Showing papers on "Haze published in 1989"
TL;DR: It is concluded that the most important factors controlling Titan's thermal structure are absorption of sunlight by the stratospheric haze and the pressure-induced gas opacity in the infrared.
491 citations
TL;DR: The available body of data on fine particles (> 1 μm radius) in the troposphere is reviewed in relation to our understanding of sources, sinks and transformation processes of atmospheric aerosols.
Abstract: The available body of data on fine particles (> 1 μm radius) in the troposphere is reviewed in relation to our understanding of sources, sinks and transformation processes of atmospheric aerosols. This review yields the following results. There are no data available to characterize the free troposphere above the boundary layer. Most of the boundary layer data suffer from the lack of a well-defined upper size limit of the samplers at about 1 μm radius and concurrent results on total fine particle mass. The fine particle composition data are consistent with our understanding of natural and anthropogenic sources of trace substances, which lead to fine particles. The chemical composition is presented for the three aerosol types: urban, non-urban continental and remote regions. Special attention needs to be focused on fine particle interaction with clouds for three reasons. Fine particles control number- and surface-distribution of the condensed matter; the state of precondensation haze and clouds provide the most important processes of fine particle elimination from the atmosphere. Furthermore, climatic effects of fine particles as expressed by their interaction with atmospheric radiation is strongest during their passage through clouds. Very little is known about the processing of aerosols through clouds. Consequently, there are large uncertainties about their climatic effect and their lifetime in the atmosphere. Finally, no single type of secular trend in particle concentration is found on a global scale. Depending on which component and which geographical region is monitored, both decreasing and increasing concentrations have been measured. The differences are consistent with our understanding of aerosol properties and their gas phase precursors. DOI: 10.1111/j.1600-0889.1989.tb00132.x
290 citations
TL;DR: In this paper, a general algorithm for determining suspended sediment concentrations in the surface waters of estuaries has been developed for use with satellite data, which uses a three-parameter general optical equation to relate sediment concentrations to water reflectances that have been corrected for sun angle effects, atmospheric path radiance, and tidal excursion.
Abstract: A general algorithm for determining suspended sediment concentrations in the surface waters of estuaries has been developed for use with satellite data. The algorithm uses a three-parameter general optical equation to relate suspended sediment concentrations to water reflectances that have been corrected for sun angle effects, atmospheric path radiance, and tidal excursion. Using data collected by the advanced very high resolution radiometer on five different dates, reflectances were determined using two different methods, one providing maximum correction for haze and the other providing minimum sensitivity to pigments. For both methods, in situ and remotely sensed samples from Delaware Bay acquired within 3.5 hours of each other agreed to within 60% at the 95% confidence level. Pixel and subpixel scale spatial variations and variability associated with in situ measurements produced about 50% of the differences. Chlorophyll concentrations of >50 μg/L produced a discrepancy in the reflectance method that provided the best haze correction. The parameter values may be adjusted to allow for variations in sediment size and pigment variations, allowing application of the calibration to estuaries having optically different suspended sediments.
213 citations
TL;DR: In this paper, the propagation properties of suspended water and ice particles which make up atmospheric haze, fog, and clouds were examined for microwave and millimeter-wave frequencies, and the rates of attenuation alpha (dB/km) and delay tau (ps/km), derived from a complex refractivity based on the Rayleigh absorption approximation of Mie's scattering theory, were derived.
Abstract: Propagation properties of suspended water and ice particles which make up atmospheric haze, fog, and clouds were examined for microwave and millimeter-wave frequencies. Rates of attenuation alpha (dB/km) and delay tau (ps/km) are derived from a complex refractivity based on the Rayleigh absorption approximation of Mie's scattering theory. Key variables are particle mass content and permittivity, which depends on frequency and temperature both for liquid and ice states. Water droplet attenuation can be estimated within a restricted (10+or-10 degrees C) temperature range using a simple two-coefficient approximation. Experimental data on signal loss and phase delay caused by fog at four frequencies (50, 82, 141, and 246 GHz) over a 0.81-km line-of-sight path were found to be consistent with the model. >
171 citations
TL;DR: Fog interception and rainfall were measured during one year in three elfin cloud forests on small mountains along the Caribbean coast of South America and one in the Venezuelan Andes.
Abstract: Fog interception and rainfall were measured during one year in three elfin cloud forests on small mountains along the Caribbean coast of South America and one in the Venezuelan Andes. (1) While rainfall increases from west to east in the small mountains along the coast, fog interception decreases. In 1985, the total annual rainfall and fog interception were 853 mm and 796 mm in the cloud forest of Serrania de Macuira, 1630 mm and 518 mm in Cerro Santa Ana and, 4461 mm and 480 mm in Cerro Copey. In the Andean forest of El Zum-bador, the 1985 rainfall was 1983 mm and the annual fog interception was only 72 mm. (2) Fog interception seems to be an important source of water to the elfin cloud forests of the small mountains which are surrounded by dry vegetation types and where the rainfall regime is highly seasonal. (3) Fog interception increases with altitude (in the same mountain), exposure (windward slopes) and leaf inclination. These variations of fog interception could partially explain the observed distribution of epiphytic flora in some of these cloud forests.
151 citations
TL;DR: In this paper, a radiation model was constructed that includes radiative interactions with atmospheric gases as well as parameterized treatments of scattering and absorption/emission by cloud droplets and haze particles.
Abstract: A radiation model is constructed that includes radiative interactions with atmospheric gases as well as parameterized treatments of scattering and absorption/emission by cloud droplets and haze particles. A unified treatment of solar and terrestrial radiation is obtained by using identical cloud and haze parameterization procedure for the shortwave and longwave region. The influence of the relative humidity of the haze particles is also considered. Snow conditions of the arctic region are simulated in terms of snow grain sizes and soot contamination in the surface layers. Data from the Arctic Stratus Cloud Experiment collected in 1980 are used for model comparisons and sensitivity studies under cloudy and hazy sky conditions. During the arctic summer, stratus clouds are a persistent feature and decrease the downward flux at the surface by about 130–200 W m−2. Arctic haze in the summertime is important if it is above the cloud layer or in air with low relative humidity, and it decreases the downwa...
138 citations
TL;DR: In this paper, the basic conditions under which ice crystal nucleation, from the homogeneous freezing of ammonium sulfate haze particles, can occur in cirrus clouds at temperatures ≲ −35°C were explored.
Abstract: A one-dimensional cloud microphysical model is applied to exploring the basic conditions under which ice crystal nucleation, from the homogeneous freezing of ammonium sulfate haze particles, can occur in cirrus clouds at temperatures ≲ −35°C. Cirrus generating regions maintained by uniform updrafts of 0.1–0.25 m s−1, and an idealized ice crystal precipitation mechanism dependent on vertical wind shear are treated in the model. The findings indicate that ice crystals are generated in a pulse-like fashion as a result of water vapor competition effects from ice crystals nucleated within an updraft, followed by precipitation. Water saturation is not required for ice crystal nucleation at ≲ −35°C, and the relative humidities required at decreasing temperatures gradually decrease. The temperature dependency of the relative humidities associated with ice production does not depend significantly on model inputs, suggesting that cirrus cloud processes follow an adjusted pseudoadiabat, which produces ice m...
107 citations
TL;DR: Aerosol particles were collected on filters for studies of their ability to nucleate ice during the second Arctic Gas and Aerosol Sampling Program (AGASP-II) in April 1986.
Abstract: Aerosol particles were collected on filters for studies of their ability to nucleate ice during the second Arctic Gas and Aerosol Sampling Program (AGASP-II) in April, 1986. The ice nuclei (IN) samples were collected from an aircraft at altitudes ranging from the surface to the vicinity of the tropopause in Arctic locations over Alaska, northern Canada and Greenland. Samples of other components of the aerosol were collected and measurements were made of other properties of the aerosol coincident in time with the IN samples. The IN filters were exposed to water saturation in a dynamic developing chamber at −15° C and −25° C. Ice crystals grew on the IN and were counted on the filters at discrete time intervals during the exposure period to determine the rate of ice nucleation and the final concentration of (IN). Results show that Arctic haze aerosol, identified by pollutant signatures, had lower IN concentrations, a lower IN to total aerosol fraction and slower ice nucleation rates than aerosol which had a chemical signature more indicative of the remote unpolluted troposphere. These observations suggest that the Arctic haze aerosol does not efficiently form ice in the arctic troposphere. This may be a factor contributing to the long-range transport of Arctic haze.
77 citations
TL;DR: On 2 and 3 April 1986, an unusually dense Arctic haze band with distinct horizontal and vertical boundaries was intercepted by a NOAA WP-3D aircraft north of Barrow, Alaska during the second Arctic Gas and Aerosol Sampling Program (AGASP-II) as discussed by the authors.
56 citations
TL;DR: The air pollution sources in Nigeria are discussed in this article, where both anthropogenic and non-anthropogenic sources of paniculate matter were found to be important both at local and international levels.
55 citations
TL;DR: In this article, airborne observations during August 1985 over Greenland and the North American Arctic revealed that dense, discrete haze layers were common above 850 mb, and the haze layers aloft were characterized by large light-scattering coefficients due to dry particles.
Abstract: Airborne observations during August 1985 over Greenland and the North American Arctic revealed that dense, discrete haze layers were common above 850 mb. No such hazes were found near the surface in areas remote from local sources of particles. The haze layers aloft were characterized by large light-scattering coefficients due to dry particles (maximum value 1.24 × 10−4m−1) and relatively high total particle concentrations (maximum value 3100 cm−3). Sulfate was the dominant ionic component of the aerosol (0.06 – 1.9 μg m−3); carbon soot was also present. Evidence for relatively fresh aerosols, accompanied by NO2 and O3 depletion, was found near, but not within, the haze layers. The hazes probably derived from anthropogenic sources and/or biomass burning at midlatitudes.
TL;DR: In this paper, an aircraft and a ground-based lidar system were used to collect data from the Canadian Arctic Haze Study (AGASP II), where vertical profiles of aerosol size distribution (≥0.17 μm), light scattering parameters and cloud particle concentrations were obtained with an instrumented aircraft and ground based lidar systems during April 1986 at Alert.
Abstract: As a component of the Canadian Arctic Haze Study, held coincident with the second Arctic Gas and Aerosol Sampling Program (AGASP II), vertical profiles of aerosol size distribution (≥0.17 μm), light scattering parameters and cloud particle concentrations were obtained with an instrumented aircraft and ground-based lidar system during April 1986 at Alert. Northwest Territories. Average aerosol number concentrations range from about 200 cm−3 over the Arctic ice cap to about 100 cm−3 at 6 km. The aerosol size spectrum is virtually free of giant or coarse aerosol particles, and does not vary significantly with altitude. Most of the aerosol volume is concentrated in the 0.17–0.50 μm size range, and the aerosol number concentration is found to be a good surrogate for the SO4
= concentration of the Arctic haze aerosol. Comparison of the aircraft and lidar data show that, when iced crystal scattering is excluded, the aerosol light scattering coefficient and the lidar backscattering coefficient are proportional to the Arctic haze aerosol concentration. Ratios of scattering to backscattering, scattering to aerosol number concentration, and backscattering to aerosol number concentration are 15.3 steradians, 1.1×10−13 m2, and 4.8×10−15 m2 sr−1, respectively. Aerosol scattering coefficients calculated from the measured size distributions using Mie scattering agree well with measured values. The calculations indicate the aerosol absorption optical depth over 6 km to range between 0.011 and 0.018. The presence of small numbers of ice crystals (10–20 crystals 1−1 measured) increased light scattering by over a factor of ten.
TL;DR: In this article, the authors found a strong positive correlation between the methane and carbon dioxide concentrations, with a linear regression slope of 17.5 ppb CH4/ppm CO2, a standard error of 0.6, and a correlation coefficient (r2) of0.95.
Abstract: Fifty flask air samples were taken during April 1986 from a NOAA WP-3D Orion aircraft which flew missions across a broad region of the Arctic as part of the second Arctic Gas and Aerosol Sampling Program (AGASP II). The samples were subsequently analyzed for both carbon dioxide (CO2) and methane (CH4). The samples were taken in well-defined layers of Arctic haze, in the background troposphere where no haze was detected, and from near the surface to the lower stratosphere. Vertical profiles were specifically measured in the vicinity of Barrow, Alaska to enable comparisons with routine surface measurements made at the NOAA/GMCC observatory. Elevated levels of both methane and carbon dioxide were found in haze layers. For samples taken in the background troposphere we found negative vertical gradients (lower concentrations aloft) for both gases. For the entire data set (including samples collected in the haze layers) we found a strong positive correlation between the methane and carbon dioxide concentrations, with a linear regression slope of 17.5 ppb CH4/ppm CO2, a standard error of 0.6, and a correlation coefficient (r2) of 0.95. This correlation between the two gases seen in the aircraft samples was corroborated by in situ surface measurements of these gases made at the Barrow observatory during March and April 1986. We also find a similar relationship between methane and carbon dioxide measured concurrenty for a short period in the moderately polluted urban atmosphere of Boulder, Colorado. We suggest that the strong correlation between methane and carbon dioxide concentrations reflects a common source region for both, with subsequent long-range transport of the polluted air to the Arctic.
TL;DR: In this article, the effect of the Arctic-haze aerosol on the parameters of solar radiation was investigated using airborne radiometric measurements of radiation parameters during the second Arctic Gas and Aerosol Sampling Project.
Abstract: The effect of the Arctic-haze aerosol on the parameters of solar radiation was investigated using airborne radiometric measurements of radiation parameters during the second Arctic Gas and Aerosol Sampling Project. Simultaneously with absorption measurements, optical depths and total, direct, and scattered radiation fields were determined. The experimentally determined parameters were used to define an aerosol model, which was then used to calculate atmospheric heating rate profiles. It was found that, besides the increased absorption (30 to 40 percent) and scattering of radiation by the atmosphere, Arctic haze reduces the surface absorption of solar energy by 6 to 10 percent, and the effective planetary albedo over ice surfaces by 3 to 6 percent.
TL;DR: In this article, an analytical electron microscopy analysis of 10 aircraft-collected cascade impactor samples from the North American Arctic was performed using analytical X-ray spectrometer, which can directly detect carbon X-rays emitted from particles and through interpretation of morphological and electron diffraction data.
TL;DR: The second phase of AGASP-II as mentioned in this paper was conducted across the Alaskan and Canadian Arctic in April 1986, to study the in situ aerosol, and the chemical and optical properties of Arctic haze.
Abstract: The second Arctic Gas and Aerosol Sampling Program (AGASP-II) was conducted across the Alaskan and Canadian Arctic in April 1986, to study the in situ aerosol, and the chemical and optical properties of Arctic haze. The NOAA WP-3D aircraft, with special instrumentation added, made six flights during AGASP-II. Measurements of wind, pressure, temperature, ozone, water vapor, condensation nuclei (CN) concentration, and aerosol scattering extinction (bsp) were used to determine the location of significant haze layers. The measurements made on the first three flights, over the Arctic Ocean north of Barrow and over the Beaufort Sea north of Barter Island, Alaska are discussed in detail in this report of the first phase of AGASP II. In the Alaskan Arctic the WP-3D detected a large and persistent region of haze between 960 and 750 mb, in a thermally stable layer, on 2, 8, and 9 April 1986. At its most dense, the haze contained CN concentrations >10,000 cm−3 and bsp of 80×10−6 m−1 suggesting active SO2 to H2SO4 gas-to-particle conversion. Calculations based upon observed SO2 concentrations and ambient relative humidities suggest that 104–105 small H2SO4 droplets could have been produced in the haze layers. High concentrations of sub-micron H2SO4 droplets were collected in haze. Ozone concentrations were 5–10 ppb higher in the haze layers than in the surrounding troposphere. Outside the regions of haze, CN concentrations ranged from 100 to 400 cm−3 and bsp values were about (20–40)×10−6 m−1. Air mass trajectories were computed to depict the air flow upwind of regions in which haze was observed. In two cases the back trajectories and ground measurements suggested the source to be in central Europe.
TL;DR: In this article, the optically absorbing carbonaceous component of the ambient aerosol from the NOAA WP-3D aircraft operating between sea level and 10 km altitude was measured in real time.
Abstract: During the second Arctic Gas and Aerosol Sampling Program conducted in April 1986, we performed measurements of the optically absorbing carbonaceous component of the ambient aerosol from the NOAA WP-3D aircraft operating between sea level and 10 km altitude. We collected the aerosol of filters that were exposed for several hours; we also operated the aethalometer to measure the concentration of aerosol black carbon in real time. The filter analyses represent averages over the altitude range and time span during which the filter was collecting. The real-time results were sorted by altitude to calculate vertical profiles of black carbon concentration. Values typically ranged from 300 to 500 ng m−3 at lower altitudes, decreasing gradually to 25 to 100 ng m−3 at 8–10 km. Strong stratification at lower altitudes was frequently observed. The magnitude of these concentrations suggests that the sources are distant regions of considerable fuel consumption. The presence of this material in the tropospheric column and its probable deposition to the high-albedo surface may result in perturbations of the solar radiation balance. The concentrations measured at the highest altitudes may mean that particulate carbon and accompanying emissions for which it is a tracer are mixing into the stratosphere.
TL;DR: In this paper, the authors used instrumental neutron activation analysis for trace element detection in aerosol filter samples collected in tropospheric Arctic haze layers, in the stratosphere, and in the marine boundary layer during the 1983 Arctic Gas and Aerosol Sampling Program.
Abstract: Thirty-six aerosol filter samples collected in tropospheric Arctic haze layers, in the stratosphere, and in the marine boundary layer during the 1983 Arctic Gas and Aerosol Sampling Program were analyzed for trace elements using instrumental neutron activation analysis. Average crustal dust concentrations were 540 ng/m3 and 330 ng/m3 for samples collected in Arctic haze over the North American and Norwegian Arctic, respectively. An average marine salt concentration of 120 ng/m3 was obtained for haze samples collected above the marine boundary layer on both sides of the Arctic.
TL;DR: In this article, the dominant role of anticyclones in transporting Arctic haze may be the result of the unique geographic and climatological situation existing during winter/spring in which both the huge Eurasian continent and the adjacent ice-covered Arctic Ocean tend to be regions where antcyclones form and exist over long periods of the winter and spring seasons.
TL;DR: Measurement of atmospheric particulates that affect visibility shows that sulfates associated with man-made emissions of sulfur dioxide are the single largest contributor to visibility reduction, except in the northwestern United States, where organic aerosols contribute significantly.
Abstract: Spatial and temporal trends in visibility are examined at a national level. It is shown that visibility is impaired in all antional parks approximately 90% of the time, and that eastern visibilities are about 10 times lower than western visibilities. Measurement of atmospheric particulates that affect visibility shows that sulfates associated with man-made emissions of sulfur dioxide are the single largest contributor to visibility reduction, except in the northwestern United States, where organic aerosols contribute significantly. In the East, coal fired power plants along the Ohio River Vallery contribute the most SO2, while oil refining activities and other industrial sources in southern California, copper smelters in southern Arizona, and industrial activity along the Gulf Coast of Mexico contribute most of the SO2, and thus sulfates, in the West.
TL;DR: In rural areas of the western United States, atmospheric mass concentrations of organic carbon are comparable to those of sulfate as mentioned in this paper, and atmospheric light-scattering coefficients are empirically as sensitive to carbon concentrations as they are to sulfate concentrations.
Abstract: In rural areas of the western United States, atmospheric mass concentrations of participate organic carbon are comparable to those of sulfate. At the low humidities characteristic of this region, atmospheric light-scattering coefficients are empirically as sensitive to carbon concentrations as they are to sulfate concentrations. The abundance and scattering effectiveness of organic particles imply that they are major contributors to the impairment of scenic views.
TL;DR: Cascade impactor samples collected over the Alaskan Arctic during the first three research flights of AGASP-II were analyzed using analytical electron microscopy to determine the morphology, mineralogy and elemental composition of individual particles as mentioned in this paper.
Abstract: Cascade impactor samples were collected over the Alaskan Arctic during the first three research flights of AGASP-II. These samples were analyzed using analytical electron microscopy to determine the morphology, mineralogy and elemental composition of individual particles. For analytical considerations, a typical impactor sample was run for approximately 20 min, thus giving excellent time resolution of discrete events. Samples collected during flights 201 and 202 consisted of stratospheric aerosol and lower-altitude haze samples. Stratospheric samples were characterized by moderate loadings of H2SO4 droplets with relatively few particles of other types. Samples collected in tropospheric haze layers generally exhibited light-to-moderate particle loadings. H2SO4 was again the most prevalent species, with crustal and anthropogenic particles also observed. One sample taken over south-central Alaska near the end of flight 203 showed high concentrations of solid crustal particles, with relatively little associated H2SO4. Giant particles larger than 5 μm were occasionally observed in this aerosol. The composition of this material closely matches that of bulk ash from the Mt. Augustine volcano, which erupted 9–13 days before collection of this sample. This brings forth the possibility that pockets of ash-rich aerosol existed over parts of south and central Alska during the AGASP-II field mission. There is no evidence that these volcanic aerosols were present in the AGASP study area north of the Brooks Range.
TL;DR: In this paper, thermal and optical techniques were used at Barrow, Alaska during AGASP II (3/20/86-4/7/86) to measure in-situ variability of major aerosol components present in Arctic Haze.
Abstract: Thermal and optical techniques were used at Barrow, Alaska during AGASP II (3/20/86–4/7/86) to measure in-situ variability of major aerosol components present in Arctic Haze. The experiment provided continuous data on the concentration, size distribution and relative proportions of sulfate species and refractory aerosol for particle diameters of 0.15 to 5 μm. Filter samples were also taken for determination of aerosol optical absorption due to soot (EC-elemental carbon). Although pronounced haze “events” were absence during this period the haze aerosol present varied in concentration between 2 and 6 μg/m3 but showed little change in relative constituents. Apart from local influences, the optical data indicated a persistent fine-mode sulfate aerosol with a NH4
+/SO4
− molar ratio of about 0.4 and a refractory component of somewhat less than 10% by mass. A preliminary comparison of soot estimates determined from the light absorption data with the size distributions of refractory aerosol observed independently by the optical particle counter showed good agreement during the sample period. In the absence of local pollution, values of single scatter albedo derived from light scattering and light absorption showed similar variation about the average value of 0.86 found by us during flights north of Barrow three years earlier during AGASP I.
TL;DR: The vertical distribution of sulfur dioxide in the Arctic atmosphere in April, 1986 was highly variable, with concentrations ranging from the detection limit to 15 parts-per-billion by volume (ppbv) as mentioned in this paper.
Abstract: Determinations of atmospheric sulfur dioxide were made across the North American Aretic using gas chromatography with a detection limit of 25 parts per trillion by volume and a precision of 25% or better. The vertical distribution of sulfur dioxide in the Arctic atmosphere in April, 1986 was highly variable, with concentrations ranging from the detection limit to 15 parts-per-billion by volume (ppbv). While SO2 exceeded 10 ppbv in an exceptional haze layer in the Alaskan Arctic, sulfur dioxide was sometimes in the 1 – 5 ppbv range when the haze was absent. This was particularly true for the Canadian Arctic in the vicinity of Alert. In the lower stratosphere over Ellesmere Island, sulfur dioxide was 0.85 ppbv.
TL;DR: In situ measurements of ambient CO2 and methane (CH4) were made at Alert using an automated gas chromatograph, as part of the Arctic Haze Study during April 1986.
Abstract: Carbon dioxide (CO2) has been measured at Alert by grab flask sampling since 1975 as part of the World Meteorological Organization's Background Air Pollution Monitoring Program. Deviations of CO2 concentration from the mean annual cycle have previously been attributed to air masses arriving at Alert from the source regions of the industrialized parts of Europe and the Soviet Union. In situ measurements of ambient CO2 and methane (CH4) were made at Alert using an automated gas chromatograph, as part of the Arctic Haze Study during April 1986. The temporal behaviour of CO2 and CH4 during this period was found to be highly correlated with measurements of particulate sulphate and other atmospheric trace species of anthropogenic origin. Examination of calculated air mass back-trajectories provided further evidence that the observed short-term increases in CO2 and CH4 mixing ratios were due to long-range transport from anthropogenic source regions.
TL;DR: In this paper, airborne measurements of the emissions from natural fires, fueled by pyrites and organic materials, at the Smoking Hills in the Northwest Territories, show that they are a regionally significant source of SO2 (∼0.3 kg s−1 or ∼104 T yr−1) and particles.
Abstract: Airborne measurements of the emissions from natural fires, fueled by pyrites and organic materials, at the Smoking Hills in the Northwest Territories, show that they are a regionally significant source of SO2 (∼0.3 kg s−1 or ∼104 T yr−1) and particles (∼0.3 kg s−1). It appears likely that the Smoking Hills are a source for some of the dense, lower-level, haze layers that occur in the North American Arctic.
TL;DR: In this paper, the authors used the upwind direction of an upwind trajectory to determine the origin of the air masses sampled during the Alaskan phase of AGASP-II (Arctic Gas and Aerosol Sampling Program) flights.
TL;DR: In this article, the authors used a dual impactor technique to obtain the distributions of the haze and its dry precursor, i.e., the accumulation aerosol, and determined an average growth factor from the shift of the distributions.
TL;DR: Using both surface and upper-air data at Kano in Nigeria, a new method of dust haze prediction for a single station is proposed in this article, which significantly removes the greatest problem facing weather forecasters in West Africa - unavailable or inadequate data due to unreliable communication and sparse upper air network.