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Aerosol Types
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Chris A. Hostetler – One of the best experts on this subject based on the ideXlab platform.
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improving estimates of pm2 5 concentration and chemical composition by application of high spectral resolution lidar hsrl and creating Aerosol Types from chemistry catch algorithm
Atmospheric Environment, 2021Co-Authors: N Meskhidze, K. W. Dawson, Chris A. Hostetler, Matthew S. Johnson, Bethany Sutherland, Xinyi Ling, Barron H Henderson, Richard A. FerrareAbstract:Abstract Improved characterization of ambient PM2.5 mass concentration and chemical speciation is a topic of interest in air quality and climate sciences. Over the past decades, considerable efforts have been made to improve ground-level PM2.5 using remotely sensed data. Here we present two new approaches for estimating atmospheric PM2.5 and chemical composition based on the High Spectral Resolution Lidar (HSRL)-retrieved Aerosol extinction values and Types and Creating Aerosol Types from Chemistry (CATCH)-derived Aerosol chemical composition. The first methodology (CMAQ-HSRL-CH) improves EPA’s Community Multiscale Air Quality (CMAQ) predictions by applying variable scaling factors derived using remotely-sensed information about Aerosol vertical distribution and Types and the CATCH algorithm. The second methodology (HSRL-CH) does not require regional model runs and can provide atmospheric PM2.5 mass concentration and chemical speciation using only the remotely sensed data and the CATCH algorithm. The resulting PM2.5 concentrations and chemical speciation derived for NASA DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality) Baltimore-Washington, D.C. Corridor (BWC) Campaign (2011) are compared to surface measurements from EPA’s Air Quality Systems (AQS) network. The analysis shows that the CMAQ-HSRL-CH method leads to considerable improvement of CMAQ’s predicted PM2.5 concentrations (R2 value increased from 0.37 to 0.63, the root meanmean square error (RMSE) was reduced from 11.9 to 7.2 μg m-3, and the normalized mean bias (NMB) was lowered from -46.0 to 4.6%). The HSRL-CH method showed statistics (R2=0.75, RMSE=8.6 μgm-3, and NMB=24.0%), which were better than the CMAQ prediction of PM2.5 alone and analogous to CMAQ-HSRL-CH. In addition to mass concentration, HSRL-CH can also provide Aerosol chemical composition without specific model simulations. We expect that the HSRL-CH method will be able to make reliable estimates of PM2.5 concentration and chemical composition where HSRL data are available.
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creating Aerosol Types from chemistry catch a new algorithm to extend the link between remote sensing and models
Journal of Geophysical Research, 2017Co-Authors: K. W. Dawson, Nicholas Meskhidze, Matthew S. Johnson, Meloë Kacenelenbogen, S P Burton, Chris A. HostetlerAbstract:Current remote sensing methods can identify Aerosol Types within an atmospheric column, presenting an opportunity to incrementally bridge the gap between remote sensing and models. Here a new algorithm was designed for Creating Aerosol Types from CHemistry (CATCH). CATCH-derived Aerosol Types—dusty mix, maritime, urban, smoke, and fresh smoke—are based on first-generation airborne High Spectral Resolution Lidar (HSRL-1) retrievals during the Ship-Aircraft Bio-Optical Research (SABOR) campaign, July/August 2014. CATCH is designed to derive Aerosol Types from model output of chemical composition. CATCH-derived Aerosol Types are determined by multivariate clustering of model-calculated variables that have been trained using retrievals of Aerosol Types from HSRL-1. CATCH-derived Aerosol Types (with the exception of smoke) compare well with HSRL-1 retrievals during SABOR with an average difference in Aerosol optical depth (AOD) <0.03. Data analysis shows that episodic free tropospheric transport of smoke is underpredicted by the Goddard Earth Observing System– with Chemistry (GEOS-Chem) model. Spatial distributions of CATCH-derived Aerosol Types for the North American model domain during July/August 2014 show that Aerosol type-specific AOD values occurred over representative locations: urban over areas with large population, maritime over oceans, smoke, and fresh smoke over typical biomass burning regions. This study demonstrates that model-generated information on Aerosol chemical composition can be translated into Aerosol Types analogous to those retrieved from remote sensing methods. In the future, spaceborne HSRL-1 and CATCH can be used to gain insight into chemical composition of Aerosol Types, reducing uncertainties in estimates of Aerosol radiative forcing.
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Creating Aerosol Types from CHemistry (CATCH): A New Algorithm to Extend the Link Between Remote Sensing and Models
Journal of Geophysical Research: Atmospheres, 2017Co-Authors: K. W. Dawson, Nicholas Meskhidze, Sharon Burton, Matthew S. Johnson, Meloë Kacenelenbogen, Chris A. HostetlerAbstract:Current remote sensing methods can identify Aerosol Types within an atmospheric column, presenting an opportunity to incrementally bridge the gap between remote sensing and models. Here a new algorithm was designed for Creating Aerosol Types from CHemistry (CATCH). CATCH-derived Aerosol Types—dusty mix, maritime, urban, smoke, and fresh smoke—are based on first-generation airborne High Spectral Resolution Lidar (HSRL-1) retrievals during the Ship-Aircraft Bio-Optical Research (SABOR) campaign, July/August 2014. CATCH is designed to derive Aerosol Types from model output of chemical composition. CATCH-derived Aerosol Types are determined by multivariate clustering of model-calculated variables that have been trained using retrievals of Aerosol Types from HSRL-1. CATCH-derived Aerosol Types (with the exception of smoke) compare well with HSRL-1 retrievals during SABOR with an average difference in Aerosol optical depth (AOD)
D G Kaskaoutis – One of the best experts on this subject based on the ideXlab platform.
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identification of key Aerosol Types and mixing states in the central indian himalayas during the gvax campaign the role of particle size in Aerosol classification
Science of The Total Environment, 2021Co-Authors: U C Dumka, D G Kaskaoutis, N Mihalopoulos, Rahul SheoranAbstract:Abstract Studies in Aerosol properties, Types and sources in the Himalayas are important for atmospheric and climatic issues due to high Aerosol loading in the neighboring plains. This study uses in situ measurements of Aerosol optical and microphysical properties obtained during the Ganges Valley Aerosol eXperiment (GVAX) at Nainital, India over the period June 2011–March 2012, aiming to identify key Aerosol Types and mixing states for two particle sizes (PM1 and PM10). Using a classification matrix based on SAE vs. AAE thresholds (scattering vs. absorption Angstrom exponents, respectively), seven Aerosol Types are identified, which are highly dependent on particle size. An Aerosol type named “large/BC mix” dominates in both PM1 (45.4%) and PM10 (46.9%) mass, characterized by aged BC mixed with other Aerosols, indicating a wide range of particle sizes and mixing states. Small particles with low spectral dependence of the absorption (AAE
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In situ identification of Aerosol Types in Athens, Greece, based on long-term optical and on online chemical characterization
Atmospheric Environment, 2021Co-Authors: D G Kaskaoutis, U C Dumka, Georgios Grivas, Iasonas Stavroulas, Eleni Liakakou, Konstantinos Dimitriou, Evangelos Gerasopoulos, N MihalopoulosAbstract:Abstract Absorption Angstrom Exponent (AAE) and Scattering Angstrom Exponent (SAE) values, derived from aethalometer and nephelometer measurements during a period of 3 years at an urban background site in Athens, are combined for the first Aerosol type classification using in situ measurements in the eastern Mediterranean. In addition, single scattering albedo (SSA) and its wavelength dependence (dSSA), as well as the chemical composition of fine Aerosols and precursor gases from collocated measurements, are utilized to provide further insights on the optical-chemical characterization and related sources of seven identified Aerosol Types. Urban Aerosols are mostly characterized as Black Carbon (BC)-dominated (76.3%), representing a background atmosphere where fossil-fuel combcombustion is dominant throughout the year, while 14.3% of the cases correspond to the mixed Brown Carbon (BrC)-BC type, with a higher frequency in winter. The BrC type is associated with the highest scattering and absorption coefficients during winter nights, representing the impact from residential wood-burning emissions. Dust mixed with urban pollution (1.2%) and large particles mixed with BC (5.3%) have a higher frequency in spring. Furthermore, aging processes and BC coating with organic and inorganic species with weak spectral absorption (AAE
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Identification of key Aerosol Types and mixing states in the central Indian Himalayas during the GVAX campaign: the role of particle size in Aerosol classification
The Science of the total environment, 2020Co-Authors: U C Dumka, D G Kaskaoutis, N Mihalopoulos, Rahul SheoranAbstract:Studies in Aerosol properties, Types and sources in the Himalayas are important for atmospheric and climatic issues due to high Aerosol loading in the neighboring plains. This study uses in situ measurements of Aerosol optical and microphysical properties obtained during the Ganges Valley Aerosol eXperiment (GVAX) at Nainital, India over the period June 2011-March 2012, aiming to identify key Aerosol Types and mixing states for two particle sizes (PM1 and PM10). Using a classification matrix based on SAE vs. AAE thresholds (scattering vs. absorption Angstrom exponents, respectively), seven Aerosol Types are identified, which are highly dependent on particle size. An Aerosol type named “large/BC mix” dominates in both PM1 (45.4%) and PM10 (46.9%) mass, characterized by aged BC mixed with other Aerosols, indicating a wide range of particle sizes and mixing states. Small particles with low spectral dependence of the absorption (AAE < 1) account for 31.6% and BC-dominated Aerosols for 14.8% in PM1, while in PM10, a large fraction (39%) corresponds to “large/low-absorbing” Aerosols and only 3.9% is characterized as “BC-dominated”. The remaining Types consist of mixtures of dust and local emissions from biofuel burning and display very small fractions. The main optical properties e.g. spectral scattering, absorption, single scattering albedo, activation ratio, as well as seasonality and dependence on wind speed and direction of identified Types are examined, revealing a large influence of air masses originating from the Indo-Gangetic Plains. This indicates that Aerosols over the central Himalayas are mostly composed by mixtures of processed and transported polluted plumes from the plains. This is the first study that identifies key Aerosol populations in the central Indian Himalayas based on in situ measurements and the results are highly important for Aerosol-type inventories, chemical transport models and reducing the uncertainty in Aerosol radiative forcing over the third pole.
A. Di Sarra – One of the best experts on this subject based on the ideXlab platform.
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surface shortwave radiative forcing of different Aerosol Types in the central mediterranean
Geophysical Research Letters, 2008Co-Authors: A. Di Sarra, G Pace, D Meloni, L De Silvestri, Salvatore Piacentino, F MonteleoneAbstract:[1] Ground based measurements of Aerosol optical depth, τ, and shortwave irradiance at the Mediterranean island of Lampedusa during 2003 and 2004 were used to estimate the surface Aerosol shortwave radiative forcing. The shortwave forcing efficiency (FE) was derived at various solar zenith angles, θ, as the derivative of the shortwave irradiance with respect to τ. Values of FE for different classes of particles, namely desert dust, DD, biomass burning/industrial Aerosols, BU, and for the whole dataset are derived. At the summer solstice the daily average FE is −86.4 W/m2 for DD, −70.5 W/m2 for BU, and −94.0 W/m2 for the whole dataset. The daily Aerosol forcing of DD is much larger than for the other Aerosol classes due to the combination of larger forcing efficiency and largest optical depths. The estimated average daily forcing at the summer solstice and equinox for DD is −30 and −24 W/m2, respectively.
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Aerosol optical properties at Lampedusa (Central Mediterranean). 2. Determination of single scattering albedo at two wavelengths for different Aerosol Types
Atmospheric Chemistry and Physics, 2006Co-Authors: D. Meloni, A. Di Sarra, G. Pace, F. MonteleoneAbstract:Aerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR) at the island of Lampedusa (35.5° N, 12.6° E), in the Central Mediterranean, in the period July 2001?September 2003. In a companion paper (Pace et al., 2006) the Aerosol optical depth (AOD) and Ångström exponent were used together with airmass backward trajectories to identify and classify different Aerosol Types. The MFRSR diffuse-to-direct ratio (DDR) at 415.6 nm and 868.7 nm for Aerosol classified as “biomass burning-urban/industrial”, originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the Aerosol single scattering albedo (SSA). A detailed radiative transfer model is initialised with the measured Aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g), and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of
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Aerosol optical properties at Lampedusa (Central Mediterranean). 2. Determination of single scattering albedo at two wavelengths for different Aerosol Types
Atmospheric Chemistry and Physics, 2006Co-Authors: D. Meloni, A. Di Sarra, G. Pace, F. MonteleoneAbstract:Abstract. Aerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR) at the island of Lampedusa (35.5° N, 12.6° E), in the Central Mediterranean, in the period July 2001–September 2003. In a companion paper (Pace et al., 2006) the Aerosol optical depth (AOD) and Ångström exponent were used together with airmass backward trajectories to identify and classify different Aerosol Types. The MFRSR diffuse-to-direct ratio (DDR) at 415.6 nm and 868.7 nm for Aerosol classified as “biomass burning-urban/industrial”, originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the Aerosol single scattering albedo (SSA). A detailed radiative transfer model is initialised with the measured Aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g), and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of <0.04 at 415.6 nm, and <0.06 at 868.7 nm; finally, an increase of the assumed surface albedo of 0.05 causes very small changes (0.01–0.02) in the retrieved SSA. The calculations show that the SSA of desert dust (DD) increases with wavelength, from 0.81±0.05 at 415.6 nm to 0.94±0.05 at 868.7 nm; on the contrary, the SSA of urban/industrial (UN) Aerosols decreases from 0.96±0.02 at 415.6 nm to 0.87±0.07 at 868.7 nm; the SSA of biomass burning (BB) particles is 0.82±0.04 at 415.6 nm and 0.80±0.05 at 868.7 nm. Episodes of UN Aerosols occur usually in June and July; long lasting BB Aerosol episodes with large AOD are observed mainly in July and August, the driest months of the year, when the development of fires is frequent.
Jhoon Kim – One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Classified Aerosol Types in South Korea during the MAPS-Seoul Campaign
Aerosol and Air Quality Research, 2018Co-Authors: Seoyoung Lee, Jhoon Kim, Jaemin Hong, Yeseul Cho, Myungje Choi, Sang Seo Park, Joon Young Ahn, Sang-kyun Kim, Kyung Jung Moon, Thomas F. EckAbstract:During the Megacity Air Pollution Studies-Seoul (MAPS-Seoul) campaign from May to June 2015, Aerosol optical properties in Korea were obtained based on the AERONET sunphotometer measurement at five sites (Anmyon, Gangneung_WNU, Gosan_SNU, Hankuk_UFS, and Yonsei_University). Using this dataset, we examine regional Aerosol Types by applying a number of known Aerosol classification methods. We thoroughly utilize five different methods to categorize the regional Aerosol Types and evaluate the results from each method by inter-comparison. The differences and similarities among the results are also discussed, contingent upon the usage of AERONET inversion products, such as the single scattering albedo. Despite several small differences, all five methods suggest the same general features in terms of the regionally dominant Aerosol type: Fine-mode Aerosols with highly absorbing radiative properties dominate at Hankuk_UFS and Yonsei_University; non-absorbing fine-mode particles form a large portion of the Aerosol at Gosan_SNU; and coarse-mode particles cause some effects at Anmyon. The analysis of 3-day back-trajectories is also performed to determine the relationship between classified Types at each site and the regional transport pattern. In particular, the spatiotemporally short-scale transport appears to have a large influence on the local Aerosol properties. As a result, we find that the domestic emission in Korea significantly contributes to the high dominance of radiation-absorbing Aerosols in the Seoul metropolitan area and the air-mass transport from China largely affects the western coastal sites, such as Anmyon and Gosan_SNU.
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Characteristics of Aerosol Types from AERONET sunphotometer measurements
Atmospheric Environment, 2010Co-Authors: Jaehwa Lee, Jhoon Kim, Chul H. Song, S.b. Kim, Y. Chun, Byung-ju Sohn, Brent N. HolbenAbstract:By using observations from the Aerosol Robotic Network (AERONET), Aerosol Types are classified according to dominant size mode and radiation absorptivity as determined by fine-mode fraction (FMF) and single-scattering albedo (SSA), respectively. The Aerosol type from anthropogenic sources is significantly different with regard to location and season, while dust Aerosol is observed persistently over North Africa and the Arabian Peninsula. For four reference locations where different Aerosol Types are observed, time series and optical properties for each Aerosol type are investigated. The results show that Aerosol Types are strongly affected by their sources and partly affected by relative humidity. The analysis and methodology of this study can be used to compare Aerosol classification results from satellite and chemical transport models, as well as to analyze Aerosol characteristics on a global scale over land for which satellite observations need to be improved.
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Validation of Aerosol Type Classification from Satellite Remote Sensing
, 2009Co-Authors: Jaehwa Lee, Jhoon Kim, Jungbin Mok, Yunjae KimAbstract:Inter‐comparison of various satellite data is performed for the purpose of validation of Aerosol type classification algorithm from satellite remote sensing, so called, MODIS‐OMI algorithm (MOA hereafter). Infrared Optical Depth Index (IODI), correlation coefficient between carbon monoxide (CO) column density and black carbon (BC) Aerosol optical thickness (AOT), and Aerosol Types from 4‐channel algorithm and CALIOP measurements are used to validate dust, BC, and Aerosol type from MOA, respectively. The agreement of dust pixels between IODI and MOA ranges 0.1 to 0.6 with respect to AOT constraint, and it is inferred that IODI is less sensitive to optically thin dust layer. Increase of the correlation coefficient between AOT and CO column density when BC pixels are taken into account supports the performance of MOA to detect BC Aerosol. The agreement of Aerosol Types from MOA and 4 CA showed reasonable consistency, and the difference can be described by different absorptivity test and retrieval accuracy of…
F. Monteleone – One of the best experts on this subject based on the ideXlab platform.
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Aerosol optical properties at Lampedusa (Central Mediterranean). 2. Determination of single scattering albedo at two wavelengths for different Aerosol Types
Atmospheric Chemistry and Physics, 2006Co-Authors: D. Meloni, A. Di Sarra, G. Pace, F. MonteleoneAbstract:Aerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR) at the island of Lampedusa (35.5° N, 12.6° E), in the Central Mediterranean, in the period July 2001?September 2003. In a companion paper (Pace et al., 2006) the Aerosol optical depth (AOD) and Ångström exponent were used together with airmass backward trajectories to identify and classify different Aerosol Types. The MFRSR diffuse-to-direct ratio (DDR) at 415.6 nm and 868.7 nm for Aerosol classified as “biomass burning-urban/industrial”, originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the Aerosol single scattering albedo (SSA). A detailed radiative transfer model is initialised with the measured Aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g), and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of
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Aerosol optical properties at Lampedusa (Central Mediterranean). 2. Determination of single scattering albedo at two wavelengths for different Aerosol Types
Atmospheric Chemistry and Physics, 2006Co-Authors: D. Meloni, A. Di Sarra, G. Pace, F. MonteleoneAbstract:Abstract. Aerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR) at the island of Lampedusa (35.5° N, 12.6° E), in the Central Mediterranean, in the period July 2001–September 2003. In a companion paper (Pace et al., 2006) the Aerosol optical depth (AOD) and Ångström exponent were used together with airmass backward trajectories to identify and classify different Aerosol Types. The MFRSR diffuse-to-direct ratio (DDR) at 415.6 nm and 868.7 nm for Aerosol classified as “biomass burning-urban/industrial”, originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the Aerosol single scattering albedo (SSA). A detailed radiative transfer model is initialised with the measured Aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g), and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of <0.04 at 415.6 nm, and <0.06 at 868.7 nm; finally, an increase of the assumed surface albedo of 0.05 causes very small changes (0.01–0.02) in the retrieved SSA. The calculations show that the SSA of desert dust (DD) increases with wavelength, from 0.81±0.05 at 415.6 nm to 0.94±0.05 at 868.7 nm; on the contrary, the SSA of urban/industrial (UN) Aerosols decreases from 0.96±0.02 at 415.6 nm to 0.87±0.07 at 868.7 nm; the SSA of biomass burning (BB) particles is 0.82±0.04 at 415.6 nm and 0.80±0.05 at 868.7 nm. Episodes of UN Aerosols occur usually in June and July; long lasting BB Aerosol episodes with large AOD are observed mainly in July and August, the driest months of the year, when the development of fires is frequent.
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Aerosol optical properties at Lampedusa (Central Mediterranean) ? 2. Determination of single scattering albedo at two wavelengths for different Aerosol Types
Atmospheric Chemistry and Physics Discussions, 2005Co-Authors: D. Meloni, A. Di Sarra, G. Pace, F. MonteleoneAbstract:Aerosol optical properties were retrieved from direct and diffuse spectral irradiance measurements made by a multi-filter rotating shadowband radiometer (MFRSR) at the island of Lampedusa (35.5° N, 12.6° E), in the Central Mediterranean, in the period July 2001?September 2003. In a companion paper (Pace et al., 2005) the Aerosol optical depth (AOD) and Ångström exponent were used together with airmass backward trajectories to identify and classify different Aerosol Types. The MFRSR diffuse-to-direct ratio (DDR) at 415.6 nm and 868.7 nm for Aerosol classified as biomass burning-urban/industrial, originating primarily from the European continent, and desert dust, originating from the Sahara, is used in this study to estimate the Aerosol single scattering albedo (SSA). A detailed radiative transfer model is initialized with the measured Aerosol optical depth; calculations are performed at the two wavelengths varying the SSA values until the modelled DDR matches the MFRSR observations. Sensitivity studies are performed to estimate how uncertainties on AOD, DDR, asymmetry factor (g), and surface albedo influence the retrieved SSA values. The results show that a 3% variation of AOD or DDR produce a change of about 0.02 in the retrieved SSA value at 415.6 and 868.7 nm; a ±0.06 variation of the asymmetry factor g produces a change of the estimated SSA of