Showing papers on "Haze published in 2010"

The Fermi Haze: A Gamma-Ray Counterpart to the Microwave Haze

Abstract: The Fermi Gamma-ray Space Telescope reveals a diffuse inverse Compton (IC) signal in the inner Galaxy with a similar spatial morphology to the microwave haze observed by WMAP, supporting the synchrotron interpretation of the microwave signal. Using spatial templates, we regress out π0 gammas, as well as IC and bremsstrahlung components associated with known soft-synchrotron counterparts. We find a significant gamma-ray excess toward the Galactic center with a spectrum that is significantly harder than other sky components and is most consistent with IC from a hard population of electrons. The morphology and spectrum are consistent with it being the IC counterpart to the electrons which generate the microwave haze seen at WMAP frequencies. In addition, the implied electron spectrum is hard; electrons accelerated in supernova shocks in the disk which then diffuse a few kpc to the haze region would have a softer spectrum. We describe the full-sky Fermi maps used in this analysis and make them available for download.

Haze types in Beijing and the influence of agricultural biomass burning

Abstract: . Emissions from agricultural biomass burning (ABB) in northern China have a significant impact on the regional and global climate. The monthly average aerosol optical depth (AOD) at 550 nm in northern China in 2007 had a maximum of 0.7 in June. The AOD measurements are consistent with regional brown hazes that occurred at that time, which was a period of severe aerosol pollution. Aerosol particles were collected in urban Beijing from 12 to 30 June 2007, during a period of high haze, and studied using transmission electron microscopy with energy-dispersive X-ray spectrometry. The dominant particle types collected in the fine fraction (diameter

Fractal Organic Hazes Provided an Ultraviolet Shield for Early Earth

Abstract: The Archean Earth (3.8 to 2.5 billion years ago) was probably enshrouded by a photochemical haze composed of fractal aggregate hydrocarbon aerosols. The fractal structure of the aerosols would have had a strong effect on the radiative properties of the haze. In this study, a fractal aggregate haze was found to be optically thick in the ultraviolet wavelengths while remaining relatively transparent in the mid-visible wavelengths. At an annual production rate of 10 14 grams per year and an average monomer radius of 50 nanometers, the haze would have provided a strong shield against ultraviolet light while causing only minimal antigreenhouse cooling.

Physics-based fast single image fog removal

Abstract: Imaging in poor weather is often severely degraded by scattering due to suspended particles in the atmosphere such as haze, fog and mist. Poor visibility becomes a major problem for most outdoor vision applications. In this paper, we propose a novel fast defogging method from a single image of a scene based on a fast bilateral filtering approach. The complexity of our method is only a linear function of the number of input image pixels and this thus allows a very fast implementation. Results on a variety of outdoor foggy images demonstrate that our method achieves good restoration for contrast and color fidelity, resulting in a large improvement in image visibility.

Strong air pollution causes widespread haze-clouds over China

Abstract: [1] North China (Huabei in Chinese) is a geographical region located between 32°N and 42°N latitude in eastern China, including several provinces and large municipalities (e.g., Beijing and Tianjin). In the past decades the region has experienced dramatic changes in air quality and climate. Among the multiple causes aerosol pollution is expected to play a particularly important role. To investigate this, a field measurement campaign was performed in April–May 2006 as part of the project Influence of Pollution on Aerosols and Cloud Microphysics in North China. Here we report the first aircraft measurements of atmospheric trace gases, aerosols, and clouds over this part of China, a region strongly affected by both natural desert dust and pollution smog. We observed very high concentrations of gaseous air pollutants and haze particles, partly together with nonprecipitating stratiform clouds. The clouds were characterized by numerous droplets, much smaller than in a less-polluted atmosphere. Our data reveal that the highly efficient coating of dust particles by pollution acids provides the predominant source of cloud condensation nuclei. The pollution-enhanced activation of dust particles into droplets is shown to be remarkably efficient so that clouds even form below 100% relative humidity. Contrary to previous analyses, we find that the haze particles influence the spectral shape of the cloud droplet size distribution such that the indirect climate cooling effect of aerosols on clouds is increased. The widespread haze, combined with low clouds, diminishes air quality and exerts an unusually strong cooling forcing on climate.

ZnO Films with Very High Haze Value for Use as Front Transparent Conductive Oxide Films in Thin-Film Silicon Solar Cells

Abstract: We successfully increased the haze value of zinc oxide (ZnO) films fabricated using metal–organic chemical vapor deposition (MOCVD) by conducting glass-substrate etching before film deposition. It was found that with increasing the glass treatment time, the surface morphology of ZnO films changed from conventional pyramid-like single texture to greater cauliflower-like multi texture. Further, the rms roughness and the haze value of the films increased remarkably. Using ZnO films with a high haze value as front transparent conductive oxide (TCO) films in hydrogenated microcrystalline silicon (µc-Si:H) solar cells, we improved the quantum efficiency of these cells particularly in the long-wavelength region.

Single image haze removal using dark channel priors

Abstract: Techniques and technologies for de-hazing hazy images are described. Some techniques provide for determining the effects of the haze and removing the same from an image to recover a de-hazed image. Thus, the de-hazed image does not contain the effects of the haze. Some disclosed technologies allow for similar results. This document also discloses systems and methods for de-hazing images. Some of the disclosed de-hazing systems include an image capture device for capturing the hazy image and a processor for removing the effects of the haze from the hazy image. These systems store the recovered, de-hazed images in a memory and/or display the de-hazed images on a display. Some of the disclosed methods include removing the effects of the haze from a hazy image and outputting the recovered, de-hazed image.

Turbidity and Haze Formation in Beer — Insights and Overview

Abstract: Beer is a complex mixture of over 450 constituents. In addition, it contains macromolecules such as proteins, nucleic acids, polysaccharides and lipids. Proteins influence the entire brewing process with regard to enzymes, which degrade starch, β-glucans and proteins; with protein-protein linkages that stabilize foam and are responsible for mouthfeel and flavour stability; and in combination with polyphenols, thought to form haze. With this complexity, problems in processability are as various as the constituents. Several substances in beer are responsible for haze formation. Organic components such as proteins, polyphenols and carbohydrates (α-glucans, β-glucans) are known to form haze. In addition, inorganic particles such as filter aids and label remains can cause increased turbidity. In this article only non-microbiological induced hazes are described. Many studies have been conducted on the identification of haze and foam active components in beer. Hence the aim of this work was to survey the different possibilities of haze formation and for haze identification. A summary is provided on methods for haze identification including dyeing methods, microscopic analyses and size exclusion chromatography.

Arctic organic aerosol measurements show particles from mixed combustion in spring haze and from frost flowers in winter

Abstract: 0.07 m gm �3 in summer to 0.43 m gm �3 in winter, and 0.35 m gm �3 in spring, showing a transition in OM composition between spring and winter. Most of the OM in spring could be attributed to anthropogenic sources, consisting primarily of alkane and carboxylic acid functional groups and correlated to elemental tracers of industrial pollution, biomass burning, and shipping emissions. PMF analysis associated OM with two factors, a Mixed Combustion factor (MCF) and an Ocean‐derived factor (ODF). Back trajectory analysis revealed that the highest fractions of the MCF were associated with air masses that had originated from northeastern Asia and the shipping lanes south of the Bering Straits. The ODF consisted of organic hydroxyl groups and correlated with organic and inorganic seawater components. The ODF accounted for more than 55% of OM in winter when the sampled air masses originated along the coastal and lake regions of the Northwest Territories of Canada. Frost flowers with organic‐salt coatings that arise by brine rejection during sea ice formation may account for this large source of carbohydrate‐like OM during the ice‐ covered winter season. While the anthropogenic sources contributed more than 0.3 m gm �3 of the springtime haze OM, ocean‐derived particles provided comparable OM sources in winter. Citation: Shaw, P. M., L. M. Russell, A. Jefferson, and P. K. Quinn (2010), Arctic organic aerosol measurements show particles from mixed combustion in spring haze and from frost flowers in winter, Geophys. Res. Lett., 37, L10803,

Temporal and spatial variation of haze during 1951-2005 in Chinese mainland

Abstract: Haze is an important indicator of air quality and,on the other hand,fog has definite meaning indicative of weather With the rapid expansion of economic scale and acceleration of urbanization,hazy weather is getting more and more serious in cities across Chinese mainlandLong-term trends and variation of haze have been obtained by studying meteorological data from 743 surface weather stations in Chinese mainland for the period between 1951 and 2005In terms of geographical distribution, hazy days were relatively few across the nation from 1956 to 1980 with the exception in the Sichuan Basin and the southern Xinjiang where haze exceeds 50 days per yearThe number of haze days increased dramatically since 1980s,and surpass 100 days over most of the eastern part of Chinese mainland and more than 150 days in metropolitan areas at the end of last century,indicating strong linkage between haze days and economic activitiesThe top 10 cities with the most haze days are as follows,Shenyang, Xingtai,Chongqing,Benxi,Xi'an,Chengdu,Suining,Laohekou,Hetian,Qiemo,Minfeng,and NeijiangMost of these cities are located in central Liaoning,the Sichuan Basin,the North China Plain,the Guanzhong Plain and the southern part of Xinjiang where is less affected by the sand stormOn the national scale,haze weather is more frequently observed in December and January than the other months,which account for 30%of the annual hazy daysSeptember is the month with the least number of haze days,only contributes 5%to the annual hazy daysThe weather stations that show an increasing trend of haze days are mainly located in the eastern and southern parts of the China,which are among the most developed zones in economy and industryThe weather stations in which a decreasing trend of haze days is observed are mainly located in the northeastern and northwestern China,due to the relatively laggard economy and industryThe northeastern China is one of the earlier regions to industrialize in China,but the achievements of recent years in industrial structure adjustment and environmental improvement have contributed to the gradual decreasing haze days in this region

A three-dimensional characterization of Arctic aerosols from airborne Sun photometer observations: PAM-ARCMIP, April 2009

Abstract: [1] The Arctic climate is modulated, in part, by atmospheric aerosols that affect the distribution of radiant energy passing through the atmosphere. Aerosols affect the surface-atmosphere radiation balance directly through interactions with solar and terrestrial radiation and indirectly through interactions with cloud particles. Better quantification of the radiative forcing by different types of aerosol is needed to improve predictions of future climate. During April 2009, the airborne campaign Pan-Arctic Measurements and Arctic Regional Climate Model Inter-comparison Project (PAM-ARCMIP) was conducted. The mission was organized by Alfred Wegener Institute for Polar and Marine Research of Germany and utilized their research aircraft, Polar-5. The goal was to obtain a snapshot of surface and atmospheric conditions over the central Arctic prior to the onset of the melt season. Characterizing aerosols was one objective of the campaign. Standard Sun photometric procedures were adopted to quantify aerosol optical depth AOD, providing a three-dimensional view of the aerosol, which was primarily haze from anthropogenic sources. Independent, in situ measurements of particle size distribution and light extinction, derived from airborne lidar, are used to corroborate inferences made using the AOD results. During April 2009, from the European to the Alaskan Arctic, from sub-Arctic latitudes to near the pole, the atmosphere was variably hazy with total column AOD at 500 nm ranging from ∼0.12 to >0.35, values that are anomalously high compared with previous years. The haze, transported primarily from Eurasian industrial regions, was concentrated within and just above the surface-based temperature inversion layer. Extinction, as measured using an onboard lidar system, was also greatest at low levels, where particles tended to be slightly larger than at upper levels. Black carbon (BC) (soot) was observed at all levels sampled, but at moderate to low concentrations compared with historical records. BC was highest near the North Pole, suggesting there had been an accumulation of soot within the Arctic vortex. Few, optically thick elevated aerosol layers were observed along the flight track, although independent lidar observations reveal evidence of the passage of volcanic plumes, which may have contributed to abnormally high values of AOD above 4 km. Enhanced opacity at higher altitudes during the campaign is attributed to an accumulation of industrial pollutants in the upper troposphere in combination with volcanic aerosol resulting from the March–April 2009 eruptions of Mount Redoubt in Alaska. The presence of Arctic haze during April 2009 is estimated to have reduced the net shortwave irradiance by ∼2–5 W m−2, resulting in a slight cooling of the surface.

Improved single image dehazing using dark channel prior

Abstract: Atmospheric conditions induced by suspended particles, such as fog and haze, severely degrade image quality. Haze removal from a single image of a weather-degraded scene remains a challenging task, because the haze is dependent on the unknown depth information. In this paper, we introduce an improved single image dehazing algorithm which based on the atmospheric scattering physics-based models. We apply the local dark channel prior on selected region to estimate the atmospheric light, and obtain more accurate result. Experiments on real images validate our approach.

Real-Time Dehazing for Image and Video

Abstract: Outdoor photography and computer vision tasks often suffer from bad weather conditions, observed objects lose visibility and contrast due to the presence of atmospheric haze, fog, and smoke. In this paper, we propose a new method for real-time image and video dehazing. Based on a newly presented haze-free image prior - dark channel prior and a common haze imaging model, for a single input image, we can estimate the global atmospheric light and extract the scene objects transmission. To prevent artifacts, we refine the transmission using a cross-bilateral filter, and finally the haze-free frame can be restored by inversing the haze imaging model. The whole process is highly parallelized, and can be easily implemented on modern GPUs to achieve real-time performance. Comparing with existing methods, our approach provides similar or better results with much less processing time. The proposed method can be further used for many applications such as outdoor surveillance, remote sensing, and intelligent vehicles. In addition, rough depth information of the scene can be obtained as a by-product.

On the roles of circulation and aerosols in the decline of mist and dense fog in Europe over the last 30 years

Abstract: . Fog and mist are meteorological phenomena that have significant contributions to temperature variations. Understanding and predicting them is also crucial for transportation risk management. It has been shown that low visibility phenomena over Europe have been declining over the past three decades. The trends in mist and haze have been correlated to atmospheric aerosol trends. However, dense fog has not received yet such focus. The goal of this paper is to examine the roles of synoptic atmospheric circulation and aerosol content on the trends of dense fog. We show that sulphur emission trends are spatially correlated with visibility trends, with a maximum correlation when visibility is between 1 km and 10 km. We find that atmospheric dynamics overall contributes up to 40% of the variability of the frequency of fog occurrences. This contribution is spatially variable and highly depends on the topography and the season, with higher values in the winter. The observed long-term circulation changes do not contribute much to the trends in low visibility found in the data. This process is illustrated on three stations (De Bilt, Zurich Airport and Potsdam) for which a long-term visibility data and a thorough meteorological description are available. We conclude that to properly represent fog in future climate simulations, it is necessary to include realistic representations of aerosol emissions and chemistry, land surface properties and atmospheric dynamics.

Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

Abstract: . As a part of the IGAC (International Global Atmospheric Chemistry) Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57° N, 126.94° E) in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC) ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (babs) from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, σabs (=babs/EC) at 550 nm was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m2 g−1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m2 g−1. Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA) with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP) events. Satellite aerosol optical thickness (AOT) and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

Standardization of Corneal Haze Measurement in Confocal Microscopy

Abstract: Eye care professionals have for years assessed the clarity of the cornea by visual inspection with a slit lamp and have used a hazy stroma, epithelium, or endothelium as an indicator of a dystrophic or poorly functioning cornea. This assessment is subjective, and several devices and methods have been described to measure the brightness of light scattered or reflected from the cornea. Photomultiplier and other light-sensing systems have been mounted in the appropriate image plane of slit lamps1,2 or custom scanning optical systems3,4 to measure light backscattered from the cornea, and although many of these devices measured light from the full-thickness of the cornea, some allowed investigators to distinguish haze in the anterior, middle, and posterior cornea.5 Current interest in factors that limit vision after penetrating, anterior, or posterior (endothelial) lamellar keratoplasty have generated a need to examine vision-limiting factors such as corneal haze after these procedures and to resolve the origin of haze in the corneal depth.6–13 The haze that can develop after refractive surgery and contact lens wear has also stimulated an interest in measurement of scattered light from the corneal stroma.3,4,14–16 At best, the spatial resolution of brightness when assessed with a slit lamp and other methods has been limited to approximately a third of the corneal thickness.3,5 Spatial resolution of the source of haze was greatly improved with the use of confocal microscopes to assess backscatter from the cornea.9,17–20 With the depth of field of 11 to 26 μm,21 investigators can identify the layer associated with pathologic scatter, measured as image brightness. Identifying the layer is particularly important when scatter is suspected to increase in surgical interfaces or in the subepithelial region after procedures such as refractive surgery and lamellar keratoplasty. Most investigators have expressed corneal haze in terms of the specific units of image intensity from the instrument used for measurement. However, image brightness from the cornea or any other tissue can be compared with brightness measured at a different time in longitudinal studies or across laboratories only if the instruments are standardized so that units that express haze are equivalent. Brightness expressed as a digitized video signal is useful only for relative measurements from the same camera and varies depending on the settings of the video camera. Measurements can be standardized in two ways. First, image intensity should be expressed in terms that are meaningful and can be compared across laboratories. Second, measurements of haze must be adjusted for differences or variations in the brightness of the light source and the sensitivity of the light detector—variables that can change over hours as well as months. The standardization should be based on backscatter measured with the same instrument from a substance that does not change from day to day, can be reproduced in any laboratory, and is readily available. In this article, we propose a method of standardizing image brightness for measurement of scattered and reflected light from the cornea in confocal microscopy. We describe the scatter characteristics from the cornea from two clinical confocal microscopes with different optical designs and characteristics, the ConfoScan 4 (Nidek Technologies, Fremont, CA) and the Tandem Scanning confocal microscope (Tandem Scanning Inc., Reston, VA). This standardization technique was used to measure corneal haze from normal untreated human corneas and from a group of corneas 3 years after laser in situ keratomileusis (LASIK), to demonstrate subtle differences in haze in specific layers of the corneal stroma.

Impact of biomass burning on ocean water quality in Southeast Asia through atmospheric deposition: field observations

Abstract: . Atmospheric nutrients have recently gained considerable attention as a significant additional source of new nitrogen (N) and phosphorus (P) loading to the ocean. The effect of atmospheric macro nutrients on marine productivity depends on the biological availability of both inorganic and organic N and P forms. During October 2006, the regional smoke haze episodes in Southeast Asia (SEA) that resulted from uncontrolled forest and peat fires in Sumatra and Borneo blanketed large parts of the region. In this work, we determined the chemical composition of nutrients in aerosols and rainwater during hazy and non-hazy days to assess their impacts on aquatic ecosystem in SEA for the first time. We compared atmospheric dry and wet deposition of N and P species in aerosol and rainwater in Singapore between hazy and non-hazy days. Air mass back trajectories showed that large-scale forest and peat fires in Sumatra and Kalimantan were a significant source of atmospheric nutrients to aquatic environments in Singapore and SEA region on hazy days. It was observed that the average concentrations of nutrients increased approximately by a factor of 3 to 8 on hazy days when compared with non-hazy days. The estimated mean dry and wet atmospheric fluxes (mg/m2/day) of total nitrogen (TN) were 12.72 ± 2.12 and 2.49 ± 1.29 during non-hazy days and 132.86 ± 38.39 and 29.43 ± 10.75 during hazy days; the uncertainty estimates are represented as 1 standard deviation (1σ) here and throughout the text. The estimated mean dry and wet deposition fluxes (mg/m2/day) of total phosphorous (TP) were 0.82 ± 0.23 and 0.13 ± 0.03 for non-hazy days and 7.89 ± 0.80 and 1.56 ± 0.65 for hazy days. The occurrences of higher concentrations of nutrients from atmospheric deposition during smoke haze episodes may have adverse consequences on receiving aquatic ecosystems with cascading impacts on water quality.

Haze removal based on advanced haze-optimized transformation AHOT for multispectral imagery

Abstract: Ever-present spatially varying haze contamination in satellite scenes limits applications using visible and near-infrared bands of low-temporal-resolution multispectral satellite images. A relative atmospheric correction technique, the virtual cloud point VCP method, which is based on advanced haze-optimized transformation AHOT, is developed for haze removal. It is an improved algorithm of the previous dark-object subtraction DOS based on haze-optimized transformation HOT. In AHOT, extra steps are added to HOT to remove confusion caused by some land-cover types. The VCP method uses the upper bound of the histogram, as well as the lower bound, so that it enlarges the digital number DN variance reduced by haze, which is not considered in DOS. To evaluate this algorithm, hazy subsets of one Landsat Thematic Mapper TM and one QuickBird image are employed. Through before-and-after comparison using true-colour images and the normalized difference vegetation index NDVI, it proves that the VCP method based on AHOT is apparently better than DOS based on HOT, when haze is distributed over urban areas where vegetation is sparse.

Monitoring haze episodes over the Yellow Sea by combining multisensor measurements

Abstract: Haze, which is composed of a wide range of aerosol particles, is one of the most hazardous weather conditions because of its adverse impact on health and its deleterious effect on visibility, leading to loss of maritime transportation. Satellite, ground-based sunphotometer and particulate matter (PM) concentration data were analysed to evaluate the causes of two severe haze episodes observed during 28-31 March and 3-6 June 2007 over the Yellow Sea. The first episode was clearly affected by the long-range transport of dust from southeastern Mongolia to eastern Inner Mongolia, covering the Onqin Daga and Horqin sandy land areas, which are important sources for the sand and dust storms (SDS) that occur frequently during the spring in East Asia. A backward trajectory analysis confirmed the transport of air mass from southeastern Mongolia. A very high aerosol optical depth (AOD) (> 2.0) and a high backscatter coefficient (about 5 × 10-2 km sr-1) of dust were observed by Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), respectively, during the first haze episode. A sudden increase in PM10 (particles ≤ 10 μm) concentration (maximum value 225 μg m-3) was observed during the haze period. A higher AOD was observed over the Yellow Sea on 6 June 2007 during the second haze event compared to the AOD observed during the first haze episode, which occurred during 4-6 June 2007. A few hotspots were detected by MODIS during the second haze episode. It was concluded that the second haze episode was probably dominated by smoke from open burning areas of crop residue in East China, when a rapid increase in PM10 concentration up to 192 μg m-3 was observed.

Aviation response to a widely dispersed volcanic ash and gas cloud from the August 2008 eruption of Kasatochi, Alaska, USA

Abstract: [1] The extensive volcanic cloud from Kasatochi's 2008 eruption caused widespread disruptions to aviation operations along Pacific oceanic, Canadian, and U.S. air routes. Based on aviation hazard warnings issued by the National Oceanic and Atmospheric Administration, U.S. Geological Survey, the Federal Aviation Administration, and Meteorological Service of Canada, air carriers largely avoided the volcanic cloud over a 5 day period by route modifications and flight cancellations. Comparison of time coincident GOES thermal infrared (TIR) data for ash detection with Ozone Monitoring Instrument (OMI) ultraviolet data for SO2 detection shows congruent areas of ash and gas in the volcanic cloud in the 2 days following onset of ash production. After about 2.5 days, the area of SO2 detected by OMI was more extensive than the area of ash indicated by TIR data, indicating significant ash depletion by fall out had occurred. Pilot reports of visible haze at cruise altitudes over Canada and the northern United States suggested that SO2 gas had converted to sulfate aerosols. Uncertain about the hazard potential of the aging cloud, airlines coped by flying over, under, or around the observed haze layer. Samples from a nondamaging aircraft encounter with Kasatochi's nearly 3 day old cloud contained volcanic silicate particles, confirming that some fine ash is present in predominantly gas clouds. The aircraft's exposure to ash was insufficient to cause engine damage; however, slightly damaging encounters with volcanic clouds from eruptions of Reventador in 2002 and Hekla in 2000 indicate the possibility of lingering hazards associated with old and/or diffuse volcanic clouds.

Haze episodes at Syowa Station, coastal Antarctica: Where did they come from?

Abstract: [1] During our aerosol measurement program at Syowa Station, Antarctica, in 2004-2007, some low-visibility (haze) phenomena were observed during winter―spring under conditions with low winds and without drifting snow and fog. During "Antarctic haze" phenomena, the number concentration of aerosol particles and black carbon concentration increased by 1 to 2 orders higher relative to background conditions at Syowa Station, whereas surface O 3 concentration dropped simultaneously, especially after polar sunrise. Chemical analysis showed that major aerosol constituents in the haze phenomena were sea salt (e.g., Na + , Cl ― ). Trajectory analysis and the Navy Aerosol Analysis and Prediction System model showed that plumes from biomass burning in South America and southern Africa were transported to Syowa Station, on the Antarctic coast, because of the eastward (occasionally westward) approach of cyclones in the Southern Ocean and subsequent poleward flow. This poleward flow from midlatitudes of the plume and injection of sea-salt particles during the transport might engender Antarctic haze phenomena at Syowa Station. Differences of 0 3 concentration between the background and the haze conditions tended to be larger in spring (after polar sunrise) than in winter. Enhancement of sea-salt particles in the haze events can serve important roles in providing additional sources of reactive halogen species.

Nanostructure-based transparent conductors having increased haze and devices comprising the same

Abstract: The present disclosure relates to modifications to nanostructure based transparent conductors to achieve increased haze/light-scattering with different and tunable degrees of scattering, different materials, and different microstructures and nanostructures.

Radiative forcing of haze during a forest fire in Spain

Abstract: Intense fires occurred in northwestern Spain on 6 September 2000, filling a valley with smoke haze. Aerosol size distribution measurements were performed during 1 day with a thermal inversion, so the aging process of the smoke aerosol could be closely monitored. In 3.5 h, the fine aerosol increased up to 0.06 μm in the geometric median diameter of the fine mode. This aging process enhanced the scattering ability of aerosols. On the basis of several hypotheses on the data obtained, shortwave radiative forcing at surface level, at top level, and in the atmosphere was estimated: instantaneous surface forcing reached up to between −80.4 and −67.4 W/m2, top of the atmosphere (TOA) instantaneous forcing reached up to between −23.4 and +4.9 W/m2, and instantaneous atmosphere forcing reached up to between +44.2 and +85.3 W/m2. The study reveals not only the absorption of solar radiation in the atmosphere by smoke aerosols but also an aerosol-induced case study, where TOA cooling forcing shifts to warming for specific aerosol single scattering albedo. The daily mean heating rate of the smoke haze was estimated at 5.9 ± 0.6 K/d.

Unlinking absorption and haze in thin film silicon solar cells front electrodes

Abstract: We study the respective influence of haze and free carrier absorption (FCA) of transparent front electrodes on the photogenerated current of micromorph thin film silicon solar cells. To decouple the haze and FCA we develop bi-layer front electrodes: a flat indium tin oxide layer assures conduction and allows us to tune FCA while the haze is adjusted by varying the thickness of a highly transparent rough ZnO layer. We show how a minimum amount of FCA leads only to a few percents absorption for a single light path but to a strong reduction of the cell current in the infrared part of the spectrum. Conversely, a current enhancement is shown with increasing front electrode haze up to a saturation of the current gain. This saturation correlates remarkably well with the haze of the front electrode calculated in silicon. This allows us to clarify the requirements for the front electrodes of micromorph cells.