Main Aerosol Types Research Articles

Analysis of Aerosol Types and Vertical Distribution in Seven Typical Cities in East Asia

Identifying the types and vertical distribution of aerosols plays a significant role in evaluating the influence of aerosols on the climate system. Based on the aerosol optical properties obtained from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), this study analyzed the long-term aerosol characteristics of seven cities in East Asia (Ulaanbaatar, Beijing, Lanzhou, Shanghai, Lhasa, Hong Kong, and Bangkok) from 2007 to 2021, including the spatiotemporal variations of aerosol optical depth (AOD), the vertical stratification characteristics of aerosols, and the main aerosol subtype. The results showed that, except for Lhasa, the AOD values of all cities exhibited a trend of initially increasing and then decreasing over the years. Except for Shanghai, the high values of AOD in the other cities occurred in the spring and summer seasons, while the low values occurred in the autumn and winter seasons. In all four seasons, the AOD contribution within the 1–3 km range accounted for more than 50% of the total. In the autumn and winter seasons, this proportion reached over 80%. The main types of aerosols and their contributions varied at different altitudes. Overall, dust, polluted continental/smoke, polluted dust, and elevated smoke dominated in all aerosol layers across each city. On the other hand, clean marine, clean continental, and dusty marine had very small proportions, accounting for less than 5% of all the cities’ aerosol layers.

Distributions and Direct Radiative Effects of Different Aerosol Types in North China

Different aerosol types exhibit distinct radiative effects in different regions, attributed to their unique optical characteristics and regional distributions. This study focuses on North China, which is impacted by both natural and anthropogenic aerosols with high concentrations and a variety of aerosol types. While many studies on aerosol direct radiative effects have been conducted in this region, the majority have focused on a specific type of aerosol or overall aerosol, leaving limited research on the direct radiative effects and contributions of different aerosol types. In this study, we use CALIPSO satellite data from 2011 to 2020 to investigate concentrations and distributions of different aerosol types. The results reveal that dust, polluted dust, polluted continental/smoke, and elevated smoke are the dominant aerosol types in North China. Based on the radiative closure experiment, we systematically calculate the radiative effects of different aerosol types and their corresponding contributions to the energy budget by combining satellite data with the Fu–Liou radiative transfer model. The annual average net aerosol direct radiative effect (ADRE) of North China is −6.1 and −13.43 W m−2 at the TOA and surface, respectively, causing a net warming effect of 7.33 W m−2 in the atmosphere. For each main aerosol type, dust contributes 93% to the shortwave ADRE in the western dust source region, while polluted dust mainly contributes 31% and 45% of the total ADRE, in Northwest China and North China Plain, respectively. Anthropogenic pollutant aerosols account for 58% of the total ADRE in Northeast China. This study holds great significance in elucidating the dominant aerosol types and their concentrations in North China, comprehending the impacts of different aerosol types on the local energy balance.

Application of Gaussian Mixture Models for aerosol type analysis in China

The relative contributions of different aerosol types to the total aerosol content were determined using sun photometer derived inversion data from four Aerosol Robotic Network (AERONET) stations in China, i.e. Beijing, NUIST, Hong Kong PolyU and SACOL. Five main aerosol types were considered: dust (DU), mixed (MI), urban industry (UI), biomass burning (BB) and maritime (MA). The identification of these aerosol types is based on cluster analysis using Gaussian mixture models (GMMs), together with the Mahalanobis distance (MD) to each reference centroid. The results show that the aerosol types are distinctly different between the different sites as regards fine and coarse particles. MI is the dominant aerosol type at four locations, with the largest contribution at NUIST (73.4%). The largest contribution of DU (18.8%) is observed at SACOL and at Beijing the contribution of UI is largest (33.7%). BB contributions are relatively small, with the largest at NUIST (2.7%). For the analysis, two periods are considered, i.e. before and after the implementation of the national ambient air quality standard (GB3095–2012) in 2012. The clustering results revealed a changing trend in the proportion of UI and MI aerosols in Chinese cities. Although the proportion of UI aerosols has increased, MI aerosols still remain dominant. The proportion of DU in SACOL station also increased. The seasonal analysis shows that DU dominates in spring at the SACOL station (55.3%), which is near the dust source area. Among the other stations, the contribution of DU due to long-range transport from the source regions, is largest (10.6%) in Beijing, with a small contribution at NUIST. The aerosol volume size distributions in different regions exhibit substantial differences due to variations in aerosol types: Beijing and SACOL are dominated by coarse mode particles, while NUIST and Hong Kong PolyU are dominated by fine mode particles.

Analysis of Long‐Term Trends in the Vertical Distribution and Transport Paths of Atmospheric Aerosols in Typical Regions of China Using 15 Years of CALIOP Data

AbstractLong‐range transport and vertical distribution of aerosols are important factors for assessing the uncertainty in aerosol radiative forcing. This paper reveals the vertical distribution and trends of aerosol optical properties in China using 15 years of Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) data. The Hybrid Single‐Particle Lagrangian integrated trajectory model was used to analyze the transport and trends of aerosols in the layer with the highest occurrence frequencies of dust, polluted dust, polluted continental and elevated smoke aerosols. The results indicated that (a) there were significant regional and seasonal differences in the vertical distribution of aerosols. The aerosol optical depth (AOD) trend in a given region depends on the changes in the aerosol type with the highest frequency and the layer corresponding to the largest AOD in the vertical profile. The frequency of polluted dust aerosols was the highest in Beijing‐Tianjin‐Hebei (BTH) and Central China. The considerable decrease in the 0–2 km AOD led to a significant trend of the column AOD. (b) The changes of AOD and main aerosol types in a region are also affected by the changes of aerosol sources and long‐range transport pathways. In the BTH, dust aerosols originated from the Mongolian Plateau, accounting for 57.88% of the total trajectories. The Pearl River Delta was dominated by elevated smoke aerosols, with trajectories mainly originating from the Myanmar and Vietnam, accounting for 27.38% and 29.59%, respectively. The trend of 15‐year backward trajectories of dust aerosols on the Tibetan Plateau indicated that the trajectory from India is increasing.

Difference between global and regional aerosol model classifications and associated implications for spaceborne aerosol optical depth retrieval

AbstractAerosol model are generally adopted to describe the physical and optical characteristics of aerosols in different regions, and this is important for climate and environmental studies as well as satellite aerosol retrieval. However, current mainstream aerosol retrieval algorithms still lack differentiated and dynamic descriptions of aerosol models, and the aerosol optical depth (AOD) retrieval accuracy is hence largely compromised. Therefore, in this study, we aimed to investigate the difference between global and regional aerosol model classifications and the impact of these differences on satellite AOD retrieval. We developed global and regional (for China) aerosol models through the K-means cluster analysis method, and used the 6SV radiative transfer model based on these global and regional aerosol models to simulate air pollution events. The cluster analysis revealed that both global and regional aerosols can be clustered into five main aerosol types with different optical and physical parameters. The aerosol types include strongly absorbing, moderately absorbing, weakly absorbing, dust and coarse-fine mixed aerosols. These two aerosol models exhibited distinct seasonal variations. Comparing the clustering results obtained with the two models at five Aerosol Robotic Network (AERONET) sites, we found that the proportion of strongly absorbing aerosols in the global results is low. According to the China clustering results, a higher proportion of strongly absorbing aerosols occurred in autumn, winter, and early spring, and dust aerosols attained an increasing proportion in spring. Comparing the aerosol parameters with observational data, the regional aerosol model performed better than the global aerosol model. Simulations of AOD during a pollution episode and in different seasons at the Beijing-CAMS site with the 6SV radiative transfer model further confirmed that the regional aerosol model achieved a better simulation accuracy than the global model. The findings suggest that regional aerosol models can provide a useful reference for satellite remote sensing algorithm, climate change and air pollution assessment, and that the dynamic description of the aerosol model is a key parameter in satellite AOD retrieval algorithms.

Satellite-Observed Four-Dimensional Spatiotemporal Characteristics of Maritime Aerosol Types over the Coastal Waters of the Guangdong–Hong Kong–Macao Greater Bay Area and the Northern South China Sea

Aerosol is important to climate and air pollution, and different aerosol types have a non-negligible impact on the environment and climate system. Based on long-term satellite lidar profiles from 2006 to 2020, the four-dimensional (x-y-z-t) spatiotemporal characteristics of different aerosol types, including clean marine (CM), dust (DU), polluted continental/smoke (PC), clean continental (CC), polluted dust (PD), elevated smoke (ES), and dusty marine (DM), over the coastal waters of the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) were revealed for the first time and compared to the surrounding northern South China Sea (NSCS). (1) The dominant aerosol types in both study areas were found to be CM, ES, and DM, whose proportions summed up to more than 85%. In spring, ES was the dominant aerosol type (>40%); in other seasons, CM dominated (>34%). The proportions of anthropogenic aerosols (PC, PD, and ES) and dust-related aerosols (DU, PD, and DM) were higher in spring and winter than in summer and autumn. (2) Vertically, the number of all aerosol types declined with increasing altitude, with the exception of abnormal increase at the heights of approximately 1.5–2.8 km in spring, which was probably attributed to the effect of local and regional anthropogenic pollutants. Below the height of 2 km, the main aerosol types were CM and DM, whereas ES, PD, and DU aerosols were dominant above 2 km. (3) Horizontally, the dominant aerosol types were spatially uniform in the lower atmosphere (<2 km), while higher altitudes (especially > 4 km) showed significant horizontal heterogeneity in space. The proportion of anthropogenic aerosols over the coastal waters of the GBA was higher than that over the NSCS, due to terrestrial pollution transportation. (4) In terms of the long-term trend, the proportion of CM aerosols was found to be steadily increasing, with the anthropogenic aerosols and dust-related aerosols showing a fluctuating and decreasing trend, which resulted from the enforcement of effective air pollution control policies. Overall, the terrestrial aerosol influence tended to decrease in the study areas. The insight into aerosol types and its variation will facilitate the understanding of the aerosol climate effects and pollutant control in the coastal waters of the GBA and the NSCS.

Climatology of Aerosols over the Caribbean Islands: Aerosol Types, Synoptic Patterns, and Transport

Abstract We present a climatological study of aerosols in four representative Caribbean Sea islands that is based on daily mean values of aerosol optical properties for the period 2008–16, using the aerosol optical depth (AOD) and Ångström exponent (AE) to classify the dominant aerosol type. A climatological assessment of the spatiotemporal distribution of the main aerosol types, their links with synoptic patterns, and the transport from different sources is provided. Maximum values of AOD occur in the rainy season, coinciding with the minimum in AE and an increased occurrence of dust, whereas the minimum of AOD occurs in the dry season, due to the predominance of marine aerosols. Marine and dust aerosol are more frequent in the easternmost islands and decrease westward because of an increase of continental and mixture dust aerosols. Therefore, the westernmost station displays the most heterogeneous composition of aerosols. Using a weather-type classification, we identify a quantifiable influence of the atmospheric circulation in the distribution of Caribbean aerosols. However, they can occur under relatively weak and/or diverse synoptic patterns, typically involving transient systems and specific configurations of the Azores high that depend on the considered station. Backward trajectories indicate that dry-season marine aerosols and rainy-season dust are transported by air parcels traveling within the tropical easterly winds. The main source region for both types of aerosols is the subtropical eastern Atlantic Ocean, except for Cuba, where the largest contributor to dry-season marine aerosols is the subtropical western Atlantic. Different aerosol types follow similar pathways, suggesting a key role of emission sources in determining the spatiotemporal distribution of Caribbean aerosols.

Global and Regional Variations and Main Drivers of Aerosol Loadings over Land during 1980–2018

Aerosol particles originated from anthropogenic emissions, volcanic eruptions, biomass burning, and fossil combustion emissions, and their radiative effect is one of the most uncertain factors in climate change. Meanwhile, aerosol particles in fine particle size could also cause irreversible effects on the human respiratory system. This study attempted to analyse the spatial and temporal variations of global aerosol optical depth (AOD, 550 nm) during 1980–2018 using MERRA-2 aerosol reanalysis products and to investigate the effects of natural/anthropogenic emissions of different types of aerosols on AOD values. The results show that the global annual mean AOD values kept high levels with significant fluctuations during 1980–1995 and showed a consistent decreasing and less volatile trend after 1995. Spatially, the AOD values are relatively higher in the Northern Hemisphere than in the Southern Hemisphere, especially in North Africa (0.329), Northern India (0.235), and Eastern China (0.347), because of the intensive natural/anthropogenic aerosol emissions there. The sulphate-based aerosols emitted by biomass burning and anthropogenic emissions are the main types of aerosols worldwide, especially in densely populated and industrialized regions such as East Asia and Europe. Dust aerosols are also the main aerosol type in desert areas. For example, the AOD and AODP values for the Sahara Desert are 0.3178 and 75.32%, respectively. Both black carbon aerosols (BC) and organic carbon aerosols (OC) are primary or secondary from carbon emissions of fossil fuels, biomass burning, and open burning. Thus, the regions with high BC and OC aerosol loadings are mainly located in densely populated or vegetated areas such as East Asia, South Asia, and Central Africa. Sea salt aerosols are mainly found in coastline areas along the warm current pathway. This study could help relevant researchers in the fields of atmospheric science, environmental protection, air pollution, and ecological environment to understand the global spatial–temporal variations and main driving factors of aerosol loadings.

Global Clear-Sky Aerosol Speciated Direct Radiative Effects over 40 Years (1980–2019)

We assess the 40-year climatological clear-sky global direct radiative effect (DRE) of five main aerosol types using the MERRA-2 reanalysis and a spectral radiative transfer model (FORTH). The study takes advantage of aerosol-speciated, spectrally and vertically resolved optical properties over the period 1980–2019, to accurately determine the aerosol DREs, emphasizing the attribution of the total DREs to each aerosol type. The results show that aerosols radiatively cool the Earth’s surface and heat its atmosphere by 7.56 and 2.35 Wm−2, respectively, overall cooling the planet by 5.21 Wm−2, partly counterbalancing the anthropogenic greenhouse global warming during 1980–2019. These DRE values differ significantly in terms of magnitude, and even sign, among the aerosol types (sulfate and black carbon aerosols cool and heat the planet by 1.88 and 0.19 Wm−2, respectively), the hemispheres (larger NH than SH values), the surface cover type (larger land than ocean values) or the seasons (larger values in local spring and summer), while considerable inter-decadal changes are evident. These DRE differences are even larger by up to an order of magnitude on a regional scale, highlighting the important role of the aerosol direct radiative effect for local and global climate.

Remote sensing of aerosol properties during intense smog events over Lahore (Pakistan)

In recent years, smog has been one of the main concerns in heavily populated urban areas like Lahore (Pakistan) and Kanpur (India). Atmospheric pollutants like aerosols play an important role in smog. In this paper, aerosol types are identified in smog episodes, based on Aerosol Robotic Network (AERONET) data, during 4-year period i.e., 2015-2018. Aerosols are classified based on fine mode fraction (FMF) and single scattering albedo (SSA). One of the main aerosol types which are abundant in every smog episode is Black Carbon (BC) aerosol while dust is present throughout the year. BC is responsible for radiation imbalance and is considered the main component in climate changes at regional and global levels. Furthermore, time series of aerosol optical depth (AOD) during smog episodes is used to identify the variability of aerosol burden in the atmosphere. Backward trajectories from the HYSPLIT model are used to trace the origin of aerosols during the days of maximum AOD.

Responses of the Optical Properties and Distribution of Aerosols to the Summer Monsoon in the Main Climate Zones of China

The influence of aerosols on climate varies greatly within different spatial zones. China has a very prominent summer monsoon climate and summer monsoon activity basically determines the climate distribution pattern. Consequently, we need to understand the aerosol optical properties and spatial distribution under the background of summer monsoon activity in China, which is the basis for further research on the impact of aerosols on the climate system. Based on Moderate Resolution Imaging Spectroradiometer (MODIS) and Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) data, the spatial response of the high aerosol optical depth (AOD) region in China to the advance and retreat of summer monsoon was analyzed. The main types of aerosol and the contribution of each type of aerosol particles to the total AOD were discussed. The results showed that before the landing of summer monsoon, the high value areas of AOD were distributed in the eastern Sichuan Basin, Changsha, Wuhan and Pearl River Delta regions. With the northward advance of the monsoon, the high value areas moved to the transition region affected by the summer monsoon and the AOD in this region was highly sensitive to the summer monsoon. The main aerosol types were dust and sulfate in this region and the contribution to total AOD was 27% and 57%, respectively; before the monsoon onset, the contribution of dust to total AOD was 16%, and that of sulfate was 18%; after the monsoon onset, the contribution of dust decreased by half to 8%, while the contribution of sulfate aerosol increased to 20%.

Optical Characteristics and Radiative Properties of Aerosols in Harbin, Heilongjiang Province during 2017

This study considers aerosol optical properties and direct radiative forcing over Harbin (126.63° E, 45.75° N), the highest latitude city in Northeast China, during 2017. Observations based on the CE-318 sun-photometer show that the annual mean values of the aerosol optical depth (AOD) at 500 nm and the Angstrom exponent (AE) at 440–870 nm over Harbin are respectively 0.26 ± 0.20 and 1.36 ± 0.26. Aerosol loading is the highest in the spring followed by winter, and the lowest loading is in autumn. AE440–870 is the highest in summer, second highest in winter, and lowest in autumn. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model is used to estimate the shortwave aerosol radiative forcing at the top of the atmosphere, on the Earth’s surface and in the atmosphere, and the annual mean values are −16.36 ± 18.42 Wm−2, −71.01 ± 27.37 Wm−2 and 54.65 ± 30.62 Wm−2, respectively, which indicate that aerosols cause climate effects of cooling the earth-atmosphere system, cooling the earth’s surface and heating the atmosphere. Four main aerosol types in Harbin are classified via AOD and AE. Specifically, clean continental, mixed type, biomass burning and urban industry, and desert dust aerosols accounted for 51%, 38%, 9%, and 2% of the total, respectively. Aerosol radiative forcing varies greatly in different seasons, and the aerosol load and type from different emission sources have an important influence on the seasonal variation of radiative forcing.

Sensitization Towards Aerosol Optical Properties And Radiative Forcing, Real Case In Morocco

Mineral dust is one of the most important aerosol components in the Earth’s atmosphere. Desert aerosol constitute the main types of tropospheric aerosols whose optical property uncertainties are still quite important. In this study, we analyse the variability of aerosol optical depth (AOD), Angstrôm Exponent (α), Single Scattering Albedo (ω0) and aerosol radiative forcing (ARF) of desert aerosol recent measurements, for six AERONET sites covering the belt desert areas: Ouarzazate (Morocco), Tamanrasset (Algeria), El Farafra (Egypt), Mezaira (Unites Arab Emirates), Kuwait University (Kuwait), Dalanzadgad (Mongolia). The annual cycle of the aerosol optical depth dialy averages shows variable values due to the changeable weather and the Sahara source. The highests were recorded at the Sahara site (2.2 at Tamanrasset) and (2.9 at Kuwait-University). The spectral single scattering albedo SSA annual averages varies in the interval (0,8-0.95) indicating dominant scattering. Desert aerosol radiative forcing shows always a negative ARF with a maximums registred in July, -90 W/m2 at surface (Mezaira) and -26 W/m2 at the top of the atmosphere (Kuwait) that imply a general trend towards regional warming of the total column atmosphere with a maximum near +55 W/m2 observed in July at UAE.

Spatial and Temporal Characteristics of AOD and Angström Exponent in the Yangtze River Delta Based on MODIS_C061

Considering the Yangtze River Delta as the research region, the applicability of the Terra-MODIS C061 deep blue algorithm (DB) AOD products was evaluated using Aerosol Robotic Network (AERONET) ground-based observations. The results demonstrated that the correlation between Terra-MODIS C061 deep blue algorithm (DB) aerosol optical depth (AOD) and AERONET AOD was high (0.95). Characteristics of spatial distribution and temporal variation of AOD and Angström exponent (AE) from 2000 to 2018 in the study area were analyzed using MOD04_L2 products from 2000 to 2018. The results showed that the AOD in the Yangtze River Delta was distributed as "eastern and northern plains high and southern and western mountains low". The AE showed a "northern low and south high" pattern. In terms of temporal distribution, from 2003 to 2007, the annual average AOD increased significantly, with a growth rate of 23%. After 2011, the AOD showed a downward trend. From 2001 to 2003, the annual average of AE rapidly increased, while after 2012, the AE decreased gradually. The AOD showed obvious seasonal changes in the Yangtze River Delta region, with high values in summer and low values in winter. The highest AOD was observed in June (0.84) in all monthly averages, while the lowest was observed in August (0.40). The seasonal average AE was high in autumn and low in spring. The highest AE of 1.47 was observed in September in all monthly averages, and the lowest of 1.08 was observed in March. Aerosol types in the Yangtze River Delta region were investigated according to the relationship between AOD and AE. The results suggested that the urban industrial aerosol was the main aerosol type in the region, followed by mixed type and clean continental aerosols.

Study of the aerosol optical characteristics over the Romanian Black Sea Coast using AERONET data

Present study is focused on the analysis of the similarities and differences in the aerosol properties retrieved from the sun-photometers operating at two sites in Western part of Black Sea, Romanian area, belonging to AERONET network (one on the sea shore at Eforie and the other on the Oil Platform Gloria at about 30 km offshore). Four years data sets (2014–2017) of aerosol optical depth, Ǻngström exponent, single scattering albedo and fine mode fraction, retrieved based on the AERONET algorithms, were used to identify the main aerosol types by season. The study emphasized similar monthly and seasonal variations for aerosol optical properties: mean multi-monthly values of AOD is from 0.1 to 0.3, AE varied between 1 and 2, and FMF varied from 0.7 to about 0.9. The dominant incidence of fine aerosol appears at both sites. Although some annual and seasonal differences between the coastal and marine stations were identified, both sites at the Black See Coast seem to be characterized by same aerosol, with a large fraction of anthropogenic component, composed by fine absorbing and non-absorbing aerosol. Pure marine fraction seems to be present mainly in autumn and in percentages varying from 5% to about 21% of the total mass, depending on the classification scheme. Regardless of the classification scheme used, the results show that dust aerosol is present at both stations less than 10%. Choosing an appropriate threshold range from various schemes to discriminate the aerosol types is not straightforward for sites on Black Sea Coast.

Seasonal variation in particle contribution and aerosol types in Shanghai based on satellite data from MODIS and CALIOP

Although the concentration of atmospheric particulate matter in Shanghai has declined in recent years, aerosols remain one of the major pollutants affecting air quality. Herein, spatio-seasonal variation in aerosol optical properties and aerosol types were studied over a 10-year period (2006–2015) in Shanghai, China, using satellite data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The average aerosol optical depth values for central urban and suburban areas of Shanghai were between 0.9 and 1.0. Clear seasonal variation in aerosol concentrations occurred, causing strongest attenuation in summer and weakest attenuation in autumn. Polluted dust, polluted continental (urban/industrial) and smoke aerosols were the main aerosol types. Desert dust aerosols occurred in the Shanghai area at higher altitudes (greater than 3 km) in spring, related to dusty weather in the north; while in winter, smoke aerosols occurred at high altitudes, related to haze pollution in the north. The aerosols detected in autumn were mainly from local sources, comprising polluted dust, polluted continental, and smoke aerosols. Aerosols in Shanghai clearly reflect both local and regional sources at different times.

Characteristics of Ice Nucleating Particles in and Around California Winter Storms

AbstractA major component of California's yearly precipitation comes from wintertime atmospheric river events which bring large amounts of moisture from the tropics up to the midlatitudes. Understanding these systems, specifically the effects of aerosol particles on precipitation associated with these storms, was a major focus of the 2015 Atmospheric Radiation Measurement Cloud Aerosol Precipitation Experiment, which was part of the wintertime California Water 2015 campaign. The measurement campaign provided sampling platforms on four aircraft, including the Atmospheric Radiation Measurement Aerial Facility G‐1, as well as the National Oceanic and Atmospheric Administration Ronald H. Brown research vessel and at a ground station in Bodega Bay, CA. Measurements of ice nucleating particles (INPs) were made with the Colorado State University Continuous Flow Diffusion Chamber aboard the G‐1, and aerosol filters were collected on the G‐1, at the Bodega Bay site and on the Ronald H. Brown for postprocessing via immersion freezing in the Colorado State University Ice Spectrometer. Aerosol composition was measured aboard the G‐1 with the Aerosol Time‐of‐Flight Mass Spectrometer. Here we present INP concentrations and aerosol chemical compositions during the course of the aircraft campaign. During the atmospheric river event, we found that marine aerosol was the main aerosol type and that marine INPs were dominant at cloud activation temperatures, which is in stark contrast to the dominance of dust INPs during the atmospheric river events in the California Water 2011 campaign.

First two and a half years of aerosol measurements with an AERONET sunphotometer at the Huancayo Observatory, Peru

Abstract: Direct sun measurements with a CIMEL sunphotometer belonging to the AERONET network have been performed in the Huancayo Observatory, Peru, from March 2015 to August 2017, two and a half years, providing for the first time information about aerosols in the specific area. The prevalence of background conditions in the measurement site has been determined for the period of study. These conditions, which constitute more than 80% of cases, are occasionally altered, mainly by high aerosols loading, as a consequence of biomass-burning events. Biomass-burning periods cover every year from mid-July to mid-October. The identification of these periods has been possible through the classification of aerosols in 6 subtypes. The month with the maximum AOD monthly average is September, and in 2016, the absolute maximum value of 0.91 was registered. The mean AOD value for the study period is 0.10 ± 0.07 and the alpha mean value is 1.49 ± 0.36, indicating presence, of small size aerosols. Some aerosol optical properties were analyzed in order to validate the aerosol classification. The aerosol size distribution revealed a bimodal character with a slight predominance of the fine mode, related to the two main types of aerosols: continental and biomass.

Seasonal and vertical distributions of aerosol type extinction coefficients with an emphasis on the impact of dust aerosol on the microphysical properties of cirrus over the Taklimakan Desert in Northwest China

In the present study, the seasonal and vertical distributions of key aerosol types and its extinction coefficient (EC) are investigated with an emphasis on the impact of desert dust aerosols on the microphysical properties of cirrus. For this, we obtained near-simultaneous and collocated datasets retrieved from the CALIPSO (Cloud-Aerosol LiDAR and Infrared Pathfinder Satellite Observations), CloudSat, and MODerate-resolution Imaging Spectroradiometer (MODIS) over the Taklimakan Desert (TMD) area situated in Northwest China during 2006–2011. We found that the main aerosol types prevalent over the TMD region are desert dust (DD), polluted dust (PD), and polluted continental/elevated smoke (PC/SE) which accounted for ∼88.38%, ∼10.81%, and ∼0.47%, respectively. The DD type was the most dominant aerosol type during the total observational period due to the nature of the desert underlying surface, and the frequent dust activities occurred over the region. Further, the concentrations of PD and PC/SE were observed larger in winter compared to the other seasons contributing ∼25.66% and 1.42%, respectively. This is likely attributed to increased burning of fossil fuels used for combustion processes in the cold season over Northwest China. On the other hand, the latitudinal distribution total aerosol loading of EC presented the south-to-north gradient with a declined tendency in all seasons due to enhanced amount of dust aerosols transported from the TMD area. Further, the seasonal mean values of total EC over TMD showed a maximum of 0.021 km−1 appeared in spring, with a minimum (0.017 km−1) in autumn. In addition, we also investigated the impact of dust aerosols on the cirrus microphysical properties namely, ice water content (IWC), ice water path (IWP), ice cloud effective radius (IER), ice number concentration (INC), and ice distribution width (IDW). The results showed that dust aerosol can possibly change the microphysical properties of cirrus over the study domain.

Characterization of aerosol types over Lake Urmia Basin

Atmospheric aerosols affect the Earth's climate, air quality, and thus human health. This study used the Aerosol Optical Depth (AOD) and the Ångström exponent to cluster different particle types over the Lake Urmia Basin. This classification found desert dust and marine (mixed with continental or local-pollution aerosols) as two main aerosol types over the region, while their sources are not well defined. Although different air masses and wind circulation over the study domain in varied months can help to distinguish aerosol sources, measurements are crucial for a complete evaluation.