A short-term intensive multi-instrumental measurement campaign (Integrated Measurements of Aerosol in Agri valley - IMAA) was carried out near the largest European oil and gas pre-treatment plant ...(Centro Olio Val d’Agri - COVA) in a populated area, where, so far, ample characterization of aerosol loading is missing. As such, between the 2 and 17 July in 2013, using a number of instruments analyses were carried out on physical, chemical, morphological and optical properties of aerosol at this distinctive site, at both ground and over the atmospheric column, including the investigation of the mixing and transformation of particles. The observation of slag silicates with a rough surface texture is consistent with the presence of oil-related activities which represent the only industrial activity in the area. Desulfurization/sulfur liquefaction processes occurring at COVA can explain the peculiar morphology of calcium-sodium-aluminum particles. The common COVA source was associated with high concentrations of sulfur, nickel and zinc, and with significant correlations between zinc-sulfur and zinc-nickel. The Optical Particle Sizer (OPS) data, hygroscopicity and optical properties of atmospheric aerosol are consistent with the typical oil-derived gaseous emissions (e.g. sulfur dioxide and methane) that strongly influence the mixing state of particles and their size distributions. Continuous combustion processes at COVA were found to be responsible for Equivalent Black Carbon (EBC) concentrations from their relevant contribution to the total number of fine particles. The expected significant contribution of WS (water soluble) and BC (Black Carbon) components to the total Aerosol Optical Depth (AOD) are consistent with the results from the radiometric model especially for July 3 and 16.
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•First multi-instrumental experiment at the largest European oil/gas pre-treatment plant area.•Integrated approach for aerosol characterization at the ground and over the column.•S, Ni and Zn found as tracers of the plant emissions.•SO2 and CH4 emissions strongly influence the state of mixing of particles.•A relevant contribution of EBC to the total number of fine particles.
In January 2016, a measurement campaign was carried out by the China Meteorological Administration, the Beijing Research Institute of Telemetry, and the Physics Department of the University of Naples ...“Federico II” in the Yulong Naxi Autonomous County (China) at 3200 m above sea level to evaluate the air quality in the high mountains with the lidar technique. Here we report on an interesting event that occurred on 16 January between 12.00 and 00.00 UTC, when a striking aerosol stratification was observed on the site. Aerosol transport events are studied starting from lidar characterization of different aerosol masses. From lidar signals at 355 and 532 nm, integrated on 30 min, the aerosol characterization is done in terms of aerosol depolarization ratio with a spatial resolution of 60 m and color ratio; these parameters allow for highlighting a phenomenon of aerosol transport from the Tibetan plateau planetary boundary layer and from northern India. The initial layer is composed of a mixture of aerosols characterized by average values of the aerosol depolarization ratio and the color ratio of (30 ± 2)% and (0.9 ± 0.2), respectively, indicating a large non-spherical aerosol composition. Then, the deposition of this aerosol load ensues, and aerosols with such features are progressively observed at lower altitudes.
Obtaining comprehensive information on the chemical composition of atmospheric particles is challenging because no single method of analytical chemistry can provide the full range of needed ...information. ...speakers discussed multimodal applications of complementary analytical methods in a context of providing comprehensive information ranging from microscopy-level details of individual particles to advanced molecular characterization of complex molecules that form particulate matter. ...presenters emphasized that future climate models would need to include dynamic evolution of aerosol composition and properties for improved predictions of their atmospheric and climate impact. ...examples of recent knowledge advances derived from laboratory studies demonstrated the types of cutting-edge studies that can be conducted in simulation chambers. With the help of modeling results, presenters demonstrated sensitivity of direct radiative effects to hygroscopic growth of aerosols, impacts of photolysis rates on gas-phase chemistry, historical trends in aerosol emissions, and radiative forcing by black and brown carbon.
•A new simple algorithm of analytical inversion of diffusion battery data is proposed.•The particle size spectrum is a sum of spectra of fractions classified by the battery.•The size spectrum of each ...fraction is approximated by a single-mode distribution.
A new simple algorithm of analytical inversion is proposed for the determination of aerosol particle size spectrum from diffusion battery penetrations. It is simpler and more transparent than analytical approaches published previously. The idea of the analytical solution is based on the operation principle of diffusion battery, which separates particles by their diffusivity into several classes. The size spectrum of particles in each class is approximated by a single-mode distribution, and the total size distribution is the sum of spectra from these classes. For this purpose, simple analytical formulas are derived to calculate the mean diameter of particles in each class from the diffusion battery penetrations. The advantage of the analytical approach is that it gives a one-to-one correspondence between the penetrations and the resulting spectrum without the necessity of complex mathematical processing, in contrast to the traditionally used numerical methods of solution of the inverse problem. However, experimental errors from the fluctuations of aerosol concentration can make the measured penetrations incompatible with any spectrum. Therefore, a smoothing procedure is proposed, which transforms incompatible penetrations into compatible ones within corridor of experimental errors.
An analysis of the optical and microphysical characteristics of aerosol passages over Sofia City, Bulgaria, was performed on the basis of data provided by the AErosol RObotic NETwork (AERONET). The ...data considered are the result of two nearly complete annual cycles of passive optical remote sensing of the atmosphere above the Sofia Site using a Cimel CE318-TS9 sun/sky/lunar photometer functioning since 5 May 2020. The values of the Aerosol Optical Depth (AOD) and the Ångström Exponent (AE) measured during each annual cycle and the overall two-year cycle exhibited similar statistics. The two-year mean AODs were 0.20 (±0.11) and 0.17 (±0.10) at the wavelengths of 440 nm (AOD440) and 500 nm, respectively. The two-year mean AEs at the wavelength pairs 440/870 nm (AE440/870) and 380/500 nm were 1.45 (±0.35) and 1.32 (±0.29). The AOD values obtained reach maxima in winter-to-spring and summer and were about two times smaller than those obtained 15 years ago using a hand-held Microtops II sun photometer. The AOD440 and AE440/870 frequency distributions outline two AOD and three AE modes, i.e., 3 × 2 groups of aerosol events identifiable using AOD–AE-based aerosol classifications, additional aerosol characteristics, and aerosol migration models. The aerosol load over the city was estimated to consist most frequently of urban (63.4%) aerosols. The relative occurrences of desert dust, biomass-burning aerosols, and mixed aerosols were, respectively, 8.0%, 9.1% and 19.5%.
The distribution of key chemicals in mainstream cigarette smoke (MCS) particles of different sizes have implications for respiratory dose. In this study, a differential mobility spectrometer (DMS) ...and an electrical low-pressure impactor (ELPI) were used to characterize MCS particles generated from three cigarettes (3R4F, Dunhill, and Hongtashan). In addition, the ELPI was used to collect smoke particles of three different aerodynamic diameters (144, 431, and 722 nm) from 3R4F MCS, which were analyzed for nicotine, solanesol and tobacco-specific nitrosamines (TSNAs). The number concentration, particle size distribution, and count median diameter (CMD) of the MCS particles characterized by DMS and ELPI were compared quantitatively. The observed difference in the physical characterization results of MCS particles may be due to a myriad of discrepancies between the two techniques. Chemical analyses of the three ELPI selected particle sizes showed that, after normalization to total particulate matter (TPM), nicotine and TSNAs were distributed evenly, whereas solanesol showed a tendency to increase with increasing particle diameter. Notably, the distribution of nicotine and four TSNAs was independent of the three particle sizes; however, the amount of solanesol showed a slight dependency on particle size, varying by less than 23.4% over the size range considered.
In the framework of the World Meteorological Organisation's Sand and Dust Storm Warning Advisory and Assessment System, we evaluated the predictions of five state-of-the-art dust forecast models ...during an intense Saharan dust outbreak affecting western and northern Europe in April 2011. We assessed the capacity of the models to predict the evolution of the dust cloud with lead times of up to 72 h using observations of aerosol optical depth (AOD) from the AErosol RObotic NETwork (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) and dust surface concentrations from a ground-based measurement network. In addition, the predicted vertical dust distribution was evaluated with vertical extinction profiles from the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP). To assess the diversity in forecast capability among the models, the analysis was extended to wind field (both surface and profile), synoptic conditions, emissions and deposition fluxes. Models predict the onset and evolution of the AOD for all analysed lead times. On average, differences among the models are larger than differences among lead times for each individual model. In spite of large differences in emission and deposition, the models present comparable skill for AOD. In general, models are better in predicting AOD than near-surface dust concentration over the Iberian Peninsula. Models tend to underestimate the long-range transport towards northern Europe. Our analysis suggests that this is partly due to difficulties in simulating the vertical distribution dust and horizontal wind. Differences in the size distribution and wet scavenging efficiency may also account for model diversity in long-range transport.
Large sets of filtered actinometer, filtered pyrheliometer and Sun photometer measurements have been carried out over the past 30 years by various groups at different Arctic and Antarctic sites and ...for different time periods. They were examined to estimate ensemble average, long‐term trends of the summer background aerosol optical depth AOD(500 nm) in the polar regions (omitting the data influenced by Arctic haze and volcanic eruptions). The trend for the Arctic was estimated to be between −1.6% and −2.0% per year over 30 years, depending on location. No significant trend was observed for Antarctica. The time patterns of AOD(500 nm) and Ångström's parameters α and β measured with Sun photometers during the last 20 years at various Arctic and Antarctic sites are also presented. They give a measure of the large variations of these parameters due to El Chichon, Pinatubo, and Cerro Hudson volcanic particles, Arctic haze episodes most frequent in winter and spring, and the transport of Asian dust and boreal smokes to the Arctic region. Evidence is also shown of marked differences between the aerosol optical parameters measured at coastal and high‐altitude sites in Antarctica. In situ optical and chemical composition parameters of aerosol particles measured at Arctic and Antarctic sites are also examined to achieve more complete information on the multimodal size distribution shape parameters and their radiative properties. A characterization of aerosol radiative parameters is also defined by plotting the daily mean values of α as a function of AOD(500 nm), separately for the two polar regions, allowing the identification of different clusters related to fifteen aerosol classes, for which the spectral values of complex refractive index and single scattering albedo were evaluated.
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