Showing papers on "Haze published in 1984"

Sulfur Dioxide: Episodic Injection Shows Evidence for Active Venus Volcanism

Abstract: Pioneer Venus ultraviolet spectra from the first 5 years of operation show a decline (by more than a factor of 10) in sulfur dioxide abundance at the cloud tops and in the amount of submicron haze above the clouds. At the time of the Pioneer Venus encounter, the values for both parameters greatly exceeded earlier upper limits. However, Venus had a similar appearance in the late 1950's, implying the episodic injection of sulfur dioxide possibly caused by episodic volcanism. The amount of haze in the Venus middle atmosphere is about ten times that found in earth's stratosphere after the most recent major volcanic eruptions, and the thermal energy required for this injection on Venus is greater by about an order of magnitude than the largest of these recent earth eruptions and about as large as the Krakatoa eruption of 1883. The episodic behavior of sulfur dioxide implies that steady-state models of the chemistry and dynamics of cloud-top regions may be of limited use.

Arctic haze and the Arctic Gas and Aerosol Sampling Program (AGASP)

Abstract: The Arctic Gas and Aerosol Sampling Program (AGASP) was conducted across the Arctic in the spring of 1983 to study the large scale air pollution phenomenon known as Arctic haze. A component of this program utilized a National Oceanic and Atmospheric Administration WP-3D Orion research aircraft to study the haze in situ. The program and aircraft instrumentation are described.

Vertical distributions of particulate carbon, sulfur, and bromine in the Arctic haze and comparison with ground‐level measurements at Barrow, Alaska

Abstract: We present results obtained during the ''AGASP 1983'' Arctic haze aircraft sampling experiment. We collected many filter samples and operated the LBL aethalometer, an instrument that responds to the aerosol graphitic (''black'') carbon concentration in real time. We found substantial concentrations of black carbon and sulfur at all altitudes in the Arctic troposphere. Maxima in the black carbon concentrations were observed at intermediate altitudes. Comparing these results with data from the NOAA-GMCC observatory near Barrow, Alaska, we find that peak concentrations aloft can be significantly greater than the ground-level measurements.

Martian north polar hazes and surface ice: Results from the Viking Survey/Completion Mission

Abstract: The character of both the retreating polar cap edge and the accompanying atmospheric ice haze has been determined during the 1979-1980 Viking Survey/Completion mission observations of the Martian north polar regions. The ability of these Viking IR observations to distinguish haze from surface condensate yields a more accurate seasonal regression for the polar cap than can be determined from visual images. The transition from ice-free ground to a predominantly ice-covered surface at the cap edge spans 5-10 deg of latitude.

Gaseous bromine in the Arctic and Arctic haze

Abstract: We report the results of measurements of five bromine-containing trace gases (CBrClF/sub 2/, CH/sub d/2BrCl, CH/sub 2/Br/sub 2/, CH/sub 2/BrCH/sub 2/Br, and CH/sub 3/Br) in the arctic during 1983 and during two of the spring 1983 AGASP aircraft flights. The results show that the anthropogenic bromine-containing trace gases CBrClF/sub 2/, CH/sub 2/BrCl, and CH/sub 2/Br/sub 2/ are more abundant during the winter or spring when arctic haze is observed. The same gases are also more abundant in the haze layers compared to their concentrations out of the haze as measured during the AGASP flights. The total bromine we measured in the arctic, however, appears to be only around 30 pptv, being about 10% more during spring when arctic haze is observed compared to the rest of the year.

Vertical and horizontal characteristics of Arctic haze during AGASP: Alaskan Arctic

Abstract: Vertical and horizontal distributions of ozone, extinction due to aerosol light scattering, condensation nucleus concentrations, aerosol spectra, and meteorological parameters were measured with a NOAA WP-3D research aircraft over the Alaskan Arctic in March 1983. Multiple layers of haze, varying in thickness from a few 10's to 100's of meters, were observed throughout the troposphere. A maximum concentration of aerosols was located between 600 and 800 mb. Distribution of the haze layers was associated with distinct meteorological boundaries. The characteristics of the haze changed in response to stages in the progression of a major Arctic haze episode. On March 17, 1983, the Arctic anticyclone was penetrated and its meteorological and aerosol properties determined.

Role of combustion‐generated carbon particles in the absorption of solar radiation in the Arctic haze

Abstract: We have studied the vertical distributions of combustion-generated graphitic carbon particles and their associated absorption coefficients in the Arctic. These distributions show substantial concentrations of graphitic particles throughout the Arctic troposphere. Vertical profiles in the Norwegian Arctic can show both a strongly layered structure and an almost uniform distribution. Concentrations of graphitic particles within layers can be as large as those found in typical urban areas in the United States. The absorption optical depths associated with these vertical profiles are large enough to cause a substantial change in the solar radiation balance over a highly reflecting surface.

The absorption of solar radiation by the Arctic atmosphere during the haze season and its effects on the radiation balance

Abstract: In this letter we report measurements of broadband spectral absorption of solar radiation by the Arctic atmosphere during haze events. A preliminary analysis of our data indicates that large changes occur in the radiative transfer processes in the Arctic during haze events. For example, the planetary albedo is estimated to increase by 2.5% over the ocean and to decrease by 9% over the ice cap. Changes of such magnitude in the radiative parameters have the potential for significant climatic effects. The need for further experimental and modeling efforts is emphasized.

Airborne observations of Arctic aerosol, IV: Optical properties of Arctic haze

Abstract: Measurements of the horizontal and vertical distribution of aerosol light absorption and light scattering coefficients (at 550nm) for the Arctic aerosol show a high degree of correlation. Apparently originating from source areas at lower latitudes and present at various degrees of dilution, the haze observed was found to have a single scattering albedo in the range of 0.77 to 0.93 and a mean of ca. 0.86. Apart from sample periods with high seasalt concentrations at low altitudes or within ice crystal layers, the single scattering albedo values presented here are well below values characteristic of typical crustal aerosol but are similar to continental urban and rural values. These low values are consistent with arguments for mid-latitude combustion source for this aerosol. The magnitude and variability in the observed optical parameters suggest near surface heating rates in the range of 0.01 to 0.1 degrees centregrade per day.

Surface aerosol measurements at Barrow during AGASP

Abstract: Surface aerosol measurements were made at the Barrow GMCC Observatory during the AGASP flight series in March 1983. The condensation nucleus, scattering extinction coefficient, size distribution, and total aerosol optical depth measurements all clearly show conditions of background Arctic haze for March 9-11, a series of haze episodes during March 12-16, and a return to background haze for March 17-18. Angstrom exponents calculated from scattering coefficient data were low during March 9-11, relatively higher during March 12-14, and highest during March 15-18. Surface aerosol data and aerosol optical depth data are in good qualitative agreement for the 10-day period studied. Background haze was present when trajectories circled the Arctic basin, and haze episodes occurred when trajectories originated in western Asia and Europe.

Aerosol distributions and an Arctic aerosol front during AGASP: Norwegian Arctic

Abstract: Vertical profiles of aerosol characteristics obtained near Svalbard, Norway, during the Arctic Gas and Aerosol Sampling Program indicate that high aerosol concentrations and strong visible haze were distributed throughout the troposphere. Layers of Arctic haze were observed in both dry air and moist air. A research flight on March 31, 1983, crossed a previously undocumented Arctic aerosol front structure. Condensation nucleus concentrations of 450/cu cm within the polluted continental air mass south of the front decreased to 80/cu cm within the clean Arctic air north of the front. Aerosols above the Aitken size range decreased one order of magnitude in both number and mass across this same air mass boundary.

Statistical analysis of trace gases in Arctic haze

Abstract: A large number of anthropogenic trace gases arising from combustion processes such as in power plants and automobiles are found to be more abundant in regions of arctic haze when compared to their concentrations in cleaner background air. The excess of concentrations of a trace gas observed in the haze is greatest for short-lived gases and least for the longer-liver species. Included among these gases are CO/sub 2/, CO, C/sub 2/-C/sub 6/ hydrocarbons, and N/sub 2/O. High concentrations of anthropogenic chlorofluorocarbons and chlorocarbons are also found in arctic haze, including F-11, F-12, CC1/sub 4/, CH/sub 3/CCl/sub 3/, perchloroethylene, trichloroethylene, dichloromethane, and chloroform. The lack of excess CH/sub 3/Cl in the haze suggests that low temperature combustion such as burning of wood does not contribute to arctic haze. The Soviet Union and Europe, because they are industrialized and have large populations at higher latitudes (>50/sup 0/N), are potential source regions for both these groups of anthropogenic trace gases.

Airborne observations of Arctic aerosols. III: Origins and effects of airmasses

Abstract: Multiple layers of haze encountered in the troposphere over the Beaufort and Chukchi Seas during April 1983 occurred in airmasses that originated in eastern USSR, eastern North America and Asia. This, together with observations on the composition and nature of the hazes, indicate that they were primarily anthropogenic in origin. Giant particles (>2 µm in diameter), on the other hand, which were distributed roughly uniformly with height in the troposphere, appeared to have both anthropogenic and natural origins. Relationships between the haze layers and adjacent regions of clean air are discussed.

On bioclimatological aspects of Harmattan dust haze in Nigeria

Abstract: Saharan dust which is transported from the Tibesti region of Africa into the tropical atmosphere and its significant effects are discussed in relation to aeronautical and ecological problems. Incidence of Harmattan dust haze in Nigeria between November and March during the Northern Hemisphere winter is described and the major health hazards associated with its occurrence are discussed. Results suggest that while large deposits of loess-rich dust may aid soil fertility at the fringes of the Saharan dust source, the increasing trend of frequency of occurrence and intensity of dust in Nigeria may worsen the health hazards in the north such as acute respiratory infections, pneumonia and bronchitis. This may become serious in the immediate future in the southern parts of Nigeria which hitherto had been spared the menace of severe Harmattan dust haze.

Airborne observations of Arctic aerosols. II: Giant particles

Abstract: Airborne measurements made in the vicinity of Barrow, Alaska during early spring have revealed relatively large concentrations of giant (>2 ..mu..m diameter) particles in the air. Their concentration varied approximately with the inverse cube of the particle diameter. These particles were not well correlated with the layers of visible haze observed. They appeared to be approximately uniformly distributed from altitudes of 0.3 to 5 km regardless of the presence of absence of arctic haze.

An investigation of the sources of summertime haze in the Blue Ridge Mountains using multivariate statistical methods

Abstract: Multivariate statistical analyses are employed to identify the source areas of the fine particulates and sulfate, which are the primary components of summer haze in the Blue Ridge Mountains of Virginia. These analyses include principal component analysis followed by stepwise multiple regression analysis. The results indicate that most of the fine particles and sulfates originate in the Midwest. The most important factor for both parameters is the residence time of the air parcels over the Midwest. The results also indicate that the sulfate is formed by photochemically initiated reactions. Production of organic aerosols from natural hydrocarbon emissions is also identified as a minor source of fine particles in the Blue Ridge Mountains area.

The appearance of carbon aerosol oarticles in the lower stratosphere

Abstract: Very small carbonaceous particles, thought to be meteoritic, have been found in small quantities in the lower stratosphere during aircraft sampling flights. The sampling was accomplished using a quartz crystal microbalance (QCM) cascade impactor operating on a U-2 aircraft as it flew stratospheric sampling missions. Post flight analyses of the samples using scanning electron microscopy, X-ray energy spectroscopy and Auger electron spectroscopy have identified carbon particles 0.1 micron aerodynamic diameter and smaller in 16 of 28 sets of samples obtained between 1979 and 1983. The presence of such carbon particles in the stratosphere has implications relating to global climate, to the conversion of SO2 to sulfuric acid, and to the phenomenon of the Arctic haze.

Observations of “Arctic Haze” during the “Ptarmigan” weather reconnaissance flights, 1948-1961

Abstract: 114 “Ptarmigan” weather reconnaissance flights over the Alaskan Arctic during 1948-1961 were analyzed for reports of “Arctic Haze” (~400 reports). Arctic Haze can reduce horizontal visibility significantly and is most frequently reported during late winter and spring, but is also found during early winter and summer. Haze is reported everywhere within the Alaskan Arctic at altitudes between the surface and 6 km. Anticyclonic silrface pressure conditions are characteristic of Arctic Haze; “clear skies” weather conditions were predominantly present with haze observations during the winter months, “cloudy skies” were predominantly present with haze observations during the summer months. We hypothesize that Arctic Haze has a dual character of origin: it is pollution-derived during winter and early spring, and desert dust-derived during late spring and summer. DOI: 10.1111/j.1600-0889.1984.tb00234.x

The intrinsic influence of catechins and procyanidins on beer haze formation

Abstract: Different concentrations of catechins and procyanidins were added to an all-malt Pilsner beer brewed from proanthocyanidin-free malt (ant 13·13 × Rupal) and tannin-free hop extract in order to evaluate their intrinsic role in beer haze formation, i.e. in the absence of malt and/or hop flavanoids. The molar tanning capacities of flavanoids depend upon their degree of polymerisation. Procyanidin B6 was much more haze active than procyanidin B3. Both immediate haze and formation of haze after 150 days of storage at room temperature was in general linearily related to the added concentration of phenolics.

Martian North Polar Cap and Haze 1981-1982

Abstract: Resultats des observations photographiques de Mars faites aux observations de Kwasan et Hida durant les phases de retrait et de reste de la calotte polaire nord a son apparition en 1981-82

Effects of Sahel dust layers upon nocturnal cooling of the atmosphere (ECLATS experiment)

Abstract: A study of the effect of a desert aerosol layer on the nocturnal cooling of the atmosphere is presented. The experimental data were obtained during the ECLATS experiment which was run in the Sahel region of the Niger in November 1980. This study uses measurements of thermodynamic and radiative parameters, aerosol size distribution, and a radiative model. The results show that the presence of a dust layer at night increases the downward infrared flux at the surface (and then modifies the energy budget) and increases the radiative cooling rate of the atmosphere, slightly in the layers near the ground (∼0.15 K h−1) and in a more important way at the top of the haze layer.

Lidar determinations of extinction in stratus clouds

Abstract: A field test has been carried out to compare calculations made from lidar data to direct sensor measurements as tools for determining extinction as a function of altitude in the first kilometer of the earth’s atmosphere during the presence of haze layers and stratus clouds; 1.06-μm wavelength lidar returns were reduced using methods based on the stable solution to the lidar equation proposed by Klett. Direct sensor data were obtained from particulate spectrometers and a point visibility meter carried aloft by a tethered hydrogen balloon. The extinction profiles obtained from reduced lidar data are qualitatively in excellent agreement with those from the airborne payload. At moderate to high extinction values encountered in stratus clouds quantitative agreement is reasonably good; in haze conditions the agreement is less satisfactory, not only between the lidar results and those from the direct sensors, but between the results from the particle size distribution data and visibility meter data as well. Nevertheless, considering that extinction can vary over 4 orders of magnitude in such profiles, it is concluded that lidar is a quantitatively useful tool for studying stratus layers and is a particularly good means for determining ceiling altitude.

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

Abstract: 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.

Ground‐based measurements of Arctic haze made at Alert, N.W.T., Canada, during the Arctic Gas and Aerosol Sampling Project (AGASP)

Abstract: Ground-based measurements of Arctic haze were made which are comparable with data obtained aboard the National Oceanographic and Atmospheric Administration (NOAA) P-3 aircraft during March, 1983. Measurements of particle size distribution, particle ionic speciation, and condensation nuclei concentration were made at Alert, N.W.T., from March 16-30. Comparison with the long-term data taken by the Canadian Arctic Air Sampling Network shows that the period is typical of haze maxima in previous years. These data allowed a favorable comparison of the particle size distribution from the aircraft and ground sampler to be made.

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

Abstract: 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.