Shawn D; Meadows, Victoria S

2018-03-01

Early Earth may have hosted a biologically mediated global organic haze during the Archean eon (3.8-2.5 billion years ago). This haze would have significantly impacted multiple aspects of our planet, including its potential for habitability and its spectral appearance. Here, we model worlds with Archean-like levels of carbon dioxide orbiting the ancient Sun and an M4V dwarf (GJ 876) and show that organic haze formation requires methane fluxes consistent with estimated Earth-like biological production rates. On planets with high fluxes of biogenic organic sulfur gases (CS 2 , OCS, CH 3 SH, and CH 3 SCH 3 ), photochemistry involving these gases can drive haze formation at lower CH 4 /CO 2 ratios than methane photochemistry alone. For a planet orbiting the Sun, at 30× the modern organic sulfur gas flux, haze forms at a CH 4 /CO 2 ratio 20% lower than at 1× the modern organic sulfur flux. For a planet orbiting the M4V star, the impact of organic sulfur gases is more pronounced: at 1× the modern Earth organic sulfur flux, a substantial haze forms at CH 4 /CO 2 ∼ 0.2, but at 30× the organic sulfur flux, the CH 4 /CO 2 ratio needed to form haze decreases by a full order of magnitude. Detection of haze at an anomalously low CH 4 /CO 2 ratio could suggest the influence of these biogenic sulfur gases and therefore imply biological activity on an exoplanet. When these organic sulfur gases are not readily detectable in the spectrum of an Earth-like exoplanet, the thick organic haze they can help produce creates a very strong absorption feature at UV-blue wavelengths detectable in reflected light at a spectral resolution as low as 10. In direct imaging, constraining CH 4 and CO 2 concentrations will require higher spectral resolution, and R > 170 is needed to accurately resolve the structure of the CO 2 feature at 1.57 μm, likely the most accessible CO 2 feature on an Archean-like exoplanet. Key Words: Organic haze-Organic sulfur gases-Biosignatures-Archean Earth. Astrobiology 18, 311-329.

UV 380 nm Reflectivity of the Earth's Surface

NASA Technical Reports Server (NTRS)

Herman, J. R.; Celarier, E.; Larko, D.

2000-01-01

The 380 nm radiance measurements of TOMS (Total Ozone Mapping Spectrometer) have been converted into a global data set of daily (1979 to 1992) Lambert equivalent reflectivities R of the Earth's surface and boundary layer (clouds, aerosols, surface haze, and snow/ice). Since UV surface reflectivity is between 2 and 8% for both land and water during all seasons of the year (except for ice and snow cover), reflectivities larger than the surface value indicates the presence of clouds, haze, or aerosols in the satellite field of view. Statistical analysis of 14 years of daily data show that most snow/ice-free regions of the Earth have their largest fraction of days each year when the reflectivity is low (R less than 10%). The 380 nm reflectivity data shows that the true surface reflectivity is 2 to 3% lower than the most frequently occurring reflectivity value for each TOMS scene. The most likely cause of this could be a combination of frequently occurring boundary-layer water or aerosol haze. For most regions, the observation of extremely clear conditions needed to estimate the surface reflectivity from space is a comparatively rare occurrence. Certain areas (e.g., Australia, southern Africa, portions of northern Africa) are cloud-free more than 80% of the year, which exposes these regions to larger amounts of UV radiation than at comparable latitudes in the Northern Hemisphere. Regions over rain-forests, jungle areas, Europe and Russia, the bands surrounding the Arctic and Antarctic regions, and many ocean areas have significant cloud cover (R greater than 15%) more than half of each year. In the low to middle latitudes, the areas with the heaviest cloud cover (highest reflectivity for most of the year) are the forest areas of northern South America, southern Central America, the jungle areas of equatorial Africa, and high mountain regions such as the Himalayas or the Andes. The TOMS reflectivity data show the presence of large nearly clear ocean areas and the effects of the major ocean currents on cloud production.

UV 380 nm reflectivity of the Earth's surface, clouds and aerosols

NASA Astrophysics Data System (ADS)

Herman, J. R.; Celarier, E.; Larko, D.

2001-03-01

The 380 nm radiance measurements of the Total Ozone Mapping Spectrometer (TOMS) have been converted into a global data set of daily (1979-1992) Lambert equivalent reflectivities R of the Earth's surface and boundary layer (clouds, aerosols, surface haze, and snow/ice) and then corrected to RPC for the presence of partly clouded scenes. Since UV surface reflectivity is between 2 and 8% for both land and water during all seasons of the year (except for ice and snow cover), reflectivities larger than the surface value indicate the presence of clouds, haze, or aerosols in the satellite field of view. A statistical analysis of 14 years of daily reflectivity data shows that most snow-/ice-free scenes observed by TOMS have a reflectivity less than 10% for the majority of days during a year. The 380 nm reflectivity data show that the true surface reflectivity is 2-3% lower than the most frequently occurring reflectivity value for each TOMS scene as seen from space. Most likely the cause is a combination of frequently occurring boundary layer water and/or aerosol haze. For most regions the observation of extremely clear conditions needed to estimate the surface reflectivity from space is a comparatively rare occurrence. Certain areas (e.g., Australia, southern Africa, portions of northern Africa) are cloud-free more than 80% of the year, which exposes these regions to larger amounts of UV radiation than at comparable latitudes in the Northern Hemisphere. Regions over rain forests, jungle areas, Europe and Russia, the bands surrounding the Arctic and Antarctic regions, and many ocean areas have significant cloud cover (R>15%) more than half of each year. In the low to middle latitudes the areas with the heaviest cloud cover (highest reflectivity for most of the year) are the forest areas of northern South America, southern Central America, the jungle areas of equatorial Africa, and high mountain regions such as the Himalayas or the Andes. The TOMS reflectivity data show both the presence of large nearly clear ocean areas and the effects of the major ocean currents on cloud production.

16 CFR 1632.1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... which contain upholstery material between the ticking and the mattress core, and any detachable... which do not contain upholstery material between the ticking and the mattress core, upholstered... outermost layer of fabric or related material that encloses the core and upholstery materials of a mattress...

Haze production rates in super-Earth and mini-Neptune atmosphere experiments

NASA Astrophysics Data System (ADS)

Hörst, Sarah M.; He, Chao; Lewis, Nikole K.; Kempton, Eliza M.-R.; Marley, Mark S.; Morley, Caroline V.; Moses, Julianne I.; Valenti, Jeff A.; Vuitton, Véronique

2018-04-01

Numerous Solar System atmospheres possess photochemically generated hazes, including the characteristic organic hazes of Titan and Pluto. Haze particles substantially impact atmospheric temperature structures and may provide organic material to the surface of a world, potentially affecting its habitability. Observations of exoplanet atmospheres suggest the presence of aerosols, especially in cooler (<800 K), smaller (<0.3× Jupiter's mass) exoplanets. It remains unclear whether the aerosols muting the spectroscopic features of exoplanet atmospheres are condensate clouds or photochemical hazes1-3, which is difficult to predict from theory alone4. Here, we present laboratory haze simulation experiments that probe a broad range of atmospheric parameters relevant to super-Earth- and mini-Neptune-type planets5, the most frequently occurring type of planet in our galaxy6. It is expected that photochemical haze will play a much greater role in the atmospheres of planets with average temperatures below 1,000 K (ref. 7), especially those planets that may have enhanced atmospheric metallicity and/or enhanced C/O ratios, such as super-Earths and Neptune-mass planets8-12. We explored temperatures from 300 to 600 K and a range of atmospheric metallicities (100×, 1,000× and 10,000× solar). All simulated atmospheres produced particles, and the cooler (300 and 400 K) 1,000× solar metallicity (`H2O-dominated' and CH4-rich) experiments exhibited haze production rates higher than our standard Titan simulation ( 10 mg h-1 versus 7.4 mg h-1 for Titan13). However, the particle production rates varied greatly, with measured rates as low as 0.04 mg h-1 (for the case with 100× solar metallicity at 600 K). Here, we show that we should expect great diversity in haze production rates, as some—but not all—super-Earth and mini-Neptune atmospheres will possess photochemically generated haze.

Haze production rates in super-Earth and mini-Neptune atmosphere experiments

NASA Astrophysics Data System (ADS)

Hörst, Sarah M.; He, Chao; Lewis, Nikole K.; Kempton, Eliza M.-R.; Marley, Mark S.; Morley, Caroline V.; Moses, Julianne I.; Valenti, Jeff A.; Vuitton, Véronique

2018-03-01

Numerous Solar System atmospheres possess photochemically generated hazes, including the characteristic organic hazes of Titan and Pluto. Haze particles substantially impact atmospheric temperature structures and may provide organic material to the surface of a world, potentially affecting its habitability. Observations of exoplanet atmospheres suggest the presence of aerosols, especially in cooler (<800 K), smaller (<0.3× Jupiter's mass) exoplanets. It remains unclear whether the aerosols muting the spectroscopic features of exoplanet atmospheres are condensate clouds or photochemical hazes1-3, which is difficult to predict from theory alone4. Here, we present laboratory haze simulation experiments that probe a broad range of atmospheric parameters relevant to super-Earth- and mini-Neptune-type planets5, the most frequently occurring type of planet in our galaxy6. It is expected that photochemical haze will play a much greater role in the atmospheres of planets with average temperatures below 1,000 K (ref. 7), especially those planets that may have enhanced atmospheric metallicity and/or enhanced C/O ratios, such as super-Earths and Neptune-mass planets8-12. We explored temperatures from 300 to 600 K and a range of atmospheric metallicities (100×, 1,000× and 10,000× solar). All simulated atmospheres produced particles, and the cooler (300 and 400 K) 1,000× solar metallicity (`H2O-dominated' and CH4-rich) experiments exhibited haze production rates higher than our standard Titan simulation ( 10 mg h-1 versus 7.4 mg h-1 for Titan13). However, the particle production rates varied greatly, with measured rates as low as 0.04 mg h-1 (for the case with 100× solar metallicity at 600 K). Here, we show that we should expect great diversity in haze production rates, as some—but not all—super-Earth and mini-Neptune atmospheres will possess photochemically generated haze.

The variation of chemical characteristics of PM2.5 and PM10 and formation causes during two haze pollution events in urban Beijing, China

NASA Astrophysics Data System (ADS)

Gao, Jiajia; Tian, Hezhong; Cheng, Ke; Lu, Long; Zheng, Mei; Wang, Shuxiao; Hao, Jiming; Wang, Kun; Hua, Shenbing; Zhu, Chuanyong; Wang, Yong

2015-04-01

Airborne particles in urban Beijing during haze days and normal days were collected and analyzed in the autumn and winter seasons to reveal the chemical characteristics variations of air pollution. The air quality in haze days was substantially worse than that in normal days. Both the relatively low wind speed and high relative humidity were in favor of the accumulation of pollution species and new formation of secondary PM2.5 in the atmosphere. Elevated concentrations of elements and water-soluble inorganic ions were found on haze days for both PM10 and PM2.5. Particularly, the crustal element, such as Fe, in both PM10 and PM2.5 were substantially higher in autumn normal days and winter haze days than those in autumn haze days and winter normal days, indicating that the abundance of Fe in autumn haze days mainly be originated from crustal dust while in winter haze days it might be primarily emitted from anthropogenic sources (iron and steel smelting) instead of road dust. Secondary ion species (SO42-, NO3-, NH4+) in particles were generated much more during haze episodes, and contributed a higher proportion in PM2.5 than in PM10 during the two sampling periods. Moreover, HYSPLIT model was used to explain the possible transport of airborne particles from distant sources. By comparing with south-type trajectory, west-type trajectory entrained larger amounts of primary crustal pollutants, while, south-type trajectory was comprised of a higher mass of anthropogenic pollution species. The results of back trajectory analysis indicated that the elevated concentration of aerosol and its chemical components during haze days might be caused by the integrated effects of accumulation under stagnant meteorological condition and the transport emissions of pollutants from anthropogenic sources surrounding Beijing city.

A case-crossover analysis of forest fire haze events and mortality in Malaysia

NASA Astrophysics Data System (ADS)

Sahani, Mazrura; Zainon, Nurul Ashikin; Wan Mahiyuddin, Wan Rozita; Latif, Mohd Talib; Hod, Rozita; Khan, Md Firoz; Tahir, Norhayati Mohd; Chan, Chang-Chuan

2014-10-01

The Southeast Asian (SEA) haze events due to forest fires are recurrent and affect Malaysia, particularly the Klang Valley region. The aim of this study is to examine the risk of haze days due to biomass burning in Southeast Asia on daily mortality in the Klang Valley region between 2000 and 2007. We used a case-crossover study design to model the effect of haze based on PM10 concentration to the daily mortality. The time-stratified control sampling approach was used, adjusted for particulate matter (PM10) concentrations, time trends and meteorological influences. Based on time series analysis of PM10 and backward trajectory analysis, haze days were defined when daily PM10 concentration exceeded 100 μg/m3. The results showed a total of 88 haze days were identified in the Klang Valley region during the study period. A total of 126,822 cases of death were recorded for natural mortality where respiratory mortality represented 8.56% (N = 10,854). Haze events were found to be significantly associated with natural and respiratory mortality at various lags. For natural mortality, haze events at lagged 2 showed significant association with children less than 14 years old (Odd Ratio (OR) = 1.41; 95% Confidence Interval (CI) = 1.01-1.99). Respiratory mortality was significantly associated with haze events for all ages at lagged 0 (OR = 1.19; 95% CI = 1.02-1.40). Age-and-gender-specific analysis showed an incremental risk of respiratory mortality among all males and elderly males above 60 years old at lagged 0 (OR = 1.34; 95% CI = 1.09-1.64 and OR = 1.41; 95% CI = 1.09-1.84 respectively). Adult females aged 15-59 years old were found to be at highest risk of respiratory mortality at lagged 5 (OR = 1.66; 95% CI = 1.03-1.99). This study clearly indicates that exposure to haze events showed immediate and delayed effects on mortality.

Severe haze in Hangzhou in winter 2013/14 and associated meteorological anomalies

NASA Astrophysics Data System (ADS)

Chen, Yini; Zhu, Zhiwei; Luo, Ling; Zhang, Jiwei

2018-03-01

Aerosol pollution over eastern China has worsened considerably in recent years, resulting in heavy haze weather with low visibility and poor air quality. The present study investigates the characteristics of haze weather in Hangzhou city, and aims to unravel the meteorological anomalies associated with the heavy haze that occurred over Hangzhou in winter 2013/14. On the interannual timescale, because of the neutral condition of tropical sea surface temperature anomalies during winter 2013/14, no significant circulation and convection anomalies were induced over East Asia, leading to a stable atmospheric condition favorable for haze weather in Hangzhou. Besides, the shift of the polar vortex, caused by changes in surface temperature and ice cover at high latitudes, induced a barotropic anomalous circulation dipole pattern. The southerly anomaly associated with this anomalous dipole pattern hindered the transportation of cold/clear air mass from Siberia to central-eastern China, leading to abnormal haze during winter 2013/14 in Hangzhou. On the intraseasonal timescale, an eastward-propagating mid-latitude Rossby wave train altered the meridional wind anomaly over East Asia, causing the intraseasonal variability of haze weather during 2013/14 in Hangzhou.

Application of fault tree approach for the causation mechanism of urban haze in Beijing--Considering the risk events related with exhausts of coal combustion.

PubMed

Huang, Weiqing; Fan, Hongbo; Qiu, Yongfu; Cheng, Zhiyu; Qian, Yu

2016-02-15

Haze weather has become a serious environmental pollution problem which occurs in many Chinese cities. One of the most critical factors for the formation of haze weather is the exhausts of coal combustion, thus it is meaningful to figure out the causation mechanism between urban haze and the exhausts of coal combustion. Based on above considerations, the fault tree analysis (FAT) approach was employed for the causation mechanism of urban haze in Beijing by considering the risk events related with the exhausts of coal combustion for the first time. Using this approach, firstly the fault tree of the urban haze causation system connecting with coal combustion exhausts was established; consequently the risk events were discussed and identified; then, the minimal cut sets were successfully determined using Boolean algebra; finally, the structure, probability and critical importance degree analysis of the risk events were completed for the qualitative and quantitative assessment. The study results proved that the FTA was an effective and simple tool for the causation mechanism analysis and risk management of urban haze in China. Copyright © 2015 Elsevier B.V. All rights reserved.

Size-resolved source apportionment of particulate matter in urban Beijing during haze and non-haze episodes

NASA Astrophysics Data System (ADS)

Tian, S. L.; Pan, Y. P.; Wang, Y. S.

2015-03-01

More size-resolved chemical information is needed before the physicochemical characteristics and sources of airborne particles can be understood, but this information remains unavailable in most regions of China due to a paucity of measurement data. In this study, we report a one-year observation of various chemical species in size-segregated particle samples collected in urban Beijing, a mega city that experiences severe haze episodes. In addition to fine particles, the measured particle size distributions showed high concentrations of coarse particles during the haze periods. The abundance and chemical compositions of the particles in this study were temporally and spatially variable, with major contributions from organic matter and secondary inorganic aerosols. The contribution of the organic matter to the mass decreased from 37.9 to 33.1%, whereas the total contribution of SO42-, NO3- and NH4+ increased from 19.1 to 32.3% on non-haze and haze days, respectively. Due to heterogeneous reactions and hygroscopic growth, the peaks in the size distributions of organic carbon, SO42-, NO3-, NH4+, Cl-, K+ and Cu shifted from 0.43-0.65 μm on non-haze days to 0.65-1.1 μm on haze days. Although the size distributions are similar for the heavy metals Pb, Cd and Tl during the observation period, their concentrations increased by a factor of more than 1.5 on haze days compared with non-haze days. We found that NH4+ with a size range of 0.43-0.65 μm, SO42- and NO3- with a size range of 0.65-1.1 μm and Ca2+ with a size range of 5.8-9 μm as well as the meteorological factors of relative humidity and wind speed were responsible for the haze pollution when the visibility was less than 15 km. Source apportionment using positive matrix factorization identified six common sources: secondary inorganic aerosols (26.1% for fine particles vs. 9.5% for coarse particles), coal combustion (19 vs. 23.6%), primary emissions from vehicles (5.9 vs. 8.0%), biomass burning (8.5 vs. 2.9%), industrial pollution (6.3 vs. 8.5%) and mineral dust (16.1 vs. 35.1%). The first four factors were higher on haze days, while the latter factors were higher on non-haze days. The sources generally increased with decreasing size with the exception of mineral dust. However, two peaks were consistently found in the fine and coarse particles. The contributing sources also varied with the wind direction; coal and oil combustion products increased during southern flows, indicating that any mitigation strategy should consider the wind pattern, especially during the haze periods. The findings indicated that the PM2.5-based dataset is insufficient for the Chinese source control policy, and detailed size-resolved information is urgently needed to characterize the important sources in urban regions and better understand severe haze pollution.

Vertical Profiles of Light Scattering, Light Absorption, and Single Scattering Albedo during the Dry, Biomass Burning Season in Southern Africa and Comparisons of In Situ and Remote Sensing Measurements of Aerosol Optical Depths

NASA Technical Reports Server (NTRS)

Magi, Brian I.; Hobbs, Peter V.; Schmid, Beat; Redermann, Jens

2003-01-01

Airborne in situ measurements of vertical profiles of aerosol light scattering, light absorption, and single scattering albedo (omega (sub 0)) are presented for a number of locations in southern Africa during the dry, biomass burning season. Features of the profiles include haze layers, clean air slots, and marked decreases in light scattering in passing from the boundary layer into the free troposphere. Frequency distributions of omega (sub 0) reflect the strong influence of smoke from biomass burning. For example, during a period when heavy smoke was advected into the region from the north, the mean value of omega (sub 0) in the boundary layer was 0.81 +/- 0.02 compared to 0.89 +/- 0.03 prior to this intrusion. Comparisons of layer aerosol optical depths derived from the in situ measurements with those measured by a Sun photometer aboard the aircraft show excellent agreement.

The effect of pollutional haze on pulmonary function

PubMed Central

Liu, Shao-Kun; Cai, Shan; Chen, Yan; Xiao, Bing; Chen, Ping

2016-01-01

Detrimental health effects of atmospheric exposure to ambient particulate matter (PM) have been investigated in numerous studies. Exposure to pollutional haze, the carrier of air pollutants such as PM and nitrogen dioxide (NO2) has been linked to lung and cardiovascular disease, resulting increases in both hospital admissions and mortality. This review focuses on the constituents of pollutional haze and its effects on pulmonary function. The article presents the available information and seeks to correlate pollutional haze and pulmonary function. PMID:26904252

Histopathological and immunohistochemical findings associated with a null mutation in the Norrie disease gene.

PubMed

Schroeder, B; Hesse, L; Brück, W; Gal, A

1997-06-01

To determine the clinical, histopathological, and immunohistochemical ocular changes associated with a null mutation in the Norrie disease protein (NDP) gene. Tissue from a six-month-old boy with bilateral retrolental membranes and retinal detachment was obtained during vitreoretinal surgery. Histological sections were stained immunohistochemically with specific antibodies. No eye diseases with severe visual impairment or blindness were reported in the parents and their families. The NDP gene was analyzed by standard molecular genetic methods. A severe reduction in the number of retinal ganglion cells and a largely disarranged and hypoplastic inner nuclear layer were visible in the tissue specimen. Areas of the tissue with advanced pathology displayed massive fibrovascular proliferation in the vitreous cavity. Shrinkage and traction resulted in folding and detachment of the outer retina. Immunohistochemical reactivity for MIB(1) antigen demonstrated many proliferating cells in the vitreous, but no proliferative activity in the neuroretina. Retinal neurons showed a high grade of differentiation and expressed uniformly neuron-specific enolase and synaptophysin. A 1-base pair insertion (544/545insA) in the NDP gene was found in the affected boy. This mutation predicts a 'functional null-allele' due to a shift in the reading frame and, thus, a premature termination of mRNA translation after 55 instead of 133 amino acids. Loss of function of the NDP gene causes marked hypoplasia of the inner retinal cell layers and fibrovascular proliferation in the vitreous cavity, leading to retinal folding and detachment. The NDP therefore seems to play a critical role in terminal differentiation of the inner retinal cell layers and establishment and maintaining of anti-proliferative cellular interactions in the vitreous.

Reversing flow development in a separating turbulent boundary layer

NASA Astrophysics Data System (ADS)

Santos, Leonardo; Lang, Amy; Wahidi, Redha; Bonacci, Andrew

2016-11-01

Fast swimming sharks have micro-structures on their skin consisting of bristling scales. These scales are hypothesized to bristle in response to backflow generated from the separated turbulent boundary layer (TBL) in regions of adverse pressure gradient (APG) on the shark body. Vortices are trapped in the cavities between the scales, which induce momentum exchange between the higher momentum fluid in the outer flow and that in the separated region. This momentum exchange causes reattachment of the separated TBL, causing the scales to return to the unbristled location, and the cycle continues. The rows of scales have widths that are comparable to the spanwise length scale of the intermittent backflow patches that appear in the region of incipient detachment of TBLs. In this experimental investigation, correlations between the shark scale's width and the spanwise size of the low backflow streaks are examined, as well as details of the incipient detachment region. The experiments are conducted in a water tunnel facility and the flow field is measured using PIV. Turbulent boundary layers are subjected to an APG via a rotating cylinder. Separated TBLs are investigated on a flat plate. The authors would like to greatfully acknowledge the Army Research Office for funding this project.

Degradation of bare and silanized silicon wafer surfaces by constituents of biological fluids.

PubMed

Dekeyser, C M; Buron, C C; Derclaye, S R; Jonas, A M; Marchand-Brynaert, J; Rouxhet, P G

2012-07-15

The 24 h stability of bare silicon wafers as such or silanized with CH(3)O-(CH(2)-CH(2)-O)(n)-C(3)H(6)-trichlorosilane (n=6-9) was investigated in water, NaCl, phosphate and carbonate solutions, and in phosphate buffered saline (PBS) at 37 °C (close to biological conditions regarding temperature, high ionic strength, and pH). The resulting surfaces were analyzed using ellipsometry, X-ray Reflectometry (XRR), X-ray Photoelectron Spectroscopy (XPS), and Atomic Force Microscopy (AFM). Incubation of the silanized wafers in phosphate solution and PBS provokes a detachment of the silane layer. This is due to a hydrolysis of Si-O bonds which is favored by the action of phosphate, also responsible for a corrosion of non-silanized wafers. The surface alteration (detachment of silane layer and corrosion of the non-silanized wafer) is also important with carbonate solution, due to a higher pH (8.3). The protection of the silicon oxide layer brought by silane against the action of the salts is noticeable for phosphate but not for carbonate. Copyright © 2012 Elsevier Inc. All rights reserved.

Dynamics of water droplets detached from porous surfaces of relevance to PEM fuel cells.

PubMed

Theodorakakos, A; Ous, T; Gavaises, M; Nouri, J M; Nikolopoulos, N; Yanagihara, H

2006-08-15

The detachment of liquid droplets from porous material surfaces used with proton exchange membrane (PEM) fuel cells under the influence of a cross-flowing air is investigated computationally and experimentally. CCD images taken on a purpose-built transparent fuel cell have revealed that the water produced within the PEM is forming droplets on the surface of the gas-diffusion layer. These droplets are swept away if the velocity of the flowing air is above a critical value for a given droplet size. Static and dynamic contact angle measurements for three different carbon gas-diffusion layer materials obtained inside a transparent air-channel test model have been used as input to the numerical model; the latter is based on a Navier-Stokes equations flow solver incorporating the volume of fluid (VOF) two-phase flow methodology. Variable contact angle values around the gas-liquid-solid contact-line as well as their dynamic change during the droplet shape deformation process, have allowed estimation of the adhesion force between the liquid droplet and the solid surface and successful prediction of the separation line at which droplets loose their contact from the solid surface under the influence of the air stream flowing around them. Parametric studies highlight the relevant importance of various factors affecting the detachment of the liquid droplets from the solid surface.

Biological regulation of atmospheric chemistry en route to planetary oxygenation

PubMed Central

Farquhar, James; Poulton, Simon W.

2017-01-01

Emerging evidence suggests that atmospheric oxygen may have varied before rising irreversibly ∼2.4 billion years ago, during the Great Oxidation Event (GOE). Significantly, however, pre-GOE atmospheric aberrations toward more reducing conditions—featuring a methane-derived organic-haze—have recently been suggested, yet their occurrence, causes, and significance remain underexplored. To examine the role of haze formation in Earth’s history, we targeted an episode of inferred haze development. Our redox-controlled (Fe-speciation) carbon- and sulfur-isotope record reveals sustained systematic stratigraphic covariance, precluding nonatmospheric explanations. Photochemical models corroborate this inference, showing Δ36S/Δ33S ratios are sensitive to the presence of haze. Exploiting existing age constraints, we estimate that organic haze developed rapidly, stabilizing within ∼0.3 ± 0.1 million years (Myr), and persisted for upward of ∼1.4 ± 0.4 Myr. Given these temporal constraints, and the elevated atmospheric CO2 concentrations in the Archean, the sustained methane fluxes necessary for haze formation can only be reconciled with a biological source. Correlative δ13COrg and total organic carbon measurements support the interpretation that atmospheric haze was a transient response of the biosphere to increased nutrient availability, with methane fluxes controlled by the relative availability of organic carbon and sulfate. Elevated atmospheric methane concentrations during haze episodes would have expedited planetary hydrogen loss, with a single episode of haze development providing up to 2.6–18 × 1018 moles of O2 equivalents to the Earth system. Our findings suggest the Neoarchean likely represented a unique state of the Earth system where haze development played a pivotal role in planetary oxidation, hastening the contingent biological innovations that followed. PMID:28289223

Biological regulation of atmospheric chemistry en route to planetary oxygenation

NASA Astrophysics Data System (ADS)

Izon, Gareth; Zerkle, Aubrey L.; Williford, Kenneth H.; Farquhar, James; Poulton, Simon W.; Claire, Mark W.

2017-03-01

Emerging evidence suggests that atmospheric oxygen may have varied before rising irreversibly ˜2.4 billion years ago, during the Great Oxidation Event (GOE). Significantly, however, pre-GOE atmospheric aberrations toward more reducing conditions—featuring a methane-derived organic-haze—have recently been suggested, yet their occurrence, causes, and significance remain underexplored. To examine the role of haze formation in Earth’s history, we targeted an episode of inferred haze development. Our redox-controlled (Fe-speciation) carbon- and sulfur-isotope record reveals sustained systematic stratigraphic covariance, precluding nonatmospheric explanations. Photochemical models corroborate this inference, showing Δ36S/Δ33S ratios are sensitive to the presence of haze. Exploiting existing age constraints, we estimate that organic haze developed rapidly, stabilizing within ˜0.3 ± 0.1 million years (Myr), and persisted for upward of ˜1.4 ± 0.4 Myr. Given these temporal constraints, and the elevated atmospheric CO2 concentrations in the Archean, the sustained methane fluxes necessary for haze formation can only be reconciled with a biological source. Correlative δ13COrg and total organic carbon measurements support the interpretation that atmospheric haze was a transient response of the biosphere to increased nutrient availability, with methane fluxes controlled by the relative availability of organic carbon and sulfate. Elevated atmospheric methane concentrations during haze episodes would have expedited planetary hydrogen loss, with a single episode of haze development providing up to 2.6-18 × 1018 moles of O2 equivalents to the Earth system. Our findings suggest the Neoarchean likely represented a unique state of the Earth system where haze development played a pivotal role in planetary oxidation, hastening the contingent biological innovations that followed.

Deteriorating haze situation and the severe haze episode during December 18-25 of 2013 in Xi'an, China, the worst event on record

NASA Astrophysics Data System (ADS)

Liu, Xiaodong; Hui, Ying; Yin, Zhi-Yong; Wang, Zhaosheng; Xie, Xiaoning; Fang, Jiangang

2016-07-01

Frequent occurrence of haze weather has been considered an urgent environmental problem in China and has attracted much attention worldwide in recent years. In this study, we examined the trend in the occurrence of haze days based on horizontal visibility in Xi'an, a major city in central China, since 2000. There were 49 haze days per year on average in Xi'an during 2000-2013, and the number of haze days has increased significantly since 2008, reaching 102 days in 2013. December is the month of the highest frequency of occurrence. During December 18-25 of 2013, the longest-lasting and most severe haze event in the recent decades occurred. The 8-day mean visibility in Xi'an was only 2.5 km with 5 days below 2 km. The mean air quality index in Xi'an during this period was 486.5, and in four of those days, it reached or exceeded the index's upper limit of 500. The exceptionally high level of PM2.5 concentration was inferred as the main reason of this severe haze episode. The local weather conditions were characterized by weak winds, enhanced atmospheric stability, and high relative humidity. Strong mid-tropospheric zonal flows in combination with weakened East Asian winter monsoon limited the cold air invasion from the higher latitudes, creating a condition of low pressure gradients in the lower troposphere and near the surface for a large region in central and eastern China. With high background emission levels, the suppressed dispersion of air pollutants eventually caused this severe haze episode affecting a large region in China.

Size distribution and sorption of polychlorinated biphenyls during haze episodes

NASA Astrophysics Data System (ADS)

Zhu, Qingqing; Liu, Guorui; Zheng, Minghui; Zhang, Xian; Gao, Lirong; Su, Guijin; Liang, Yong

2018-01-01

There is a lack of studies on the size distribution of polychlorinated biphenyls (PCBs) during haze days, and their sorption mechanisms on aerosol particles remain unclear. In this study, PCBs in particle-sized aerosols from urban atmospheres of Beijing, China were investigated during haze and normal days. The concentrations, gas/particle partitioning, size distribution, and associated human daily intake of PCBs via inhalation were compared during haze days and normal days. Compared with normal days, higher particle mass-associated PCB levels were measured during haze days. The concentrations of ∑PCBs in particulate fractions were 11.9-134 pg/m3 and 6.37-14.9 pg/m3 during haze days and normal days, respectively. PCBs increased with decreasing particle size (>10 μm, 10-2.5 μm, 2.5-1.0 μm, and ≤1.0 μm). During haze days, PCBs were overwhelmingly associated with a fine particle fraction of ≤1.0 μm (64.6%), while during normal days the contribution was 33.7%. Tetra-CBs were the largest contributors (51.8%-66.7%) both in the gas and particle fractions during normal days. The profiles in the gas fraction were conspicuously different than those in the PM fractions during haze days, with di-CBs predominating in the gas fraction and higher homologues (tetra-CBs, penta-CBs, and hexa-CBs) concurrently accounting for most of the PM fractions. The mean-normalized size distributions of particulate mass and PCBs exhibited unimodal patterns, and a similar trend was observed for PCBs during both days. They all tended to be in the PM fraction of 1.0-2.5 μm. Adsorption might be the predominating mechanism for the gas-particle partitioning of PCBs during haze days, whereas absorption might be dominative during normal days.

Heterogeneous chemistry: a mechanism missing in current models to explain secondary inorganic aerosol formation during the January 2013 haze episode in North China

DOE PAGES

Zheng, B.; Zhang, Q.; Zhang, Y.; ...

2015-02-25

Severe regional haze pollution events occurred in eastern and central China in January 2013, which had adverse effects on the environment and public health. Extremely high levels of particulate matter with aerodynamic diameter of 2.5 μm or less (PM 2.5) with dominant components of sulfate and nitrate are responsible for the haze pollution. Although heterogeneous chemistry is thought to play an important role in the production of sulfate and nitrate during haze episodes, few studies have comprehensively evaluated the effect of heterogeneous chemistry on haze formation in China by using the 3-D models due to of a lack of treatmentsmore » for heterogeneous reactions in most climate and chemical transport models. In this work, the WRF-CMAQ model with newly added heterogeneous reactions is applied to East Asia to evaluate the impacts of heterogeneous chemistry and the meteorological anomaly during January 2013 on regional haze formation. As the parameterization of heterogeneous reactions on different types of particles is not well established yet, we arbitrarily selected the uptake coefficients from reactions on dust particles and then conducted several sensitivity runs to find the value that can best match observations. The revised CMAQ with heterogeneous chemistry not only captures the magnitude and temporal variation of sulfate and nitrate, but also reproduces the enhancement of relative contribution of sulfate and nitrate to PM 2.5 mass from clean days to polluted haze days. Finally, these results indicate the significant role of heterogeneous chemistry in regional haze formation and improve the understanding of the haze formation mechanisms during the January 2013 episode.« less

On the use of Lagrangian variables in descriptions of unsteady boundary-layer separation

NASA Technical Reports Server (NTRS)

Cowley, Stephen J.; Vandommelen, Leon L.; Lam, Shui T.

1990-01-01

The Lagrangian description of unsteady boundary layer separation is reviewed from both analytical and numerical perspectives. It is explained in simple terms how particle distortion gives rise to unsteady separation, and why a theory centered on Lagrangian coordinates provides the clearest description of this phenomenon. Some of the more recent results for unsteady three dimensional compressible separation are included. The different forms of separation that can arise from symmetries are emphasized. A possible description of separation is also included when the detaching vorticity layer exits the classical boundary layer region, but still remains much closer to the surface than a typical body-lengthscale.

Characterization of edge turbulence in different states of divertor detachment using reflectometry in the ASDEX Upgrade tokamak

NASA Astrophysics Data System (ADS)

Nikolaeva, V.; Guimarais, L.; Manz, P.; Carralero, D.; Manso, M. E.; Stroth, U.; Silva, C.; Conway, G. D.; Seliunin, E.; Vicente, J.; Brida, D.; Aguiam, D.; Santos, J.; Silva, A.; ASDEX Upgrade team; MST1 team

2018-05-01

Transport in the scrape-off layer (SOL) depends on the state of divertor detachment. L-mode discharges were analyzed where the state of divertor detachment is varied through a density ramp-up. By means of reflectometry measurements at the low (LFS) and the high field side (HFS), midplane density fluctuations are studied for the first time in ASDEX Upgrade simultaneously at both sides of the tokamak. Radial density fluctuation profiles (δ {n}e/{n}e) increase with radius in both the HFS and the LFS. It is found that in the SOL density fluctuations at the LFS have about a factor of two larger amplitude than at the HFS in agreement with ballooned transport. Density fluctuations at the LFS show a modest variation with increasing background density resulting mainly from a rise of low frequency components. Experimental results are in good agreement with an enhanced convection of filaments at the LFS at the beginning of outer divertor detachment leading to a flatter SOL density profile. In this phase of the discharge, density fluctuations measured at the HFS far-SOL display a strong increase, which may be associated with the presence of faster filaments originated at the LFS.

Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

NASA Astrophysics Data System (ADS)

Lee, Seong Yun; Kim, Jae Young; Lee, Jun Young; Song, Ho Jun; Lee, Sangkug; Choi, Kyung Ho; Shin, Gyojic

2014-06-01

An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

77 FR 41279 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-13

... Promulgation of Air Quality Implementation Plans; Pennsylvania; Regional Haze State Implementation Plan AGENCY... the Regional Haze State Implementation Plan (SIP) (hereafter RH SIP) revision submitted by the... anthropogenic impairment of visibility in mandatory Class I areas [[Page 41280

Arctic sea ice, Eurasia snow, and extreme winter haze in China.

PubMed

Zou, Yufei; Wang, Yuhang; Zhang, Yuzhong; Koo, Ja-Ho

2017-03-01

The East China Plains (ECP) region experienced the worst haze pollution on record for January in 2013. We show that the unprecedented haze event is due to the extremely poor ventilation conditions, which had not been seen in the preceding three decades. Statistical analysis suggests that the extremely poor ventilation conditions are linked to Arctic sea ice loss in the preceding autumn and extensive boreal snowfall in the earlier winter. We identify the regional circulation mode that leads to extremely poor ventilation over the ECP region. Climate model simulations indicate that boreal cryospheric forcing enhances the regional circulation mode of poor ventilation in the ECP region and provides conducive conditions for extreme haze such as that of 2013. Consequently, extreme haze events in winter will likely occur at a higher frequency in China as a result of the changing boreal cryosphere, posing difficult challenges for winter haze mitigation but providing a strong incentive for greenhouse gas emission reduction.

Evaluation of FSO System Availability in Haze Condition

NASA Astrophysics Data System (ADS)

Anis, A. A.; Rashidi, C. B. M.; Aljunid, S. A.; Rahman, A. K.

2018-03-01

In this paper, we proposed the evaluation of FSO system availability in haze condition. The atmospheric attenuation by weather conditions in the atmosphere as the most challenging problem of FSO system as the system performance is severely degraded and causing the signal optic to be transmitted poorly. The effects of haze condition on the performance of FSO system is stressed out and focused in this paper. From the evaluation of the analysis, designs of FSO system are proposed to obtain a system with improved link performance in haze conditions. The scattering coefficient and the atmospheric attenuation are determined using Beer’s Lambert equation. From the research, the link performance of the system is greatly improved using Design 2 with minimum BER of 10-127127 and maximu m Q Factor of 23.98. The FSO system using Design 2 has better performance compared to Design 1 in haze condition as the optical signals could penetrate the dense haze better without losing much optical power during the transmission to the scattering.

Dehazed Image Quality Assessment by Haze-Line Theory

NASA Astrophysics Data System (ADS)

Song, Yingchao; Luo, Haibo; Lu, Rongrong; Ma, Junkai

2017-06-01

Images captured in bad weather suffer from low contrast and faint color. Recently, plenty of dehazing algorithms have been proposed to enhance visibility and restore color. However, there is a lack of evaluation metrics to assess the performance of these algorithms or rate them. In this paper, an indicator of contrast enhancement is proposed basing on the newly proposed haze-line theory. The theory assumes that colors of a haze-free image are well approximated by a few hundred distinct colors, which form tight clusters in RGB space. The presence of haze makes each color cluster forms a line, which is named haze-line. By using these haze-lines, we assess performance of dehazing algorithms designed to enhance the contrast by measuring the inter-cluster deviations between different colors of dehazed image. Experimental results demonstrated that the proposed Color Contrast (CC) index correlates well with human judgments of image contrast taken in a subjective test on various scene of dehazed images and performs better than state-of-the-art metrics.

Arctic sea ice, Eurasia snow, and extreme winter haze in China

PubMed Central

Zou, Yufei; Wang, Yuhang; Zhang, Yuzhong; Koo, Ja-Ho

2017-01-01

The East China Plains (ECP) region experienced the worst haze pollution on record for January in 2013. We show that the unprecedented haze event is due to the extremely poor ventilation conditions, which had not been seen in the preceding three decades. Statistical analysis suggests that the extremely poor ventilation conditions are linked to Arctic sea ice loss in the preceding autumn and extensive boreal snowfall in the earlier winter. We identify the regional circulation mode that leads to extremely poor ventilation over the ECP region. Climate model simulations indicate that boreal cryospheric forcing enhances the regional circulation mode of poor ventilation in the ECP region and provides conducive conditions for extreme haze such as that of 2013. Consequently, extreme haze events in winter will likely occur at a higher frequency in China as a result of the changing boreal cryosphere, posing difficult challenges for winter haze mitigation but providing a strong incentive for greenhouse gas emission reduction. PMID:28345056

Haze and cloud distribution in Uranus' atmosphere based on high-contrast spatially resolved polarization measurements

NASA Astrophysics Data System (ADS)

Kostogryz, Nadiia; Berdyugina, Svetlana; Gisler, Daniel; Berkefeld, Thomas

2017-04-01

In planetary atmospheres, main sources of opacity are molecular absorption and scattering on molecules, hazes and aerosols. Hence, light reflected from a planetary atmosphere can be linearly polarized. Polarization study of inner solar system planets and exoplanets is a powerful method to characterize their atmospheres, because of a wide range of observable phase angles. For outer solar system planets, observable phase angles are very limited. For instance, Uranus can only be observed up to 3.2 degrees away from conjunctions, and its disk-integrated polarization is close to zero due to the back-scattering geometry. However, resolving the disk of Uranus and measuring the center-to-limb polarization can help constraining the vertical atmospheric structure and the nature of scattering aerosols and particles. In October 2016, we carried out polarization measurements of Uranus in narrow-band filters centered at methane bands and the adjacent continuum using the GREGOR Planet Polarimeter (GPP). The GPP is a high-precision polarimeter and is mounted at the 1.5-m GREGOR solar telescope, which is suitable for observing at night. In order to reach a high spatial resolution, the instrument uses an adaptive-optics system of the telescope. To interpret our measurements, we solve the polarized radiative transfer problem taking into account different scattering and absorption opacities. We calculate the center-to-limb variation of polarization of Uranus' disk in the continuum spectrum and in methane bands. By varying the vertical distribution of haze and cloud layers, we derive the vertical structure of the best-fit Uranus atmosphere.

Epipolis-laser in situ keratomileusis versus photorefractive keratectomy for the correction of myopia: a meta-analysis.

PubMed

Wu, Wenjing; Wang, Yan; Xu, Lulu

2015-10-01

It is unclear whether epipolis-laser in situ keratomileusis (Epi-LASIK) has any significant advantage over photorefractive keratectomy (PRK) for correcting myopia. We undertook this meta-analysis of randomized controlled trials and cohort studies to examine possible differences in efficacy, predictability, and side effects between Epi-LASIK and PRK for correcting myopia. A system literature review was conducted in the PubMed, Cochrane Library EMBASE. The statistical analysis was performed by RevMan 5.0 software. The results included efficacy outcomes (percentage of eyes with 20/20 uncorrected visual acuity post-treatment), predictability (proportion of eyes within ±0.5 D of the target refraction), epithelial healing time, and the incidence of significant haze and pain scores after surgery. There are seven articles with total 987 eyes suitable for the meta-analysis. There is no statistical significance in the predictability between Epi-LASIK and PRK, the risk ratio (RR) is 1.03, 95% confidence interval (CI) [0.92, 1.16], p = 0.18; with respect to efficacy, the odds ratio is 1.43, 95% CI = [0.85, 2.40], p = 0.56 between Epi-LASIK and PRK, there is no statistical significance either. The epithelial cell layer healing time and the pain scores and the incidence of significant haze showed no significance between these two techniques although more pains can be found in Epi-LASIK than PRK at the early-stage post-operation. According to the above analysis, Epi-LASIK has good efficacy and predictability as PRK. In addition, both techniques have low pain scores and low incidence of significant haze.

Impact to lung health of haze from forest fires: the Singapore experience.

PubMed

Emmanuel, S C

2000-06-01

From late July to the beginning of October 1997, countries of Southeast Asia experienced severe smoke haze pollution from uncontrolled forest fires mainly in the Indonesian states of Kalimantan and Sumatra. In Singapore, the impact of the 1997 haze was felt in the period from the end of August to the first week of November 1997 as a result of prevailing winds. The Ministry of the Environment monitors ambient air quality by a country-wide telemetric air quality monitoring and management network, with 15 stations located throughout the island, linked via a public telephone network to a central control station at the Environment Building. The monitoring methods used are the United States Environmental Protection Agency (USEPA) reference methods. The Pollutant Standards Index (PSI) developed by the USEPA is used for the reporting of daily air pollution concentrations. Intervals on the PSI scale are related to the potential health effects of the daily measured concentrations of the five major air pollutants: sulfur dioxide, particulate matter (PM10), nitrogen dioxide, ozone and carbon monoxide. Public sector health facilities which come under the Ministry of Health, have computerized patient care systems which enable the routine ongoing surveillance of disease conditions for the period of the haze. Attention during the period of the haze was focused on conditions related to health effects of the haze. Data sources for the monitoring of the lung health effects of the haze included morbidity from public sector outpatient care facilities, accidents and emergency departments, public sector inpatient care facilities and national mortality data. Findings from the health impact of the haze showed that there was a 30% increase in outpatient attendance for haze-related conditions. An increase in PM10 levels from 50 microg/m3 to 150 microg/m3 was significantly associated with increases of 12% of upper respiratory tract illness, 19% asthma and 26% rhinitis. Supplementary findings from scanning the electron microscopic sizing of the haze particles showed that 94% of the particles in the haze were below 2.5 microm in diameter. This was consistent with emissions from combustion sources originating over 500 km from Singapore. This has been of some concern because particles smaller than 2.5 microm in diameter can easily bypass normal body defence metabolism and penetrate deeply into the alveoli of the lungs. During the same period, there was also an increase in accident and emergency attendance for haze-related conditions. There was no significant increase in hospital admissions or in mortality. The present study found that the health effects from the 1997 smoke haze in Singapore were generally mild.

Haze, public health and mitigation measures in China: A review of the current evidence for further policy response.

PubMed

Gao, Jinghong; Woodward, Alistair; Vardoulakis, Sotiris; Kovats, Sari; Wilkinson, Paul; Li, Liping; Xu, Lei; Li, Jing; Yang, Jun; Li, Jing; Cao, Lina; Liu, Xiaobo; Wu, Haixia; Liu, Qiyong

2017-02-01

With rapid economic development, China has been plagued by choking air pollution in recent years, and the frequent occurrence of haze episodes has caused widespread public concern. The purpose of this study is to describe the sources and formation of haze, summarize the mitigation measures in force, review the relationship between haze pollution and public health, and to discuss the challenges, potential research directions and policy options. Haze pollution has both natural and man-made causes, though it is anthropogenic sources that are the major contributors. Accumulation of air pollutants, secondary formation of aerosols, stagnant meteorological conditions, and trans-boundary transportation of pollutants are the principal causes driving the formation and evolution of haze. In China, haze includes gaseous pollutants and fine particles, of which PM 2.5 is the dominant component. Short and long-term exposure to haze pollution are associated with a range of negative health outcomes, including respiratory diseases, cardiovascular and cerebrovascular diseases, mental health problems, lung cancer and premature death. China has paid increasing attention to the improvement of air quality, and has introduced action plans and policies to tackle pollution, but many interventions have only temporary effects. There may be fierce resistance from industry groups and some government agencies, and often it is challenging to enforce relevant control measures and laws. We discuss the potential policy options for prevention, the need for wider public dialogue and the implications for scientific research. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanoscale deicing by molecular dynamics simulation.

PubMed

Xiao, Senbo; He, Jianying; Zhang, Zhiliang

2016-08-14

Deicing is important to human activities in low-temperature circumstances, and is critical for combating the damage caused by excessive accumulation of ice. The aim of creating anti-icing materials, surfaces and applications relies on the understanding of fundamental nanoscale ice adhesion mechanics. Here in this study, we employ all-atom modeling and molecular dynamics simulation to investigate ice adhesion. We apply force to detach and shear nano-sized ice cubes for probing the determinants of atomistic adhesion mechanics, and at the same time investigate the mechanical effect of a sandwiched aqueous water layer between ice and substrates. We observe that high interfacial energy restricts ice mobility and increases both ice detaching and shearing stresses. We quantify up to a 60% decrease in ice adhesion strength by an aqueous water layer, and provide atomistic details that support previous experimental studies. Our results contribute quantitative comparison of nanoscale adhesion strength of ice on hydrophobic and hydrophilic surfaces, and supply for the first time theoretical references for understanding the mechanics at the atomistic origins of macroscale ice adhesion.

An effect of surface properties on detachment of adhered solid to cooling surface for formation of clathrate hydrate slurry

NASA Astrophysics Data System (ADS)

Daitoku, Tadafumi; Utaka, Yoshio

In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10 °C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the heat transfer surface properties on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally.

Morphological evolution of carbon nanofibers encapsulating SnCo alloys and its effect on growth of the solid electrolyte interphase layer.

PubMed

Shin, Jungwoo; Ryu, Won-Hee; Park, Kyu-Sung; Kim, Il-Doo

2013-08-27

Two distinctive one-dimensional (1-D) carbon nanofibers (CNFs) encapsulating irregularly and homogeneously segregated SnCo nanoparticles were synthesized via electrospinning of polyvinylpyrrolidone (PVP) and polyacrylonitrile (PAN) polymers containing Sn-Co acetate precursors and subsequent calcination in reducing atmosphere. CNFs synthesized with PVP, which undergoes structural degradation of the polymer during carbonization processes, exhibited irregular segregation of heterogeneous alloy particles composed of SnCo, Co3Sn2, and SnO with a size distribution of 30-100 nm. Large and exposed multiphase SnCo particles in PVP-driven amorphous CNFs (SnCo/PVP-CNFs) kept decomposing liquid electrolyte and were partly detached from CNFs during cycling, leading to a capacity fading at the earlier cycles. The closer study of solid electrolyte interphase (SEI) layers formed on the CNFs reveals that the gradual growth of fiber radius due to continuous increment of SEI layer thickness led to capacity fading. In contrast, SnCo particles in PAN-driven CNFs (SnCo/PAN-CNFs) showed dramatically reduced crystallite sizes (<10 nm) of single phase SnCo nanoparticles which were entirely embedded in dense, semicrystalline, and highly conducting 1-D carbon matrix. The growth of SEI layer was limited and saturated during cycling. As a result, SnCo/PAN-CNFs showed much improved cyclability (97.9% capacity retention) and lower SEI layer thickness (86 nm) after 100 cycles compared to SnCo/PVP-CNFs (capacity retention, 71.9%; SEI layer thickness, 593 nm). This work verifies that the thermal behavior of carbon precursor is highly responsible for the growth mechanism of SEI layer accompanied with particles detachment and cyclability of alloy particle embedded CNFs.

40 CFR 52.1235 - Regional haze.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Regional haze. 52.1235 Section 52.1235 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Minnesota § 52.1235 Regional haze. (a) [Reserved] (b)(1) NO X...

40 CFR 52.1235 - Regional haze.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Regional haze. 52.1235 Section 52.1235 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Minnesota § 52.1235 Regional haze. (a) [Reserved] (b)(1) NO X...

Complications after procedures of photorefractive keratectomy

NASA Astrophysics Data System (ADS)

Gierek-Ciaciura, Stanislawa

1998-10-01

Purpose: The aim of this study was to investigate the saveness of the PRK procedures. Material and method: 151 eyes after PRK for correction of myopia and 112 after PRK for correction of myopic astigmatism were examined. All PRK procedures have been performed with an excimer laser manufactured by Aesculap Meditec. Results: Haze, regression, decentration infection and overcorrection were found. Conclusions: The most often complication is regression. Corneal inflammation in the early postoperative period may cause the regression or haze. The greater corrected refractive error the greater haze degree. Haze decreases with time.

Mitigation of severe urban haze pollution by a precision air pollution control approach.

PubMed

Yu, Shaocai; Li, Pengfei; Wang, Liqiang; Wu, Yujie; Wang, Si; Liu, Kai; Zhu, Tong; Zhang, Yuanhang; Hu, Min; Zeng, Liming; Zhang, Xiaoye; Cao, Junji; Alapaty, Kiran; Wong, David C; Pleim, Jon; Mathur, Rohit; Rosenfeld, Daniel; Seinfeld, John H

2018-05-25

Severe and persistent haze pollution involving fine particulate matter (PM 2.5 ) concentrations reaching unprecedentedly high levels across many cities in China poses a serious threat to human health. Although mandatory temporary cessation of most urban and surrounding emission sources is an effective, but costly, short-term measure to abate air pollution, development of long-term crisis response measures remains a challenge, especially for curbing severe urban haze events on a regular basis. Here we introduce and evaluate a novel precision air pollution control approach (PAPCA) to mitigate severe urban haze events. The approach involves combining predictions of high PM 2.5 concentrations, with a hybrid trajectory-receptor model and a comprehensive 3-D atmospheric model, to pinpoint the origins of emissions leading to such events and to optimize emission controls. Results of the PAPCA application to five severe haze episodes in major urban areas in China suggest that this strategy has the potential to significantly mitigate severe urban haze by decreasing PM 2.5 peak concentrations by more than 60% from above 300 μg m -3 to below 100 μg m -3 , while requiring ~30% to 70% less emission controls as compared to complete emission reductions. The PAPCA strategy has the potential to tackle effectively severe urban haze pollution events with economic efficiency.

Singapore’s willingness to pay for mitigation of transboundary forest-fire haze from Indonesia

NASA Astrophysics Data System (ADS)

Lin, Yuan; Wijedasa, Lahiru S.; Chisholm, Ryan A.

2017-02-01

Haze pollution over the past four decades in Southeast Asia is mainly a result of forest and peatland fires in Indonesia. The economic impacts of haze include adverse health effects and disruption to transport and tourism. Previous studies have used a variety of approaches to assess the economic impacts of haze and the forest fires more generally. But no study has used contingent valuation to assess non-market impacts of haze on individuals. Here we apply contingent valuation to estimate impacts of haze on Singapore, one of most severely affected countries. We used a double-bounded dichotomous-choice survey design and the Kaplan-Meier-Turnbull method to infer the distribution of Singaporeans’ willingness to pay (WTP) for haze mitigation. Our estimate of mean individual WTP was 0.97% of annual income (n = 390). To calculate total national WTP, we stratified by income, the demographic variable most strongly related to individual WTP. The total WTP estimate was 643.5 million per year (95% CI [527.7 million, 765.0 million]). This estimate is comparable in magnitude to previously estimated impacts of Indonesia’s fires and also to the estimated costs of peatland protection and restoration. We recommend that our results be incorporated into future cost-benefit analyses of the fires and mitigation strategies.

Chalk-Ex: Transport of Optically Active Particles from the Surface Mixed Layer

DTIC Science & Technology

2002-09-30

and K. A. Kilpatrick. 1998. Scattering and attenuation properties of Emiliania huxleyi cells and their detached coccoliths. Limnol. Oceanogr. 43...coccolithophore Emiliania huxleyi under steady-state light-limited growth. Marine Ecology Progress Series. 142: 87-97. Bidigare, R. R. , M. Latasa, Z

Laboratory Simulations on Haze Formation in Cool Exoplanet Atmospheres

NASA Astrophysics Data System (ADS)

He, Chao; Horst, Sarah; Lewis, Nikole; Yu, Xinting; McGuiggan, Patricia; Moses, Julianne I.

2017-10-01

The Kepler mission has shown that the most abundant types of planets are super-Earths and mini-Neptunes among ~3500 confirmed exoplanets, and these types of exoplanets are expected to exhibit a wide variety of atmospheric compositions. Recent transit spectra have demonstrated that clouds and/or hazes could play a significant role in these planetary atmospheres (Deming et al. 2013, Knutson et al. 2014, Kreidberg et al. 2014, Pont, et al. 2013). However, very little laboratory work has been done to understand the formation of haze over a broad range of atmospheric compositions. Here we conducted a series of laboratory simulations to investigate haze formation in a range of planetary atmospheres using our newly built Planetary HAZE Research (PHAZER) chamber (He et al. 2017). We ran experimental simulations for nine different atmospheres: three temperatures (300 K, 400 K, and 600 K) and three metallicities (100, 1000, and 10000 times solar metallicity) using AC glow discharge as an energy source to irradiate gas mixtures. We found that haze particles are formed in all nine experiments, but the haze production rates are dramatically different for different cases. We investigated the particle sizes of the haze particles deposited on quartz discs using atomic force microscopy (AFM). The AFM images show that the particle size varies from 30 nm to 200 nm. The haze particles are more uniform for 100x solar metallicity experiments (30 nm to 40 nm) while the particles sizes for 1000x and 10000x solar metallicity experiments have wider distributions (30 nm to 200 nm). The particle size affects the scattering of light, and thus the temperature structure of planetary atmospheres. The haze production rates and particle size distributions obtained here can serve as critical inputs to atmospheric physical and chemical tools to understand the exoplanetary atmospheres and help guide future TESS and JWST observations of super-Earths and mini-Neptunes.Ref:Deming, D., et al. 2013, ApJ, 774, 95.He, C., et al. 2017, APJL, 841, L31.Knutson, H. A., et al. 2014, Nat. 505, 66.Kreidberg, L., et al. 2014, Nat. 505, 69.Pont, F., et al. 2013, MNRAS, 432, 2917.

Organic Haze as a Biosignature in Anoxic Earth-Like Atmospheres

NASA Technical Reports Server (NTRS)

Arney, Giada; Domagal-Goldman, Shawn D.; Meadows, Victoria S.

2017-01-01

Early Earth may have hosted a biologically mediated global organic haze during the Archean eon (3.8-2.5 billion years ago). This haze would have significantly impacted multiple aspects of our planet, including its potential for habitability and its spectral appearance. Here, we model worlds with Archean-like levels of carbon dioxide orbiting the ancient Sun and anM4Vdwarf (GJ 876) and show that organic haze formation requires methane fluxes consistent with estimated Earth-like biological production rates. On planets with high fluxes of biogenic organic sulfur gases (CS2, OCS, CH3SH, and CH3SCH3), photochemistry involving these gases can drive haze formation at lower CH4/CO2 ratios than methane photochemistry alone. For a planet orbiting the Sun, at 30x the modern organic sulfur gas flux, haze forms at a CH4/CO2 ratio 20% lower than at 1x the modern organic sulfur flux. For a planet orbiting the M4V star, the impact of organic sulfur gases is more pronounced: at 1x the modern Earth organic sulfur flux, a substantial haze forms at CH4/CO2 approx. 0.2, but at 30x the organic sulfur flux, the CH4/CO2 ratio needed to form haze decreases by a full order of magnitude. Detection of haze at an anomalously low CH4/ CO2 ratio could suggest the influence of these biogenic sulfur gases and therefore imply biological activity on an exoplanet. When these organic sulfur gases are not readily detectable in the spectrum of an Earth-like exoplanet, the thick organic haze they can help produce creates a very strong absorption feature at UV-blue wavelengths detectable in reflected light at a spectral resolution as low as 10. In direct imaging, constraining CH4 and CO2 concentrations will require higher spectral resolution, and R > 170 is needed to accurately resolve the structure of the CO2 feature at 1.57 microns, likely the most accessible CO2 feature on an Archean-like exoplanet.

Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres

PubMed Central

Domagal-Goldman, Shawn D.; Meadows, Victoria S.

2018-01-01

Abstract Early Earth may have hosted a biologically mediated global organic haze during the Archean eon (3.8–2.5 billion years ago). This haze would have significantly impacted multiple aspects of our planet, including its potential for habitability and its spectral appearance. Here, we model worlds with Archean-like levels of carbon dioxide orbiting the ancient Sun and an M4V dwarf (GJ 876) and show that organic haze formation requires methane fluxes consistent with estimated Earth-like biological production rates. On planets with high fluxes of biogenic organic sulfur gases (CS2, OCS, CH3SH, and CH3SCH3), photochemistry involving these gases can drive haze formation at lower CH4/CO2 ratios than methane photochemistry alone. For a planet orbiting the Sun, at 30× the modern organic sulfur gas flux, haze forms at a CH4/CO2 ratio 20% lower than at 1× the modern organic sulfur flux. For a planet orbiting the M4V star, the impact of organic sulfur gases is more pronounced: at 1× the modern Earth organic sulfur flux, a substantial haze forms at CH4/CO2 ∼ 0.2, but at 30× the organic sulfur flux, the CH4/CO2 ratio needed to form haze decreases by a full order of magnitude. Detection of haze at an anomalously low CH4/CO2 ratio could suggest the influence of these biogenic sulfur gases and therefore imply biological activity on an exoplanet. When these organic sulfur gases are not readily detectable in the spectrum of an Earth-like exoplanet, the thick organic haze they can help produce creates a very strong absorption feature at UV-blue wavelengths detectable in reflected light at a spectral resolution as low as 10. In direct imaging, constraining CH4 and CO2 concentrations will require higher spectral resolution, and R > 170 is needed to accurately resolve the structure of the CO2 feature at 1.57 μm, likely the most accessible CO2 feature on an Archean-like exoplanet. Key Words: Organic haze—Organic sulfur gases—Biosignatures—Archean Earth. Astrobiology 18, 311–329. PMID:29189040

Aerosol physical and chemical properties retrieved from ground-based remote sensing measurements during heavy haze days in Beijing winter

NASA Astrophysics Data System (ADS)

Li, Z. Q.; Gu, X.; Wang, L.; Li, D.; Li, K.; Dubovik, O.; Schuster, G.; Goloub, P.; Zhang, Y.; Li, L.; Xie, Y.; Ma, Y.; Xu, H.

2013-02-01

With the development of economy in the past thirty years, many large cities in the eastern and southwestern China are experiencing increased haze events and atmospheric pollution, causing significant impacts on the regional environment and even climate. However, knowledge on the aerosol physical and chemical properties in heavy haze conditions is still insufficient. In this study, two winter heavy haze events in Beijing occurred in 2011 and 2012 were selected and investigated by using the ground-based remote sensing measurements. We used CIMEL CE318 sun-sky radiometer to derive haze aerosol optical, physical and chemical properties, including aerosol optical depth (AOD), size distribution, complex refractive indices and fractions of chemical components like black carbon (BC), brown carbon (BrC), mineral dust (DU), ammonium sulfate-like (AS) components and aerosol water content (AW). The retrieval results from a total of five haze days showed that the aerosol loading and properties during the two winter haze events were relatively stable. Therefore, a parameterized heavy haze characterization was drawn to present a research case for future studies. The averaged AOD is 3.2 at 440 nm and Ångström exponent is 1.3 from 440-870 nm. The coarse particles occupied a considerable fraction of the bimodal size distribution in winter haze events, with the mean particle radius of 0.21 and 2.9 μm for the fine and coarse mode respectively. The real part of the refractive indices exhibited a relatively flat spectral behavior with an average value of 1.48 from 440 to 1020 nm. The imaginary part showed obviously spectral variation with the value at 440 nm (about 0.013) higher than other three wavelengths (e.g. about 0.008 at 675 nm). The chemical composition retrieval results showed that BC, BrC, DU, AS and AW occupied 1%, 2%, 49%, 15% and 33% respectively on average for the investigated haze events. The comparison of these remote sensing results with in situ BC and PM2.5 measurements were also presented in the paper.

Identification of two key genes controlling chill haze stability of beer in barley (Hordeum vulgare L).

PubMed

Ye, Lingzhen; Huang, Yuqing; Dai, Fei; Ning, Huajiang; Li, Chengdao; Zhou, Meixue; Zhang, Guoping

2015-06-11

In bright beer, haze formation is a serious quality problem, degrading beer quality and reducing its shelf life. The quality of barley (Hordeum vulgare L) malt, as the main raw material for beer brewing, largely affects the colloidal stability of beer. In this study, the genetic mechanism of the factors affecting beer haze stability in barley was studied. Quantitative trait loci (QTL) analysis of alcohol chill haze (ACH) in beer was carried out using a Franklin/Yerong double haploid (DH) population. One QTL, named as qACH, was detected for ACH, and it was located on the position of about 108 cM in chromosome 4H and can explain about 20 % of the phenotypic variation. Two key haze active proteins, BATI-CMb and BATI-CMd were identified by proteomics analysis. Bioinformatics analysis showed that BATI-CMb and BATI-CMd had the same position as qACH in the chromosome. It may be deduced that BATI-CMb and BATI-CMd are candidate genes for qACH, controlling colloidal stability of beer. Polymorphism comparison between Yerong and Franklin in the nucleotide and amino acid sequence of BATI-CMb and BATI-CMd detected the corresponding gene specific markers, which could be used in marker-assisted selection for malt barley breeding. We identified a novel QTL, qACH controlling chill haze of beer, and two key haze active proteins, BATI-CMb and BATI-CMd. And further analysis showed that BATI-CMb and BATI-CMd might be the candidate genes associated with beer chill haze.

Titan solar occultation observations reveal transit spectra of a hazy world.

PubMed

Robinson, Tyler D; Maltagliati, Luca; Marley, Mark S; Fortney, Jonathan J

2014-06-24

High-altitude clouds and hazes are integral to understanding exoplanet observations, and are proposed to explain observed featureless transit spectra. However, it is difficult to make inferences from these data because of the need to disentangle effects of gas absorption from haze extinction. Here, we turn to the quintessential hazy world, Titan, to clarify how high-altitude hazes influence transit spectra. We use solar occultation observations of Titan's atmosphere from the Visual and Infrared Mapping Spectrometer aboard National Aeronautics and Space Administration's (NASA) Cassini spacecraft to generate transit spectra. Data span 0.88-5 μm at a resolution of 12-18 nm, with uncertainties typically smaller than 1%. Our approach exploits symmetry between occultations and transits, producing transit radius spectra that inherently include the effects of haze multiple scattering, refraction, and gas absorption. We use a simple model of haze extinction to explore how Titan's haze affects its transit spectrum. Our spectra show strong methane-absorption features, and weaker features due to other gases. Most importantly, the data demonstrate that high-altitude hazes can severely limit the atmospheric depths probed by transit spectra, bounding observations to pressures smaller than 0.1-10 mbar, depending on wavelength. Unlike the usual assumption made when modeling and interpreting transit observations of potentially hazy worlds, the slope set by haze in our spectra is not flat, and creates a variation in transit height whose magnitude is comparable to those from the strongest gaseous-absorption features. These findings have important consequences for interpreting future exoplanet observations, including those from NASA's James Webb Space Telescope.

Formation and inversion of extensional ramp-syncline basins with pre-kinematic salt layers. Experimental results and application to Iberian Mesozoic analogues

NASA Astrophysics Data System (ADS)

Roma, Maria; Pla, Oriol; Butillé, Mireia; Roca, Eduard; Ferrer, Oriol

2015-04-01

The widespread extensional deformation that took place during Jurassic to Cretaceous times in the Western Europe and north-Atlantic realm resulted in the formation of several rift systems. Some of the basins associated to these rifts show broad syncline-shapes filled by thick sedimentary successions deposited overlying a hyperextended crust (i.e., Parentis, Cameros, Organyà or Columbrets basins in Iberia). The development of these syncline basins has been associated to the slip of low-angle lithospheric-scale extensional faults with ramp/flat geometries. The shape and kinematics of such faults have been usually established using the architecture of syn-kinematic layers and assuming a complete coupling of the hangingwall rocks and a layer parallel flexural slip deformation mechanism. However almost all these basins include pre-kinematic Upper Triassic salt layers which undubtoufully acted as an effective detachment decoupling the structure of sub- and suprasalt units. The presence of this salt is denoted by the growth of salt structures as diapirs or salt walls at the edges of these basins where the overburden was thinner. During latest Cretaceous and Cenozoic these basins were partially inverted and often incorporated into thrust-and-fold belts as the Pyrenees . Contractional deformation resulted in the reactivation of major extensional faults and, above the salt, the squeezing of pre-existent salt structures. The pre-kinematic salt clearly acted again as as a major detachment decoupling the contractional deformation. Using an experimental approach (scaled sand-box models) the aim of our research is threefold: 1) to determine the geometrical features of the hangingwall above a convex upwards ramp of a low angle extensional fault with and without pre-kinematic salt, and consequently; 2) to decipher the role played by a pre-kinematic viscous layer, such as salt, in the development of these syncline basins; and 3) to characterize the contractional deformation that took place in them during a later contractional inversion. To achieve this goal an experimental program including seven different sand-box models has been carried out. The experimental results show that fault shape controls the geometry and the kinematic evolution of the ramp synclines formed on the hangingwall during extension and subsequent inversion. Regarding this, the experiments also demonstrate that the presence of a viscous layer changed significantly the kinematic of the basin developing two clearly different structural styles above and below the polymer. The kinematic of this basin during extension change dramatically when the silicone layer was depleted with the formation of primary welds. Since this moment model's kinematic becomes similar to the models without silicone. During the inversion, models show that low shortening produced the contractional reactivation of the major fault arched and uplifted the basin. In this scenario, if salt is rather continuous, took place an incipient reactivation of the silicone layer as a contractional detachment. By contrast, high shortening produces the total inversion of the detachment faults and the pop-up of the extensional basin. Finally, models are compared with different natural analogues from Iberia validating previous published interpretations or proposing new interpretations inferring the geometry of the major fault, specially if the presence of a salt interlayer in the deformed rocks is known or suspected.

Titan haze: structure and properties of cyanoacetylene and cyanoacetylene-acetylene photopolymers

NASA Technical Reports Server (NTRS)

Clarke, D. W.; Ferris, J. P.

1997-01-01

The structure and morphological properties of polymers produced photochemically from the UV irradiation of cyanoacetylene and cyanoacetylene mixtures have been examined to evaluate their possible contribution to the haze layers found on Titan. A structural analysis of these polymers may contribute to our understanding of the data returned from the Huygens probe of the Cassini mission that will pass through the atmosphere of Titan in the year 2004. Infrared analysis, elemental analysis, and thermal methods (thermogravimetric analysis, thermolysis, pyrolysis) were used to examine structures of polycyanoacetylenes produced by irradiation of the gas phase HC3N at 185 and 254 nm. The resulting brown to black polymer, which exists as small particles, is believed to be a branched chain of conjugated carbon-carbon double bonds, which, on exposure to heat, cyclizes to form a graphitic structure. Similar methods of analysis were used to show that when HC3N is photolyzed in the presence of Titan's other atmospheric constituents (CH4, C2H6, C2H2, and CO), a copolymer is formed in which the added gases are incorporated as substituents on the polymer chain. Of special significance is the copolymer of HC3N and acetylene (C2H2). Even in experiments where C2H2 was absorbing nearly all of the incident photons, the ratio of C2H2 to HC3N found in the resulting polymer was only 2:1. Scanning electron microscopy was used to visually examine the polymer particles. While pure polyacetylene particles are amorphous spheres roughly 1 micrometer in diameter, polycyanoacetylenes appear to be strands of rough, solid particles slightly smaller in size. The copolymer of HC3N and C2H2 exhibits characteristics of both pure polymers. This is particularly important as pure polyacetylenes do not match the optical constants measured for Titan's atmospheric hazes. The copolymers produced by the incorporation of other minor atmospheric constituents, like HC3N, into the polyacetylenes are expected to have optical constants more comparable to those of the Titan haze.

Determination of the complex refractive indices of Titan haze analogs using photothermal deflection spectroscopy

NASA Astrophysics Data System (ADS)

Vuitton, Véronique; Tran, Buu N.; Persans, Peter D.; Ferris, James P.

2009-10-01

The spectrometers of the Cassini mission to the Saturn system have detected haze layers reaching up to 800 km in Titan's atmosphere. Knowledge of the complex refractive index ( k) of the haze is important for modeling the surface and atmosphere of Titan and retrieving some information about the functional groups present in the aerosols. Plasma discharges or ultraviolet radiation are commonly used to drive the formation of solid organics assumed to be good analogs of the Titan aerosols. [Tran, B.N., Ferris, J.P., Chera, J.J., 2003a. The photochemical formation of a Titan haze analog. Structural analysis by X-ray photoelectron and infrared spectroscopy. Icarus 162, 114-124; Tran, B.N., Force, M., Briggs, R., Ferris J.P., Persans, P., Chera, J.J., 2008. Photochemical processes on Titan: Irradiation of mixtures of gases that simulate Titan's atmosphere. Icarus 177, 106-115] reported the index of refraction of analogs synthesized by far ultraviolet irradiation of various gas mixtures. k was determined in the 200-800 nm wavelength range from transmission and reflection spectroscopy. However, this technique is limited by (i) uncertainties in the absorption values because of the small amounts of organics available, (ii) light scattering by the surface roughness and particulates in the sample. These limitations prompted us to perform new measurements using photothermal deflection spectroscopy (PDS), a technique based on the conversion of absorbed light into heat in the material of interest. By combining traditional spectroscopy ( λ < 500 nm) and PDS ( λ > 500 nm), we determined values of k over the 375-1550 nm range. k values as low as 10 -4 above 1000 nm were determined. This is one order of magnitude lower than the measurements generally used as a reference for Titan's aerosols analogs [Khare, B.N., Sagan, C., Arakawa, E.T., Suits, F., Callicott, T.A., Williams, M.W., 1984. Optical-constants of organic Tholins produced in a simulated Titanian atmosphere—from soft-X-ray to microwave-frequencies. Icarus 60(1), 127-137]. We recommend that these results were used in models to describe the optical properties of the aerosols produced in Titan's stratosphere.

76 FR 44534 - Approval and Promulgation of Air Quality Implementation Plans; Tennessee; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-26

... EPA cannot read your comment due to technical difficulties and cannot contact you for clarification... on the Tennessee Regional Haze SIP. As noted in the CSAPR, EPA has not conducted any technical analysis to determine whether compliance with the CSAPR would satisfy Regional Haze Best Available Retrofit...

Black Haze: Violence, Sacrifice, and Manhood in Black Greek-Letter Fraternities

ERIC Educational Resources Information Center

Jones, Ricky L.

2004-01-01

As a fraternity member, past chapter president, and former national committee representative, Ricky L. Jones is uniquely qualified to write about the sometimes deadly world of black fraternity hazing. Examining five major black Greek-letter fraternities, Jones maintains that hazing rituals within these fraternities are more deeply ingrained,…

77 FR 5191 - Approval and Promulgation of Air Quality Implementation Plans; District of Columbia; Regional...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-02

... Promulgation of Air Quality Implementation Plans; District of Columbia; Regional Haze State Implementation Plan... of Columbia Regional Haze Plan, a revision to the District of Columbia State Implementation Plan (SIP... existing anthropogenic impairment of visibility in mandatory Class I areas through a regional haze program...

76 FR 36450 - Approval and Promulgation of Air Quality Implementation Plans; State of Nevada; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-22

... Technology (BART) E. Long-Term Strategy (LTS) F. Coordination of the Regional Haze SIP and Reasonably... for 2018 2. Establishing the Reasonable Progress Goal 3. Interstate Consultation G. Long-Term Strategy... implementation of the regional haze program will require long-term coordination among states, Tribal governments...

Constraining Aerosol Properties with the Spectrally-Resolved Phase Function of Pluto's Hazes

NASA Astrophysics Data System (ADS)

Parker, A. H.; Howett, C.; Olkin, C.; Protopapa, S.; Grundy, W. M.; Gladstone, R.; Young, L. A.; Horst, S. M.; Weaver, H. A., Jr.; Moore, J. M.; Ennico Smith, K.; Stern, A.

2017-12-01

The Multi-spectral Visible Imaging Camera (MVIC) and Lisa Hardaway Infrared Mapping Spectrometer (LEISA) aboard New Horizons imaged Pluto at high phase throughout departure from the system in July of 2015. The repeated MVIC color scans captured the phase behavior of Pluto's atmospheric hazes through phase angles of 165.0 to 169.5 degrees in four bandpasses in the visible and NIR. A spatially-resolved departure LEISA scan delivered moderate SNR NIR spectra of the hazes over wavelengths from 1.25 - 2.5 microns. Here we present our analysis of the departure MVIC and LEISA data, extracting high precision color phase curves of the hazes using the most up-to-date radiometric calibration and NIR gain drift corrections. We interpret these phase curves and spectra using Mie theory to constrain the size and composition of haze particles, with results indicating broad similarity to Titan aerosol analogues ("tholins"). Finally, we will explore the implications of the nature of these haze particles for the evolution of Pluto's surface as they settle out onto it over time.

Causation mechanism analysis for haze pollution related to vehicle emission in Guangzhou, China by employing the fault tree approach.

PubMed

Huang, Weiqing; Fan, Hongbo; Qiu, Yongfu; Cheng, Zhiyu; Xu, Pingru; Qian, Yu

2016-05-01

Recently, China has frequently experienced large-scale, severe and persistent haze pollution due to surging urbanization and industrialization and a rapid growth in the number of motor vehicles and energy consumption. The vehicle emission due to the consumption of a large number of fossil fuels is no doubt a critical factor of the haze pollution. This work is focused on the causation mechanism of haze pollution related to the vehicle emission for Guangzhou city by employing the Fault Tree Analysis (FTA) method for the first time. With the establishment of the fault tree system of "Haze weather-Vehicle exhausts explosive emission", all of the important risk factors are discussed and identified by using this deductive FTA method. The qualitative and quantitative assessments of the fault tree system are carried out based on the structure, probability and critical importance degree analysis of the risk factors. The study may provide a new simple and effective tool/strategy for the causation mechanism analysis and risk management of haze pollution in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China

PubMed Central

Cheng, Yafang; Zheng, Guangjie; Wei, Chao; Mu, Qing; Zheng, Bo; Wang, Zhibin; Gao, Meng; Zhang, Qiang; He, Kebin; Carmichael, Gregory; Pöschl, Ulrich; Su, Hang

2016-01-01

Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to ~300 μg m−3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO2, which is oxidized by NO2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution. PMID:28028539

Thermo-responsive cell culture carriers based on poly(vinyl methyl ether)—the effect of biomolecular ligands to balance cell adhesion and stimulated detachment

NASA Astrophysics Data System (ADS)

Teichmann, Juliane; Nitschke, Mirko; Pette, Dagmar; Valtink, Monika; Gramm, Stefan; Härtel, Frauke V.; Noll, Thomas; Funk, Richard H. W.; Engelmann, Katrin; Werner, Carsten

2015-08-01

Two established material systems for thermally stimulated detachment of adherent cells were combined in a cross-linked polymer blend to merge favorable properties. Through this approach poly(N-isopropylacrylamide) (PNiPAAm) with its superior switching characteristic was paired with a poly(vinyl methyl ether)-based composition that allows adjusting physico-chemical and biomolecular properties in a wide range. Beyond pure PNiPAAm, the proposed thermo-responsive coating provides thickness, stiffness and swelling behavior, as well as an apposite density of reactive sites for biomolecular functionalization, as effective tuning parameters to meet specific requirements of a particular cell type regarding initial adhesion and ease of detachment. To illustrate the strength of this approach, the novel cell culture carrier was applied to generate transplantable sheets of human corneal endothelial cells (HCEC). Sheets were grown, detached, and transferred onto planar targets. Cell morphology, viability and functionality were analyzed by immunocytochemistry and determination of transepithelial electrical resistance (TEER) before and after sheet detachment and transfer. HCEC layers showed regular morphology with appropriate TEER. Cells were positive for function-associated marker proteins ZO-1, Na+/K+-ATPase, and paxillin, and extracellular matrix proteins fibronectin, laminin and collagen type IV before and after transfer. Sheet detachment and transfer did not impair cell viability. Subsequently, a potential application in ophthalmology was demonstrated by transplantation onto de-endothelialized porcine corneas in vitro. The novel thermo-responsive cell culture carrier facilitates the generation and transfer of functional HCEC sheets. This paves the way to generate tissue engineered human corneal endothelium as an alternative transplant source for endothelial keratoplasty.

Numerical simulations used for a validity check on the laser induced photo-detachment diagnostic method in electronegative plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oudini, N.; Taccogna, F.; Bendib, A.

2014-06-15

Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainlymore » carried out in a Hydrogen plasma with an electronegativity of α = 1, with a parametric study for α up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.« less

Thermo-responsive cell culture carriers based on poly(vinyl methyl ether)-the effect of biomolecular ligands to balance cell adhesion and stimulated detachment.

PubMed

Teichmann, Juliane; Nitschke, Mirko; Pette, Dagmar; Valtink, Monika; Gramm, Stefan; Härtel, Frauke V; Noll, Thomas; Funk, Richard H W; Engelmann, Katrin; Werner, Carsten

2015-08-01

Two established material systems for thermally stimulated detachment of adherent cells were combined in a cross-linked polymer blend to merge favorable properties. Through this approach poly( N -isopropylacrylamide) (PNiPAAm) with its superior switching characteristic was paired with a poly(vinyl methyl ether)-based composition that allows adjusting physico-chemical and biomolecular properties in a wide range. Beyond pure PNiPAAm, the proposed thermo-responsive coating provides thickness, stiffness and swelling behavior, as well as an apposite density of reactive sites for biomolecular functionalization, as effective tuning parameters to meet specific requirements of a particular cell type regarding initial adhesion and ease of detachment. To illustrate the strength of this approach, the novel cell culture carrier was applied to generate transplantable sheets of human corneal endothelial cells (HCEC). Sheets were grown, detached, and transferred onto planar targets. Cell morphology, viability and functionality were analyzed by immunocytochemistry and determination of transepithelial electrical resistance (TEER) before and after sheet detachment and transfer. HCEC layers showed regular morphology with appropriate TEER. Cells were positive for function-associated marker proteins ZO-1, Na + /K + -ATPase, and paxillin, and extracellular matrix proteins fibronectin, laminin and collagen type IV before and after transfer. Sheet detachment and transfer did not impair cell viability. Subsequently, a potential application in ophthalmology was demonstrated by transplantation onto de-endothelialized porcine corneas in vitro . The novel thermo-responsive cell culture carrier facilitates the generation and transfer of functional HCEC sheets. This paves the way to generate tissue engineered human corneal endothelium as an alternative transplant source for endothelial keratoplasty.

Thermo-responsive cell culture carriers based on poly(vinyl methyl ether)—the effect of biomolecular ligands to balance cell adhesion and stimulated detachment

PubMed Central

Teichmann, Juliane; Nitschke, Mirko; Pette, Dagmar; Valtink, Monika; Gramm, Stefan; Härtel, Frauke V; Noll, Thomas; Funk, Richard H W; Engelmann, Katrin; Werner, Carsten

2015-01-01

Two established material systems for thermally stimulated detachment of adherent cells were combined in a cross-linked polymer blend to merge favorable properties. Through this approach poly(N-isopropylacrylamide) (PNiPAAm) with its superior switching characteristic was paired with a poly(vinyl methyl ether)-based composition that allows adjusting physico-chemical and biomolecular properties in a wide range. Beyond pure PNiPAAm, the proposed thermo-responsive coating provides thickness, stiffness and swelling behavior, as well as an apposite density of reactive sites for biomolecular functionalization, as effective tuning parameters to meet specific requirements of a particular cell type regarding initial adhesion and ease of detachment. To illustrate the strength of this approach, the novel cell culture carrier was applied to generate transplantable sheets of human corneal endothelial cells (HCEC). Sheets were grown, detached, and transferred onto planar targets. Cell morphology, viability and functionality were analyzed by immunocytochemistry and determination of transepithelial electrical resistance (TEER) before and after sheet detachment and transfer. HCEC layers showed regular morphology with appropriate TEER. Cells were positive for function-associated marker proteins ZO-1, Na+/K+-ATPase, and paxillin, and extracellular matrix proteins fibronectin, laminin and collagen type IV before and after transfer. Sheet detachment and transfer did not impair cell viability. Subsequently, a potential application in ophthalmology was demonstrated by transplantation onto de-endothelialized porcine corneas in vitro. The novel thermo-responsive cell culture carrier facilitates the generation and transfer of functional HCEC sheets. This paves the way to generate tissue engineered human corneal endothelium as an alternative transplant source for endothelial keratoplasty. PMID:27877823

Numerical simulations used for a validity check on the laser induced photo-detachment diagnostic method in electronegative plasmas

NASA Astrophysics Data System (ADS)

Oudini, N.; Taccogna, F.; Bendib, A.; Aanesland, A.

2014-06-01

Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainly carried out in a Hydrogen plasma with an electronegativity of α = 1, with a parametric study for α up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.

Transboundary smoke haze pollution in Malaysia: inpatient health impacts and economic valuation.

PubMed

Othman, Jamal; Sahani, Mazrura; Mahmud, Mastura; Ahmad, Md Khadzir Sheikh

2014-06-01

This study assessed the economic value of health impacts of transboundary smoke haze pollution in Kuala Lumpur and adjacent areas in the state of Selangor, Malaysia. Daily inpatient data from 2005, 2006, 2008, and 2009 for 14 haze-related illnesses were collected from four hospitals. On average, there were 19 hazy days each year during which the air pollution levels were within the Lower Moderate to Hazardous categories. No seasonal variation in inpatient cases was observed. A smoke haze occurrence was associated with an increase in inpatient cases by 2.4 per 10,000 populations each year, representing an increase of 31 percent from normal days. The average annual economic loss due to the inpatient health impact of haze was valued at MYR273,000 ($91,000 USD). Copyright © 2014 Elsevier Ltd. All rights reserved.

AN INFRARED VIEW OF SATURN

NASA Technical Reports Server (NTRS)

2002-01-01

In honor of NASA Hubble Space Telescope's eighth anniversary, we have GIFt wrapped Saturn in vivid colors. Actually, this image is courtesy of the new Near Infrared Camera and Multi-Object Spectrometer (NICMOS), which has taken its first peek at Saturn. The false-color image - taken Jan. 4, 1998 - shows the planet's reflected infrared light. This view provides detailed information on the clouds and hazes in Saturn's atmosphere. The blue colors indicate a clear atmosphere down to a main cloud layer. Different shadings of blue indicate variations in the cloud particles, in size or chemical composition. The cloud particles are believed to be ammonia ice crystals. Most of the northern hemisphere that is visible above the rings is relatively clear. The dark region around the south pole at the bottom indicates a big hole in the main cloud layer. The green and yellow colors indicate a haze above the main cloud layer. The haze is thin where the colors are green but thick where they are yellow. Most of the southern hemisphere (the lower part of Saturn) is quite hazy. These layers are aligned with latitude lines, due to Saturn's east-west winds. The red and orange colors indicate clouds reaching up high into the atmosphere. Red clouds are even higher than orange clouds. The densest regions of two storms near Saturn's equator appear white. On Earth, the storms with the highest clouds are also found in tropical latitudes. The smaller storm on the left is about as large as the Earth, and larger storms have been recorded on Saturn in 1990 and 1994. The rings, made up of chunks of ice, are as white as images of ice taken in visible light. However, in the infrared, water absorption causes various colorations. The most obvious is the brown color of the innermost ring. The rings cast their shadow onto Saturn. The bright line seen within this shadow is sunlight shining through the Cassini Division, the separation between the two bright rings. It is best observed on the left side, just above the rings. This view is possible due to a rare geometry during the observation. The next time this is observable from Earth will be in 2006. An accurate investigation of the ring's shadow also shows sunlight shining through the Encke Gap, a thin division very close to the outer edge of the ring system. Two of Saturn's satellites were recorded, Dione on the lower left and Tethys on the upper right. Tethys is just ending its transit across the disk of Saturn. They appear in different colors, yellow and green, indicating different conditions on their icy surfaces. Wavelengths: A color image consists of three exposures (or three film layers). For visible true-color images, the wavelengths of these three exposures are 0.4, 0.5, and 0.6 micrometers for blue, green, and red light, respectively. This Saturn image was taken at longer infrared wavelengths of 1.0, 1.8, and 2.1 micrometers, displayed as blue, green, and red. Reflected sunlight is seen at all these wavelengths, since Saturn's own heat glows only at wavelengths above 4 micrometers. Image credit: Erich Karkoschka (University of Arizona), and NASA

Macular telangiectasia type 2 (MacTel) in a 34-year-old patient.

PubMed

Nicolai, Heleen; Wirix, Mieke; Spielberg, Leigh; Leys, Anita

2014-09-23

We report macular telangiectasia type 2 (MacTel) in a 34-year-old man, the youngest patient so far published with MacTel type 2. The patient presented with metamorphopsia and impaired reading ability. Diagnosis was based on bilateral abnormal macular autofluorescence, perifoveal telangiectasia with fluorescein angiographic hyperfluorescence without cystoid oedema, a small foveal avascular zone, asymmetric configuration of the foveal pit, disruptions in the inner segment/outer segment layer and hyper-reflective haze and spots in the outer nuclear layer. Although MacTel usually manifests with a slowly progressive decrease in visual acuity in the fifth to seventh decades of life, younger patients may occasionally be diagnosed with the disease. Awareness of subtle signs of the condition is essential for early diagnosis. 2014 BMJ Publishing Group Ltd.

Macular telangiectasia type 2 (MacTel) in a 34-year-old patient

PubMed Central

Nicolai, Heleen; Wirix, Mieke; Spielberg, Leigh; Leys, Anita

2014-01-01

We report macular telangiectasia type 2 (MacTel) in a 34-year-old man, the youngest patient so far published with MacTel type 2. The patient presented with metamorphopsia and impaired reading ability. Diagnosis was based on bilateral abnormal macular autofluorescence, perifoveal telangiectasia with fluorescein angiographic hyperfluorescence without cystoid oedema, a small foveal avascular zone, asymmetric configuration of the foveal pit, disruptions in the inner segment/outer segment layer and hyper-reflective haze and spots in the outer nuclear layer. Although MacTel usually manifests with a slowly progressive decrease in visual acuity in the fifth to seventh decades of life, younger patients may occasionally be diagnosed with the disease. Awareness of subtle signs of the condition is essential for early diagnosis. PMID:25249218

Triton - Scattering models and surface/atmosphere constraints

NASA Technical Reports Server (NTRS)

Thompson, W. Reid

1989-01-01

Modeling of Triton's spectrum indicates a bright scattering layer of optical depth tau about 3 overlying an optically deep layer of CH4 with high absorption and little scattering. UV absorption in the spectrum indicates tau about 0.3 of red-yellow haze, although some color may also arise from complex organics partially visible on the surface. An analysis of this and other (spectro)photometric evidence indicates that Triton most likely has a bright surface, which was partially visible in 1977-1980. Geometric albedo p = 0.62 + 0.18 or - 0.12 radius r = 1480 + or - 180 km, and temperature T = 48 + or - 6 K. With scattering optical depths of 0.3-3 and about 1-10 mb of N2, a Mars-like atmospheric density and surface visibility pertain.

An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data

USGS Publications Warehouse

Chavez, P.S.

1988-01-01

Digital analysis of remotely sensed data has become an important component of many earth-science studies. These data are often processed through a set of preprocessing or "clean-up" routines that includes a correction for atmospheric scattering, often called haze. Various methods to correct or remove the additive haze component have been developed, including the widely used dark-object subtraction technique. A problem with most of these methods is that the haze values for each spectral band are selected independently. This can create problems because atmospheric scattering is highly wavelength-dependent in the visible part of the electromagnetic spectrum and the scattering values are correlated with each other. Therefore, multispectral data such as from the Landsat Thematic Mapper and Multispectral Scanner must be corrected with haze values that are spectral band dependent. An improved dark-object subtraction technique is demonstrated that allows the user to select a relative atmospheric scattering model to predict the haze values for all the spectral bands from a selected starting band haze value. The improved method normalizes the predicted haze values for the different gain and offset parameters used by the imaging system. Examples of haze value differences between the old and improved methods for Thematic Mapper Bands 1, 2, 3, 4, 5, and 7 are 40.0, 13.0, 12.0, 8.0, 5.0, and 2.0 vs. 40.0, 13.2, 8.9, 4.9, 16.7, and 3.3, respectively, using a relative scattering model of a clear atmosphere. In one Landsat multispectral scanner image the haze value differences for Bands 4, 5, 6, and 7 were 30.0, 50.0, 50.0, and 40.0 for the old method vs. 30.0, 34.4, 43.6, and 6.4 for the new method using a relative scattering model of a hazy atmosphere. ?? 1988.

A solar escalator on Mars: Self-lifting of dust layers by radiative heating

NASA Astrophysics Data System (ADS)

Daerden, F.; Whiteway, J. A.; Neary, L.; Komguem, L.; Lemmon, M. T.; Heavens, N. G.; Cantor, B. A.; Hébrard, E.; Smith, M. D.

2015-09-01

Dust layers detected in the atmosphere of Mars by the light detection and ranging (LIDAR) instrument on the Phoenix Mars mission are explained using an atmospheric general circulation model. The layers were traced back to observed dust storm activity near the edge of the north polar ice cap where simulated surface winds exceeded the threshold for dust lifting by saltation. Heating of the atmospheric dust by solar radiation caused buoyant instability and mixing across the top of the planetary boundary layer (PBL). Differential advection by wind shear created detached dust layers above the PBL that ascended due to radiative heating and arrived at the Phoenix site at heights corresponding to the LIDAR observations. The self-lifting of the dust layers is similar to the "solar escalator" mechanism for aerosol layers in the Earth's stratosphere.

Rapid detachment of Giardia lamblia trophozoites as a mechanism of antimicrobial action of the isoflavone formononetin

PubMed Central

Lauwaet, Tineke; Andersen, Yolanda; Van de Ven, Liesbeth; Eckmann, Lars; Gillin, Frances D.

2010-01-01

Objectives Attachment to the small intestinal mucosa is crucial for initiating and maintaining Giardia infection. We tested the effect of isoflavones on Giardia attachment. Methods We evaluated the effect of formononetin on trophozoite attachment to glass, to intestinal epithelial cell layers in vitro and to murine small intestinal explants, and on the intestinal load in mice. Results We found that the isoflavone formononetin inhibits both attachment and flagellar motility within minutes and reduces the trophozoite load of Giardia in mice within 1.5 h after treatment. Conclusions The antigiardial activity of formononetin is at least partially due to its capacity to rapidly detach trophozoites. PMID:20067984

Supra choroidal buckling in managing myopic vitreoretinal interface disorders: 1-year data.

PubMed

El Rayes, Ehab N

2014-01-01

To evaluate the efficacy of supra choroidal buckling procedure using a supra choroidal catheter, as a new approach in treating myopic vitreomacular interface disorders specially in difficult cases of myopic traction maculopathy with or without macular hole retinal detachment in posterior staphyloma depending on the concept of indenting the choroid only, from a 1-year data study. A newly developed supra choroidal catheter was used to deliver stabilized, cross-linked, long-acting hyaluronic acid as a filler in the supra choroidal space in the area of the staphyloma forming a choroidal indenting effect. Before the injection, pars plana vitrectomy was performed without internal limiting membrane peeling to avoid the risk of break of the roof of foveal detachment in case of foveoschisis. This indentation was used to treat 11 patients with myopic foveoschisis and 12 patients with myopic macular hole retinal detachment, 5 of whom had failed primary repair by vitrectomy before inclusion in this trial. Clinical and optical coherence tomographic evaluations of these patients were performed over 1-year follow-up. Retinal layer restoration was achieved in all 11 eyes with myopic foveoschisis. This was gradual over a period of 2 to 6 weeks postoperatively. No recurrence over the 12-month follow-up was observed. Visual acuity improved by 1 line or more in 9 eyes (81.8%). Of the 12 eyes, 10 with macular hole detachment (83%) showed closure of the holes in association with the resolution of the detachment; 2 eyes showed resolution of the detachment and flatting of the edge of the holes but with incomplete closure on optical coherence tomography. Eight eyes (66.6%) showed improvement in visual acuity by 1 or more lines with no recurrence of retinal detachment over the 12-month follow-up period. The indentation effect was sufficient over the 12-month follow-up period. The indentation effect achieved by supra choroidal approach can be used as a method of managing myopic foveoschisis and myopic macular hole with detachment even in eyes with failed primary vitrectomy, counteracting the role of posterior staphyloma in the role of the disease. The indentation effect is sufficient for first year of follow-up.

Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China

NASA Astrophysics Data System (ADS)

Cheng, Yafang; Zheng, Guangjie; Wei, Chao; Mu, Qing; Zheng, Bo; Wang, Zhibin; Gao, Meng; Zhang, Qiang; Wang, Kebin; Carmichael, Gregory; Pöschl, Ulrich; Su, Hang

2017-04-01

Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to 300 μg m-3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO2, which is oxidized by NO2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution. Reference: Cheng, Y., Zheng, G., Wei, C., Mu, Q., Zheng, B., Wang, Z., Gao, M., Zhang, Q., He, K., Carmichael, G., Pöschl, U., and Su, H.: Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China, Science Advances, 2, 10.1126/sciadv.1601530, 2016.

Episode-Based Evolution Pattern Analysis of Haze Pollution: Method Development and Results from Beijing, China.

PubMed

Zheng, Guangjie; Duan, Fengkui; Ma, Yongliang; Zhang, Qiang; Huang, Tao; Kimoto, Takashi; Cheng, Yafang; Su, Hang; He, Kebin

2016-05-03

Haze episodes occurred in Beijing repeatedly in 2013, resulting in 189 polluted days. These episodes differed in terms of sources, formation processes, and chemical composition and thus required different control policies. Therefore, an overview of the similarities and differences among these episodes is needed. For this purpose, we conducted one-year online observations and developed a program that can simultaneously divide haze episodes and identify their shapes. A total of 73 episodes were identified, and their shapes were linked with synoptic conditions. Pure-haze events dominated in wintertime, whereas mixed haze-dust (PM2.5/PM10 < 60%) and mixed haze-fog (Aerosol Water/PM2.5 ∼ 0.3) events dominated in spring and summer-autumn, respectively. For all types, increase of ratio of PM2.5 in PM10 was typically achieved before PM2.5 reached ∼150 μg/m(3). In all PM2.5 species observed, organic matter (OM) was always the most abundant component (18-60%), but it was rarely the driving factor: its relative contribution usually decreased as the pollution level increased. The only OM-driven episode observed was associated with intensive biomass-burning activities. In comparison, haze evolution generally coincided with increasing sulfur and nitrogen oxidation ratios (SOR and NOR), indicating the enhanced production of secondary inorganic species. Applicability of these conclusions required further tests with simultaneously multisite observations.

Reactive Nitrogen Chemistry in Aerosol Water as a Source of Sulfate during Haze Events in China

NASA Astrophysics Data System (ADS)

Su, H.; Zheng, G.; Wei, C.; Mu, Q.; Zheng, B.; Wang, Z.; Zhang, Q.; Gao, M.; He, K.; Carmichael, G. R.; Poeschl, U.; Cheng, Y.

2017-12-01

Fine particle pollution associated with winter haze threatens the health of over 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations up to 300 μg m-3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models relying on sulfate production mechanisms that require photochemical oxidants, cannot predict these high levels due to the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor where the alkaline aerosol components trap SO2, which is oxidized by NO2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content leading to faster sulfate production and more severe haze pollution. Reference: Cheng, Y., Zheng, G., Wei, C., Mu, Q., Zheng, B., Wang, Z., Gao, M., Zhang, Q., He, K., Carmichael, G., Pöschl, U., and Su, H.: Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China, Science Advances, 2, 10.1126/sciadv.1601530, 2016.

[Retinal whitening following vitrectomy for epiretinal macular membrane].

PubMed

Uemura, A

1993-09-01

To investigate the clinical pictures of retinal whitening following epiretinal membrane dissection. I studied retrospectively the records of 18 eyes which had undergone vitrectomy. Two types of retinal whitening were observed: cotton wool-like spots within the superficial retinal layers and a linear or dendritic pattern within the deep retinal layers. The spots were mainly noted in idiopathic cases and resolved completely in a few weeks, and the pattern was observed in macular pucker cases after retinal detachment surgery and persisted for a long time after vitrectomy.

40 CFR 51.306 - Long-term strategy requirements for reasonably attributable visibility impairment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... every 3 years until the date of submission of the State's first plan addressing regional haze visibility... and regional haze visibility impairment, and the State must submit the first such coordinated long... first regional haze plan. In addition, the plan must provide for review of the long-term strategy as it...

40 CFR 51.306 - Long-term strategy requirements for reasonably attributable visibility impairment.

Code of Federal Regulations, 2011 CFR

2011-07-01

... every 3 years until the date of submission of the State's first plan addressing regional haze visibility... and regional haze visibility impairment, and the State must submit the first such coordinated long... first regional haze plan. In addition, the plan must provide for review of the long-term strategy as it...

It Happens, Just Not to Me: Hazing on a Canadian University Campus

ERIC Educational Resources Information Center

Massey, Kyle D.; Massey, Jennifer

2017-01-01

Research on hazing in higher education has primarily focused on Greek-letter organizations and athletes, with little research beyond these two subsets of college students. The purpose of this qualitative study was to explore the attitudes of students from the general student population at a Canadian university with regard to hazing and identify…

77 FR 72742 - Approval and Promulgation of State Implementation Plans: State of Washington; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-06

... Ecology (Ecology) submitted its Regional Haze State Implementation Plan (SIP) on December 22, 2010 to meet... Ecology submitted an update to the SIP submittal containing a revised and updated BART determination for... organized as follows: I. What is the background for this final action? Ecology submitted its Regional Haze...

76 FR 43963 - Regional Haze State Implementation Plan; State of Nevada; Extension of Comment Period

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-22

... deadline for written comments on the proposed approval of the Regional Haze SIP by 30 days to August 22... technical materials that form the basis of Nevada's Regional Haze SIP and EPA's proposed approval. The EPA...'s proposed approval of the technical analyses presented in Nevada's plan. DATES: The comment period...

Nonlinear Response of Iceberg Melting to Ocean Currents

NASA Astrophysics Data System (ADS)

Cenedese, C.; FitzMaurice, A.; Straneo, F.

2017-12-01

Icebergs calving into Greenlandic Fjords frequently experience strongly sheared flows over their draft, but the impact of this flow past the iceberg on the melt plumes generated along the iceberg sides is not fully captured by existing parameterizations. We present a series of novel laboratory experiments to determine the dependence of side submarine melt rates on a background flow. We show, for the first time, that two distinct regimes of melting exist depending on the melt plume behavior (side-attached or side-detached). These two regimes produce a nonlinear dependence of melt rate on velocity, and different distributions of meltwater in the water column. Iceberg meltwater may either be confined to a thin surface layer, when the melt plumes are side-attached, or mixed down to the iceberg draft, when the melt plumes are side-detached. In a two-layer vertically sheared flow the average flow speed in existing melt parameterizations gives an underestimate of the submarine melt rate, in part due to the nonlinearity of the dependence of melt rate on flow speed, but also because vertical shear in the velocity profile fundamentally changes the flow splitting around the ice block and consequently the velocity felt by the ice surface. Including this nonlinear velocity dependence in melting parameterizations applied to observed icebergs increases iceberg side melt in the attached regime, improving agreement with observations of iceberg submarine melt rates. We show that both attached and detached plume regimes are relevant to icebergs observed in a Greenland fjord.

In situ acidity and pH of size-fractionated aerosols during a recent smoke-haze episode in Southeast Asia.

PubMed

Behera, Sailesh N; Cheng, Jinping; Balasubramanian, Rajasekhar

2015-10-01

The characterization of aerosol acidity has received increased attention in recent years due to its influence on atmospheric visibility, climate change and human health. Distribution of water soluble inorganic (WSI) ions in 12 different size fractions of aerosols was investigated under two different atmospheric conditions (smoke-haze and non-haze periods) in 2012 using the Micro-Orifice Uniform Deposit Impactor (MOUDI) and nano-MOUDI for the first time in Singapore. To estimate the in situ acidity ([H(+)]Ins) and in situ aerosol pH (pHIS), the Aerosol Inorganic Model version-IV under deliquescent mode of airborne particles was used at prevailing ambient temperature and relative humidity. The study revealed an increase in the levels of airborne particulate matter (PM) mass and concentrations of WSI ions for all size fractions during the smoke-haze period, which was caused by the trans-boundary transport of biomass burning-impacted air masses from Indonesia. A bimodal distribution was observed for concentrations of SO4(2-), NO3(-), Cl(-), K(+) and Na(+), whereas concentrations of NH4(+), Ca(2+) and Mg(2+) showed a single mode distribution. The concentration of WSI ions in PM1.8 during the smoke-haze period increased by 3.8 (for SO4(2-)) to 10.5 (for K(+)) times more than those observed during the non-haze period. The pHIS were observed to be lower during the smoke-haze period than that during the non-haze period for all size fractions of PM, indicating that atmospheric aerosols were more acidic due to the influence of biomass burning emissions. The particles in the accumulation mode were more acidic than those in the coarse mode.

Effect of post crosslinking haze on the repeatability of Scheimpflug-based and slit-scanning imaging devices

PubMed Central

Shetty, Rohit; Agrawal, Aarti; Deshmukh, Rashmi; Kaweri, Luci; Rao, Harsha L; Nagaraja, Harsha; Jayadev, Chaitra

2017-01-01

Purpose: The aim of this study was to analyze the effect of postcollagen crosslinking (CXL) haze on the measurement and repeatability of pachymetry and mean keratometry (Km) of four corneal topographers. Materials and Methods: Sixty eyes of sixty patients with progressive keratoconus who had undergone accelerated CXL (ACXL) underwent imaging with a scanning slit imaging device (Orbscan II) and three Scheimpflug imaging devices (Pentacam HR, Sirius, and Galilei). Post-ACXL haze was measured using the densitometry software on the Pentacam HR. Readings of the thinnest corneal thickness (TCT) and Km from three scans of each device were analyzed. Effect of haze on the repeatability of TCT and Km measurements was evaluated using regression models. Repeatability was assessed by coefficient of variation. Results: Corneal densitometry in different zones affected the repeatability of TCT measurement of Orbscan (P < 0.05) significantly but not the repeatability of TCT with Pentacam HR and Sirius (P = 0.03 and 0.05, respectively). Km values were affected by haze when measured with the Pentacam HR (P < 0.05). The repeatability of Km readings for all devices was unaffected by haze. In the anterior 0–2 mm and 2–6 mm zone, TCT (P = 0.43 and 0.45, respectively), Km values (P = 0.4 and 0.6, respectively), repeatability of TCT (P = 0.1 in both zones), and Km (P = 0.5 and 0.1, respectively) with Galilei were found to be the most reliable. Conclusion: Galilei measurements appear to be least affected by post-ACXL haze when compared with other devices. Hence, topography measurements in the presence of haze need to be interpreted with caution. PMID:28513495

Physicochemical and toxicological characteristics of urban aerosols during a recent Indonesian biomass burning episode.

PubMed

Pavagadhi, Shruti; Betha, Raghu; Venkatesan, Shriram; Balasubramanian, Rajasekhar; Hande, Manoor Prakash

2013-04-01

Air particulate matter (PM) samples were collected in Singapore from 21 to 29 October 2010. During this time period, a severe regional smoke haze episode lasted for a few days (21-23 October). Physicochemical and toxicological characteristics of both haze and non-haze aerosols were evaluated. The average mass concentration of PM2.5 (PM with aerodynamic diameter of ≤2.5 μm) increased by a factor of 4 during the smoke haze period (107.2 μg/m(3)) as compared to that during the non-smoke haze period (27.0 μg/m(3)). The PM2.5 samples were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency and 10 transition metals. Out of the seven PAHs known as potential or suspected carcinogens, five were found in significantly higher levels in smoke haze aerosols as compared to those in the background air. Metal concentrations were also found to be higher in haze aerosols. Additionally, the toxicological profile of the PM2.5 samples was evaluated using a human epithelial lung cell line (A549). Cell viability and death counts were measured after a direct exposure of PM2.5 samples to A459 cells for a period of 48 h. The percentage of metabolically active cells decreased significantly following a direct exposure to PM samples collected during the haze period. To provide further insights into the toxicological characteristics of the aerosol particles, glutathione levels, as an indirect measure of oxidative stress and caspase-3/7 levels as a measure of apoptotic death, were also evaluated.

Titan solar occultation observations reveal transit spectra of a hazy world

PubMed Central

Robinson, Tyler D.; Maltagliati, Luca; Marley, Mark S.; Fortney, Jonathan J.

2014-01-01

High-altitude clouds and hazes are integral to understanding exoplanet observations, and are proposed to explain observed featureless transit spectra. However, it is difficult to make inferences from these data because of the need to disentangle effects of gas absorption from haze extinction. Here, we turn to the quintessential hazy world, Titan, to clarify how high-altitude hazes influence transit spectra. We use solar occultation observations of Titan’s atmosphere from the Visual and Infrared Mapping Spectrometer aboard National Aeronautics and Space Administration’s (NASA) Cassini spacecraft to generate transit spectra. Data span 0.88–5 μm at a resolution of 12–18 nm, with uncertainties typically smaller than 1%. Our approach exploits symmetry between occultations and transits, producing transit radius spectra that inherently include the effects of haze multiple scattering, refraction, and gas absorption. We use a simple model of haze extinction to explore how Titan’s haze affects its transit spectrum. Our spectra show strong methane-absorption features, and weaker features due to other gases. Most importantly, the data demonstrate that high-altitude hazes can severely limit the atmospheric depths probed by transit spectra, bounding observations to pressures smaller than 0.1–10 mbar, depending on wavelength. Unlike the usual assumption made when modeling and interpreting transit observations of potentially hazy worlds, the slope set by haze in our spectra is not flat, and creates a variation in transit height whose magnitude is comparable to those from the strongest gaseous-absorption features. These findings have important consequences for interpreting future exoplanet observations, including those from NASA’s James Webb Space Telescope. PMID:24876272

Pluto's Haze from 2002 - 2015: Correlation with the Solar Cycle

NASA Astrophysics Data System (ADS)

Young, Eliot; Klein, Viliam; Hartig, Kara; Resnick, Aaron; Mackie, Jason; Carriazo, Carolina; Watson, Charles; Skrutskie, Michael; Verbiscer, Anne; Nelson, Matthew; Howell, Robert; Wasserman, Lawrence; Hudson, Gordon; Gault, David; Barry, Tony; Sicardy, Bruno; Cole, Andrew; Giles, Barry; Hill, Kym

2017-04-01

Occultations by Pluto were observed 2002, 2007, 2011 and 2015, with each event observed simultaneously in two or more wavelengths. Separate wavelengths allow us to discriminate between haze opacity and refractive effects due to an atmosphere's thermal profile - these two effects are notoriously hard to separate if only single-wavelength lightcurves are available. Of those four occultations, the amount of haze in Pluto's atmosphere was highest in 2002 (Elliot et al. 2003 report an optical depth of 0.11 at 0.73 µm in the zenith direction), but undetectable in the 2007 and 2011 events (we find optical depth upper limits of 0.012 and 0.010 at 0.6 µm). Cheng et al. (2016) report a zenith optical depth of 0.018 at 0.6 µm from the haze profiles seen in New Horizons images. These four data points are correlated with the solar cycle. The 2002 haze detection occurred just after the peak of solar cycle 23, the 2007 and 2011 non-detections occurred during the solar minimum between peaks 23 and 24, and the New Horizons flyby took place just after the peak of solar cycle 24. This suggests that haze production on Pluto (a) is driven by solar UV photons or charged particles, (b) that sources and sinks on Pluto have timescales shorter than a few Earth years, and (c) the haze precursors on Pluto are not produced by Lyman-alpha radiation, because Lyman-alpha output only decreased by about one third in between the cycle 23 and 24 peaks, much less than the observed change in Pluto's haze abundances. References: Elliot, J.L. et al. (2003) Nature, Volume 424, Issue 6945, pp. 165-168.

Characteristics and source apportionment of fine haze aerosol in Beijing during the winter of 2013

NASA Astrophysics Data System (ADS)

Shang, Xiaona; Zhang, Kai; Meng, Fan; Wang, Shihao; Lee, Meehye; Suh, Inseon; Kim, Daigon; Jeon, Kwonho; Park, Hyunju; Wang, Xuezhong; Zhao, Yuxi

2018-02-01

For PM2.5 filter samples collected daily at the Chinese Research Academy of Environmental Sciences (Beijing, China) from December of 2013 to February of 2014 (the winter period), chemical characteristics and sources were investigated with an emphasis on haze events in different alert levels. During the 3 months, the average PM2.5 concentration was 89 µg m-3, exceeding the Chinese national standard of 75 µg m-3 in 24  h. The maximum PM2.5 concentration was 307 µg m-3, which characterizes developed-type pollution (PM2.5 / PM10>0.5) in the World Health Organization criteria. PM2.5 was dominated by SO42-, NO3-, and pseudo-carbonaceous compounds with obvious differences in concentrations and proportions between non-haze and haze episodes. The non-negative matrix factorization (NMF) analysis provided reasonable PM2.5 source profiles, by which five sources were identified: soil dust, traffic emission, biomass combustion, industrial emission, and coal combustion accounting for 13, 22, 12, 28, and 25  % of the total, respectively. The dust impact increased with northwesterlies during non-haze periods and decreased under stagnant conditions during haze periods. A blue alert of heavy air pollution was characterized by the greatest contribution from industrial emissions (61  %). During the Chinese Lantern Festival, an orange alert was issued and biomass combustion was found to be the major source owing to firework explosions. Red-alert haze was almost equally contributed by local traffic and transported coal combustion emissions from the vicinity of Beijing (approximately 40  % each) that was distinguished by the highest levels of NO3- and SO42-, respectively. This study also reveals that the severity and source of haze are largely dependent on meteorological conditions.

PLAM - a meteorological pollution index for air quality and its applications in fog-haze forecasts in north China

NASA Astrophysics Data System (ADS)

Yang, Y.; Wang, J.; Gong, S.; Zhang, X.; Wang, H.; Wang, Y.; Wang, J.; Li, D.; Guo, J.

2015-03-01

Using surface meteorological observation and high resolution emission data, this paper discusses the application of PLAM/h Index (Parameter Linking Air-quality to Meteorological conditions/haze) in the prediction of large-scale low visibility and fog-haze events. Based on the two-dimensional probability density function diagnosis model for emissions, the study extends the diagnosis and prediction of the meteorological pollution index PLAM to the regional visibility fog-haze intensity. The results show that combining the influence of regular meteorological conditions and emission factors together in the PLAM/h parameterization scheme is very effective in improving the diagnostic identification ability of the fog-haze weather in North China. The correlation coefficients for four seasons (spring, summer, autumn and winter) between PLAM/h and visibility observation are 0.76, 0.80, 0.96 and 0.86 respectively and all their significance levels exceed 0.001, showing the ability of PLAM/h to predict the seasonal changes and differences of fog-haze weather in the North China region. The high-value correlation zones are respectively located in Jing-Jin-Ji (Beijing, Tianjin, Hebei), Bohai Bay rim and the southern Hebei-northern Henan, indicating that the PLAM/h index has relations with the distribution of frequent heavy fog-haze weather in North China and the distribution of emission high-value zone. Comparatively analyzing the heavy fog-haze events and large-scale fine weather processes in winter and summer, it is found that PLAM/h index 24 h forecast is highly correlated to the visibility observation. Therefore, PLAM/h index has better capability of doing identification, analysis and forecasting.

PLAM - a meteorological pollution index for air quality and its applications in fog-haze forecasts in North China

NASA Astrophysics Data System (ADS)

Yang, Y. Q.; Wang, J. Z.; Gong, S. L.; Zhang, X. Y.; Wang, H.; Wang, Y. Q.; Wang, J.; Li, D.; Guo, J. P.

2016-02-01

Using surface meteorological observation and high-resolution emission data, this paper discusses the application of the PLAM/h index (Parameter Linking Air-quality to Meteorological conditions/haze) in the prediction of large-scale low visibility and fog-haze events. Based on the two-dimensional probability density function diagnosis model for emissions, the study extends the diagnosis and prediction of the meteorological pollution index PLAM to the regional visibility fog-haze intensity. The results show that combining the influence of regular meteorological conditions and emission factors together in the PLAM/h parameterization scheme is very effective in improving the diagnostic identification ability of the fog-haze weather in North China. The determination coefficients for four seasons (spring, summer, autumn, and winter) between PLAM/h and visibility observation are 0.76, 0.80, 0.96, and 0.86, respectively, and all of their significance levels exceed 0.001, showing the ability of PLAM/h to predict the seasonal changes and differences of fog-haze weather in the North China region. The high-value correlation zones are located in Jing-Jin-Ji (Beijing, Tianjin, Hebei), Bohai Bay rim, and southern Hebei-northern Henan, indicating that the PLAM/h index is related to the distribution of frequent heavy fog-haze weather in North China and the distribution of emission high-value zone. Through comparative analysis of the heavy fog-haze events and large-scale clear-weather processes in winter and summer, it is found that PLAM/h index 24 h forecast is highly correlated with the visibility observation. Therefore, the PLAM/h index has good capability in identification, analysis, and forecasting.

Divertor heat flux mitigation in the National Spherical Torus Experimenta)

NASA Astrophysics Data System (ADS)

Soukhanovskii, V. A.; Maingi, R.; Gates, D. A.; Menard, J. E.; Paul, S. F.; Raman, R.; Roquemore, A. L.; Bell, M. G.; Bell, R. E.; Boedo, J. A.; Bush, C. E.; Kaita, R.; Kugel, H. W.; Leblanc, B. P.; Mueller, D.; NSTX Team

2009-02-01

Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6MWm-2to0.5-2MWm-2 in small-ELM 0.8-1.0MA, 4-6MW neutral beam injection-heated H-mode discharges. A self-consistent picture of the outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

Structure of Haze Forming Proteins in White Wines: Vitis vinifera Thaumatin-Like Proteins

PubMed Central

Marangon, Matteo; Van Sluyter, Steven C.; Waters, Elizabeth J.; Menz, Robert I.

2014-01-01

Grape thaumatin-like proteins (TLPs) play roles in plant-pathogen interactions and can cause protein haze in white wine unless removed prior to bottling. Different isoforms of TLPs have different hazing potential and aggregation behavior. Here we present the elucidation of the molecular structures of three grape TLPs that display different hazing potential. The three TLPs have very similar structures despite belonging to two different classes (F2/4JRU is a thaumatin-like protein while I/4L5H and H2/4MBT are VVTL1), and having different unfolding temperatures (56 vs. 62°C), with protein F2/4JRU being heat unstable and forming haze, while I/4L5H does not. These differences in properties are attributable to the conformation of a single loop and the amino acid composition of its flanking regions. PMID:25463627

Structure of haze forming proteins in white wines: Vitis vinifera thaumatin-like proteins.

PubMed

Marangon, Matteo; Van Sluyter, Steven C; Waters, Elizabeth J; Menz, Robert I

2014-01-01

Grape thaumatin-like proteins (TLPs) play roles in plant-pathogen interactions and can cause protein haze in white wine unless removed prior to bottling. Different isoforms of TLPs have different hazing potential and aggregation behavior. Here we present the elucidation of the molecular structures of three grape TLPs that display different hazing potential. The three TLPs have very similar structures despite belonging to two different classes (F2/4JRU is a thaumatin-like protein while I/4L5H and H2/4MBT are VVTL1), and having different unfolding temperatures (56 vs. 62°C), with protein F2/4JRU being heat unstable and forming haze, while I/4L5H does not. These differences in properties are attributable to the conformation of a single loop and the amino acid composition of its flanking regions.

Research on the Spatial-Temporal Distribution Pattern of the Network Attention of Fog and Haze in China

NASA Astrophysics Data System (ADS)

Weng, Lingyan; Han, Xugao

2018-01-01

Understanding the spatial-temporal distribution pattern of fog and haze is the base to deal with them by adjusting measures to local conditions. Taking 31 provinces in China mainland as the research areas, this paper collected data from Baidu index on the network attention of fog and haze in relevant areas from 2011 to 2016, and conducted an analysis of their spatial-temporal distribution pattern by using autocorrelation analysis. The results show that the network attention of fog and haze has an overall spatial distribution pattern of “higher in the eastern and central, lower in the western China”. There are regional differences in different provinces in terms of network attention. Network attention of fog and haze indicates an obvious geographical agglomeration phenomenon, which is a gradual enlargement of the agglomeration area of higher value with a slight shrinking of those lower value agglomeration areas.

The Greenhouse and Anti-Greenhouse Effects on Titan

NASA Technical Reports Server (NTRS)

McKay, C. P.; Cuzzi, Jeffrey N. (Technical Monitor)

1994-01-01

Titan is the largest moon of Saturn and is the only moon in the solar system with a substantial atmosphere. Its atmosphere is mostly made of nitrogen, with a few percent CH4, 0.1% H2 and an uncertain level of Ar (less than 10%). The surface pressure is 1.5 atms and the surface temperature is 95 K, decreasing to 71 at the tropopause before rising to stratospheric temperatures of 180 K. In pressure and composition Titan's atmosphere is the closest twin to Earth's. The surface of Titan remains unknown, hidden by the thick smog layer, but it may be an ocean of liquid methane and ethane. Titan's atmosphere has a greenhouse effect which is much stronger than the Earth's - 92% of the surface warming is due to greenhouse radiation. However an organic smog layer in the upper atmosphere produces an anti-greenhouse effect that cuts the greenhouse warming in half - removing 35% of the incoming solar radiation. Models suggest that during its formation Titan's atmosphere was heated to high temperatures due to accretional energy. This was followed by a cold Triton-like period which gradually warmed to the present conditions. The coupled greenhouse and haze anti-greenhouse may be relevant to recent suggestions for haze shielding of a CH4 - NH3 early atmosphere on Earth or Mars. When the NASA/ESA mission to the Saturn System, Cassini, launches in a few years it will carry a probe that will be sent to the surface of Titan and show us this world that is strange and yet in many ways similar to our own.

Tectono-sedimentary evolution of the Permian-Triassic extension event in the Zagros basin (Iran): results from analogue modelling

NASA Astrophysics Data System (ADS)

Madani-kivi, M.; Zulauf, G.

2015-12-01

Since the 1970s, the largest oil and gas reservoirs have been discovered in the Permian-Early Triassic formationsin Saudi Arabia. Thus, this time period is important for the discovery of new oil reserves in Iran. The Arabian passivecontinental margin has undergone lithospheric extension during the Permian-Triassic, which led to the formation of theNeo-Tethys. The aim of this paper is to describe the development of the continental rift basin in the Zagros region basedon the tectono-sedimentological evolution. We have studied well-log data to specify the distribution of synrift depositsin the Zagros and have related this information to the modelling. Environmental changes indicated by various sedimentarysequences, from a siliciclastic basin to a carbonate platform setting, are described. The Cambrian Hormuz salt, whichoverlies the metamorphosed Precambrian basement, becomes effective as a basal detachment layer influencing the styleof overburden deformation during the Permian-Triassic extension event. We have investigated the formation of variousstructures linked to the presence or absence of the Hormuz layer by analogue modelling and relating these structures to theLate Palaeozoic sedimentation. Based on results of the analogue modelling, we argue that the basal detachment layer (Hormuzseries) has contributed to the various structural styles of the extensional basin development in the Fars domain and theLorestan domain.

Three dimensional Visualization of Jupiter's Equatorial Region

NASA Technical Reports Server (NTRS)

1997-01-01

Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

This frame is a view from above and to the south of the visualized area, showing the entire model. The entire region is overlain by a thin, transparent haze. In places the haze is high and thick, especially to the east (to the right of) the hotspot.

Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on more sophisticated studies of Jupiter's cloud structure. The upper and lower clouds are separated in the rendering by an arbitrary amount, and the height variations are exaggerated by a factor of 25.

The lower cloud is colored using the same false color scheme used in previously released image products, assigning red, green, and blue to the 756, 727, and 889 nanometer mosaics, respectively. Light bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the lower cloud with an overlying thin haze.

The images used cover latitudes 1 to 10 degrees and are centered at longitude 336 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers (about 930,000 miles) by the Solid State Imaging (CCD) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Origin and tectonic significance of a Mesozoic multi-layer over-thrust system within the Yangtze Block (South China)

NASA Astrophysics Data System (ADS)

Yan, Dan-Ping; Zhou, Mei-Fu; Song, Hong-Lin; Wang, Xin-Wen; Malpas, John

2003-01-01

In the Yangtze Block (South China), a well-developed Mesozoic thrust system extends through the Xuefeng and Wuling mountains in the southeast to the Sichuan basin in the northwest. The system comprises both thin- and thick-skinned thrust units separated by a boundary detachment fault, the Dayin fault. To the northwest, the thin-skinned belt is characterized by either chevron anticlines and box synclines to the northwest or chevron synclines to the southeast. The former structural style displays narrow exposures for the cores of anticlines and wider exposures for the cores of synclines. Thrust detachments occur along Silurian (Fs) and Lower Cambrian (Fc) strata and are dominantly associated with the anticlines. To the southeast, this style of deformation passes gradually into one characterized by chevron synclines with associated principal detachment faults along Silurian (Fs), Cambrian (Fc) and Lower Sinian (Fz) strata. There are, however, numerous secondary back thrusts. Therefore, the thin-skinned belt is like the Valley and Ridge Province of the North American Applachian Mountains. The thick-skinned belt structurally overlies the thin-skinned belt and is characterized by a number of klippen including the Xuefeng and Wuling nappes. It is thus comparable to the Blue Ridge Province of Appalachia. The structural pattern of this thrust system in South China can be explained by a model involving detachment faulting along various stratigraphic layers at different stages of its evolution. The system was developed through a northwest stepwise progression of deformation with the earliest delamination along Lower Sinian strata (Fz). Analyses of balanced geological cross-sections yield about 18.1-21% (total 88 km) shortening for the thin-skinned unit and at least this amount of shortening for the thick-skinned unit. The compressional deformation from southeast to northwest during Late Jurassic to Cretaceous time occurred after the westward progressive collision of the Yangtze Block with the North China Block and suggests that the orogenic event was intracontinental in nature.

As Deaths Mount, a Question Is Raised: Are Students Hard-Wired for Hazing?

ERIC Educational Resources Information Center

Hoover, Eric

2012-01-01

Hazing is the beast in academe's basement, often lurking unseen and unreported, only to rise again and again despite countless rules and zero-tolerance policies. It takes many forms, some physically violent, some emotionally cruel, some booze-soaked, some silly. Since 1970, colleges have seen at least one hazing-related fatality each year, and the…

Tropospheric haze and colors of the clear daytime sky.

PubMed

Lee, Raymond L

2015-02-01

To casual observers, haze's visible effects on clear daytime skies may seem mundane: significant scattering by tropospheric aerosols visibly (1) reduces the luminance contrast of distant objects and (2) desaturates sky blueness. However, few published measurements of hazy-sky spectra and chromaticities exist to compare with these naked-eye observations. Hyperspectral imaging along sky meridians of clear and hazy skies at one inland and two coastal sites shows that they have characteristic colorimetric signatures of scattering and absorption by haze aerosols. In addition, a simple spectral transfer function and a second-order scattering model of skylight reveal the net spectral and colorimetric effects of haze.

An analysis of haze effects on LANDSAT multispectral scanner data

NASA Technical Reports Server (NTRS)

Johnson, W. R.; Sestak, M. L. (Principal Investigator)

1981-01-01

Early season changes in optical depth change brightness, primarily along the soil line; and during crop development, changes in optical depth change both greenness and brightness. Thus, the existence of haze in the imagery could cause an unsuspecting analyst to interpret the spectral appearance as indicating an episodal event when, in fact, haze was present. The techniques for converting LANDSAT-3 data to simulate LANDSAT-2 data are in error. The yellowness and none such computations are affected primarily. Yellowness appears well correlated to optical depth. Experimental evidence with variable background and variable optical depth is needed, however. The variance of picture elements within a spring wheat field is related to its equivalent in optical depth changes caused by haze. This establishes the sensitivity of channel 1 (greenness) pixels to changes in haze levels. The between field picture element means and variances were determined for the spring wheat fields. This shows the variability of channel data on two specific dates, emphasizing that crop development can be influenced by many factors. The atmospheric correction program ATCOR reduces segment data from LANDSAT acquisitions to a common haze level and improves the results of analysis.

Modeling Exoplanetary Haze and Cloud Effects for Transmission Spectroscopy in the TRAPPIST-1 System

NASA Astrophysics Data System (ADS)

Moran, Sarah E.; Horst, Sarah M.; Lewis, Nikole K.; Batalha, Natasha E.; de Wit, Julien

2018-01-01

We present theoretical transmission spectra of the planets TRAPPIST-1d, e, f, and g using a version of the CaltecH Inverse ModEling and Retrieval Algorithms (CHIMERA) atmospheric modeling code. We use particle size, aerosol production rates, and aerosol composition inputs from recent laboratory experiments relevant for the TRAPPIST-1 system to constrain cloud and haze behavior and their effects on transmission spectra. We explore these cloud and haze cases for a variety of theoretical atmospheric compositions including hydrogen-, nitrogen-, and carbon dioxide-dominated atmospheres. Then, we demonstrate the feasibility of physically-motivated, laboratory-supported clouds and hazes to obscure spectral features at wavelengths and resolutions relevant to instruments on the Hubble Space Telescope and the upcoming James Webb Space Telescope. Lastly, with laboratory based constraints of haze production rates for terrestrial exoplanets, we constrain possible bulk atmospheric compositions of the TRAPPIST-1 planets based on current observations. We show that continued collection of optical data, beyond the supported wavelength range of the James Webb Telescope, is necessary to explore the full effect of hazes for transmission spectra of exoplanetary atmospheres like the TRAPPIST-1 system.

Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015

PubMed Central

Sun, Yele; Chen, Chen; Zhang, Yingjie; Xu, Weiqi; Zhou, Libo; Cheng, Xueling; Zheng, Haitao; Ji, Dongsheng; Li, Jie; Tang, Xiao; Fu, Pingqing; Wang, Zifa

2016-01-01

We investigate the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze episode that occurred in northern China during winter 2015 using comprehensive ground and vertical measurements, along with receptor and dispersion model analysis. Our results indicate that the life cycle of a severe winter haze episode typically consists of four stages: (1) rapid formation initiated by sudden changes in meteorological parameters and synchronous increases in most aerosol species, (2) persistent evolution with relatively constant variations in secondary inorganic aerosols and secondary organic aerosols, (3) further evolution associated with fog processing and significantly enhanced sulfate levels, and (4) clearing due to dry, cold north-northwesterly winds. Aerosol composition showed substantial changes during the formation and evolution of the haze episode but was generally dominated by regional secondary aerosols (53–67%). Our results demonstrate the important role of regional transport, largely from the southwest but also from the east, and of coal combustion emissions for winter haze formation in Beijing. Also, we observed an important downward mixing pathway during the severe haze in 2015 that can lead to rapid increases in certain aerosol species. PMID:27243909

Aerosol physical and chemical properties retrieved from ground-based remote sensing measurements during heavy haze days in Beijing winter

NASA Astrophysics Data System (ADS)

Li, Z.; Gu, X.; Wang, L.; Li, D.; Xie, Y.; Li, K.; Dubovik, O.; Schuster, G.; Goloub, P.; Zhang, Y.; Li, L.; Ma, Y.; Xu, H.

2013-10-01

With the increase in economic development over the past thirty years, many large cities in eastern and southwestern China are experiencing increased haze events and atmospheric pollution, causing significant impacts on the regional environment and even climate. However, knowledge on the aerosol physical and chemical properties in heavy haze conditions is still insufficient. In this study, two winter heavy haze events in Beijing that occurred in 2011 and 2012 were selected and investigated by using the ground-based remote sensing measurements. We used a CIMEL CE318 sun-sky radiometer to retrieve haze aerosol optical, physical and chemical properties, including aerosol optical depth (AOD), size distribution, complex refractive indices and aerosol fractions identified as black carbon (BC), brown carbon (BrC), mineral dust (DU), ammonium sulfate-like (AS) components and aerosol water content (AW). The retrieval results from a total of five haze days showed that the aerosol loading and properties during the two winter haze events were comparable. Therefore, average heavy haze property parameters were drawn to present a research case for future studies. The average AOD is about 3.0 at 440 nm, and the Ångström exponent is 1.3 from 440 to 870 nm. The fine-mode AOD is 2.8 corresponding to a fine-mode fraction of 0.93. The coarse particles occupied a considerable volume fraction of the bimodal size distribution in winter haze events, with the mean particle radius of 0.21 and 2.9 μm for the fine and coarse modes respectively. The real part of the refractive indices exhibited a relatively flat spectral behavior with an average value of 1.48 from 440 to 1020 nm. The imaginary part showed spectral variation, with the value at 440 nm (about 0.013) higher than the other three wavelengths (about 0.008 at 675 nm). The aerosol composition retrieval results showed that volume fractions of BC, BrC, DU, AS and AW are 1, 2, 49, 15 and 33%, respectively, on average for the investigated haze events. The preliminary uncertainty estimation and comparison of these remote sensing results with in situ BC and PM2.5 measurements are also presented in the paper.

Activities of the Department of Astronomy and McDonald Observatory of the University of Texas at Austin

NASA Technical Reports Server (NTRS)

Smith, H. J.

1986-01-01

McDonald Observatory of the University of Texas at Austin reports on its activities during the period 1 Jan. 1986 to 30 June 1986. Extensive observations of Halley's Comet were obtained. The comet exhibited large variability; moreover, its variability was much more rapid than can be accounted for by water vaporization as the sole controller of activity. Jupiter satellite Io's atmosphere was found to be distended by more than the equilibrium scale height but less than for unimpeded streaming into space. The atmosphere is at least temporarily bound to IO. Uranus' (3-0) H2 quadrupole line shapes require a modification of Baines and Bergstralh's standard model which incorporates at high altitude absorbing haze in addition to the lower haze layer. A fraction of normal H2 equal to 0.25 + or 0.10 is derived, in good agreement with the standard model. This result is unchanged when the preliminary temperature structure derived by the Voyager Radio Occultation Experiment is used instead of Appleby's model c. Out of the six Pluto-Charon mutual events observed this year, data were obtained on four. Preliminary analysis is yielding improved estimates for the diameters, masses, densities, and albedos of these objects.

A Jovian Hotspot in True and False Colors (Time set 3)

NASA Technical Reports Server (NTRS)

1997-01-01

True and false color views of an equatorial 'hotspot' on Jupiter. These images cover an area 34,000 kilometers by 11,000 kilometers. The top mosaic combines the violet (410 nanometers or nm) and near-infrared continuum (756 nm) filter images to create an image similar to how Jupiter would appear to human eyes. Differences in coloration are due to the composition and abundances of trace chemicals in Jupiter's atmosphere. The bottom mosaic uses Galileo's three near-infrared wavelengths (756 nm, 727 nm, and 889 nm displayed in red, green, and blue) to show variations in cloud height and thickness. Bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the deep cloud with an overlying thin haze. The light blue region to the left is covered by a very high haze layer. The multicolored region to the right has overlapping cloud layers of different heights. Galileo is the first spacecraft to distinguish cloud layers on Jupiter.

North is at the top. The mosaics cover latitudes 1 to 10 degrees and are centered at longitude 336 degrees West. The planetary limb runs along the right edge of the image. Cloud patterns appear foreshortened as they approach the limb. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers by the Solid State Imaging system aboard NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

A Jovian Hotspot in True and False Colors (Time set 1)

NASA Technical Reports Server (NTRS)

1997-01-01

True and false color views of an equatorial 'hotspot' on Jupiter. These images cover an area 34,000 kilometers by 11,000 kilometers. The top mosaic combines the violet (410 nanometers or nm) and near-infrared continuum (756 nm) filter images to create an image similar to how Jupiter would appear to human eyes. Differences in coloration are due to the composition and abundances of trace chemicals in Jupiter's atmosphere. The bottom mosaic uses Galileo's three near-infrared wavelengths (756 nm, 727 nm, and 889 nm displayed in red, green, and blue) to show variations in cloud height and thickness. Bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the deep cloud with an overlying thin haze. The light blue region to the left is covered by a very high haze layer. The multicolored region to the right has overlapping cloud layers of different heights. Galileo is the first spacecraft to distinguish cloud layers on Jupiter.

North is at the top. The mosaics cover latitudes 1 to 10 degrees and are centered at longitude 336 degrees West. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers by the Solid State Imaging system aboard NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Urban and Rural Ozone Collect over Lusaka (Zambia, 15.5 S, 28 E) during SAFARI-2000 (September 2000)

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacquelyn C.; Freiman, M. Tai; Phalane, N. Agnes; Coetzee, Gert J. R.

2002-01-01

In early September, throughout south central Africa, seasonal clearing of dry vegetation and the production of charcoal for cooking leads to intense smoke haze and ozone formation. Ozone soundings made over Lusaka in early September 2000 recorded layers of high ozone (greater than 125 ppbv at 5 km) during two stagnant periods, broken by a frontal passage that reduced boundary layer ozone by 30%. During the 6-day measurement period, surface ozone concentrations ranged from 50-95 ppbv and integrated tropospheric ozone from the soundings was 39-54 Dobson Units (note 1.3 km elevation at the launch site). A stable layer of high ozone at 2-5 km was advected from rural burning regions in western Zambia and neighboring countries, making Lusaka a collection point for transboundary pollution. This is confirmed by trajectories that show ozone leaving Angola, Namibia, Botswana and South Africa before heading toward the Indian Ocean and returning to Lusaka via Mozambique and Zimbabwe. Ozone in the mixed layer at Lusaka is heavily influenced by local sources.

The characteristics of atmospheric phthalates in Shanghai: A haze case study and human exposure assessment

NASA Astrophysics Data System (ADS)

Li, Yingjie; Wang, Jiahui; Ren, Bainian; Wang, Hongli; Qiao, Liping; Zhu, Jiping; Li, Li

2018-04-01

While phthalates in indoor environments are extensively studied, reports on phthalates in outdoor air, particularly their associations with haze weather events are rare. Phthalates, especially dimethyl phthalate, are known to react with criteria air pollutants contributing to the formation of secondary organic aerosols. This study investigated phthalates levels in the atmosphere in Shanghai with a focus on their associations with different air quality weather events. The air quality during the study period was classified into three levels: non-haze, light pollution and moderate pollution. Phthalates levels were found to be lower in non-haze weather events (236 ng/m3) and higher in moderate pollution weather events (up to 700 ng/m3). Meteorological factors of relative humidity and wind speed had an inverse relationship with phthalates levels. Particulate matter had a positive correlation with phthalates levels. Hydroxyl radical initiated photo-reaction of dimethyl phthalate was evident by its inverse relationship with total atmospheric oxidant (O3 + NO2), indicating that dimethyl phthalate could be one of the precursors of secondary organic aerosol causing haze weather events. Daily intake of phthalates through exposure to outdoor air is estimated to be relatively minor; children intake remains higher on a body weight basis. This is the first study demonstrating the relationship of phthalates and different air quality conditions in haze weather events. The knowledge contributes to our understanding on the cause of haze weather events in China and elsewhere.

77 FR 11958 - Approval and Promulgation of Air Quality Implementation Plans; State of Missouri; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-28

...EPA is proposing a limited approval of a revision to the Missouri State Implementation Plan (SIP) submitted by the State of Missouri through the Missouri Department of Natural Resources (MDNR) on August 5, 2009, and supplemental information submitted on January 30, 2012, that addresses regional haze for the first implementation period. This revision addresses the requirements of the Clean Air Act (CAA or ``Act'') and EPA's rules that require states to prevent any future and remedy any existing anthropogenic impairment of visibility in mandatory Class I areas caused by emissions of air pollutants from numerous sources located over a wide geographic area (also referred to as the ``regional haze program''). States are required to assure reasonable progress toward the national goal of achieving natural visibility conditions in Class I areas. EPA is proposing a limited approval of this SIP revision to implement the regional haze requirements for Missouri on the basis that the revision, as a whole, strengthens the Missouri SIP. In a separate action EPA has previously proposed a limited disapproval of the Missouri regional haze SIP because of deficiencies in the State's regional haze SIP submittal arising from the remand by the U.S. Court of Appeals for the District Court of Columbia (DC Circuit) to the EPA of the Clean Air Interstate Rule (CAIR). See 76 FR 82219. Therefore, we are not taking action in this notice to address the State's reliance on CAIR to meet certain regional haze requirements.

Source appointment of fine particle number and volume concentration during severe haze pollution in Beijing in January 2013.

PubMed

Liu, Zirui; Wang, Yuesi; Hu, Bo; Ji, Dongsheng; Zhang, Junke; Wu, Fangkun; Wan, Xin; Wang, Yonghong

2016-04-01

Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012-2013, causing major environmental and health problems. To better understand these extreme events, particle number size distribution (PNSD) and particle chemical composition (PCC) data collected in an intensive winter campaign in an urban site of Beijing were used to investigate the sources of ambient fine particles. Positive matrix factorization (PMF) analysis resolved a total of eight factors: two traffic factors, combustion factors, secondary aerosol, two accumulation mode aerosol factors, road dust, and long-range transported (LRT) dust. Traffic emissions (54%) and combustion aerosol (27%) were found to be the most important sources for particle number concentration, whereas combustion aerosol (33%) and accumulation mode aerosol (37%) dominated particle volume concentrations. Chemical compositions and sources of fine particles changed dynamically in the haze episodes. An enhanced role of secondary inorganic species was observed in the formation of haze pollution. Regional transport played an important role for high particles, contribution of which was on average up to 24-49% during the haze episodes. Secondary aerosols from urban background presented the largest contributions (45%) for the rapid increase of fine particles in the severest haze episode. In addition, the invasion of LRT dust aerosols further elevated the fine particles during the extreme haze episode. Our results showed a clear impact of regional transport on the local air pollution, suggesting the importance of regional-scale emission control measures in the local air quality management of Beijing.

Rapid fabrication of detachable three-dimensional tissues by layering of cell sheets with heating centrifuge.

PubMed

Haraguchi, Yuji; Kagawa, Yuki; Hasegawa, Akiyuki; Kubo, Hirotsugu; Shimizu, Tatsuya

2018-01-18

Confluent cultured cells on a temperature-responsive culture dish can be harvested as an intact cell sheet by decreasing temperature below 32°C. A three-dimensional (3-D) tissue can be fabricated by the layering of cell sheets. A resulting 3-D multilayered cell sheet-tissue on a temperature-responsive culture dish can be also harvested without any damage by only temperature decreasing. For shortening the fabrication time of the 3-D multilayered constructs, we attempted to layer cell sheets on a temperature-responsive culture dish with centrifugation. However, when a cell sheet was attached to the culture surface with a conventional centrifuge at 22-23°C, the cell sheet hardly adhere to the surface due to its noncell adhesiveness. Therefore, in this study, we have developed a heating centrifuge. In centrifugation (55g) at 36-37°C, the cell sheet adhered tightly within 5 min to the dish without significant cell damage. Additionally, centrifugation accelerated the cell sheet-layering process. The heating centrifugation shortened the fabrication time by one-fifth compared to a multilayer tissue fabrication without centrifugation. Furthermore, the multilayered constructs were finally detached from the dishes by decreasing temperature. This rapid tissue-fabrication method will be used as a valuable tool in the field of tissue engineering and regenerative therapy. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018. © 2018 American Institute of Chemical Engineers.

Spectral domain optical coherence tomography imaging in optic disk pit associated with outer retinal dehiscence

PubMed Central

Wong, Chee Wai; Wong, Doric; Mathur, Ranjana

2014-01-01

A 37-year-old Bangladeshi male presented with an inferotemporal optic disk pit and serous macular detachment in the left eye. Imaging with spectral domain optical coherence tomography (OCT) revealed a multilayer macular schisis pattern with a small subfoveal outer retinal dehiscence. This case illustrates a rare phenotype of optic disk maculopathy with macular schisis and a small outer retinal layer dehiscence. Spectral domain OCT was a useful adjunct in delineating the retinal layers in optic disk pit maculopathy, and revealed a small area of outer retinal layer dehiscence that could only have been detected on high-resolution OCT. PMID:25349471

Formation of freestanding ZrO{sub 2} nanotubes for Cr(VI) removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bashirom, Nurulhuda, E-mail: nurulhuda.usm2014@gmail.com; Ye, Beh Chin, E-mail: cyebeh@gmail.com; Razak, Khairunisak Abdul, E-mail: khairunisak@usm.my

2016-07-06

Freestanding ZrO{sub 2} nanotubes (ZNTs) were produced using a simple anodization method in fluorinated ethylene glycol electrolyte containing 1 ml 1 M K{sub 2}CO{sub 3}. The pH of the bath was kept constant at 8. The potassium carbonate (K{sub 2}CO{sub 3}) was added into electrolyte to promote the detachment of anodic ZrO{sub 2} film from the underlying zirconium (Zr) substrate. The poor adherence of ZNTs layer was due to generation of CO{sub 2} gas that was thought to occur between metal|oxide interfaces. The effect of anodization voltages towards the detachment of ZNTs layer was systematically studied at 20 V, 40more » V, 50 V and 60 V for 1 hour. The formation of CO{sub 2} gas is a function of anodization voltage, in which at 60 V, a good anodic film separation seen due to higher formation of CO{sub 2} gas. A preliminary study shown the capability of ZNTs in removing 5 ppm of Cr(VI) aqueous solution under illumination of UV light.« less

Geospatial Analysis of Atmospheric Haze Effect by Source and Sink Landscape

NASA Astrophysics Data System (ADS)

Yu, T.; Xu, K.; Yuan, Z.

2017-09-01

Based on geospatial analysis model, this paper analyzes the relationship between the landscape patterns of source and sink in urban areas and atmospheric haze pollution. Firstly, the classification result and aerosol optical thickness (AOD) of Wuhan are divided into a number of square grids with the side length of 6 km, and the category level landscape indices (PLAND, PD, COHESION, LPI, FRAC_MN) and AOD of each grid are calculated. Then the source and sink landscapes of atmospheric haze pollution are selected based on the analysis of the correlation between landscape indices and AOD. Next, to make the following analysis more efficient, the indices selected before should be determined through the correlation coefficient between them. Finally, due to the spatial dependency and spatial heterogeneity of the data used in this paper, spatial autoregressive model and geo-weighted regression model are used to analyze atmospheric haze effect by source and sink landscape from the global and local level. The results show that the source landscape of atmospheric haze pollution is the building, and the sink landscapes are shrub and woodland. PLAND, PD and COHESION are suitable for describing the atmospheric haze effect by source and sink landscape. Comparing these models, the fitting effect of SLM, SEM and GWR is significantly better than that of OLS model. The SLM model is superior to the SEM model in this paper. Although the fitting effect of GWR model is more unsuited than that of SLM, the influence degree of influencing factors on atmospheric haze of different geography can be expressed clearer. Through the analysis results of these models, following conclusions can be summarized: Reducing the proportion of source landscape area and increasing the degree of fragmentation could cut down aerosol optical thickness; And distributing the source and sink landscape evenly and interspersedly could effectively reduce aerosol optical thickness which represents atmospheric haze pollution; For Wuhan City, the method of adjusting the built-up area slightly and planning the non-built-up areas reasonably can be taken to reduce atmospheric haze pollution.

Atmospheric chemistry in the Arctic and subarctic - influence of natural fires, industrial emissions, and stratospheric inputs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wofsy, S.C.; Sachse, G.W.; Gregory, G.L.

1992-10-01

Layers with enhanced concentrations of trace gases intercepted by the NASA Electra aircraft over Alaska during the Arctic Boundary Layer Expedition (ABLE 3A) in July-August 1988 are discussed. Haze layers apparently associated with boreal fires were enriched in hydrocarbons and NO(y), with emission factors corresponding closely to laboratory data for smoldering combustion. It is argued that atmospheric composition was strongly modified by wildfires during several periods of the ABLE 3A mission. The associated enhancement of NO(y) was smaller than observed for most other combustion processes but was nonetheless significant in the context of very low background concentrations. Ozone production inmore » fire plumes was negligible. Ambient O3 was supplied by the stratosphere, with little direct input from midlatitude source during summer. It is argued that NO(y) was supplied about equally by the stratosphere and by wildfires. Hydrocarbons and CO appear to derive from biomass fires and from human activities. 47 refs.« less

Geologic age: using radioactive decay to determine geologic age

USGS Publications Warehouse

,

1997-01-01

At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas. Certain layers are in the form of sand bars and gravel banks -- rock debris spread over the land by streams. Some rocks were once lava flows or beds of cinders and ash thrown out of ancient volcanoes; others are portions of large masses of once-molten rock that cooled very slowly far beneath the Earth's surface. Other rocks were so transformed by heat and pressure during the heaving and buckling of the Earth's crust in periods of mountain building that their original features were obliterated.

Atmospheric chemistry in the Arctic and subarctic - Influence of natural fires, industrial emissions, and stratospheric inputs

NASA Technical Reports Server (NTRS)

Wofsy, S. C.; Sachse, G. W.; Gregory, G. L.; Blake, D. R.; Bradshaw, J. D.; Sandholm, S. T.; Singh, H. B.; Barrick, J. A.; Harriss, R. C.; Talbot, R. W.

1992-01-01

Layers with enhanced concentrations of trace gases intercepted by the NASA Electra aircraft over Alaska during the Arctic Boundary Layer Expedition (ABLE 3A) in July-August 1988 are discussed. Haze layers apparently associated with boreal fires were enriched in hydrocarbons and NO(y), with emission factors corresponding closely to laboratory data for smoldering combustion. It is argued that atmospheric composition was strongly modified by wildfires during several periods of the ABLE 3A mission. The associated enhancement of NO(y) was smaller than observed for most other combustion processes but was nonetheless significant in the context of very low background concentrations. Ozone production in fire plumes was negligible. Ambient O3 was supplied by the stratosphere, with little direct input from midlatitude source during summer. It is argued that NO(y) was supplied about equally by the stratosphere and by wildfires. Hydrocarbons and CO appear to derive from biomass fires and from human activities.

Frost-free North Polar Layers in the Good Old Summertime

NASA Technical Reports Server (NTRS)

2006-01-01

17 October 2006 The middle portion of the northern summer season is the ideal time of year to capture relatively dust- and haze-free views of martian north polar terrain. This year, much more of the north polar cap has sublimed away than has been evident in previous northern summers going back to 1999, when Mars Global Surveyor (MGS) began the Mapping Phase of the mission. This MGS Mars Orbiter Camera (MOC) image shows a nearly ice-free view of layers exposed by erosion in the north polar region. The light-toned patches are remnants of water ice frost. The layers are generally considered by the Mars scientific community to be record of past depositions of ice and dust. This picture is located near 82.5oN, 118.6oW, and covers an area about 3 km by 10 km (1.9 by 6.2 miles). Sunlight illuminates the scene from the upper left; the image was acquired on 22 September 2006.

Development and characterization of high refractive index and high scattering acrylate polymer layers

NASA Astrophysics Data System (ADS)

Eiselt, Thomas; Gomard, Guillaume; Preinfalk, Jan; Gleißner, Uwe; Lemmer, Uli; Hanemann, Thomas

2016-11-01

In this work, we develop a wet-processable scattering layer exhibiting a high refractive index that can be used in organic light-emitting diodes for light outcoupling purposes. The composite layers contain an acrylate casting resin, benzylmethacrylate, and phenanthrene, which is employed to increase the refractive index. The mixtures are first rheologically characterized and then polymerized with heat and UV radiation. For the refractive index measurements, the polymerized samples require a planar surface without air bubbles. To produce flat samples, a special construction consisting of a glass plate, a teflon sheet, a silicone ring (PDMS mold), another teflon sheet, and another glass plate is developed. Glue clamps are used to hold the construction together. The refractive index of the samples can be increased from 1.565 to 1.585 at 20°C at a wavelength of 589 nm following the addition of 20 wt% phenanthrene. A master mixture with a high refractive index is taken for further experiments. Nanoscaled titanium dioxide is added and dispersed into the master mixture and then spin coated on a glass substrate. These layers are optically characterized. Most of the presented layers present the expected haze of over 50%.

Impact of different detachment topographies on pull-apart basin evolution - analog modelling and computer visualisation

NASA Astrophysics Data System (ADS)

Hoprich, M.; Decker, K.; Grasemann, B.; Sokoutis, D.; Willingshofer, E.

2009-04-01

Former analog modeling on pull-apart basins dealt with different sidestep geometries, the symmetry and ratio between velocities of moving blocks, the ratio between ductile base and model thickness, the ratio between fault stepover and model thickness and their influence on basin evolution. In all these models the pull-apart basin is deformed over an even detachment. The Vienna basin, however, is considered a classical thin-skinned pull-apart with a rather peculiar basement structure. Deformation and basin evolution are believed to be limited to the brittle upper crust above the Alpine-Carpathian floor thrust. The latter is not a planar detachment surface, but has a ramp-shaped topography draping the underlying former passive continental margin. In order to estimate the effects of this special geometry, nine experiments were accomplished and the resulting structures were compared with the Vienna basin. The key parameters for the models (fault and basin geometry, detachment depth and topography) were inferred from a 3D GoCad model of the natural Vienna basin, which was compiled from seismic, wells and geological cross sections. The experiments were scaled 1:100.000 ("Ramberg-scaling" for brittle rheology) and built of quartz sand (300 µm grain size). An average depth of 6 km (6 cm) was calculated for the basal detachment, distances between the bounding strike-slip faults of 40 km (40 cm) and a finite length of the natural basin of 200 km were estimated (initial model length: 100 cm). The following parameters were changed through the experimental process: (1) syntectonic sedimentation; (2) the stepover angle between bounding strike slip faults and basal velocity discontinuity; (3) moving of one or both fault blocks (producing an asymmetrical or symmetrical basin); (4) inclination of the basal detachment surface by 5°; (6) installation of 2 and 3 ramp systems at the detachment; (7) simulation of a ductile detachment through a 0.4 cm thick PDMS layer at the basin floor. The surface of the model was photographed after each deformation increment through the experiment. Pictures of serial cross sections cut through the models in their final state every 4 cm were also taken and interpreted. The formation of en-echelon normal faults with relay ramps is observed in all models. These faults are arranged in an acute angle to the basin borders, according to a Riedel-geometry. In the case of an asymmetric basin they emerge within the non-moving fault block. Substantial differences between the models are the number, the distance and the angle of these Riedel faults, the length of the bounding strike-slip faults and the cross basin symmetry. A flat detachment produces straight fault traces, whereas inclined detachments (or inclined ramps) lead to "bending" of the normal faults, rollover and growth strata thickening towards the faults. Positions and the sizes of depocenters also vary, with depocenters preferably developing above ramp-flat-transitions. Depocenter thicknesses increase with ramp heights. A similar relation apparently exists in the natural Vienna basin, which shows ramp-like structures in the detachment just underneath large faults like the Steinberg normal fault and the associated depocenters. The 3-ramp-model also reveals segmentation of the basin above the lowermost ramp. The evolving structure is comparable to the Wiener Neustadt sub-basin in the southern part of the Vienna basin, which is underlain by a topographical high of the detachment. Cross sections through the ductile model show a strong disintergration into a horst-and-graben basin. The thin silicon putty base influences the overlying strata in a way that the basin - unlike the "dry" sand models - becomes very flat and shallow. The top view shows an irregular basin shape and no rhombohedral geometry, which characterises the Vienna basin. The ductile base also leads to a symmetrical distribution of deformation on both fault blocks, even though only one fault block is moved. The stepover angle, the influence of gravitation in a ramp or inclined system and the strain accomodation by a viscous silicone layer can be summarized as factors controlling the characteristics of the models.

Stromal haze, myofibroblasts, and surface irregularity after PRK.

PubMed

Netto, Marcelo V; Mohan, Rajiv R; Sinha, Sunilima; Sharma, Ajay; Dupps, William; Wilson, Steven E

2006-05-01

The aim of this study was to investigate the relationship between the level of stromal surface irregularity after photorefractive keratectomy (PRK) and myofibroblast generation along with the development of corneal haze. Variable levels of stromal surface irregularity were generated in rabbit corneas by positioning a fine mesh screen in the path of excimer laser during ablation for a variable percentage of the terminal pulses of the treatment for myopia that does not otherwise generate significant opacity. Ninety-six rabbits were divided into eight groups: [see table in text]. Slit lamp analysis and haze grading were performed in all groups. Rabbits were sacrificed at 4 hr or 4 weeks after surgery and histochemical analysis was performed on corneas for apoptosis (TUNEL assay), myofibroblast marker alpha-smooth muscle actin (SMA), and integrin alpha4 to delineate the epithelial basement membrane. Slit-lamp grading revealed severe haze formation in corneas in groups IV and VI, with significantly less haze in groups II, III, and VII and insignificant haze compared with the unwounded control in groups I and V. Analysis of SMA staining at 4 weeks after surgery, the approximate peak of haze formation in rabbits, revealed low myofibroblast formation in group I (1.2+/-0.2 cells/400x field) and group V (1.8+/-0.4), with significantly more in groups II (3.5+/-1.8), III (6.8+/-1.6), VII (7.9+/-3.8), IV (12.4+/-4.2) and VI (14.6+/-5.1). The screened groups were significantly different from each other (p < 0.05), with myofibroblast generation increasing with higher surface irregularity in the -4.5 diopter PRK groups. The -9.0 diopter PRK group VI had significantly more myofibroblast generation than the -9.0 diopter PRK with PTK-smoothing group VII (p < 0.01). Areas of basement membrane disruption were demonstrated by staining corneas for integrin alpha4 and were prominent in corneas with grade I or higher haze. SMA-positive myofibroblasts tended to be present sub-adjacent to basement membrane defects. Late apoptosis was detected at 1 month after surgery within clusters of myofibroblasts in the sub-epithelial stroma. In conclusion, these results demonstrated a relationship between the level of corneal haze formation after PRK and the level of stromal surface irregularity. PTK-smoothing with methylcellulose was an effective method to reduce stromal surface irregularity and decreased both haze and associated myofibroblast density. We hypothesize that stromal surface irregularity after PRK for high myopia results in defective basement membrane regeneration and increased epithelium-derived TGFbeta signalling to the stroma that increases myofibroblast generation. Late apoptosis appears to have a role in the disappearance of myofibroblasts and haze over time.

[Characteristics of mass size distributions of water-soluble, inorganic ions during summer and winter haze days of Beijing].

PubMed

Huang, Yi-Min; Liu, Zi-Rui; Chen, Hong; Wang, Yue-Si

2013-04-01

To investigate the size distribution characteristics of water soluble inorganic ions in haze days, the particle samples were collected by two Andersen cascade impactors in Beijing during summer and winter time and each sampling period lasted two weeks. Online measurement of PM10 and PM2.5 using TEOM were also conducted at the same time. Sources and formation mechanism of water soluble inorganic ions were analyzed based on their size distributions. The results showed that average concentrations of PM10 and PM 2.5 were (245.5 +/- 8.4) microg x m(-3) and (120.2 +/- 2.0) microg x m(-3) during summer haze days (SHD), and were (384.2 +/- 30.2) microg x m(-3) and (252.7 +/- 47.1) microg x m(-3) during winter haze days (WHD), which suggested fine particles predominated haze pollution episode in both seasons. Total water-soluble inorganic ions concentrations were higher in haze days than those in non-haze days, especially in fine particles. Furthermore, concentrations of secondary inorganic ions (SO4(2-), NO3(-) and NH4(+)) increased quicker than other inorganic ions in fine particles during haze days, indicating secondary inorganic ions played an important role in the formation of haze pollution. Similar size distributions were found for all Sinorganic water soluble ions except for NO3(-), during SHD and WHD. SO4(2-) and NH4(+) dominated in the fine mode (PM1.0) while Mg2+ and Ca2+ accumulated in coarse fraction, Na+, Cl- and K+ showed a bimodal distribution. For NO3(-), however, it showed a bimodal distribution during SHD and a unimodal distribution dominated in the fine fraction was found during WHD. The average mass median aerodynamic diameter (MMAD) of SO4(2-) was 0.64 microm in SHD, which suggested the formation of SO4(2-) was mainly attributed to in-cloud processes. Furthermore, a higher apparent conversion rate of sulfur dioxide (SOR) was found in SHD, indicating more fine particles were produced by photochemical reaction in haze days than that in non-haze days. The MMAD of SO4(2-) increased to 0.89 microm in WHD, local emission of SO2 and the subsequently heterogeneous reaction became the main source of SO4(2-) during winter time. The average MMADs of NO3(-) were 2.85 microm and 0.80 microm in SHD and WHD, respectively. Influenced by the seasonal temperature difference, NO3(-) mainly existed in the form of calcium nitrate in coarse mode during SHD while the fine mode nitrate was associated with ammonium during WHD.

n/a

NASA Image and Video Library

1988-08-08

A recent Hubble Space Telescope (HST) view reveals Uranus surrounded by its 4 major rings and 10 of its 17 known satellites. This false color image was generated by Erich Karoschka using data taken with Hubble's Near Infrared Camera and Multi-Object Spectrometer. The HST recently found about 20 clouds. The colors in the image indicate altitude. The green and blue regions show where the atmosphere is clear and can be penetrated by sunlight. In yellow and grey regions, the sunlight reflects from a higher haze or cloud layer. The orange and red colors indicate very high clouds, such as cirrus clouds on Earth.

Upper limit set for level of lightning activity on Titan

NASA Technical Reports Server (NTRS)

Desch, M. D.; Kaiser, M. L.

1990-01-01

Because optically thick cloud and haze layers prevent lightning detection at optical wavelength on Titan, a search was conducted for lightning-radiated signals (spherics) at radio wavelengths using the planetary radioastronomy instrument aboard Voyager 1. Given the maximum ionosphere density of about 3000/cu cm, lightning spherics should be detectable above an observing frequency of 500 kHz. Since no evidence for spherics is found, an upper limit to the total energy per flash in Titan lightning of about 10 to the 6th J, or about 1000 times weaker than that of typical terrestrial lightning, is inferred.

Aerosol formation and distribution in the Arctic during AGASP-II, March-April 1986

NASA Technical Reports Server (NTRS)

Schnell, Russell C.; Kahl, Jonathan D.; Herbert, Gary A.; Bodhaine, B. A.; Bridgman, Howard A.

1988-01-01

The Arctic Gas and Aerosol Sampling Program has undertaken the determination of the distribution, transport, chemistry, aerosol physics, and radiative effects of the 'Arctic haze' air-pollution phenomenon. Attention has been given the April 2-3, 1986 haze zone, with large condensation nuclei, SO2, and soot-carbon concentrations, which appeared near the Barrow Baseline Station. The composite trajectory of the haze zone has been determined, as has its probable source region. After travelling 10,000 km, the haze still had SO2, aerosol black carbon, and condensation nuclei concentrations in excess of those measured off the East Coast of the U.S. in January of the same year.

Research on multi-source image fusion technology in haze environment

NASA Astrophysics Data System (ADS)

Ma, GuoDong; Piao, Yan; Li, Bing

2017-11-01

In the haze environment, the visible image collected by a single sensor can express the details of the shape, color and texture of the target very well, but because of the haze, the sharpness is low and some of the target subjects are lost; Because of the expression of thermal radiation and strong penetration ability, infrared image collected by a single sensor can clearly express the target subject, but it will lose detail information. Therefore, the multi-source image fusion method is proposed to exploit their respective advantages. Firstly, the improved Dark Channel Prior algorithm is used to preprocess the visible haze image. Secondly, the improved SURF algorithm is used to register the infrared image and the haze-free visible image. Finally, the weighted fusion algorithm based on information complementary is used to fuse the image. Experiments show that the proposed method can improve the clarity of the visible target and highlight the occluded infrared target for target recognition.

Comparison of different measurement methods for transmittance haze

NASA Astrophysics Data System (ADS)

Yu, Hsueh-Ling; Hsaio, Chin-Chai

2009-08-01

Transmittance haze is increasingly important to the LCD and solar cell industry. Most commercial haze measurement instruments are designed according to the method recommended in the documentary standards like ASTM D 1003 (ASTM 2003 Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics), JIS K 7361 (JIS 1997 Plastics—Determination of the Total Luminous Transmittance of Transparent Materials—Part 1: Single Beam Instrument) and ISO 14782 (ISO 1997 Plastics—Determination of Haze of Transparent Materials). To improve the measurement accuracy of the current standards, a new apparatus was designed by the Center for Measurement Standards (Yu et al 2006 Meas. Sci. Technol. 17 N29-36). Besides the methods mentioned above, a double-beam method is used in the design of some instruments. There are discrepancies between the various methods. But no matter which method is used, a white standard is always needed. This paper compares the measurement results from different methods, presents the effect of the white standard, and analyses the measurement uncertainty.

An evaluation of the signature extension approach to large area crop inventories utilizing space image data. [Kansas and North Dakota

NASA Technical Reports Server (NTRS)

Nalepka, R. F. (Principal Investigator); Cicone, R. C.; Stinson, J. L.; Balon, R. J.

1977-01-01

The author has identified the following significant results. Two examples of haze correction algorithms were tested: CROP-A and XSTAR. The CROP-A was tested in a unitemporal mode on data collected in 1973-74 over ten sample segments in Kansas. Because of the uniformly low level of haze present in these segments, no conclusion could be reached about CROP-A's ability to compensate for haze. It was noted, however, that in some cases CROP-A made serious errors which actually degraded classification performance. The haze correction algorithm XSTAR was tested in a multitemporal mode on 1975-76 LACIE sample segment data over 23 blind sites in Kansas and 18 sample segments in North Dakota, providing wide range of haze levels and other conditions for algorithm evaluation. It was found that this algorithm substantially improved signature extension classification accuracy when a sum-of-likelihoods classifier was used with an alien rejection threshold.

Hygroscopic analysis of individual Beijing haze aerosol particles by environmental scanning electron microscopy

NASA Astrophysics Data System (ADS)

Bai, Zhangpeng; Ji, Yuan; Pi, Yiqun; Yang, Kaixiang; Wang, Li; Zhang, Yinqi; Zhai, Yadi; Yan, Zhengguang; Han, Xiaodong

2018-01-01

Investigating the hygroscopic behavior of haze aerosol particles is essential for understanding their physicochemical properties and their impacts on regional weather and visibility. An environmental scanning electron microscope equipped with a home-made transmission-scattering electron imaging setup and an energy dispersive spectrometer was used for in-situ observations of pure water-soluble (WS) salts and Beijing haze particles. This imaging setup showed obvious advantages for improving the resolution and acquiring internal information of mixed particles in hydrated environments. We measured the deliquescence relative humidity of pure NaCl, NH4NO3, and (NH4)2SO4 by deliquescence-crystallization processes with an accuracy of up to 0.3% RH. The mixed haze particles showed hygroscopic activation like water uptake and morphological changes when they included WS components such as nitrates, sulfates, halides, ammoniums, and alkali metal salts. In addition, the hygroscopic behavior provides complementary information for analyzing possible phases in mixed haze particles.

Ice haze, snow, and the Mars water cycle

NASA Technical Reports Server (NTRS)

Kahn, Ralph

1990-01-01

Light curves and extinction profiles derived from Martian limb observations are used to constrain the atmospheric temperature structure in regions of the atmosphere with thin haze and to analyze the haze particle properties and atmospheric eddy mixing. Temperature between 170 and 190 K are obtained for three cases at levels in the atmosphere ranging from 20 to 50 km. Eddy diffusion coefficients around 100,000 sq cm/s, typical of a nonconvecting atmosphere, are derived in the haze regions at times when the atmosphere is relatively clear of dust. This parameter apparently changes by more than three orders of magnitude with season and local conditions. The derived particle size parameter varies systematically by more than an order of magnitude with condensation level, in such a way that the characteristic fall time is always about one Martian day. Ice hazes provide a mechanism for scavenging water vapor in the thin Mars atmosphere and may play a key role in the seasonal cycle of water on Mars.

Attribution of Anthropogenic Influence on Atmospheric Patterns Conducive to Recent Most Severe Haze Over Eastern China

NASA Astrophysics Data System (ADS)

Li, Ke; Liao, Hong; Cai, Wenju; Yang, Yang

2018-02-01

Severe haze pollution in eastern China has caused substantial health impacts and economic loss. Conducive atmospheric conditions are important to affect occurrence of severe haze events, and circulation changes induced by future global climate warming are projected to increase the frequency of such events. However, a potential contribution of an anthropogenic influence to recent most severe haze (December 2015 and January 2013) over eastern China remains unclear. Here we show that the anthropogenic influence, which is estimated by using large ensemble runs with a climate model forced with and without anthropogenic forcings, has already increased the probability of the atmospheric patterns conducive to severe haze by at least 45% in January 2013 and 27% in December 2015, respectively. We further confirm that simulated atmospheric circulation pattern changes induced by anthropogenic influence are driven mainly by increased greenhouse gas emissions. Our results suggest that more strict reductions in pollutant emissions are needed under future anthropogenic warming.

Attribution of Anthropogenic Influence on Atmospheric Patterns Conducive to Recent Most Severe Haze Over Eastern China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ke; Liao, Hong; Cai, Wenju

Severe haze pollution in eastern China has caused substantial health impacts and economic loss. Conducive atmospheric conditions are important to affect occurrence of severe haze events, and circulation changes induced by future global climate warming are projected to increase the frequency of such events. However, a potential contribution of an anthropogenic influence to recent most severe haze (December 2015 and January 2013) over eastern China remains unclear. Here we show that the anthropogenic influence, which is estimated by using large ensemble runs with a climate model forced with and without anthropogenic forcings, has already increased the probability of the atmosphericmore » patterns conducive to severe haze by at least 45% in January 2013 and 27% in December 2015, respectively. We further confirm that simulated atmospheric circulation pattern changes induced by anthropogenic influence are driven mainly by increased greenhouse gas emissions. Our results suggest that more strict reductions in pollutant emissions are needed under future anthropogenic warming.« less

Boot of Italy taken during Expedition Six

NASA Image and Video Library

2003-02-25

ISS006-E-33736 (25 February 2003) --- The boot of Italy crosses the image in this southwest-looking view taken by an Expedition Six crewmember onboard the International Space Station (ISS). The spine of Italy is highlighted with snow and the largely cloud-covered Mediterranean Sea is at the top. The Adriatic Sea transverses most of the bottom of the image and Sicily appears top left beyond the toe of the boot. The heel lies out of the left side of the image. Corsica and Sardinia appear right of center partly under cloud. The floor of the Po River valley, lower right, is obscured by haze. Experience gained from similar haze events, in which atmospheric pressure, humidity and visibility and atmospheric chemistry were known, suggests that the haze as industrial smog. Industrial haze from the urban region of the central and upper Po valley accumulates to visible concentrations under conditions of high atmospheric pressure and the surrounding mountains prevent easy dispersal. This view illustrates the markedly different color and texture of cloud versus industrial aerosol haze.

Particle size distributions and gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in ambient air during haze days and normal days.

PubMed

Zhang, Xian; Zheng, Minghui; Liang, Yong; Liu, Guorui; Zhu, Qingqing; Gao, Lirong; Liu, Wenbin; Xiao, Ke; Sun, Xu

2016-12-15

Little information is available on the distributions of airborne polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during haze days. In this study, PCDD/F concentrations, particle size distributions, and gas-particle partitioning in a Beijing suburban area during haze days and normal days were investigated. High PCDD/F concentrations, 3979-74,702fgm -3 (173-3885fgI-TEQm -3 ), were found during haze days and ~98% of the PCDD/Fs were associated with particles. Most PCDD/F congeners (>90%) were associated with particles. PCDD/F concentrations increased as particle sizes decreased and 95% of the particle-bound PCDD/Fs were associated with inhalable fine particles with aerodynamic diameters<2.5μm. PCDD/Fs were mainly absorbed in the particles and the Harner-Bidleman model predicted the particulate fractions of the PCDD/F congeners in the air samples well. The investigated PCDD/F concentrations and particle-bound distributions were different during normal days than during haze days. Temporal airborne PCDD/F trends in a suburban area during haze conditions could support better understanding of the exposure risk posed by toxic PCDD/Fs associated with fine particles. Copyright © 2016 Elsevier B.V. All rights reserved.

The Characteristics of Atmospheric Phthalates in Shanghai: a Haze Case Study

NASA Astrophysics Data System (ADS)

Li, Y.; Wang, J.; Ren, B.; Wang, H.; Qiao, L.; Zhu, J.; Li, L.

2017-12-01

While phthalates in indoor environments are extensively studied, reports on phthalates in outdoor air, particularly their associations with haze events are rare. Phthalates, especially dimethyl phthalate, are known to react with criteria air pollutants contributing to the formation of secondary organic aerosols. This study investigated phthalates levels in outdoor air in Shanghai with a focus on their associations with different air quality conditions. The air quality during the study period was classified into three levels: non-haze, light pollution and moderate pollution based on the Air Quality Index. Phthalates levels were found to be lower in non haze (236 ng/m3) and higher in moderate pollution weather (up to 700 ng/m3). Meteorological factors of relative humidity and wind speed had an inverse relationship with phthalates levels. Airborne particulate matter had a positive correlation with phthalates levels. Hydroxyl radical initiated photo-reaction of dimethyl phthalate was observed through its inverse relationship with total atmospheric oxidant (O3 + NO2), indicating that dimethyl phthalate could be one of the precursors of secondary organic aerosol causing haze. This is the first study demonstrating the relationship of phthalates and different air quality conditions. The knowledge contributes to our understanding on the cause of haze events in China and elsewhere.

Characterization of Black and Brown Carbon Concentrations and Sources during winter in Beijing

NASA Astrophysics Data System (ADS)

Yan, Caiqing; Liu, Yue; Hansen, Anthony D. A.; Močnik, Griša; Zheng, Mei

2017-04-01

Carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), play important roles in air quality, human health, and climate change. A better understanding of sources of light-absorbing carbonaceous aerosol (including black carbon and brown carbon) is particular critical for formulating emission-based control strategies and reducing uncertainties in current aerosol radiative forcing estimates. Beijing, the capital of China, has experienced serious air pollution problems and high concentrations of carbonaceous aerosols in recent years, especially during heating seasons. During November and December of 2016, several severe haze episodes occurred in Beijing, with hourly average PM2.5 mass concentration up to 400 μg/m3. In this study, concentration levels and sources of black carbon and brown carbon were investigated based on 7-wavelength Aethalometer (AE-33) with combination of other PM2.5 chemical composition information. Contributions of traffic and non-traffic emissions (e.g., coal combustion, biomass burning) were apportioned, and brown carbon was separated from black carbon. Our preliminary results showed that (1) Concentrations of BC were around 5.3±4.2 μg/m3 during the study period, with distinct diurnal variations during haze and non-haze days. (2) Traffic emissions contributed to about 37±17% of total BC, and exhibited higher contributions during non-haze days compared to haze days. (3) Coal combustion was a major source of black carbon and brown carbon in Beijing, which was more significant compared to biomass burning. Sources and the relative contributions to black carbon and brown carbon during haze and non-haze days will be further discussed.

Classification and its scale analysis of Severe Haze recently observed in Korea

NASA Astrophysics Data System (ADS)

Lee, K. M.; Eun, S. H.; Kim, B. G.; Kim, S. W.; Park, J. S.

2015-12-01

Cloud-aerosol-precipitation interactions mechanism is heavily dependent upon scale problems, and thus the first thing to understand its mechanism is to quantify the time (or spatial) scale of forcing driver, aerosols. This study is focused on recently occurring dense haze episodes accompanied with severe visibility impairment from 2011 to 2013 at two adjacent monitoring stations (Baengnyeongdo and Seoul) in Korea. Baengnyeongdo is an island being located 200 km west from Seoul. First of all, we have tested various flow charts to classify the various categories of heavy haze events by making use of aerosol scattering coefficient, PM2.5, and time lag difference of PM2.5 increase time at both stations, backward trajectories, and the ratio of PM2.5 to PM10 specifically in the quantitative perspective. One of them is selected for this study. Long range transported haze (LH) and Yellow Sand (YS) show very distinctive time lags of both PM2.5 and PM10 between both stations, but much higher ratio of PM2.5 to PM10 for LH in comparison with YS. Meanwhile urban haze (UH) has a significant increase in PM2.5 only at Seoul as easily expected. Time scales (e-folding time) of aerosol light scattering coefficients for LH and UH are 6-12 hrs and 7-16 hrs, respectively calculated for several episodes according to the criteria developed, which eventually corresponds to spatial scale of 120 - 240 km, 140 - 320 km, respectively by assuming average boundary wind speed, 5.6 m/s (Anderson et al., 2003). In general, long-range transported hazes have larger temporal and spatial dimension (about meso-a scale) than domestic hazes, after carefully designed classification of haze episodes. These results can be an useful basis for the estimation of regional aerosol radiative forcings in East Asia.

Role of secondary aerosols in haze formation in summer in the Megacity Beijing.

PubMed

Han, Tingting; Liu, Xingang; Zhang, Yuanhang; Qu, Yu; Zeng, Limin; Hu, Min; Zhu, Tong

2015-05-01

A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility

The Lithium Vapor Box Divertor

NASA Astrophysics Data System (ADS)

Goldston, Robert; Hakim, Ammar; Hammett, Gregory; Jaworski, Michael; Myers, Rachel; Schwartz, Jacob

2015-11-01

Projections of scrape-off layer width to a demonstration power plant suggest an immense parallel heat flux, of order 12 GW/m2, which will necessitate nearly fully detached operation. Building on earlier work by Nagayama et al. and by Ono et al., we propose to use a series of differentially pumped boxes filled with lithium vapor to isolate the buffering vapor from the main plasma chamber, allowing stable detachment. This powerful differential pumping is only available for condensable vapors, not conventional gases. We demonstrate the properties of such a system through conservation laws for vapor mass and enthalpy, and then include plasma entrainment and ultimately an estimate of radiated power. We find that full detachment should be achievable with little leakage of lithium to the main plasma chamber. We also present progress towards solving the Navier-Stokes equation numerically for the chain of vapor boxes, including self-consistent wall boundary conditions and fully-developed shocks, as well as concepts for an initial experimental demonstration-of-concept. This work supported by DOE Contract No. DE-AC02-09CH11466.

Edaravone, an ROS Scavenger, Ameliorates Photoreceptor Cell Death after Experimental Retinal Detachment

PubMed Central

Roh, Mi In; Murakami, Yusuke; Thanos, Aristomenis; Miller, Joan W.

2011-01-01

Purpose. To investigate whether edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, would be neuroprotective against photoreceptor cell death in a rat model of retinal detachment (RD). Methods. RD was induced in adult Brown Norway rats by subretinal injection of sodium hyaluronate. Edaravone (3, 5, or 10 mg/kg) or physiologic saline was administered intraperitoneally once a day until death on day 3 or 5. Oxidative stress in the retina was assessed by 4-hydroxynonenal staining or ELISA for protein carbonyl content. Photoreceptor death was assessed by TUNEL and measurement of the outer nuclear layer thickness. Western blot analysis and caspase activity assays were performed. Inflammatory cytokine secretion and inflammatory cell infiltration were evaluated by ELISA and immunostaining, respectively. Results. RD resulted in increased generation of ROS. Treatment with 5 mg/kg edaravone significantly reduced the ROS level, along with a decrease in TUNEL-positive cells in the photoreceptor layer. A caspase assay also confirmed decreased activation of caspase-3, -8, and -9 in RD treated with edaravone. The level of the antiapoptotic Bcl-2 was increased in detached retinas after edaravone treatment, whereas the levels of the stress-activated p-ERK1/2 were decreased. In addition, edaravone treatment resulted in a significant decrease in the levels of TNF-α, MCP-1, and macrophage infiltration. Conclusions. Oxidative stress plays an important role in photoreceptor cell death after RD. Edaravone treatment may aid in preventing photoreceptor cell death after RD by suppressing ROS-induced photoreceptor damage. PMID:21310909

The role of detachment and interlayer shear zones in the structural evolution of the southern Espinhaço range, eastern Brazil

NASA Astrophysics Data System (ADS)

Kuchenbecker, Matheus; Sanglard, Júlio Carlos Destro

2018-07-01

Sedimentary rocks usually show a significant mechanical anisotropy due to its layered nature. Because of this, they play an important role controlling rock deformation and the study of the deformation partitioning caused by rheological heterogeneities becomes a crucial step to understand the inversion of sedimentary basins. The detachment and interlayer shear zones, described at southern Espinhaço range, correspond to part of the structural collection that records the compressive deformation which is associated to the Brazilian-Pan African orogeny during Gondwana amalgamation. The mechanical contrast between lithological units is the main parameter of control for the occurrence of these zones which can be found with variable thickness from millimeter interlayer shear zones to regional-sized basement-cover detachment zones. The phyllitic layers are the most incompetent lithotype among metasedimentary rocks and they play an important role in the ductile-brittle regional deformation by accommodating much of the deformation during faulting and/or folding. Even though being a more competent rock, internal interlayer shear zones and other shear structures can be found in quartzite when in contact with weaker rocks. These structures accommodate a significant amount of deformation at the southern Espinhaço range and, because of this, they are of great value in understanding the inversion of the Espinhaço basins during West Gondwana assembly. The focus of the present paper is to discuss the main situations where interlayer shear occurs, to present a brief compendium of the main structures associated to this process and to add parameters to its recognition and interpretation.

Three dimensional Visualization of Jupiter's Equatorial Region

NASA Technical Reports Server (NTRS)

1997-01-01

Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

This frame is a view to the northeast, from between the cloud layers and above the streaks in the lower cloud leading towards the hotspot. The upper haze layer has some features that match the lower cloud, such as the bright streak in the foreground of the frame. These are probably thick clouds that span several tens of vertical kilometers.

Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on more sophisticated studies of Jupiter's cloud structure. The upper and lower clouds are separated in the rendering by an arbitrary amount, and the height variations are exaggerated by a factor of 25.

The lower cloud is colored using the same false color scheme used in previously released image products, assigning red, green, and blue to the 756, 727, and 889 nanometer mosaics, respectively. Light bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the lower cloud with an overlying thin haze.

The images used cover latitudes 1 to 10 degrees and are centered at longitude 336 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers (about 930,000 miles) by the Solid State Imaging (CCD) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Three dimensional Visualization of Jupiter's Equatorial Region

NASA Technical Reports Server (NTRS)

1997-01-01

Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.

This frame is a view to the northeast, from between the cloud layers and above the streaks in the lower cloud leading towards the hotspot. The hotspot is clearly visible as a deep blue feature. The cloud streaks end near the hotspot, consistent with the idea that clouds traveling along these streak lines descend and evaporate as they approach the hotspot. The upper haze layer is slightly bowed upwards above the hotspot.

Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.

The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on more sophisticated studies of Jupiter's cloud structure. The upper and lower clouds are separated in the rendering by an arbitrary amount, and the height variations are exaggerated by a factor of 25.

The lower cloud is colored using the same false color scheme used in previously released image products, assigning red, green, and blue to the 756, 727, and 889 nanometer mosaics, respectively. Light bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. The dark blue hotspot in the center is a hole in the lower cloud with an overlying thin haze.

The images used cover latitudes 1 to 10 degrees and are centered at longitude 336 degrees west. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers (about 930,000 miles) by the Solid State Imaging (CCD) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

An Infrared View of Saturn

NASA Technical Reports Server (NTRS)

1998-01-01

In honor of NASA Hubble Space Telescope's eighth anniversary, we have gift wrapped Saturn in vivid colors. Actually, this image is courtesy of the new Near Infrared Camera and Multi-Object Spectrometer (NICMOS), which has taken its first peek at Saturn. The false-color image - taken Jan. 4, 1998 - shows the planet's reflected infrared light. This view provides detailed information on the clouds and hazes in Saturn's atmosphere.

The blue colors indicate a clear atmosphere down to a main cloud layer. Different shadings of blue indicate variations in the cloud particles, in size or chemical composition. The cloud particles are believed to be ammonia ice crystals. Most of the northern hemisphere that is visible above the rings is relatively clear. The dark region around the south pole at the bottom indicates a big hole in the main cloud layer.

The green and yellow colors indicate a haze above the main cloud layer. The haze is thin where the colors are green but thick where they are yellow. Most of the southern hemisphere (the lower part of Saturn) is quite hazy. These layers are aligned with latitude lines, due to Saturn's east-west winds.

The red and orange colors indicate clouds reaching up high into the atmosphere. Red clouds are even higher than orange clouds. The densest regions of two storms near Saturn's equator appear white. On Earth, the storms with the highest clouds are also found in tropical latitudes. The smaller storm on the left is about as large as the Earth, and larger storms have been recorded on Saturn in 1990 and 1994.

The rings, made up of chunks of ice, are as white as images of ice taken in visible light. However, in the infrared, water absorption causes various colorations. The most obvious is the brown color of the innermost ring. The rings cast their shadow onto Saturn. The bright line seen within this shadow is sunlight shining through the Cassini Division, the separation between the two bright rings. It is best observed on the left side, just above the rings. This view is possible due to a rare geometry during the observation. The next time this observable from Earth will be in 2006. An accurate investigation of the ring's shadow also shows sunlight shining through the Encke Gap, a thin division very close to the outer edge of the ring system.

Two of Saturn's satellites were recorded, Dione on the lower left and Tethys on the upper right. Tethys is just ending its transit across the disk of Saturn. They appear in different colors, yellow and green, indicating different conditions on their icy surfaces.

Wavelengths: A color image consists of three exposures (or three film layers). For visible true-color images, the wavelengths of these three exposures are 0.4, 0.5, and 0.6 micrometers for blue, green, and red light, respectively. This Saturn image was taken at longer infrared wavelengths of 1.0, 1.8, and 2.1 micrometers, displayed as blue, green, and red. Reflected sunlight is seen at all these wavelengths, since Saturn's own heat glows only at wavelengths above 4 micrometers.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Detachment of Chain-Forming Neuroblasts by Fyn-Mediated Control of cell-cell Adhesion in the Postnatal Brain.

PubMed

Fujikake, Kazuma; Sawada, Masato; Hikita, Takao; Seto, Yayoi; Kaneko, Naoko; Herranz-Pérez, Vicente; Dohi, Natsuki; Homma, Natsumi; Osaga, Satoshi; Yanagawa, Yuchio; Akaike, Toshihiro; García-Verdugo, Jose Manuel; Hattori, Mitsuharu; Sobue, Kazuya; Sawamoto, Kazunobu

2018-05-09

In the rodent olfactory system, neuroblasts produced in the ventricular-subventricular zone of the postnatal brain migrate tangentially in chain-like cell aggregates toward the olfactory bulb (OB) through the rostral migratory stream (RMS). After reaching the OB, the chains are dissociated and the neuroblasts migrate individually and radially toward their final destination. The cellular and molecular mechanisms controlling cell-cell adhesion during this detachment remain unclear. Here we report that Fyn, a nonreceptor tyrosine kinase, regulates the detachment of neuroblasts from chains in the male and female mouse OB. By performing chemical screening and in vivo loss-of-function and gain-of-function experiments, we found that Fyn promotes somal disengagement from the chains and is involved in neuronal migration from the RMS into the granule cell layer of the OB. Fyn knockdown or Dab1 (disabled-1) deficiency caused p120-catenin to accumulate and adherens junction-like structures to be sustained at the contact sites between neuroblasts. Moreover, a Fyn and N-cadherin double-knockdown experiment indicated that Fyn regulates the N-cadherin-mediated cell adhesion between neuroblasts. These results suggest that the Fyn-mediated control of cell-cell adhesion is critical for the detachment of chain-forming neuroblasts in the postnatal OB. SIGNIFICANCE STATEMENT In the postnatal brain, newly born neurons (neuroblasts) migrate in chain-like cell aggregates toward their destination, where they are dissociated into individual cells and mature. The cellular and molecular mechanisms controlling the detachment of neuroblasts from chains are not understood. Here we show that Fyn, a nonreceptor tyrosine kinase, promotes the somal detachment of neuroblasts from chains, and that this regulation is critical for the efficient migration of neuroblasts to their destination. We further show that Fyn and Dab1 (disabled-1) decrease the cell-cell adhesion between chain-forming neuroblasts, which involves adherens junction-like structures. Our results suggest that Fyn-mediated regulation of the cell-cell adhesion of neuroblasts is critical for their detachment from chains in the postnatal brain. Copyright © 2018 the authors 0270-6474/18/384599-12$15.00/0.

Fundus autofluorescence findings in a mouse model of retinal detachment.

PubMed

Secondi, Roberta; Kong, Jian; Blonska, Anna M; Staurenghi, Giovanni; Sparrow, Janet R

2012-08-07

Fundus autofluorescence (fundus AF) changes were monitored in a mouse model of retinal detachment (RD). RD was induced by transscleral injection of hyaluronic acid (Healon) or sterile balanced salt solution (BSS) into the subretinal space of 4-5-day-old albino Abca4 null mutant and Abca4 wild-type mice. Images acquired by confocal scanning laser ophthalmoscopy (Spectralis HRA) were correlated with spectral domain optical coherence tomography (SD-OCT), infrared reflectance (IR), fluorescence spectroscopy, and histologic analysis. Results. In the area of detached retina, multiple hyperreflective spots in IR images corresponded to punctate areas of intense autofluorescence visible in fundus AF mode. The puncta exhibited changes in fluorescence intensity with time. SD-OCT disclosed undulations of the neural retina and hyperreflectivity of the photoreceptor layer that likely corresponded to histologically visible photoreceptor cell rosettes. Fluorescence emission spectra generated using flat-mounted retina, and 488 and 561 nm excitation, were similar to that of RPE lipofuscin. With increased excitation wavelength, the emission maximum shifted towards longer wavelengths, a characteristic typical of fundus autofluorescence. In detached retinas, hyper-autofluorescent spots appeared to originate from photoreceptor outer segments that were arranged within retinal folds and rosettes. Consistent with this interpretation is the finding that the autofluorescence was spectroscopically similar to the bisretinoids that constitute RPE lipofuscin. Under the conditions of a RD, abnormal autofluorescence may arise from excessive production of bisretinoid by impaired photoreceptor cells.

Hazing in the U.S. Armed Forces: Recommendations for Hazing Prevention Policy and Practice

DTIC Science & Technology

2015-01-01

playing abusive tricks; threatening or oering violence or bodily harm to another; striking; branding; tattooing; shav- ing; greasing; painting...or bodily harm to another; striking; branding; tattooing; shav- ing; greasing; painting; “pinning,” “tacking on,” “blood wings”; or forcing or...particular issue for hazing denitions that address psychological, mental, or emotional harm. Specically, as one of the most thorough previous reviews of

Solar Irradiance Changes and Phytoplankton Productivity in Earth's Ocean Following Astrophysical Ionizing Radiation Events

NASA Astrophysics Data System (ADS)

Neale, Patrick J.; Thomas, Brian C.

2016-04-01

Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer (>600 nm) wavelengths of photosynthetically available radiation (PAR, 400-700 nm). On the other hand, the NO2 haze decreases atmospheric transmission in the long-wavelength UVA (315-400 nm) and short-wavelength PAR. Here, we use the results of previous simulations of incident spectral irradiance following an ionizing radiation event to predict changes in terran productivity focusing on photosynthesis of marine phytoplankton. The prediction is based on a spectral model of photosynthetic response, which was developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and on remote-sensing-based observations of spectral water transparency, temperature, wind speed, and mixed layer depth. Predicted productivity declined after a simulated ionizing event, but the effect integrated over the water column was small. For integrations taking into account the full depth range of PAR transmission (down to 0.1% of utilizable PAR), the decrease was at most 2-3% (depending on strain), with larger effects (5-7%) for integrations just to the depth of the surface mixed layer. The deeper integrations were most affected by the decreased utilizable PAR at depth due to the NO2 haze, whereas shallower integrations were most affected by the increased surface UV. Several factors tended to dampen the magnitude of productivity responses relative to increases in surface-damaging radiation, for example, most inhibition in the modeled strains is caused by UVA and PAR, and the greatest relative increase in damaging exposure is predicted to occur in the winter when UV and productivity are low.

Pluto's Atmosphere, Then and Now

NASA Astrophysics Data System (ADS)

Elliot, J. L.; Buie, M.; Person, M. J.; Qu, S.

2002-09-01

The KAO light curve for the 1988 stellar occultation by Pluto exhibits a sharp drop just below half light, but above this level the light curve is consistent with that of an isothermal atmosphere (T = 105 +/- 8 K, with N2 as its major constituent). The sharp drop in the light curve has been interpreted as being caused by: (i) a haze layer, (ii) a large thermal gradient, or (iii) some combination of these two. Modeling Pluto's atmosphere with a haze layer yields a normal optical depth >= 0.145 (Elliot & Young 1992, AJ 103, 991). On the other hand, if Pluto's atmosphere is assumed to be clear, the occultation light curve can be inverted with a new method that avoids the large-body approximations. Inversion of the KAO light curve with this method yields an upper isothermal part, followed by a sharp thermal gradient that reaches a maximum magnitude of -3.9 +/- 0.6 K km-1 at the end of the inversion (r = 1206 +/- 10 km). Even though we do not yet understand the cause of the sharp drop, the KAO light curve can be used as a benchmark for examining subsequent Pluto occultation light curves to determine whether Pluto's atmospheric structure has changed since 1988. As an example, the Mamiña light curve for the 2002 July 20 Pluto occultation of P126A was compared with the KAO light curve by Buie et al. (this conference), who concluded that Pluto's atmospheric structure has changed significantly since 1988. Further analysis and additional light curves from this and subsequent occultations (e.g. 2002 August 21) will allow us to elucidate the nature of these changes. This work was supported, in part, by grants from NASA (NAG5-9008 and NAG5-10444) and NSF (AST-0073447).

Air quality in Malaysia: impacts, management issues and future challenges.

PubMed

Awang, M B; Jaafar, A B; Abdullah, A M; Ismail, M B; Hassan, M N; Abdullah, R; Johan, S; Noor, H

2000-06-01

Observations have been made on the long-term trends of major air pollutants in Malaysia including nitrogen dioxide, carbon monoxide, the ozone and total suspended particulate matter (particularly PM10), and sulfur dioxide, emitted from industrial and urban areas from early 1970s until late 1998. The data show that the status of atmospheric environment in Malaysia, in particular in highly industrialized areas such as Klang Valley, was determined both by local and transboundary emissions and could be described as haze and non-haze periods. During the non-haze periods, vehicular emissions accounted for more than 70% of the total emissions in the urban areas and have demonstrated two peaks in the diurnal variations of the aforementioned air pollutants, except ozone. The morning 'rush-hour' peak was mainly due to vehicle emissions, while the late evening peak was mainly attributed to meteorological conditions, particularly atmospheric stability and wind speed. Total suspended particulate matter was the main pollutant with its concentrations at few sites often exceeding the Recommended Malaysia Air Quality Guidelines. The levels of other pollutants were generally within the guidelines. Since 1980, six major haze episodes were officially reported in Malaysia: April 1983, August 1990, June 1991, October 1991, August to October 1994, and July to October 1997. The 1997 haze episode was the worst ever experienced by the country. Short-term observations using continuous monitoring systems during the haze episodes during these periods clearly showed that suspended particulate matter (PM10) was the main cause of haze and was transboundary in nature. Large forest fires in parts of Sumatra and Kalimantan during the haze period, clearly evident in satellite images, were identified as the probable key sources of the widespread heavy haze that extended across Southeast Asia from Indonesia to Singapore, Malaysia and Brunei. The results of several studies have also provided strong evidence that biomass burning is the dominating source of particulate matter. The severity and extent of 1997's haze pollution was unprecedented, affecting some 300 million people across the region. The amount of economic costs suffered by Southeast Asian countries during this environmental disaster was enormous and is yet to be fully determined. Among the important sectors severely affected were air and land transport, shipping, construction, tourism and agro-based industries. The economic cost of the haze-related damage to Malaysia presented in this study include short-term health costs, production losses, tourism-related losses and the cost of avertive action. Although the cost reported here is likely to be underestimated, they are nevertheless significant (roughly RM1 billion). The general air quality of Malaysia since 1970 has deteriorated. Studies have shown that should no effective countermeasures be introduced, the emissions of sulfur dioxide, nitrogen oxides, particulate matter, hydrocarbons and carbon monoxide in the year 2005 would increase by 1.4, 2.12, 1.47 and 2.27 times, respectively, from the 1992 levels.

Chemical characterization and source identification of PM2.5 at multiple sites in the Beijing-Tianjin-Hebei region, China

NASA Astrophysics Data System (ADS)

Huang, Xiaojuan; Liu, Zirui; Liu, Jingyun; Hu, Bo; Wen, Tianxue; Tang, Guiqian; Zhang, Junke; Wu, Fangkun; Ji, Dongsheng; Wang, Lili; Wang, Yuesi

2017-11-01

The simultaneous observation and analysis of atmospheric fine particles (PM2.5) on a regional scale is an important approach to develop control strategies for haze pollution. In this study, samples of filtered PM2.5 were collected simultaneously at three urban sites (Beijing, Tianjin, and Shijiazhuang) and at a regional background site (Xinglong) in the Beijing-Tianjin-Hebei (BTH) region from June 2014 to April 2015. The PM2.5 at the four sites was mainly comprised of organic matter, secondary inorganic ions, and mineral dust. Positive matrix factorization (PMF) demonstrated that, on an annual basis, secondary inorganic aerosol was the largest PM2.5 source in this region, accounting for 29.2-40.5 % of the PM2.5 mass at the urban sites; the second-largest PM2.5 source was motor vehicle exhaust, particularly in Beijing (24.9 %), whereas coal combustion was also a large source in Tianjin (12.4 %) and Shijiazhuang (15.5 %), with particular dominance in winter. Secondary inorganic aerosol plays a vital role in the haze process, with the exception of the spring haze in Shijiazhuang and Tianjin, for which the dust source was crucial. In addition to secondary transformations, local direct emissions (coal combustion and motor vehicle exhaust) significantly contribute to the winter haze at the urban sites. Moreover, with the aggravation of haze pollution, the OC / EC mass ratio of PM2.5 decreased considerably and the nitrate-rich secondary aerosol increased during all four seasons in Beijing, both of which indicate that local motor vehicle emissions significantly contribute to the severe haze episodes in Beijing. To assess the impacts of regional transport on haze pollution, the PMF results were further processed with backward-trajectory cluster analysis, revealing that haze pollution usually occurred when air masses originating from polluted industrial regions in the south prevailed and is characterized by high PM2.5 loadings with considerable contributions from secondary aerosols. This study suggests that control strategies to mitigate haze pollution in the BTH region should focus on the reduction of gaseous precursor emissions from fossil fuel combustion (motor vehicle emissions in Beijing and coal combustion in Tianjin, Hebei, and nearby provinces).

On the multiday haze in the Asian continental outflow: the important role of synoptic conditions combined with regional and local sources

NASA Astrophysics Data System (ADS)

Seo, Jihoon; Kim, Jin Young; Youn, Daeok; Lee, Ji Yi; Kim, Hwajin; Lim, Yong Bin; Kim, Yumi; Cher Jin, Hyoun

2017-08-01

The air quality of the megacities in populated and industrialized regions like East Asia is affected by both local and regional emission sources. The combined effect of regional transport and local emissions on multiday haze was investigated through a synthetic analysis of PM2. 5 sampled at both an urban site in Seoul, South Korea and an upwind background site on Deokjeok Island over the Yellow Sea during a severe multiday haze episode in late February 2014. Inorganic components and carbonaceous species of daily PM2. 5 samples were measured, and gaseous pollutants, local meteorological factors, and synoptic meteorological conditions were also determined. A dominance of fine-mode particles (PM2. 5 / PM10 ˜ 0.8), a large secondary inorganic fraction (76 %), high OC / EC (> 7), and highly oxidized aerosols (oxygen-to-carbon ratio of ˜ 0.6 and organic-mass-to-carbon ratio of ˜ 1.9) under relatively warm, humid, and stagnant conditions characterize the multiday haze episode in Seoul; however, the early and late stages of the episode show different chemical compositions of PM2. 5. High concentrations of sulfate in both Seoul and the upwind background in the early stage suggest a significant regional influence on the onset of the multiday haze. At the same time, high concentrations of nitrate and organic compounds in Seoul, which are local and highly correlated with meteorological factors, suggest the contribution of local emissions and secondary formation under stagnant meteorological conditions to the haze. A slow eastward-moving high-pressure system from southern China to the East China Sea induces the regional transport of aerosols and potential gaseous precursors for secondary aerosols from the North China Plain in the early stage but provides stagnant conditions conducive to the accumulation and the local formation of aerosols in the late stage. A blocking ridge over Alaska that developed during the episode hinders the zonal propagation of synoptic-scale systems and extends the haze period to several days. This study provides chemical insights into haze development sequentially by regional transport and local sources, and shows that the synoptic condition plays an important role in the dynamical evolution of long-lasting haze in the Asian continental outflow region.

Aerosol radiative effect in UV, VIS, NIR, and SW spectra under haze and high-humidity urban conditions

NASA Astrophysics Data System (ADS)

Zhang, Ming; Ma, Yingying; Gong, Wei; Wang, Lunche; Xia, Xiangao; Che, Huizheng; Hu, Bo; Liu, Boming

2017-10-01

Aerosol properties derived from sun-photometric observations at Wuhan during a haze period were analyzed and used as input in a radiative transfer model to calculate the aerosol radiative effect (ARE) in ultraviolet (UV), visible (VIS), near-infrared (NIR), and shortwave (SW) spectra. The results showed that the aerosol optical depth (AOD) at 440 nm increased from 0.32 under clear-air conditions to 0.85 during common haze and 1.39 during severe haze. An unusual inverse relationship was found between the Ångström exponent (AE) and AOD during the haze period at Wuhan. Under high-humidity conditions, the fine-mode median radius of aerosols increased from 0.113 μm to approximately 0.2-0.5 μm as a result of hygroscopic growth, which led to increases in the AOD and decreases in the AE simultaneously. These changes were responsible for the inverse relationship between AE and AOD at Wuhan. The surface ARE in the UV (AREUV), VIS (AREVIS), NIR (ARENIR), and SW (ARESW) spectra changed from -4.46, -25.37, -12.15, and -41.99 W/m2 under clear-air conditions to -9.48, -53.96, -29.81, and -93.25 W/m2 during common hazy days and -12.89, -80.16, -55.17, and -148.22 W/m2 during severe hazy days, respectively, and the percentages of AREUV, AREVIS, and ARENIR in ARESW changed from 11%, 61%, and 28%-9%, 54%, and 37%, respectively. Meanwhile, the ARE efficiencies (REE) in SW varied from -206.5 W/m2 under clear-air conditions to -152.94 W/m2 during the common haze period and -131.47 W/m2 during the severe haze period. The smallest decreasing rate of the REE in NIR was associated with the increase of ARENIR. The weakened REE values were related to the strong forward scattering and weak backward scattering of fine aerosol particles with increasing size resulting from hygroscopic growth, while the variation of the single scattering albedo showed less impact. Source region analysis by back trajectories and the concentration weighted trajectory (CWT) method showed that black carbon came from nearby regions with low trajectories, and the surrounding haze areas were major sources of fine-mode particles in the haze in Wuhan.

Structure and composition of Pluto's atmosphere from the New Horizons solar ultraviolet occultation

NASA Astrophysics Data System (ADS)

Young, Leslie A.; Kammer, Joshua A.; Steffl, Andrew J.; Gladstone, G. Randall; Summers, Michael E.; Strobel, Darrell F.; Hinson, David P.; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine B.; Ennico, Kimberly; McComas, David J.; Cheng, Andrew F.; Gao, Peter; Lavvas, Panayotis; Linscott, Ivan R.; Wong, Michael L.; Yung, Yuk L.; Cunningham, Nathanial; Davis, Michael; Parker, Joel Wm.; Schindhelm, Eric; Siegmund, Oswald H. W.; Stone, John; Retherford, Kurt; Versteeg, Maarten

2018-01-01

The Alice instrument on NASA's New Horizons spacecraft observed an ultraviolet solar occultation by Pluto's atmosphere on 2015 July 14. The transmission vs. altitude was sensitive to the presence of N2, CH4, C2H2, C2H4, C2H6, and haze. We derived line-of-sight abundances and local number densities for the 5 molecular species, and line-of-sight optical depth and extinction coefficients for the haze. We found the following major conclusions: (1) We confirmed temperatures in Pluto's upper atmosphere that were colder than expected before the New Horizons flyby, with upper atmospheric temperatures near 65-68 K. The inferred enhanced Jeans escape rates were (3-7) × 1022 N2 s-1 and (4-8) × 1025 CH4 s-1 at the exobase (at a radius of ∼ 2900 km, or an altitude of ∼1710 km). (2) We measured CH4 abundances from 80 to 1200 km above the surface. A joint analysis of the Alice CH4 and Alice and REX N2 measurements implied a very stable lower atmosphere with a small eddy diffusion coefficient, most likely between 550 and 4000 cm2 s-1. Such a small eddy diffusion coefficient placed the homopause within 12 km of the surface, giving Pluto a small planetary boundary layer. The inferred CH4 surface mixing ratio was ∼ 0.28-0.35%. (3) The abundance profiles of the ;C2Hx hydrocarbons; (C2H2, C2H4, C2H6) were not simply exponential with altitude. We detected local maxima in line-of-sight abundance near 410 km altitude for C2H4, near 320 km for C2H2, and an inflection point or the suggestion of a local maximum at 260 km for C2H6. We also detected local minima near 200 km altitude for C2H4, near 170 km for C2H2, and an inflection point or minimum near 170-200 km for C2H6. These compared favorably with models for hydrocarbon production near 300-400 km and haze condensation near 200 km, especially for C2H2 and C2H4 (Wong et al., 2017). (4) We found haze that had an extinction coefficient approximately proportional to N2 density.

[Distribution of atmospheric ultrafine particles during haze weather in Hangzhou].

PubMed

Chen, Qiu-Fang; Sun, Zai; Xie, Xiao-Fang

2014-08-01

Atmospheric ultrafine particles (UFPs) were monitored with fast mobility particle sizer (FMPS) in continuous haze weather and the haze fading process during December 6 to 11, 2013 in Hangzhou. Particle concentration and size distribution were studied associated with meteorological factors. The results showed that number concentrations were the highest at night and began to reduce in the morning. There was a small peak at 8 o'clock in the morning and 18 o'clock in the afternoon. It showed an obvious peak traffic source, which indicated that traffic emissions played a great role in the atmospheric pollution. During haze weather, the highest number concentration of UFPs reached 8 x 10(4) cm(-3). Particle size spectrum distribution was bimodal, the peak particle sizes were 15 nm and 100 nm respectively. Majority of UFPs were Aitken mode and Accumulation mode and the size of most particles concentrated near 100 nm. Average CMD(count medium diameter) was 85.89 nm. During haze fading process, number concentration and particles with size around 100 nm began to reduce and peak size shifted to small size. Nuclear modal particles increased and were more than accumulation mode. Average CMD was 58.64 nm. Meteorological factors such as the visibility and wind were negatively correlated with the particle number concentration. Correlation coefficient R were -0.225 and - 0.229. The humidity was correlated with number concentration. Correlation coefficient R was 0.271. The atmosphere was stable in winter and the level temperature had small correlation with number concentration. Therefore, study on distribution of atmospheric ultrafine particles during haze weather had the significance on the formation mechanism and control of haze weather.

The indoor-outdoor characteristics of water-soluble ion in PM2.5 in Tianjin wintertime.

PubMed

Wang, Baoqing; Niu, Honghong; Liu, Bowei; Hu, Xinxin; Ren, Zihui

2018-05-15

The indoor and outdoor PM 2.5 mass concentration, water-soluble ion by filter sampler was analyzed on December 3-21, 2015 during wintertime in Tianjin, China. The results indicate that high humidity conditions result in the accumulation of atmospheric pollutants and reduce atmosphere visibility. The I/O ratio for PM 2.5 concentration in dormitory and lab are less than 1 in haze days. Indoor PM 2.5 concentration increases rapidly with outdoor PM 2.5 concentration increasing in haze days. The filtration factors of the dormitory and lab indicate nearly half of the outdoor PM 2.5 enters indoor environment. The human activities in dormitory could cause more the formation of PM 2.5 than those in lab. The concentration of SO 4 2- is the highest ion in water-soluble ion for outdoor PM 2.5 . The SO 4 2- , NO 3 - , NH 4 + , and Cl - are generated mainly by outdoor sources; however, the Na + , Ca 2+ , and Mg 2+ are generated mainly by indoor sources. The NH 4 NO 3 , (NH 4 ) 2 SO 4 , and NH 4 Cl accounts for 20.2~41.8%, 32.0~51.4%, and 6.4~10.6% of the total water-soluble ion in different indoor-outdoor environment. The total secondary aerosols including NH 4 NO 3 , (NH 4 ) 2 SO 4 , and NH 4 Cl in PM 2.5 are 28.3, 42.1, 28.2, 31.0, and 33.9% in outdoor environment for haze days, outdoor environment for non-haze days, dormitory for haze days, dormitory for non-haze days, and lab for haze days, respectively.

Severe haze episodes and seriously polluted fog water in Ji'nan, China.

PubMed

Wang, Xinfeng; Chen, Jianmin; Sun, Jianfeng; Li, Weijun; Yang, Lingxiao; Wen, Liang; Wang, Wenxing; Wang, Xinming; Collett, Jeffrey L; Shi, Yang; Zhang, Qingzhu; Hu, Jingtian; Yao, Lan; Zhu, Yanhong; Sui, Xiao; Sun, Xiaomin; Mellouki, Abdelwahid

2014-09-15

Haze episodes often hit urban cities in China recently. Here, we present several continuous haze episodes with extremely high PM2.5 levels that occurred over several weeks in early 2013 and extended across most parts of the northern and eastern China-far exceeding the Beijing-Tianjin-Hebei region. Particularly, the haze episode covered ~1 million km(2) on January 14, 2013 and the daily averaged PM2.5 concentration exceeded 360 μg m(-3) in Ji'nan. The observed maximum hourly PM2.5 concentration in urban Ji'nan reached 701 μg m(-3) at 7:00 am (local time) in January 30. During these haze episodes, several fog events happened and the concurrent fog water was found to be seriously polluted. For the fog water collected in Ji'nan from 10:00 pm in January 14 to 11:00 am in January 15, sulfate, nitrate, and ammonium were the major ions with concentrations of 1.54 × 10(6), 8.98 × 10(5), and 1.75 × 10(6) μeq L(-1), respectively, leading to a low in-situ pH of 3.30. The sulfate content in the fog sample was more than 544 times as high as those observed in other areas. With examination of the simultaneously observed data on PM2.5 and its chemical composition, the fog played a role in scavenging and removing fine particles from the atmosphere during haze episodes and thus was seriously contaminated. However, the effect was not sufficient to obviously cleanse air pollution and block haze episodes. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of rainwater chemical composition after a Southeast Asia haze event: insight of transboundary pollutant transport during the northeast monsoon.

PubMed

Nadzir, Mohd Shahrul Mohd; Lin, Chin Yik; Khan, Md Firoz; Latif, Mohd Talib; Dominick, Doreena; Hamid, Haris Hafizal Abdul; Mohamad, Noorlin; Maulud, Khairul Nizam Abdul; Wahab, Muhammad Ikram Abdul; Kamaludin, Nurul Farahana; Lazim, Mohamad Azwani Shah Mat

2017-06-01

Open biomass burning in Peninsula Malaysia, Sumatra, and parts of the Indochinese region is a major source of transboundary haze pollution in the Southeast Asia. To study the influence of haze on rainwater chemistry, a short-term investigation was carried out during the occurrence of a severe haze episode from March to April 2014. Rainwater samples were collected after a prolonged drought and analyzed for heavy metals and major ion concentrations using inductively coupled plasma mass spectroscopy (ICP-MS) and ion chromatography (IC), respectively. The chemical composition and morphology of the solid particulates suspended in rainwater were examined using a scanning electron microscope coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). The dataset was further interpreted using enrichment factors (EF), statistical analysis, and a back trajectory (BT) model to find the possible sources of the particulates and pollutants. The results show a drop in rainwater pH from near neutral (pH 6.54) to acidic (

77 FR 11937 - Approval and Promulgation of Air Quality Implementation Plans; State of Alabama; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-28

...EPA is proposing a limited approval of a revision to the Alabama state implementation plan (SIP) submitted by the State of Alabama through the Alabama Department of Environmental Management (ADEM), on July 15, 2008, that addresses regional haze for the first implementation period. This revision addresses the requirements of the Clean Air Act (CAA or Act) and EPA's rules that require states to prevent any future and remedy any existing anthropogenic impairment of visibility in mandatory Class I areas (national parks and wilderness areas) caused by emissions of air pollutants from numerous sources located over a wide geographic area (also referred to as the ``regional haze program''). States are required to assure reasonable progress towards the national goal of achieving natural visibility conditions in Class I areas. EPA is proposing a limited approval of this SIP revision to implement the regional haze requirements for Alabama on the basis that the revision, as a whole, strengthens the Alabama SIP. Additionally, EPA is proposing to rescind the federal regulations previously approved into the Alabama SIP on November 24, 1987, and to rely on the provisions in Alabama's July 15, 2008, SIP submittal to meet the long-term strategy (LTS) requirements for reasonably attributable visibility impairment (RAVI). EPA has previously proposed a limited disapproval of the Alabama regional haze SIP because of deficiencies in the State's regional haze SIP submittal arising from the remand by the U.S. Court of Appeals for the District of Columbia Circuit (DC Circuit) to EPA of the Clean Air Interstate Rule (CAIR). Consequently, EPA is not proposing to take action in this rulemaking to address the State's reliance on CAIR to meet certain regional haze requirements.

The Short-Term Effects of Visibility and Haze on Mortality in a Coastal City of China: A Time-Series Study

PubMed Central

Yang, Jun; Woodward, Alistair; Li, Mengmeng; He, Tianfeng; Wang, Aihong; Lu, Beibei; Liu, Xiaobo; Xu, Guozhang; Liu, Qiyong

2017-01-01

Few studies have been conducted to investigate the acute health effects of visibility and haze, which may be regarded as proxy indicators of ambient air pollution. We used a distributed lag non-linear model (DLNM) combined with quasi-Poisson regression to estimate the relationship between visibility, haze and mortality in Ningbo, a coastal city of China. We found that the mortality risk of visibility was statistically significant only on the current day, while the risk of haze and PM10 peaked on the second day and could last for three days. When the visibility was less than 10 km, each 1 km decrease of visibility at lag 0 day was associated with a 0.78% (95% CI: 0.22–1.36%) increase in total mortality and a 1.61% (95% CI: 0.39–2.85%) increase in respiratory mortality. The excess risk of haze at lag 0–2 days on total mortality, cardiovascular and respiratory mortality was 7.76% (95% CI: 3.29–12.42%), 7.73% (95% CI: 0.12–15.92%) and 17.77% (95% CI: 7.64–28.86%), respectively. Greater effects of air pollution were observed during the cold season than in the warm season, and the elderly were at higher risk compared to youths. The effects of visibility and haze were attenuated by single pollutants. These findings suggest that visibility and haze could be used as surrogates of air quality where pollutant data are scarce, and strengthen the evidence to develop policy to control air pollution and protect vulnerable populations. PMID:29156645

Secondary aerosol formation promotes water uptake by organic-rich wildfire haze particles in equatorial Asia

NASA Astrophysics Data System (ADS)

Chen, Jing; Hapsari Budisulistiorini, Sri; Miyakawa, Takuma; Komazaki, Yuichi; Kuwata, Mikinori

2018-06-01

The diameter growth factor (GF) of 100 nm haze particles at 85 % relative humidity (RH) and their chemical characteristics were simultaneously monitored at Singapore in October 2015 during a pervasive wildfire haze episode that was caused by peatland burning in Indonesia. Non-refractory submicron particles (NR-PM1) were dominated by organics (OA; approximating 77.1 % in total mass), whereas sulfate was the most abundant inorganic constituent (11.7 % on average). A statistical analysis of the organic mass spectra showed that most organics (36.0 % of NR-PM1 mass) were highly oxygenated. Diurnal variations of GF, number fractions of more hygroscopic mode particles, mass fractions of sulfate, and mass fractions of oxygenated organics (OOA) synchronized well, peaking during the day. The mean hygroscopicity parameter (κ) of the haze particles was 0.189 ± 0.087, and the mean κ values of organics were 0.157 ± 0.108 (κorg, bulk organics) and 0.266 ± 0.184 (κOOA, OOA), demonstrating the important roles of both sulfate and highly oxygenated organics in the hygroscopic growth of organics-dominated wildfire haze particles. κorg correlated with the water-soluble organic fraction insignificantly, but it positively correlated with f44 (fraction of the ion fragment at m/z 44 in total organics) (R = 0.70), implying the oxygenation degree of organics could be more critical for the water uptake of organic compounds. These results further suggest the importance of sulfate and secondary organic aerosol formation in promoting the hygroscopic growth of wildfire haze particles. Further detailed size-resolved as well as molecular-level chemical information about organics is necessary for the profound exploration of water uptake by wildfire haze particles in equatorial Asia.