Study Of Atmospheric Aerosols Research Articles

Quantitative assessment of the potential of optimal estimation for aerosol retrieval from geostationary weather satellites in the frame of the iAERUS‐GEO algorithm

AbstractSatellite remote sensing enables the study of atmospheric aerosols at large spatial scales, with geostationary platforms making this possible at sub‐daily frequencies. High‐temporal‐resolution aerosol observations can be made from geostationary data by using robust numerical inversion methods such as the widely‐used optimal estimation (OE) theory. This is the case of the instantaneous Aerosol and surfacE Retrieval Using Satellites in GEOstationary orbit (iAERUS‐GEO) algorithm, which successfully retrieves aerosol optical depth (AOD) maps from the Meteosat Second Generation weather satellite based on a simple implementation of the OE approach combined with the Levenberg–Marquardt method. However, the exact gain in inversion performances that can be obtained from the multiple and more advanced possibilities offered by OE is not well documented in the current literature. Against this background, this article presents the quantitative assessment of OE for the future improvement of the iAERUS‐GEO algorithm. To this end, we use a series of comprehensive experiments based on AOD maps retrieved by iAERUS‐GEO using different OE implementations, and ground‐based observations used as reference data. First, we assess the varying importance in the inversion process of satellite observations and a priori information according to the content of satellite aerosol information. Second, we quantify the gain of AOD estimation in log space versus linear space in terms of accuracy, AOD distribution and number of successful retrievals. Finally, we evaluate the accuracy improvement of simultaneous AOD and surface reflectance retrieval as a function of the regions covered by the Meteosat Earth's disk.

Hygroscopic growth and collision studies of atmospheric aerosols across scaled particle sizes

In this paper, the hygroscopic growth and collision evolution of ammonium sulfate droplets are calculated at both the continuum and transition regime scales, and the results show that the variation of particle size across the scales will have a significant effect on the direction and degree of hygroscopic evolution of particles as well as the number of new particles generated by collision. At the continuum regime scale, solute effects determine whether water vapor condenses on the particle surface or escapes into the atmosphere. At the transition regime scale, curvature effects will result in an 80% overestimation of the hygroscopic growth of ammonium sulfate droplets and a threefold increase in the time to reach hygroscopic equilibrium. Collision results show that the droplet concentration decreased by 97% for 25 nm droplets, and increased by 13% for 250 nm droplets, which suggests that small droplets are more influenced by collision.

Lidar ratio calculations from in situ aerosol optical, microphysical and chemical measurements: Observations at puy de Dôme, France and analysis with CALIOP

The ratio between lidar extinction and backscatter coefficients, also known as lidar ratio (LR), is an important parameter in atmospheric aerosol studies. In this paper, we propose a method to determine the 532 nm LR using in situ measurements performed over the 2015–2016 period at the puy de Dôme (PUY) station, central France, located at about 1465 m altitude. This method uses a Mie code with the measured aerosols size distribution and refractive index determined from aerosols optical measurements as inputs. The LR values obtained have been compared to LR calculated also with a Mie code but with refractive index determined from the measured aerosol chemical composition. A good correlation is observed for the period 2015–2016 with an agreement which increases to 99% after a significant imaginary part refractive index reduction, corresponding to much less carbonated particles than initially estimated. >50% of the LR values calculated at the station are within the 60–80 sr range under ambient atmospheric conditions. A statistical comparison with the CALIOP spatial lidar retrieval gives a good agreement at the location of PUY between retrieved values (62 sr) with a negligible bias and a dispersion indicative of a similar variability of LR (about 14 sr). The influence of air mass history on the LR has also been studied using backward trajectory analysis and CALIOP aerosol types along the trajectories, identifying five source regions. For continental, smoke and polluted dust aerosols types, CALIOP and PUY LR show a good agreement. For dusty and mainly clean marine aerosols, the differences observed between both suggest that air masses coming from the Atlantic Ocean sector at altitudes lower than 2.5 km, have experienced mixing with continental air masses during their travel increasing their LR before reaching the PUY station.

Study of Atmospheric Aerosol in the Baikal Mountain Basin with Shipborne and Ground-Based Lidars

The results of long-term lidar studies of the peculiarities of the vertical structure of atmospheric aerosols over Lake Baikal are presented. The paper provides an analysis of data obtained over the period from 2010 to 2022. The studies were carried out under both the background conditions and the extreme natural conditions associated with severe wildfires in Siberia. The parameters of the lidars used in regular summer expeditions to Lake Baikal are briefly described. The data analysis shows that the vertical structure of the aerosol in the lower troposphere up to 2000 m above Baikal in summer is often a stable structure of several aerosol layers tens to hundreds of meters thick. There can be no mixing of layers because the water in the lake is very cold and the aerosol does not rise to higher layers while the air is warming up during the day. The difference is shown between the spatiotemporal structures of aerosol plumes from local wildfires within the lake area and from distant sources. The Angstrom parameter and the aerosol optical depth are calculated for different atmospheric conditions: ηβ = 1.57 ± 0.16 and τ = 0.09 for background conditions; ηβ = 1.41 ± 0.07 and τ = 0.64 for the cases of the observation of smoke aerosol from distant wildfires; and ηβ = 1.05 ± 0.08 and τ = 0.25 for the cases of the observation of smoke aerosol from nearby wildfires.

Capturing High‐Resolution Air Pollution Features Using the Multi‐Scale Infrastructure for Chemistry and Aerosols Version 0 (MUSICAv0) Global Modeling System

AbstractThe Multi‐Scale Infrastructure for Chemistry and Aerosols (MUSICA) enables the study of atmospheric chemistry and aerosols at global to local scales. MUSICA version 0 (MUSICAv0) is a configuration of the Community Earth System Model (CESM) with regional refinement (RR). We compared the regional scale spatial and temporal variabilities of air pollutants simulated by this newly developed multiscale model and a widely used regional model—WRF‐Chem (the Weather Research and Forecasting model coupled with Chemistry). The O3 and PM2.5 mean biases of the two WRF‐Chem simulations over the U.S. are 5–9 ppb and −3 μg/m3 during August and September 2020. The MUSICAv0 simulation has larger O3 mean bias (11 ppb) but smaller PM2.5 mean bias (−1 μg/m3) compared to the two WRF‐Chem simulations. As indicated by spatial and temporal statistical measures, the variability in meteorological parameters (temperature, precipitation), and ozone and PM2.5 are similar across a range of temporal and spatial scales in MUSICAv0 and WRF‐Chem. We demonstrate the new capability of the global MUSICAv0 at regional scale through two examples—(a) plumes from western U.S. fires that passed through the domain boundary of WRF‐Chem and were transported back into the domain and impacted air quality on the eastern U.S.; and (b) impact of stratospheric intrusion on the troposphere.

Single-Particle Analysis of Atmospheric Aerosols: Applications of Raman Spectroscopy

Atmospheric aerosols, produced as a consequence of different anthropogenic and natural processes, impart significant control over the global energy budget, climate, and human–environmental health. Their size varies across the nano–micrometer scale. Based on their origin, they may be classified into primary or secondary aerosols. Biomass burning, incomplete combustion of fossil fuels, volcanic eruptions, and traffic-related and wind-driven suspensions contribute to primary aerosol emissions. In contrast, gas-to-particle conversion within the atmosphere leads to secondary particle production. The study of atmospheric aerosols is vital to the field of atmospheric research. The dynamic nature (highly variable concentration composition and size with space and time) of aerosols makes them difficult to investigate. Today, aerosol research involves the application of various spectrometric and spectroscopic techniques. The single-particle analysis of aerosols is yet a challenge. In this review, the merits and demerits of various offline and online techniques used for aerosol research are discussed in a nutshell. Mass spectrometric techniques fail in distinguishing certain species. However, Raman spectroscopy’s emergence for the compositional analysis of aerosols resolves most of the present characterization challenges. This review focuses on Raman spectroscopy applications, the merits of this technique, and its immense scope for the measurement of various types of aerosols and their properties. Surface-enhanced Raman spectroscopy (SERS) has an advantage over conventional micro-Raman spectroscopy (MRS). The review depicts the dominance of SERS, specifically in the context of the measurement of ambient atmospheric aerosols. This review discusses two important components, namely laboratory simulation and ambient aerosol studies.

Circular polarization in atmospheric aerosols

Abstract. Recent technological advances have demonstrated the feasibility of deploying spaceborne optical detectors with full polarimetric capabilities. The measurement of all four Stokes coefficients opens significant new opportunities for atmospheric aerosol studies and applications. While considerable amounts of attention have been dedicated to sensors with sensitivity to the total intensity and linear polarization (represented by Stokes coefficients I, U, Q), there has been less attention to the additional information brought by measuring circular polarization (coefficient V). This report fills this gap in knowledge by providing an overview of aerosol sources of circular polarization in the atmosphere and discusses possible remote sensing signatures. In this paper, circularly polarized radiation that results from the interaction of incident unpolarized radiation is considered in three physical settings: optical activity originating in biogenic aerosols, alignment of non-spherical particles in the presence of electrical fields (such as dust, smoke, and volcanic ash), and aerosol multiple scattering effects. Observational and theoretical evidence of, and the settings and conditions for, non-zero aerosol circular polarization generated from incident unpolarized radiation are here gathered and discussed. In addition, novel radiative transfer simulations are shown to illustrate notable spectral and other features where circular polarization may provide additional information that is possibly independent from total intensity and linear polarization-only observations. Current techniques for the detection of aerosol composition (also referred as aerosol type) from space provide limited information. Remote identification of aerosols such as smoke, volcanic ash, and dust particles can only be accomplished with some degree of confidence for moderate to high concentrations. When the same aerosols are found at lower concentrations (but still high enough to be of importance for air quality and cloud formation), these methods often produce ambiguous results. The circular polarization of aerosols is rarely utilized, and we explore its value for improved determination aerosol composition. This study is presented as an overview with a goal to provide a new perspective on an overlooked optical property and to trigger interest in further exploration of this subject.

Evidence of human impact in Antarctic region by studying atmospheric aerosols

Air quality is a global concerning topic because of its great impact on the environment and health. Because of that, the study of atmospheric aerosols looking for harmful pollutants is rising, as well as the interest in the origin of the contaminants. Depending on the nature and size of the aerosols, some elements can be detected at a great distance from the emission source, even in Antarctica, where this study is conducted. Several samples of PM filters from 2018 to 2019 (Deception Island) and 2019–2020 (Livingston Island) campaigns have been analyzed by three powerful spectroscopic techniques: FESEM (Field Emission Scanning Electron Microscopy), LIBS (Laser Induced Breakdown Spectroscopy), and ICP-MS (Inductively Coupled Plasma Mass Spectrometry). These techniques have allowed us to find some heavy metals in the air of the Antarctic region (Al, Fe, Ti, Ni, Cr, and Mn). Deeper studies on ICP-MS results have confirmed those results and have also provided information on their potential sources. Thus, while Al, Fe, Ti and Mn concentrations can be explained by crustal origin, Ni and Cr presented high values only coherent with important human contribution. The results point out that the Antarctic region is no longer a clean and isolated environment from human pollution.

A deep study on real-time atmospheric aerosols and variability over Indian subcontinent environment

Study of atmospheric aerosols is very complex owing to their short life time and, chemical constituents. Aerosol loading is highly regional and there life time is very short. An attempt has been made in this paper to study the variability of atmospheric aerosols over Indian subcontinent using a statistical parameter Coefficient of Variation (COV). The magnitude of variability over this region is studied. The factors influencing the variability are studied to find the reasons for difference in magnitude over different regions. Rainfall naturally influences the variability aerosols due to scavenging, but if it is the only factor influencing the variability, the study is absurd. It is found that the influence of rainfall on COV is not pronounced as it is not a seasonal phenomenon. Influence of other parameters viz. Topography, wind vector, thermal power plants and population on variability of aerosols is clearly found. These results help in classifying aerosol zones on the basis of variability of aerosol optical depth. The study also helps in finding the cause of aerosol loading over a region. Measures can be taken to decrease the loading if it is due to local sources.

Terrestrial lipid biomarkers in marine aerosols over the western North Pacific during 1990–1993 and 2006–2009

Terrestrial lipid biomarkers are one of the key tracers in the studies of atmospheric aerosols. Here, we investigated such organic compounds in marine aerosols collected at Chichijima Island, the western North Pacific for two 4-year periods: 1990–1993 and 2006–2009. A homologous series of lipid biomarkers including C18–C37n-alkanes, C9–C34 fatty acids, and C14–C35 fatty alcohols were determined by gas chromatography/mass spectrometry (GC/MS). The atmospheric levels of these tracers increased from 1990–1993 to 2006–2009. Their seasonal trends were clearly characterized by winter–spring maxima and summer–fall minima. The relative abundance of the high-molecular-weight (HMW) n-alkanes (C25–C37) and n-alcohols (C20–C35) in total HMW lipids peaked in winter and winter/fall, respectively, whereas those of HMW fatty acids (C20–C34) peaked in summer. Air-mass backward trajectory analyses suggest that the Asian continent, Southeast Asia including tropical regions, and the Central Pacific are the main source regions. The seasonal shift and distribution of the carbon preference index and average chain length for the HMW lipids were controlled by the changes in climatic factors and source regions. The higher abundance of terrestrial lipids during 2006–2009 than 1990–1993 indicates a higher emission from terrestrial plantation in the 2000s than in the early 1990s in upwind regions of East Asia. Furthermore, HMW lipid compounds exhibited much stronger positive correlations with levoglucosan, a biomass-burning tracer, during 2006–2009 than 1990–1993, suggesting that biomass-burning emissions contributed more significantly in this century.

Heterogeneous Nucleation of Butanol on NaCl: A Computational Study of Temperature, Humidity, Seed Charge, and Seed Size Effects.

Using a combination of quantum chemistry and cluster size distribution dynamics, we study the heterogeneous nucleation of n-butanol and water onto sodium chloride (NaCl)10 seeds at different butanol saturation ratios and relative humidities. We also investigate how the heterogeneous nucleation of butanol is affected by the seed size through comparing (NaCl)5, (NaCl)10, and (NaCl)25 seeds and by seed electrical charge through comparing (Na10Cl9)+, (NaCl)10, and (Na9Cl10)− seeds. Butanol is a common working fluid for condensation particle counters used in atmospheric aerosol studies, and NaCl seeds are frequently used for calibration purposes and as model systems, for example, sea spray aerosol. In general, our simulations reproduce the experimentally observed trends for the NaCl–BuOH–H2O system, such as the increase of nucleation rate with relative humidity and with temperature (at constant supersaturation of butanol). Our results also provide molecular-level insights into the vapor–seed interactions driving the first steps of the heterogeneous nucleation process. The main purpose of this work is to show that theoretical studies can provide molecular understanding of initial steps of heterogeneous nucleation and that it is possible to find cost-effective yet accurate-enough combinations of methods for configurational sampling and energy evaluation to successfully model heterogeneous nucleation of multicomponent systems. In the future, we anticipate that such simulations can also be extended to chemically more complex seeds.

Production Flux and Chemical Characteristics of Spray Aerosol Generated From Raindrop Impact on Seawater and Soil

AbstractRaindrops impacting water or soil generate bubbles, which can burst and eject spray aerosols. However, aerosols resulting from raindrop impact are often overlooked in atmospheric aerosol studies, and their production flux and chemical characteristics have not been quantified. Here we measured the production rate, size distribution, and chemical composition of spray aerosols from laboratory simulations of raindrops impinging on seawater and soils. It was found that the number of spray aerosols produced from each raindrop impact on seawater grows exponentially with increasing raindrop diameter. The spray aerosol production flux was then calculated for a range of rain rates. The spray aerosol production rate from raindrop impact on soil was approximately one order of magnitude lower than that from impact on seawater, but the production rate was enhanced drastically when water ponded on the soil surface. The chemical compositions of the generated spray aerosols were characterized by a single particle mass spectrometer. Generally, spray aerosol from raindrop impact on seawater contained sodium, potassium, calcium, and other metals as well as some organic carbon. The spray aerosols from raindrop impact on soils contained metals and some organic carbon. These aerosol production flux and composition findings are critical to identification of raindrop impact produced aerosols and further investigation of their roles in the atmosphere.

How a small accelerator can be useful for interdisciplinary applications: the study of air pollution

There are an increasing number of articles in the scientific literature dealing with the study of atmospheric aerosol because it has negative impacts on human health, atmospheric visibility and a role in the radiative forcing. Particle-induced X-ray emission (PIXE) has been used since its birth for the study of the aerosol composition, and for a long time, it has been the dominating technique for its elemental analysis. However, nowadays other competitive techniques play a dominant role, such as inductively coupled plasma–mass/atomic emission spectroscopy, energy-dispersive X-ray fluorescence and synchrotron radiation. Therefore, it is important to find specific applications where it can give unique information or the final results in a far simpler way. Furthermore, a proper experimental setup must be used to fully exploit the potential of PIXE. Thanks to the capability of detecting all the crustal elements, PIXE analyses are unrivaled in the study of mineral dust. Among the detectable elements, there are also important markers of anthropogenic sources, which allow effective source apportionment studies in polluted urban environments using multivariate methods. Examples regarding recent monitoring campaigns will be presented to show how PIXE is still on the cutting edge for the study of particulate matter.

Determination of 7Be, 210Pb and 22Na Activity in Air and Rainwater samples by Gamma-ray Spectroscopy

The activity concentration of cosmogenic radionuclides in atmospheric aerosol has been used in many applications, such as air mass transport models and solar activity reconstructions. One of the most studied cosmogenic radionuclides is 7Be which is being monitored at the Nuclear Engineering Department of the National Technical University of Athens (NED- NTUA) since many years, with high accuracy and precision. Sodium-22 is another cosmogenic radionuclide met in such studies, however less reported due to its very low activity concentration, of the order of 1 μBq/m3 [1], [2] – roughly four orders of magnitude lower than that of 7Be. Besides cosmogenic radionuclides, radionuclides of terrestrial origin like the 222Rn progeny 210Pb are also used in atmospheric aerosol studies. Lead-210 serves as an ideal tracer of continental air masses because 222Rn emission from oceans and lakes is negligible (<1%) compared to land sources. However, its deposition exhibits geographic and seasonal variations depending on 226Ra content of the top soils, soil-porosity and meteorology of a particular region [3]. Values reported for 210Pb activity in the air range from 0.1 to 3.4 mBq/m3 [4]. During this research, an investigation regarding the detection of 210Pb and 22Na in atmospheric aerosol and the determination of 7Be/22Na ratio has been conducted at NED-NTUA. Sampling and analysis methods were appropriately selected to allow for the detection of all three nuclides in aerosol samples. In order to study the role of precipitation in surface air 7Be, 210Pb and 22Na activity concentration, a procedure for collecting and analyzing rainwater was also developed. From the results obtained so far it is concluded that with the sampling and analysis procedures followed, 210Pb can be easily determined with reasonable accuracy. As far as 22Na is concerned, it was concluded that it can be detected although with high uncertainty, since its activity concentration is within the limits of detection.

Ionic content in an ice core from the West Antarctic Ice Sheet: 1882-2008 A.D.

The study of atmospheric aerosols through polar ice cores is one of the most common and robust tools for the investigation of past changes in the circulation and chemistry of the atmosphere. Only a few subannual resolution records are available for the development of paleochemical and environmental interpretations. Here, we report the ionic content record for the period of 1882–2008 A.D. in an ice core recovered at the ice divide of the West Antarctic Ice Sheet. The ion concentrations found in the core were determined by ion chromatography on more than 2,000 samples and the basic statistics were calculated for major inorganic and organic ions. The dating of the core layers was based on the seasonality of SO 4 2‑ , NO 3 - , and Na + , checked by the identification of the Krakatau (1883), Agung (1963) and Pinatubo/Hudson (1991) volcanic eruption signals. Significant aerosol input events were identified and grouped considering the ions present, their provenance and the season. The ionic balance, together with the decomposition of some origin indicators, showed that 36% of the ionic charge is derived from sea salt aerosols, 13% from mineral dust, and 17% from biogenic marine activity, while 34% are mainly products of chemical reactivity in the atmosphere.

Wavelet Analysis of Atmospheric Aerosols as Ambient Air Pollutants

Atmospheric aerosols, also known as atmospheric particulate matter or suspended particulate matter (SPM), are microscopic solid or liquid matter suspended in Earth's atmosphere that are transported and dispersed in the atmosphere. Study of atmospheric aerosols as ambient air pollutants has attracted the great interest of scientists due to the effect on human health and its major role in climate change. Reduced lung function, development in respiratory diseases and premature death are the effect of long-term exposure to ambient air pollution. The atmospheric aerosols affect the climate of the earth by changing the amount of incoming solar radiation and outgoing terrestrial long wave radiation retained in the earth's system and their climate effects are the biggest source of uncertainty in future climate predictions. Wavelet transforms provide excellent analysis of non-stationary time series and extracts important hidden information from a signal or data set. For the data set of SPM and RSPM of Moradabad for given time interval, Haar wavelet transform of Level1 is applied. Skewness and Kurtosis parameter describes the lack of the symmetry of data and correlation coefficient between SPM and RSPM describes the linear relationship between them.

Characterization of aerosol loading in urban and suburban locations: Impact on atmospheric extinction

The study of atmospheric aerosols remains a very strong factor in the understanding of the Earth’s climate and predicting the air quality within any given environment. In view of this, analysis of ...

Development of an atmospheric polarization Scheimpflug lidar system based on a time-division multiplexing scheme.

A polarization Scheimpflug lidar system based on the Scheimpflug principle has been developed by employing two linearly polarized 808nm laser diodes and a complementary metal-oxide-semiconductor (CMOS) image sensor. The polarization of one laser diode is rotated 90° by a half-wave plate. The two laser beams with orthogonal polarizations are combined by a polarization beam splitter and transmitted into the atmosphere. The corresponding parallel- and perpendicular-polarized backscattering echoes are detected by the 45° tilted CMOS sensor using a time-division multiplexing scheme. A 24h continuous atmospheric vertical profiling of the depolarization ratio has been performed by using the polarization Scheimpflug lidar system. The promising results successfully demonstrated that the present lidar system has potential for the polarization studies of atmospheric aerosols.

Study of atmospheric aerosols by IBA techniques: The LABEC experience

Abstract At the 3 MV Tandetron accelerator of the LABEC laboratory of INFN (Florence, Italy) an external beam facility is fully dedicated to PIXE-PIGE measurements of the elemental composition of atmospheric aerosols. All the elements with Z > 10 are simultaneously detected by PIXE typically in one minute. This setup allows us an easy automatic positioning, changing and scanning of samples collected by different kinds of devices: long series of daily PM (Particulate Matter) samples can be analysed in short times, as well as size-segregated and high time-resolution aerosol samples. Thanks to the capability of detecting all the crustal elements, PIXE-PIGE analyses are unrivalled in the study of mineral dust: consequently, they are very effective in the study of natural aerosols, like, for example, Saharan dust intrusions. Among the detectable elements there are also important markers of anthropogenic sources, which allow effective source apportionment studies in polluted urban environments using a multivariate method like Positive Matrix Factorization (PMF). Examples regarding recent monitoring campaigns, performed in urban and remote areas, both daily and with high time resolution (hourly samples), as well as with size selection, are presented. The importance of the combined use of the Particle Induced Gamma Ray emission technique (PIGE) and of other complementary (non-nuclear) techniques is highlighted.

Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall.

The nucleation of atmospheric vapours is an important source of new aerosol particles that can subsequently grow to form cloud condensation nuclei in the atmosphere. Most field studies of atmospheric aerosols over continents are influenced by atmospheric vapours of anthropogenic origin (for example, ref. 2) and, in consequence, aerosol processes in pristine, terrestrial environments remain poorly understood. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions, but the origin of small aerosol particles that grow into cloud condensation nuclei in the Amazon boundary layer remains unclear. Here we present aircraft- and ground-based measurements under clean conditions during the wet season in the central Amazon basin. We find that high concentrations of small aerosol particles (with diameters of less than 50 nanometres) in the lower free troposphere are transported from the free troposphere into the boundary layer during precipitation events by strong convective downdrafts and weaker downward motions in the trailing stratiform region. This rapid vertical transport can help to maintain the population of particles in the pristine Amazon boundary layer, and may therefore influence cloud properties and climate under natural conditions.