Identification of columnar aerosol types under high aerosol optical depth conditions for a single AERONET site in Korea

Abstract. A new method, called ElEx (elastic extinction), is proposed for the estimation of extinction coefficient lidar profiles using only the information provided by the elastic and polarization channels of a lidar system. The method is applicable to lidar measurements both during daytime and nighttime under well-defined aerosol mixtures. ElEx uses the particle backscatter profiles at 532 nm and the vertically resolved particle linear depolarization ratio measurements at the same wavelength. The particle linear depolarization ratio and the lidar ratio values of pure aerosol types are also taken from literature. The total extinction profile is then estimated and compared well with Raman retrievals. In this study, ElEx was applied in an aerosol mixture of marine and dust particles at Finokalia station during the CHARADMExp campaign. Any difference between ElEx and Raman extinction profiles indicates that the nondust component could be probably attributed to polluted marine or polluted continental aerosols. Comparison with sun photometer aerosol optical depth observations is performed as well during daytime. Differences in the total aerosol optical depth are varying between 1.2 % and 72 %, and these differences are attributed to the limited ability of the lidar to correctly represent the aerosol optical properties in the near range due to the overlap problem.

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Understanding the aerosol information content in multi-spectral reflectance measurements using a synergetic retrieval algorithm

Atmospheric Measurement Techniques ◽

10.5194/amt-3-1589-2010 ◽

2010 ◽

Vol 3 (6) ◽

pp. 1589-1598 ◽

Cited By ~ 8

Author(s):

D. Martynenko ◽

T. Holzer-Popp ◽

H. Elbern ◽

M. Schroedter-Homscheidt

Keyword(s):

Content Analysis ◽

Information Content ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Degrees Of Freedom ◽

Surface Albedo ◽

Water Soluble ◽

Retrieval Algorithm ◽

Aerosol Types ◽

Reflectance Measurements

Abstract. An information content analysis for multi-wavelength SYNergetic AErosol Retrieval algorithm SYNAER was performed to quantify the number of independent pieces of information that can be retrieved. In particular, the capability of SYNAER to discern various aerosol types is assessed. This information content depends on the aerosol optical depth, the surface albedo spectrum and the observation geometry. The theoretical analysis is performed for a large number of scenarios with various geometries and surface albedo spectra for ocean, soil and vegetation. When the surface albedo spectrum and its accuracy is known under cloud-free conditions, reflectance measurements used in SYNAER is able to provide for 2–4° of freedom that can be attributed to retrieval parameters: aerosol optical depth, aerosol type and surface albedo. The focus of this work is placed on an information content analysis with emphasis to the aerosol type classification. This analysis is applied to synthetic reflectance measurements for 40 predefined aerosol mixtures of different basic components, given by sea salt, mineral dust, biomass burning and diesel aerosols, water soluble and water insoluble aerosols. The range of aerosol parameters considered through the 40 mixtures covers the natural variability of tropospheric aerosols. After the information content analysis performed in Holzer-Popp et al. (2008) there was a necessity to compare derived degrees of freedom with retrieved aerosol optical depth for different aerosol types, which is the main focus of this paper. The principle component analysis was used to determine the correspondence between degrees of freedom for signal in the retrieval and derived aerosol types. The main results of the analysis indicate correspondence between the major groups of the aerosol types, which are: water soluble aerosol, soot, mineral dust and sea salt and degrees of freedom in the algorithm and show the ability of the SYNAER to discern between this aerosol types. The results of the work will be further used for the development of the promising methodology of the construction error covariance matrices in the assimilation system.

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High temporal resolution estimates of columnar aerosol microphysical parameters from spectrum of aerosol optical depth by linear estimation: application to long-term AERONET and star-photometry measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-8-3117-2015 ◽

2015 ◽

Vol 8 (8) ◽

pp. 3117-3133 ◽

Cited By ~ 18

Author(s):

D. Pérez-Ramírez ◽

I. Veselovskii ◽

D. N. Whiteman ◽

A. Suvorina ◽

M. Korenskiy ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Temporal Resolution ◽

High Temporal Resolution ◽

Linear Estimation ◽

Night Time ◽

Microphysical Properties ◽

Fine Mode ◽

Using Data ◽

Aerosol Types

Abstract. This work deals with the applicability of the linear estimation technique (LE) to invert spectral measurements of aerosol optical depth (AOD) provided by AERONET CIMEL sun photometers. The inversion of particle properties using only direct-sun AODs allows the evaluation of parameters such as effective radius (reff) and columnar volume aerosol content (V) with significantly better temporal resolution than the operational AERONET algorithm which requires both direct sun and sky radiance measurements. Sensitivity studies performed demonstrate that the constraints on the range of the inversion are very important to minimize the uncertainties, and therefore estimates of reff can be obtained with uncertainties less than 30 % and of V with uncertainties below 40 %. The LE technique is applied to data acquired at five AERONET sites influenced by different aerosol types and the retrievals are compared with the results of the operational AERONET code. Good agreement between the two techniques is obtained when the fine mode predominates, while for coarse mode cases the LE results systematically underestimate both reff and V. The highest differences are found for cases where no mode predominates. To minimize these biases, correction functions are developed using the multi-year database of observations at selected sites, where the AERONET retrieval is used as the reference. The derived corrections are tested using data from 18 other AERONET stations offering a range of aerosol types. After correction, the LE retrievals provide better agreement with AERONET for all the sites considered. Finally, the LE approach developed here is applied to AERONET and star-photometry measurements in the city of Granada (Spain) to obtain day-to-night time evolution of columnar aerosol microphysical properties.

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A Study on the Variation of Aerosol Optical Depth according to Aerosol Types in Northeast Asia using AErONET Sun/Sky radiometer Data

Journal of Korean Society for Atmospheric Environment ◽

10.5572/kosae.2018.34.5.668 ◽

2018 ◽

Vol 34 (5) ◽

pp. 668-676

Author(s):

Youngmin Noh

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Northeast Asia ◽

Aerosol Types

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Bayesian uncertainty quantification in aerosol optical depth retrieval applied to TROPOMI measurements

10.5194/amt-2021-328 ◽

2021 ◽

Author(s):

Anu Kauppi ◽

Antti Kukkurainen ◽

Antti Lipponen ◽

Marko Laine ◽

Antti Arola ◽

...

Keyword(s):

Model Selection ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Bayesian Model Averaging ◽

Forward Model ◽

Selection Problem ◽

Aerosol Model ◽

Model Discrepancy ◽

Aerosol Types ◽

Model Selection Problem

Abstract. We present here an aerosol model selection based statistical method in Bayesian framework for retrieving atmospheric aerosol optical depth (AOD) and pixel-level uncertainty. Especially, we focus on to provide more realistic uncertainty estimate by taking into account a model selection problem when searching for the solution by fitting look-up table (LUT) models to a satellite measured top-of-atmosphere reflectance. By means of Bayesian model averaging over the best-fitting aerosol models we take into account an aerosol model selection uncertainty and get also a shared inference about AOD. Moreover, we acknowledge model discrepancy, i.e. forward model error, arising from approximations and assumptions done in forward model simulations. We have estimated the model discrepancy empirically by a statistical approach utilizing residuals of model fits. We use the measurements from the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor in ultraviolet and visible bands, and in one wavelength band 675 nm in near-infrared, in order to study the functioning of the retrieval in a broad wavelength range. We exploit a fundamental classification of the aerosol models as weakly absorbing, biomass burning and desert dust aerosols. For experimental purpose we have included some dust type of aerosols having non-spherical particle shapes. For this study we have created the aerosol model LUTs with radiative transfer simulations using the libRadtran software package. It is reasonably straightforward to experiment with different aerosol types and evaluate the most probable aerosol type by the model selection method. We demonstrate the method in wildfire and dust events in a pixel level. In addition, we have evaluated in detail the results against ground-based remote sensing data from the AErosol RObotic NETwork (AERONET). Based on the case studies the method has ability to identify the appropriate aerosol types, but in some wildfire cases the AOD is overestimated compared to the AERONET result. The resulting uncertainty when accounting for the model selection problem and the imperfect forward modelling is higher compared to uncertainty when only measurement error is included in an observation model, as can be expected.

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Understanding the aerosol information content in multi-spectral reflectance measurements using a synergetic retrieval algorithm

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-3-2579-2010 ◽

2010 ◽

Vol 3 (3) ◽

pp. 2579-2602 ◽

Cited By ~ 1

Author(s):

D. Martynenko ◽

T. Holzer-Popp ◽

H. Elbern ◽

M. Schroedter-Homscheidt

Keyword(s):

Content Analysis ◽

Information Content ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Degrees Of Freedom ◽

Surface Albedo ◽

Retrieval Algorithm ◽

Multi Wavelength ◽

Aerosol Types ◽

Reflectance Measurements

Abstract. The multi-wavelength SYNergetic AErosol Retrieval algorithm SYNAER (Holzer-Popp et al., 2002) is used to retrieve aerosol parameters from the Advanced Along Tracking Scanning Radiometer (AATSR) and the Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY). An information content analysis (Holzer-Popp et al., 2008) was performed to quantify the number of independent pieces of information can be retrieved from the combined reflectance measurements of aerosols by both instruments. In particular, the capability of SYNAER to discern various aerosol types is assessed. The focus of this work is further placed on an information content analysis with emphasis to the aerosol type classification. This analysis is applied to synthetic reflectance measurements for 40 predefined aerosol mixtures of different basic components, given by sea salt, mineral dust, biomass burning and diesel aerosols, water soluble and water insoluble aerosols. The range of aerosol parameters considered through the 40 mixtures covers the natural variability of tropospheric aerosols. In this work the capability of the multi-wavelength algorithm to discern aerosol types is investigated. After the information content analysis performed in Holzer-Popp et al. (2008) there was a necessity to compare derived degrees of freedom with retrieved aerosol optical depth for different aerosol types, which is the main focus of this paper. This information content depends on the aerosol optical depth, the surface albedo spectrum and the observation geometry. This theoretical analysis is performed for a large number of scenarios with various geometries and surface albedo spectra for ocean, soil and vegetation. When the surface albedo spectrum and its accuracy is known under cloud-free conditions, reflectance measurements used in SYNAER is able to provide for 2 to 4 degrees of freedom that can be attributed to retrieval parameters: aerosol optical depth, aerosol type and surface albedo.

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Assessment of aerosol types on improving the estimation of surface PM2.5 concentrations by using ground-based aerosol optical depth dataset

Atmospheric Pollution Research ◽

10.1016/j.apr.2019.07.016 ◽

2019 ◽

Vol 10 (6) ◽

pp. 1843-1851 ◽

Cited By ~ 1

Author(s):

Qi-Xiang Chen ◽

Chun-Lin Huang ◽

Yuan Yuan ◽

Qian-Jun Mao ◽

He-Ping Tan

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Aerosol Types

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Spatiotemporal variability and contribution of different aerosol types to the aerosol optical depth over the Eastern Mediterranean

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-13853-2016 ◽

2016 ◽

Vol 16 (21) ◽

pp. 13853-13884 ◽

Cited By ~ 35

Author(s):

Aristeidis K. Georgoulias ◽

Georgia Alexandri ◽

Konstantinos A. Kourtidis ◽

Jos Lelieveld ◽

Prodromos Zanis ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Eastern Mediterranean ◽

Spatiotemporal Variability ◽

Marine Aerosols ◽

Anthropogenic Aerosols ◽

Relative Contribution ◽

Fine Mode ◽

Natural Aerosols ◽

Aerosol Types

Abstract. This study characterizes the spatiotemporal variability and relative contribution of different types of aerosols to the aerosol optical depth (AOD) over the Eastern Mediterranean as derived from MODIS (Moderate Resolution Imaging Spectroradiometer) Terra (March 2000–December 2012) and Aqua (July 2002–December 2012) satellite instruments. For this purpose, a 0.1° × 0.1° gridded MODIS dataset was compiled and validated against sun photometric observations from the AErosol RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium-sized cities, industrial zones and power plant complexes, seasonal variabilities and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is ∼ 0.22 ± 0.19, with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic aerosols, transport of pollution and smoke from biomass burning in central and eastern Europe and transport of dust from the Sahara and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry–aerosol-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different aerosol types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine-mode natural aerosols over land and anthropogenic, dust and marine aerosols over the sea is examined. The relative contribution of the different aerosol types to the total AOD550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic aerosols, dust and fine-mode natural aerosols account for ∼ 51, ∼ 34 and ∼ 15 % of the total AOD550 over land, while, anthropogenic aerosols, dust and marine aerosols account ∼ 40, ∼ 34 and ∼ 26 % of the total AOD550 over the sea, based on MODIS Terra and Aqua observations.

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Spatiotemporal variability and contribution of different aerosol types to the Aerosol Optical Depth over the Eastern Mediterranean

10.5194/acp-2016-401 ◽

2016 ◽

Cited By ~ 2

Author(s):

Aristeidis K. Georgoulias ◽

Georgia Alexandri ◽

Konstantinos A. Kourtidis ◽

Jos Lelieveld ◽

Prodromos Zanis ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Eastern Mediterranean ◽

Spatiotemporal Variability ◽

Marine Aerosols ◽

Anthropogenic Aerosols ◽

Relative Contribution ◽

Fine Mode ◽

Natural Aerosols ◽

Aerosol Types

Abstract. This study characterizes the spatiotemporal variability and relative contribution of different types of aerosols to the Aerosol Optical Depth (AOD) over the Eastern Mediterranean as derived from MODIS Terra (3/2000–12/2012) and Aqua (7/2002–12/2012) satellite instruments. For this purpose, a 0.1°×0.1° gridded MODIS dataset was compiled and validated against AERONET sunphotometric observations. The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium sized cities, industrial zones, and power plant complexes, seasonal variabilities, and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is ~ 0.22 ± 0.19 with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic aerosols, transport of pollution and smoke from biomass burning in Central and Eastern Europe, and transport of dust from the Sahara Desert and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-aerosol-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different aerosol types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine mode natural aerosols over land and anthropogenic, dust and marine aerosols over the sea is examined. The relative contribution of the different aerosol types to the total AOD550 exhibits a low/high seasonal variability over land/oceanic areas, respectively. Overall, anthropogenic aerosols, dust and fine mode natural aerosols account for ~ 51 %, ~ 34 % and ~ 15 % of the total AOD550 over land, while, anthropogenic aerosols, dust and marine aerosols account ~ 40 %, ~ 34 % and ~ 26 % of the total AOD550 over the sea, based on MODIS Terra and Aqua observations.

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A 4-D climatology (1979–2009) of the monthly aerosol optical depth distribution over the Mediterranean region from a comparative evaluation and blending of remote sensing and model products

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-8469-2012 ◽

2012 ◽

Vol 5 (6) ◽

pp. 8469-8538 ◽

Cited By ~ 1

Author(s):

P. Nabat ◽

S. Somot ◽

M. Mallet ◽

I. Chiapello ◽

J. J. Morcrette ◽

...

Keyword(s):

Organic Carbon ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Satellite Data ◽

Mediterranean Region ◽

Northern Africa ◽

Sea Salt ◽

Data Sets ◽

Sulfate Aerosols ◽

Aerosol Types

Abstract. Since the 1980s several spaceborne sensors have been used to retrieve the aerosol optical depth (AOD) over the Mediterranean region. In parallel, AOD climatologies coming from different numerical model simulations are now also available, permitting to distinguish the contribution of several aerosol types to the total AOD. In this work, we perform a comparative analysis of this unique multi-year database in terms of total AOD and of its apportionment by the five main aerosol types (soil dust, sea-salt, sulfate, black and organic carbon). We use 8 different satellite-derived monthly AOD products: NOAA/AVHRR, SeaWiFS, TERRA/MISR, TERRA/MODIS, AQUA/MODIS, ENVISAT/MERIS, PARASOL/POLDER and MSG/SEVIRI, as well as 3 more historical data sets: NIMBUS7/CZCS, NIMBUS7/TOMS and METEOSAT/MVIRI. Monthly model datasets include the aerosol climatology from Tegen et al. (1997), the climate-chemistry models LMDz-OR-INCA and RegCM-4, and the reanalyses GEMS and MACC. Ground-based Level-2 AERONET AOD observations from 47 stations around the basin are used here to evaluate the model and satellite data. The sensor MODIS (on AQUA and TERRA) has the best average AOD scores over this region, showing a relevant spatio-temporal variability and highlighting high dust loads over Northern Africa and the sea (spring and summer), and sulfate aerosols over continental Europe (summer). The comparison also shows limitations of certain data sets (especially MERIS and SeaWiFS standard products). Models reproduce the main patterns of the AOD variability over the basin. The MACC reanalysis is the closest to AERONET data but appears to underestimate dust over Northern Africa, where RegCM-4 is found closer to MODIS thanks to its interactive scheme for dust emissions. The vertical dimension is also investigated using the CALIOP instrument. This study confirms differences between dust aerosols which can be lifted up to 5000 m, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003–2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology. We extend the 2003–2009 reconstruction to the past up to 1979 using the 2003–2009 average and applying the decreasing trend in sulfate aerosols from the LMDz-OR-INCA model, based on the recent emission reconstruction proposed by Lamarque et al. (2010). Finally optical properties of the different aerosol types in this region are proposed from the literature so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosol-climate studies.

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