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Research Director
01 April 2006 - 01 April 2021
Research or Laboratory Scientist
01 April 1997 - 01 April 2006
Research or Laboratory Scientist
01 September 1985 - 01 April 1997
Dr. Oleg DUBOVIK specializes in retrievals of aerosol properties from satellite, ground-based, and airborne remote sensing observations. Dr. Dubovik has received his PhD from Institute of Physics, Minsk, Belarus in 1992. Then, he worked in Japan for two years, participating in ADEOS/ILAS algorithm developments, and nine years in USA at GSFC/NASA research center. Since 2006, Dr. Dubovik works in the Laboratoire d'Optique Atmosphérique, Université Lille, France as CNRS “Research Director”. Main scientific accomplishments of Dr. Dubovik include following developments: - aerosol retrieval algorithm for AERONET federated network of ground-based radiometers; - one of pioneering climatologies of absorption and optical properties of ambient tropospheric aerosol; - popular efficient software for modeling scattering by non-spherical aerosol particles. Dr. Dubovik focuses on refinement of methodological aspects of numerical inversion for needs of remote sensing by applying elaborated statistical optimization approach. The developed principles were recently realized GRASP open source algorithm (https://www.grasp-open.com/) that can be applied to retrieval detailed aerosol properties fro diverse observations including both passive and active observations from satellite or ground. For example, GRASP has been used for deriving extended set of parameters from POLDER, 3MI/Metop, Sentinel -3, -4, 5p satellites, combination of ground-based observations by lidar and radiometer, etc.
This paper explores the potential of all-sky cameras to retrieve aerosol properties with GRASP code (Generalized Retrieval of Atmosphere and Surface Properties). To this end, normalized sky radiances (NSR) extracted from an all-sky camera at three effective wavelengths (467, 536 and 605 nm) are used in this study. NSR observations are a set of relative (uncalibrated) sky radiances in arbitrary units. NSR observations have been simulated for different aerosol loads and types with the forward radiative transfer module of GRASP, indicating that NSR observations contain information about the aerosol type as well as about the aerosol optical depth (AOD), at least for low and moderate aerosol loads. An additional sensitivity study with synthetic data has been carried out to quantify the theoretical accuracy and precision on the aerosol properties (AOD, size distribution parameters, etc.) retrieved by GRASP using NSR observations as input. As result, the theoretical accuracy on AOD is within ±0.02 for AOD values lower or equal than 0.4; while the theoretical precision goes from 0.01 to 0.05 when AOD at 467 nm varies from 0.1 to 0.5. NSR measurements recorded at Valladolid (Spain) with an all-sky camera for more than two years have been inverted with GRASP. The retrieved aerosol properties are compared with independent values provided by co-located AERONET (AErosol RObotic NETwork) measurements. AOD from both data sets correlate with determination coefficient (r2) values about 0.87. Finally, the novel multi-pixel approach of GRASP is applied to daily camera radiances together, by constraining the temporal variation in certain aerosol properties. This temporal linkage (multi-pixel approach) provides promising results, reducing the highly temporal variation in some aerosol properties retrieved with the standard (one by one or single-pixel) approach. This work implies an advance in the use of all-sky cameras for the retrieval of aerosol properties.
Roberto Román; Juan C. Antuña-Sánchez; Victoria E. Cachorro; Carlos Toledano; Benjamín Torres; David Mateos; David Fuertes; César López; Ramiro González; Tatyana Lapionok; Oleg Dubovik; Ángel M. de Frutos. Retrieval of aerosol properties using relative radiance measurements from an all-sky camera. 2021, 2021, 1 -69.
AMA StyleRoberto Román, Juan C. Antuña-Sánchez, Victoria E. Cachorro, Carlos Toledano, Benjamín Torres, David Mateos, David Fuertes, César López, Ramiro González, Tatyana Lapionok, Oleg Dubovik, Ángel M. de Frutos. Retrieval of aerosol properties using relative radiance measurements from an all-sky camera. . 2021; 2021 ():1-69.
Chicago/Turabian StyleRoberto Román; Juan C. Antuña-Sánchez; Victoria E. Cachorro; Carlos Toledano; Benjamín Torres; David Mateos; David Fuertes; César López; Ramiro González; Tatyana Lapionok; Oleg Dubovik; Ángel M. de Frutos. 2021. "Retrieval of aerosol properties using relative radiance measurements from an all-sky camera." 2021, no. : 1-69.
Pollution haze is a frequent phenomenon in the North China Plain (NCP) appearing during winter when the aerosol is affected by various pollutant sources and has complex distribution of the aerosol properties, while different aerosol components may have various critical effects on air quality, human health and radiative balance. Therefore, large-scale and accurate aerosol components characterization is urgently and highly desirable but hardly achievable at the regional scale. In this respect, directional and polarimetric remote sensing observations have great potential for providing information about the aerosol components. In this study, a state-of-the-art GRASP/Component approach was employed for attempting to characterize aerosol components in the NCP using POLDER/PARASOL satellite observations. The analysis was done for January 2012 in Beijing (BJ) and Shanxi (SX). The results indicate a peak of the BC mass concentration in an atmospheric column of 82.8 mg/m2 in the SX region, with a mean of 29.2 mg/m2 that is about four times higher than one in BJ (8.9 mg/m2). The mean BrC mass concentrations are, however, higher in BJ (up to ca. 271 mg/m2) than that in SX, which can be attributed to a higher anthropogenic emission. The mean amount of fine ammonium sulfate-like particles observed in the BJ region was three times lower than in SX (131 mg/m2). The study also analyzes meteorological and air quality data for characterizing the pollution event in BJ. During the haze episode, the results suggest a rapid increase in the fine mode aerosol volume concentration associated with a decrease of a scale height of aerosol down to 1500 m. As expected, the values of aerosol optical depth (AOD), absorbing aerosol optical depth (AAOD) and fine mode aerosol optical depth (AODf) are much higher on hazy days. The mass fraction of ammonium sulfate-like aerosol increases from about 13% to 29% and mass concentration increases from 300 mg/m2 to 500 mg/m2. The daily mean PM2.5 concentration and RH independently measured during these reported pollution episodes reach up to 425 g/m3 and 80% correspondingly. The monthly mean mass concentrations of other aerosol components in the BJ are found to be in agreement with the results of previous research works. Finally, a preliminary comparison of these remote sensing derived results with literature and in situ PM2.5 measurements is also presented.
Yang Ou; Lei Li; Zhengqiang Li; Ying Zhang; Oleg Dubovik; Yevgeny Derimian; Cheng Chen; David Fuertes; Yisong Xie; Anton Lopatin; Fabrice Ducos; Zongren Peng. Spatio-Temporal Variability of Aerosol Components, Their Optical and Microphysical Properties over North China during Winter Haze in 2012, as Derived from POLDER/PARASOL Satellite Observations. Remote Sensing 2021, 13, 2682 .
AMA StyleYang Ou, Lei Li, Zhengqiang Li, Ying Zhang, Oleg Dubovik, Yevgeny Derimian, Cheng Chen, David Fuertes, Yisong Xie, Anton Lopatin, Fabrice Ducos, Zongren Peng. Spatio-Temporal Variability of Aerosol Components, Their Optical and Microphysical Properties over North China during Winter Haze in 2012, as Derived from POLDER/PARASOL Satellite Observations. Remote Sensing. 2021; 13 (14):2682.
Chicago/Turabian StyleYang Ou; Lei Li; Zhengqiang Li; Ying Zhang; Oleg Dubovik; Yevgeny Derimian; Cheng Chen; David Fuertes; Yisong Xie; Anton Lopatin; Fabrice Ducos; Zongren Peng. 2021. "Spatio-Temporal Variability of Aerosol Components, Their Optical and Microphysical Properties over North China during Winter Haze in 2012, as Derived from POLDER/PARASOL Satellite Observations." Remote Sensing 13, no. 14: 2682.
The Sierra Nevada Lidar aerOsol Profiling Experiment I and II (SLOPE I and II) campaigns were intended to determine the vertical structure of aerosols by remote sensing instruments and test the various retrieval schemes for obtaining aerosol microphysical and optical properties with in situ measurements. The SLOPE I and II campaigns were developed during the summers of 2016 and 2017, respectively, combining active and passive remote sensing with in situ measurements at stations belonging to the AGORA observatory (Andalusian Global ObseRvatory of the Atmosphere) in the Granada area (Spain). In this work, we use the in situ measurements of these campaigns to evaluate aerosol properties retrieved by the GRASP code (Generalized Retrieval of Atmosphere and Surface Properties) combining lidar and sun–sky photometer measurements. We show an overview of aerosol properties retrieved by GRASP during the SLOPE I and II campaigns. In addition, we evaluate the GRASP retrievals of total aerosol volume concentration (discerning between fine and coarse modes), extinction and scattering coefficients, and for the first time we present an evaluation of the absorption coefficient. The statistical analysis of aerosol optical and microphysical properties, both column-integrated and vertically resolved, from May to July 2016 and 2017 shows a large variability in aerosol load and types. The results show a strong predominance of desert dust particles due to North African intrusions. The vertically resolved analysis denotes a decay of the atmospheric aerosols with an altitude up to 5 km a.s.l. Finally, desert dust and biomass burning events were chosen to show the high potential of GRASP to retrieve vertical profiles of aerosol properties (e.g. absorption coefficient and single scattering albedo) for different aerosol types. The aerosol properties retrieved by GRASP show good agreement with simultaneous in situ measurements (nephelometer, aethalometer, scanning mobility particle sizer, and aerodynamic particle sizer) performed at the Sierra Nevada Station (SNS) in Granada. In general, GRASP overestimates the in situ data at the SNS with a mean difference lower than 6 µm3 cm−3 for volume concentration, and 11 and 2 Mm−1 for the scattering and absorption coefficients. On the other hand, the comparison of GRASP with airborne measurements also shows an overestimation with mean absolute differences of 14 ± 10 and 1.2 ± 1.2 Mm−1 for the scattering and absorption coefficients, showing a better agreement for the absorption (scattering) coefficient with higher (lower) aerosol optical depth. The potential of GRASP shown in this study will contribute to enhancing the representativeness of the aerosol vertical distribution and provide information for satellite and global model evaluation.
Jose Antonio Benavent-Oltra; Juan Andrés Casquero-Vera; Roberto Román; Hassan Lyamani; Daniel Pérez-Ramírez; María José Granados-Muñoz; Milagros Herrera; Alberto Cazorla; Gloria Titos; Pablo Ortiz-Amezcua; Andrés Esteban Bedoya-Velásquez; Gregori De Arruda Moreira; Noemí Pérez; Andrés Alastuey; Oleg Dubovik; Juan Luis Guerrero-Rascado; Francisco José Olmo-Reyes; Lucas Alados-Arboledas. Overview of the SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun–sky photometer measurements. Atmospheric Chemistry and Physics 2021, 21, 9269 -9287.
AMA StyleJose Antonio Benavent-Oltra, Juan Andrés Casquero-Vera, Roberto Román, Hassan Lyamani, Daniel Pérez-Ramírez, María José Granados-Muñoz, Milagros Herrera, Alberto Cazorla, Gloria Titos, Pablo Ortiz-Amezcua, Andrés Esteban Bedoya-Velásquez, Gregori De Arruda Moreira, Noemí Pérez, Andrés Alastuey, Oleg Dubovik, Juan Luis Guerrero-Rascado, Francisco José Olmo-Reyes, Lucas Alados-Arboledas. Overview of the SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun–sky photometer measurements. Atmospheric Chemistry and Physics. 2021; 21 (12):9269-9287.
Chicago/Turabian StyleJose Antonio Benavent-Oltra; Juan Andrés Casquero-Vera; Roberto Román; Hassan Lyamani; Daniel Pérez-Ramírez; María José Granados-Muñoz; Milagros Herrera; Alberto Cazorla; Gloria Titos; Pablo Ortiz-Amezcua; Andrés Esteban Bedoya-Velásquez; Gregori De Arruda Moreira; Noemí Pérez; Andrés Alastuey; Oleg Dubovik; Juan Luis Guerrero-Rascado; Francisco José Olmo-Reyes; Lucas Alados-Arboledas. 2021. "Overview of the SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun–sky photometer measurements." Atmospheric Chemistry and Physics 21, no. 12: 9269-9287.
We analyse the airborne measurements of above-cloud aerosols from the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign performed in Namibia during August and September 2017. The study aims to retrieve the aerosol above-cloud direct radiative effect (DRE) with well-defined uncertainties. To improve the retrieval of the aerosol and cloud properties, the airborne demonstrator of the Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) satellite instrument, called the Observing System Including PolaRisation in the Solar Infrared Spectrum (OSIRIS), was deployed on-board the SAFIRE (Service des Avions Français Instrumentés pour la Rechercheen Environnement) Falcon 20 aircraft during 10 flights performed over land, over the ocean, and along the Namibian coast. The airborne instrument OSIRIS provides observations at high temporal and spatial resolutions for aerosol above clouds (AACs) and cloud properties. OSIRIS was supplemented with the Photomètre Léger Aéroporté pour la surveillance des Masses d'Air version 2 (PLASMA2). The combined airborne measurements allow, for the first time, the validation of AAC algorithms previously developed for satellite measurements. The variations in the aerosol properties are consistent with the different atmospheric circulation regimes observed during the deployment. Airborne observations typically show strong aerosol optical depth (AOD; up to 1.2 at 550 nm) of fine-mode particles from biomass burning (extinction Ångström exponent varying between 1.6 and 2.2), transported above bright stratocumulus decks (mean cloud top around 1 km above mean sea level), with cloud optical thickness (COT) up to 35 at 550 nm. The above-cloud visible AOD retrieved with OSIRIS agrees within 10 % of the PLASMA2 sun photometer measurements in the same environment. The single scattering albedo (SSA) is one of the most influential parameters on the AAC DRE calculation that remains largely uncertain in models. During the AEROCLO-sA campaign, the average SSA obtained by OSIRIS at 550 nm is 0.87, which is in agreement within 3 %, on average, with previous polarimetric-based satellite and airborne retrievals. The strong absorption of the biomass burning plumes in the visible range is generally consistent with the observations from the Aerosol Robotic Network (AERONET) ground-based sun photometers. This, however, shows a significant increase in the particles' absorption at 440 nm in northern Namibia and Angola, which indicates more absorbing organic species within the observed smoke plumes. Biomass burning aerosols are also vertically collocated, with significant amounts of water content up to the top of the plume at around 6 km height in our measurements. The detailed characterization of aerosol and cloud properties, water vapour, and their uncertainties obtained from OSIRIS and PLASMA2 measurements allows us to study their impacts on the AAC DRE. The high-absorbing load of AAC, combined with high cloud albedo, leads to unprecedented DRE estimates, which are higher than previous satellite-based estimates. The average AAC DRE calculated from the airborne measurements in the visible range is +85 W m−2 (standard deviation of 26 W m−2), with instantaneous values up to +190 W m−2 during intense events. These high DRE values, associated with their uncertainties, have to be considered as new upper cases in order to evaluate the ability of models to reproduce the radiative impact of the aerosols over the southeastern Atlantic region.
Aurélien Chauvigné; Fabien Waquet; Frédérique Auriol; Luc Blarel; Cyril Delegove; Oleg Dubovik; Cyrille Flamant; Marco Gaetani; Philippe Goloub; Rodrigue Loisil; Marc Mallet; Jean-Marc Nicolas; Frédéric Parol; Fanny Peers; Benjamin Torres; Paola Formenti. Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements. Atmospheric Chemistry and Physics 2021, 21, 8233 -8253.
AMA StyleAurélien Chauvigné, Fabien Waquet, Frédérique Auriol, Luc Blarel, Cyril Delegove, Oleg Dubovik, Cyrille Flamant, Marco Gaetani, Philippe Goloub, Rodrigue Loisil, Marc Mallet, Jean-Marc Nicolas, Frédéric Parol, Fanny Peers, Benjamin Torres, Paola Formenti. Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements. Atmospheric Chemistry and Physics. 2021; 21 (10):8233-8253.
Chicago/Turabian StyleAurélien Chauvigné; Fabien Waquet; Frédérique Auriol; Luc Blarel; Cyril Delegove; Oleg Dubovik; Cyrille Flamant; Marco Gaetani; Philippe Goloub; Rodrigue Loisil; Marc Mallet; Jean-Marc Nicolas; Frédéric Parol; Fanny Peers; Benjamin Torres; Paola Formenti. 2021. "Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements." Atmospheric Chemistry and Physics 21, no. 10: 8233-8253.
Global measurements of absorbing aerosol optical depth (AAOD) are scarce and mostly provided by the ground network AERONET (AErosol RObotic NETwork). In recent years, several satellite products of AAOD have been developed. This study's primary aim is to establish the usefulness of these datasets for AEROCOM (Aerosol Comparisons between Observations and Models) model evaluation with a focus on the years 2006, 2008 and 2010. The satellite products are super-observations consisting of 1∘×1∘×30 min aggregated retrievals. This study consists of two papers, the current one that deals with the assessment of satellite observations and a second paper (Schutgens et al., 2021) that deals with the evaluation of models using those satellite data. In particular, the current paper details an evaluation with AERONET observations from the sparse AERONET network as well as a global intercomparison of satellite datasets, with a focus on how minimum AOD (aerosol optical depth) thresholds and temporal averaging may improve agreement between satellite observations. All satellite datasets are shown to have reasonable skill for AAOD (three out of four datasets show correlations with AERONET in excess of 0.6) but less skill for SSA (single-scattering albedo; only one out of four datasets shows correlations with AERONET in excess of 0.6). In comparison, satellite AOD shows correlations from 0.72 to 0.88 against the same AERONET dataset. However, we show that performance vs. AERONET and inter-satellite agreements for SSA improve significantly at higher AOD. Temporal averaging also improves agreements between satellite datasets. Nevertheless multi-annual averages still show systematic differences, even at high AOD. In particular, we show that two POLDER (Polarization and Directionality of the Earth's Reflectances) products appear to have a systematic SSA difference over land of ∼0.04, independent of AOD. Identifying the cause of this bias offers the possibility of substantially improving current datasets. We also provide evidence that suggests that evaluation with AERONET observations leads to an underestimate of true biases in satellite SSA. In the second part of this study we show that, notwithstanding these biases in satellite AAOD and SSA, the datasets allow meaningful evaluation of AEROCOM models.
Nick Schutgens; Oleg Dubovik; Otto Hasekamp; Omar Torres; Hiren Jethva; Peter J. T. Leonard; Pavel Litvinov; Jens Redemann; Yohei Shinozuka; Gerrit de Leeuw; Stefan Kinne; Thomas Popp; Michael Schulz; Philip Stier. AEROCOM and AEROSAT AAOD and SSA study – Part 1: Evaluation and intercomparison of satellite measurements. Atmospheric Chemistry and Physics 2021, 21, 6895 -6917.
AMA StyleNick Schutgens, Oleg Dubovik, Otto Hasekamp, Omar Torres, Hiren Jethva, Peter J. T. Leonard, Pavel Litvinov, Jens Redemann, Yohei Shinozuka, Gerrit de Leeuw, Stefan Kinne, Thomas Popp, Michael Schulz, Philip Stier. AEROCOM and AEROSAT AAOD and SSA study – Part 1: Evaluation and intercomparison of satellite measurements. Atmospheric Chemistry and Physics. 2021; 21 (9):6895-6917.
Chicago/Turabian StyleNick Schutgens; Oleg Dubovik; Otto Hasekamp; Omar Torres; Hiren Jethva; Peter J. T. Leonard; Pavel Litvinov; Jens Redemann; Yohei Shinozuka; Gerrit de Leeuw; Stefan Kinne; Thomas Popp; Michael Schulz; Philip Stier. 2021. "AEROCOM and AEROSAT AAOD and SSA study – Part 1: Evaluation and intercomparison of satellite measurements." Atmospheric Chemistry and Physics 21, no. 9: 6895-6917.
The exploration of aerosol retrieval synergies from diverse combinations of ground-based passive Sun-photometric measurements with collocated active lidar ground-based and radiosonde observations using versatile Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm is presented. Several potentially fruitful aspects of observation synergy were considered. First, a set of passive and active ground-based observations collected during both day- and nighttime was inverted simultaneously under the assumption of temporal continuity of aerosol properties. Such an approach explores the complementarity of the information in different observations and results in a robust and consistent processing of all observations. For example, the interpretation of the nighttime active observations usually suffers from the lack of information about aerosol particles sizes, shapes and complex refractive index. In the realized synergy retrievals, the information propagating from the nearby Sun-photometric observations provides sufficient constraints for reliable interpretation of both day- and nighttime lidar observations. Second, the synergetic processing of such complementary observations with enhanced information content allows for optimizing the aerosol model used in the retrieval. Specifically, the external mixture of several aerosol components with predetermined sizes, shapes and composition has been identified as an efficient approach for achieving reliable retrieval of aerosol properties in several situations. This approach allows for achieving consistent and accurate aerosol retrievals from processing stand-alone advanced lidar observations with reduced information content about aerosol columnar properties. Third, the potential of synergy processing of the ground-based Sun-photometric and lidar observations, with the in situ backscatter sonde measurements was explored using the data from KAUST.15 and KAUST.16 field campaigns held at King Abdullah University of Science and Technology (KAUST) in the August of 2015 and 2016. The inclusion of radiosonde data has been demonstrated to provide significant additional constraints to validate and improve the accuracy and scope of aerosol profiling. The results of all retrieval setups used for processing both synergy and stand-alone observation data sets are discussed and intercompared.
Anton Lopatin; Oleg Dubovik; David Fuertes; Georgiy Stenchikov; Tatyana Lapyonok; Igor Veselovskii; Frank G. Wienhold; Illia Shevchenko; Qiaoyun Hu; Sagar Parajuli. Synergy processing of diverse ground-based remote sensing and in situ data using the GRASP algorithm: applications to radiometer, lidar and radiosonde observations. Atmospheric Measurement Techniques 2021, 14, 2575 -2614.
AMA StyleAnton Lopatin, Oleg Dubovik, David Fuertes, Georgiy Stenchikov, Tatyana Lapyonok, Igor Veselovskii, Frank G. Wienhold, Illia Shevchenko, Qiaoyun Hu, Sagar Parajuli. Synergy processing of diverse ground-based remote sensing and in situ data using the GRASP algorithm: applications to radiometer, lidar and radiosonde observations. Atmospheric Measurement Techniques. 2021; 14 (3):2575-2614.
Chicago/Turabian StyleAnton Lopatin; Oleg Dubovik; David Fuertes; Georgiy Stenchikov; Tatyana Lapyonok; Igor Veselovskii; Frank G. Wienhold; Illia Shevchenko; Qiaoyun Hu; Sagar Parajuli. 2021. "Synergy processing of diverse ground-based remote sensing and in situ data using the GRASP algorithm: applications to radiometer, lidar and radiosonde observations." Atmospheric Measurement Techniques 14, no. 3: 2575-2614.
The high variability of atmospheric aerosol in space and time poses significant challenges for aerosol observation and simulation, as well as for the design of aerosol monitoring systems. Multi-Angular Polarimeters (MAP) have been identified to provide highly accurate data for characterizing in detail columnar properties of atmospheric aerosol. Obtaining such multi-angular observations at high spatial resolution is very challenging, and even more so from satellite observations. At present, the most advanced MAP instruments are intended to provide observations at the spatial resolution of about 2 km to 4 km. The practical understanding of aerosol loading and type variability at fine to moderate spatial scales is still limited. In this paper, we provide insight on the spatial variability of ambient aerosol by combining the full archive of AERONET observations with ancillary wind speeds from the Modern-Era Retrospective Analysis for Research Application, version 2 (MERRA-2) reanalysis dataset. First, the temporal variability of aerosol observations at the smallest AERONET time scale of 15-30 minutes was used to estimate maximum temporal variability of the aerosol loading (aerosol optical depth - AOD), size (Ångström exponent - AE) and absorption (single scattering albedo - SSA) over a selection of 30 typical AERONET sites. In the subsequent step, the derived aerosol temporal variability for AOD, AE and SSA are converted to maximum spatial variability using the mean wind speed from MERRA-2. In the final step, the mean aerosol variability difference was analyzed at spatial scales of 2 km and 4 km, which are the spatial scales considered for the MAP instrument to be deployed as part of the Copernicus Anthropogenic CO2 Monitoring (CO2M) mission. The mean aerosol parameters obtained at these spatial scales showed very small differences: only 0.004 for AOD (440 nm), 0.004 for AE (440/870), and 0.0005 for SSA (440 nm). The analysis of maximum spatial variation of aerosol concentrations showed some non-negligible spikes, up to ∼0.2 for AOD (440 nm) at spatial scales of 4 km. However, those high fluctuations correspond to highly polluted urban sites (i.e. Beijing and Mexico City), and the maximum AOD changes per km remain at ∼6% with respect to the total AOD. The maximum spatial variability for AE and SSA also showed no significant deviations at 4 km (<0.2 for AE; <0.03 for SSA). Therefore, we conclude that using a 4 km spatial resolution for MAP sensors is sufficient for capturing the main features of aerosol variability that is required for the CO2M mission.
Cheng Chen; Oleg Dubovik; Gregory L. Schuster; David Fuertes; Yasjka Meijer; Jochen Landgraf; Yana Karol; Zhengqiang Li. Characterization of temporal and spatial variability of aerosols from ground-based climatology: towards evaluation of satellite mission requirements. Journal of Quantitative Spectroscopy and Radiative Transfer 2021, 268, 107627 .
AMA StyleCheng Chen, Oleg Dubovik, Gregory L. Schuster, David Fuertes, Yasjka Meijer, Jochen Landgraf, Yana Karol, Zhengqiang Li. Characterization of temporal and spatial variability of aerosols from ground-based climatology: towards evaluation of satellite mission requirements. Journal of Quantitative Spectroscopy and Radiative Transfer. 2021; 268 ():107627.
Chicago/Turabian StyleCheng Chen; Oleg Dubovik; Gregory L. Schuster; David Fuertes; Yasjka Meijer; Jochen Landgraf; Yana Karol; Zhengqiang Li. 2021. "Characterization of temporal and spatial variability of aerosols from ground-based climatology: towards evaluation of satellite mission requirements." Journal of Quantitative Spectroscopy and Radiative Transfer 268, no. : 107627.
Sentinel-5p/TROPOMI instrument provides hyperspectral measurements in UV, VIS and infrared spectral range. Though the main purpose of the satellite is trace gases characterization, it is capable of aerosol and surface studies. In particular, S5p/TROPOMI measurements in UV provide unique information about absorption and elevation properties of aerosol. Moreover, measurements in wide spectral range are very sensitive to aerosol size and surface type.
In the framework of ESA S5P+I AOD/BRDF project an innovative algorithm for aerosol and surface retrieval from S5p/TROPOMI instrument is being developed. It integrates the advanced GRASP algorithm with the heritage AOD and DLER algorithm previously applied to TOMS, GOME(-2), SCIAMACHY and OMI sensors. The innovative algorithm is expected to provide surface BRDF and AOD with the accuracy required by most trace gas retrieval algorithms.
Here we present the results of aerosol and surface validation and inter-comparison obtained within ESA S5p+I project. New advanced possibility of aerosol and surface characterization from S5p/TROPOMI instrument will be discussed.
Pavel Litvinov; Oleg Dubovik; Cheng Chen; Anton Lopatin; Tatyana Lapyonok; David Fuertes; Lukas Bindreiter; Verena Lanzinger; Christoph Holter; Andreas Hangler; Michael Aspetsberger; Martin de Graaf; Gijsbert Tilstra; Piet Stammes; Christian Retscher. Surface and aerosol retrieval from S5P/TROPOMI: new possibilities and expected performance. 2021, 1 .
AMA StylePavel Litvinov, Oleg Dubovik, Cheng Chen, Anton Lopatin, Tatyana Lapyonok, David Fuertes, Lukas Bindreiter, Verena Lanzinger, Christoph Holter, Andreas Hangler, Michael Aspetsberger, Martin de Graaf, Gijsbert Tilstra, Piet Stammes, Christian Retscher. Surface and aerosol retrieval from S5P/TROPOMI: new possibilities and expected performance. . 2021; ():1.
Chicago/Turabian StylePavel Litvinov; Oleg Dubovik; Cheng Chen; Anton Lopatin; Tatyana Lapyonok; David Fuertes; Lukas Bindreiter; Verena Lanzinger; Christoph Holter; Andreas Hangler; Michael Aspetsberger; Martin de Graaf; Gijsbert Tilstra; Piet Stammes; Christian Retscher. 2021. "Surface and aerosol retrieval from S5P/TROPOMI: new possibilities and expected performance." , no. : 1.
We use the Generalized Retrieval of Aerosol Surface Properties algorithm (GRASP) to compare with dust concentration profiles derived from the NMME-DREAM model for a specific dust episode. The GRASP algorithm provides the possibility of deriving columnar and vertically-resolved aerosol properties from a combination of lidar and sun-photometer observations. Herein, we apply GRASP for analysis of a Saharan dust outburst observed during the “PREparatory: does dust TriboElectrification affect our ClimaTe” campaign (PreTECT) that took place at the North coast of Crete, at the Finokalia ACTRIS station. GRASP provides column-averaged and vertically resolved microphysical and optical properties of the particles. The retrieved dust concentration profiles are compared with modeled concentration profiles derived from the NMME-DREAM dust model. To strengthen the results, we use dust concentration profiles from the POlarization-LIdar PHOtometer Networking method (POLIPHON). A strong underestimation of the maximum dust concentration is observed from the NMME-DREAM model. The reported differences between the retrievals and the model indicate a high potential of the GRASP algorithm for future studies of dust model evaluation.
Dimitra Konsta; Alexandra Tsekeri; Stavros Solomos; Nikolaos Siomos; Anna Gialitaki; Eleni Tetoni; Anton Lopatin; Philippe Goloub; Oleg Dubovik; Vassilis Amiridis; Panagiotis Nastos. The Potential of GRASP/GARRLiC Retrievals for Dust Aerosol Model Evaluation: Case Study during the PreTECT Campaign. Remote Sensing 2021, 13, 873 .
AMA StyleDimitra Konsta, Alexandra Tsekeri, Stavros Solomos, Nikolaos Siomos, Anna Gialitaki, Eleni Tetoni, Anton Lopatin, Philippe Goloub, Oleg Dubovik, Vassilis Amiridis, Panagiotis Nastos. The Potential of GRASP/GARRLiC Retrievals for Dust Aerosol Model Evaluation: Case Study during the PreTECT Campaign. Remote Sensing. 2021; 13 (5):873.
Chicago/Turabian StyleDimitra Konsta; Alexandra Tsekeri; Stavros Solomos; Nikolaos Siomos; Anna Gialitaki; Eleni Tetoni; Anton Lopatin; Philippe Goloub; Oleg Dubovik; Vassilis Amiridis; Panagiotis Nastos. 2021. "The Potential of GRASP/GARRLiC Retrievals for Dust Aerosol Model Evaluation: Case Study during the PreTECT Campaign." Remote Sensing 13, no. 5: 873.
Summary and conclusions Thus, after more than a half of century form the launching first satellite, the remote sensing of the Earth Planet from space has evolved in highly elaborated tool driving fundamental scientific and applied daily activities vital for the humanity. A very large number of satellite instruments have been developed and launched, and they have supplied a huge amount of data for diverse requirements. The number of satellite instruments and the quality and scope of the information collected by satellites is constantly improving. At the same time, the accumulated experience of the satellite remote sensing community reveals the challenges that need to be addressed for future development. Although each observation of the atmosphere, land, or ocean surface (and other fields of remote sensing) may have specific and quite different issues, several conceptual challenges are common for many satellite remote sensing disciplines. Specifically, the increase in value of the data and efficiency of satellite remote sensing approaches will likely be related to successes in: • increasing both coverage and resolution in spatial and temporal records of observations;• increasing information content of observations by deploying the satellite instruments with enhanced capabilities and exploring synergies of complimentary observations, e.g. synergy of passive imagery with active vertical profiling of the atmosphere and hyperspectral spectrometry, combining observations of di...
Oleg Dubovik; Gregory L. Schuster; Feng Xu; Yongxiang Hu; Hartmut Bösch; Jochen Landgraf; Zhengqiang Li. Grand Challenges in Satellite Remote Sensing. Frontiers in Remote Sensing 2021, 2, 1 .
AMA StyleOleg Dubovik, Gregory L. Schuster, Feng Xu, Yongxiang Hu, Hartmut Bösch, Jochen Landgraf, Zhengqiang Li. Grand Challenges in Satellite Remote Sensing. Frontiers in Remote Sensing. 2021; 2 ():1.
Chicago/Turabian StyleOleg Dubovik; Gregory L. Schuster; Feng Xu; Yongxiang Hu; Hartmut Bösch; Jochen Landgraf; Zhengqiang Li. 2021. "Grand Challenges in Satellite Remote Sensing." Frontiers in Remote Sensing 2, no. : 1.
The Sierra Nevada Lidar aerOsol Profiling Experiment I and II (SLOPE I and II) campaigns were intended to determine the vertical structure of the aerosol by remote sensing instruments and test the various retrieval schemes for obtaining aerosol microphysical and optical properties with in-situ measurements. These campaigns deployed a set of in-situ and remote sensing instruments at the stations include in AGORA observatory (Andalusian Global ObseRvatory of the Atmosphere) in the Granada area (Spain) along summer in 2016 and 2017. In this work, using the in-situ measurements performed at a high-altitude station, Sierra Nevada station, and airborne flights, we evaluate the retrievals of aerosol properties by GRASP code (Generalized Retrieval of Atmosphere and Surface Properties) combining lidar and sun-sky photometer measurements. Besides, we show an overview of aerosol properties retrieved by GRASP during SLOPE I and II campaigns. We evaluate the GRASP retrievals of total aerosol volume concentration (discerning between fine and coarse modes), extinction and scattering coefficients, and for the first time we present an evaluation of absorption coefficient. The statistical analysis of the aerosol optical and microphysical properties, both column-integrated and vertically-resolved, from May to July 2016 and 2017 shows a large variability in aerosol load and types. The results show a strong predominance of desert dust particles due to the North African intrusions. The vertically-resolved analysis denotes a decay of the atmospheric aerosols with altitude up to 5 km a.s.l. Finally, two events of desert dust and biomass burning were used to show the high potential of GRASP to retrieve and study the aerosol properties profiles such as absorption coefficient and single scattering albedo for different aerosol types. The aerosol properties retrieved by GRASP show good agreement with simultaneous in situ measurements performed at Sierra Nevada Station (SNS) in Granada. In general, GRASP overestimates the in situ data at SNS with a mean difference lower than 6 µm3/cm3 for volume concentration, 11 Mm−1 and 2 Mm−1 for scattering and absorption coefficient. On the other hand, the comparison of GRASP with airborne measurements also shows an overestimation with mean absolute differences of 14 ± 10 Mm−1 and 1.2 ± 1.2 Mm−1 for scattering and absorption coefficients, showing a better agreement for absorption (scattering) coefficient with higher (lower) aerosol optical depth. The potentiality of GRASP showed in this study will contribute to enhancing the representativeness of the aerosol vertical distribution and provide information for satellite and global model evaluation.
Jose Antonio Benavent-Oltra; Juan Andrés Casquero-Vera; Roberto Román; Hassan Lyamani; Daniel Pérez-Ramírez; Maria José Granados-Muñoz; Milagros Herrera; Alberto Cazorla; Gloria Titos; Pablo Ortiz-Amezcua; Andrés Esteban Bedoya-Velásquez; Gregori De Arruda Moreira; Noemí Pérez; Andrés Alastuey; Oleg Dubovik; Juan Luis Guerrero-Rascado; Francisco José Olmo-Reyes; Lucas Alados-Arboledas. Overview of SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun-sky photometer measurements. 2021, 2021, 1 -33.
AMA StyleJose Antonio Benavent-Oltra, Juan Andrés Casquero-Vera, Roberto Román, Hassan Lyamani, Daniel Pérez-Ramírez, Maria José Granados-Muñoz, Milagros Herrera, Alberto Cazorla, Gloria Titos, Pablo Ortiz-Amezcua, Andrés Esteban Bedoya-Velásquez, Gregori De Arruda Moreira, Noemí Pérez, Andrés Alastuey, Oleg Dubovik, Juan Luis Guerrero-Rascado, Francisco José Olmo-Reyes, Lucas Alados-Arboledas. Overview of SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun-sky photometer measurements. . 2021; 2021 ():1-33.
Chicago/Turabian StyleJose Antonio Benavent-Oltra; Juan Andrés Casquero-Vera; Roberto Román; Hassan Lyamani; Daniel Pérez-Ramírez; Maria José Granados-Muñoz; Milagros Herrera; Alberto Cazorla; Gloria Titos; Pablo Ortiz-Amezcua; Andrés Esteban Bedoya-Velásquez; Gregori De Arruda Moreira; Noemí Pérez; Andrés Alastuey; Oleg Dubovik; Juan Luis Guerrero-Rascado; Francisco José Olmo-Reyes; Lucas Alados-Arboledas. 2021. "Overview of SLOPE I and II campaigns: aerosol properties retrieved with lidar and sun-sky photometer measurements." 2021, no. : 1-33.
Proven by multiple theoretical and practical studies, multi-angular spectral polarimetry is ideal for comprehensive retrieval of properties of aerosols. Furthermore, a large number of advanced space polarimeters have been launched recently or planned to be deployed in the coming few years (Dubovik et al., 2019). Nevertheless, at present, practical utilization of aerosol products from polarimetry is rather limited, due to the relatively small number of polarimetric compared to photometric observations, as well as challenges in making full use of the extensive information content available in these complex observations. Indeed, while in recent years several new algorithms have been developed to provide enhanced aerosol retrievals from satellite polarimetry, the practical value of available aerosol products from polarimeters yet remains to be proven. In this regard, this paper presents the analysis of aerosol products obtained by the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm from POLDER/PARASOL observations. After about a decade of development, GRASP has been adapted for operational processing of polarimetric satellite observations and several aerosol products from POLDER/PARASOL observations have been released. These updated PARASOL/GRASP products are publicly available (e.g., http://www.icare.univ-lille.fr, last access: 16 October 2018, http://www.grasp-open.com/products/, last access: 28 March 2020); the dataset used in the current study is registered under https://doi.org/10.5281/zenodo.3887265 (Chen et al., 2020). The objective of this study is to comprehensively evaluate the GRASP aerosol products obtained from POLDER/PARASOL observations. First, the validation of the entire 2005–2013 archive was conducted by comparing to ground-based Aerosol Robotic Network (AERONET) data. The subjects of the validation are spectral aerosol optical depth (AOD), aerosol absorption optical depth (AAOD) and single-scattering albedo (SSA) at six wavelengths, as well as Ångström exponent (AE), fine-mode AOD (AODF) and coarse-mode AOD (AODC) interpolated to the reference wavelength 550 nm. Second, an inter-comparison of PARASOL/GRASP products with the PARASOL/Operational, MODIS Dark Target (DT), Deep Blue (DB) and Multi-Angle Implementation of Atmospheric Correction (MAIAC) aerosol products for the year 2008 was performed. Over land both satellite data validations and inter-comparisons were conducted separately for different surface types, discriminated by bins of normalized difference vegetation index (NDVI): < 0.2, 0.2 ≤ and < 0.4, 0.4 ≤ and < 0.6, and ≥ 0.6. Three PARASOL/GRASP products were analyzed: GRASP/HP (“High Precision”), Optimized and Models. These different products are consistent but were obtained using different assumptions in aerosol modeling with different accuracies of atmospheric radiative transfer (RT) calculations. Specifically, when using GRASP/HP or Optimized there is direct retrieval of the aerosol size distribution and spectral complex index of refraction. When using GRASP/Models, the aerosol is approximated by a mixture of several prescribed aerosol components, each with their own fixed size distribution and optical properties, and only the concentrations of those components are retrieved. GRASP/HP employs the most accurate RT calculations, while GRASP/Optimized and GRASP/Models are optimized to achieve the best trade-off between accuracy and speed. In all these three options, the underlying surface reflectance is retrieved simultaneously with the aerosol properties, and the radiative transfer calculations are performed “online” during the retrieval. All validation results obtained for the full archive of PARASOL/GRASP products show solid quality of retrieved aerosol characteristics. The GRASP/Models retrievals, however, provided the most solid AOD products, e.g., AOD (550 nm) is unbiased and has the highest correlation (R ∼ 0.92) and the highest fraction of retrievals (∼ 55.3 %) satisfying the accuracy requirements of the Global Climate Observing System (GCOS) when compared to AERONET observations. GRASP/HP and GRASP/Optimized AOD products show a non-negligible positive bias (∼ 0.07) when AOD is low (< 0.2). On the other hand, the detailed aerosol microphysical characteristics (AE, AODF, AODC, SSA, etc.) provided by GRASP/HP and GRASP/Optimized correlate generally better with AERONET than do the results of GRASP/Models. Overall, GRASP/HP processing demonstrates the high quality of microphysical characteristics retrieval versus AERONET. Evidently, the GRASP/Models approach is more adapted for retrieval of total AOD, while the detailed aerosol microphysical properties are limited when a mixture of aerosol models with fixed optical properties are used. The results of a comparative analysis of PARASOL/GRASP and MODIS products showed that, based on validation against AERONET, the PARASOL/GRASP AOD (550 nm) product is of similar and sometimes of higher quality compared to the MODIS products. All AOD retrievals are more accurate and in good agreement over ocean. Over land, especially over bright surfaces, the retrieval quality degrades and the differences in total AOD products increase. The detailed aerosol characteristics, such as AE, AODF and AODC from PARASOL/GRASP, are generally more reliable, especially over land. The global inter-comparisons of PARASOL/GRASP versus MODIS showed rather robust agreement, though some patterns and tendencies were observed. Over ocean, PARASOL/Models and MODIS/DT AOD agree well with the correlation coefficient of 0.92. Over land, the correlation between PARASOL/Models and the different MODIS products is lower, ranging from 0.76 to 0.85. There is no significant global offset; though over bright surfaces MODIS products tend to show higher values compared to PARASOL/Models when AOD is low and smaller values for moderate and high AODs. Seasonal AOD means...
Cheng Chen; Oleg Dubovik; David Fuertes; Pavel Litvinov; Tatyana Lapyonok; Anton Lopatin; Fabrice Ducos; Yevgeny Derimian; Maurice Herman; Didier Tanré; Lorraine A. Remer; Alexei Lyapustin; Andrew M. Sayer; Robert C. Levy; N. Christina Hsu; Jacques Descloitres; Lei Li; Benjamin Torres; Yana Karol; Milagros Herrera; Marcos Herreras; Michael Aspetsberger; Moritz Wanzenboeck; Lukas Bindreiter; Daniel Marth; Andreas Hangler; Christian Federspiel. Validation of GRASP algorithm product from POLDER/PARASOL data and assessment of multi-angular polarimetry potential for aerosol monitoring. Earth System Science Data 2020, 12, 3573 -3620.
AMA StyleCheng Chen, Oleg Dubovik, David Fuertes, Pavel Litvinov, Tatyana Lapyonok, Anton Lopatin, Fabrice Ducos, Yevgeny Derimian, Maurice Herman, Didier Tanré, Lorraine A. Remer, Alexei Lyapustin, Andrew M. Sayer, Robert C. Levy, N. Christina Hsu, Jacques Descloitres, Lei Li, Benjamin Torres, Yana Karol, Milagros Herrera, Marcos Herreras, Michael Aspetsberger, Moritz Wanzenboeck, Lukas Bindreiter, Daniel Marth, Andreas Hangler, Christian Federspiel. Validation of GRASP algorithm product from POLDER/PARASOL data and assessment of multi-angular polarimetry potential for aerosol monitoring. Earth System Science Data. 2020; 12 (4):3573-3620.
Chicago/Turabian StyleCheng Chen; Oleg Dubovik; David Fuertes; Pavel Litvinov; Tatyana Lapyonok; Anton Lopatin; Fabrice Ducos; Yevgeny Derimian; Maurice Herman; Didier Tanré; Lorraine A. Remer; Alexei Lyapustin; Andrew M. Sayer; Robert C. Levy; N. Christina Hsu; Jacques Descloitres; Lei Li; Benjamin Torres; Yana Karol; Milagros Herrera; Marcos Herreras; Michael Aspetsberger; Moritz Wanzenboeck; Lukas Bindreiter; Daniel Marth; Andreas Hangler; Christian Federspiel. 2020. "Validation of GRASP algorithm product from POLDER/PARASOL data and assessment of multi-angular polarimetry potential for aerosol monitoring." Earth System Science Data 12, no. 4: 3573-3620.
To study the feasibility of a fluorescence lidar for aerosol characterization, the fluorescence channel is added to the LILAS multiwavelength Mie–Raman lidar of Lille University, France. A part of the fluorescence spectrum induced by 355 nm laser radiation is selected by the interference filter of 44 nm bandwidth centered at 466 nm. Such an approach has proved to have high sensitivity, allowing fluorescence signals from weak aerosol layers to be detected and the fluorescence backscattering coefficient from the ratio of fluorescence and nitrogen Raman backscatters to be calculated. Observations were performed during the November 2019–February 2020 period. The fluorescence capacity (ratio of fluorescence to elastic backscattering coefficients), measured under conditions of low relative humidity, varied in a wide range, being the highest for the smoke and the lowest for the dust particles. The results presented also demonstrate that the fluorescence measurements can be used for monitoring the aerosol inside the cloud layers.
Igor Veselovskii; Qiaoyun Hu; Philippe Goloub; Thierry Podvin; Mikhail Korenskiy; Olivier Pujol; Oleg Dubovik; Anton Lopatin. Combined use of Mie–Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment. Atmospheric Measurement Techniques 2020, 13, 6691 -6701.
AMA StyleIgor Veselovskii, Qiaoyun Hu, Philippe Goloub, Thierry Podvin, Mikhail Korenskiy, Olivier Pujol, Oleg Dubovik, Anton Lopatin. Combined use of Mie–Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment. Atmospheric Measurement Techniques. 2020; 13 (12):6691-6701.
Chicago/Turabian StyleIgor Veselovskii; Qiaoyun Hu; Philippe Goloub; Thierry Podvin; Mikhail Korenskiy; Olivier Pujol; Oleg Dubovik; Anton Lopatin. 2020. "Combined use of Mie–Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment." Atmospheric Measurement Techniques 13, no. 12: 6691-6701.
Nick Schutgens; Oleg Dubovik; Otto Hasekamp; Omar Torres; Hiren Jethva; Peter J. T. Leonard; Pavel Litvinov; Jens Redemann; Yohei Shinozuka; Gerrit De Leeuw; Stefan Kinne; Thomas Popp; Michael Schulz; Philip Stier. Supplementary material to "AEROCOM/AEROSAT AAOT & SSA study, part I: evaluation and intercomparison of satellite measurements". 2020, 1 .
AMA StyleNick Schutgens, Oleg Dubovik, Otto Hasekamp, Omar Torres, Hiren Jethva, Peter J. T. Leonard, Pavel Litvinov, Jens Redemann, Yohei Shinozuka, Gerrit De Leeuw, Stefan Kinne, Thomas Popp, Michael Schulz, Philip Stier. Supplementary material to "AEROCOM/AEROSAT AAOT & SSA study, part I: evaluation and intercomparison of satellite measurements". . 2020; ():1.
Chicago/Turabian StyleNick Schutgens; Oleg Dubovik; Otto Hasekamp; Omar Torres; Hiren Jethva; Peter J. T. Leonard; Pavel Litvinov; Jens Redemann; Yohei Shinozuka; Gerrit De Leeuw; Stefan Kinne; Thomas Popp; Michael Schulz; Philip Stier. 2020. "Supplementary material to "AEROCOM/AEROSAT AAOT & SSA study, part I: evaluation and intercomparison of satellite measurements"." , no. : 1.
Global measurements of absorptive aerosol optical depth (AAOD) are scarce and mostly provided by the ground network AERONET (AErosol RObotic NETwork). In recent years, several satellite products of AAOD have appeared. This study's primary aim is to establish the usefulness of these datasets for AEROCOM (AEROsol Comparisons between Observations and Models) model evaluation with a focus on the years 2006, 2008 and 2010. The satellite products are super-observations consisting of 1° × 1° × 30min aggregated retrievals. This study consist of two parts: 1) an assessment of satellite datasets; 2) their application to the evaluation of AEROCOM models. The current paper describes the first part and details an evaluation with AERONET observations from the sparse AERONET network as well as a global intercomparison of satellite datasets, with a focus on how minimum AOD (Aerosol Optical Depth) thresholds and temporal averaging may improve agreement. All satellite datasets are shown to have reasonable skill for AAOD (3 out of 4 datasets show correlations with AERONET in excess of 0.6) but less skill for SSA (Single Scattering Albedo; only 1 out of 4 datasets shows correlations with AERONET in excess of 0.6). In comparison, satellite AOD shows correlations from 0.72 to 0.88 against the same AERONET dataset. We do show that performance vs. AERONET and satellite agreements for SSA significantly improve at higher AOD. Temporal averaging also improves agreements between satellite datasets. Nevertheless multi-annual averages still show systematic differences, even at high AOD. In particular, we show that two POLDER products appear to have a systematic SSA difference over land of about 0.04, independent of AOD. Identifying the cause of this bias offers the possibility of substantially improving current datasets. We also provide evidence that suggests that evaluation with AERONET observations leads to an underestimate of true biases in satellite SSA. In the second part of this study we show that, notwithstanding these biases in satellite AAOD and SSA, the datasets allow meaningful evaluation of AEROCOM models.
Nick Schutgens; Oleg Dubovik; Otto Hasekamp; Omar Torres; Hiren Jethva; Peter J. T. Leonard; Pavel Litvinov; Jens Redemann; Yohei Shinozuka; Gerrit de Leeuw; Stefan Kinne; Thomas Popp; Michael Schulz; Philip Stier. AEROCOM/AEROSAT AAOT & SSA study, part I: evaluation and intercomparison of satellite measurements. 2020, 2020, 1 -35.
AMA StyleNick Schutgens, Oleg Dubovik, Otto Hasekamp, Omar Torres, Hiren Jethva, Peter J. T. Leonard, Pavel Litvinov, Jens Redemann, Yohei Shinozuka, Gerrit de Leeuw, Stefan Kinne, Thomas Popp, Michael Schulz, Philip Stier. AEROCOM/AEROSAT AAOT & SSA study, part I: evaluation and intercomparison of satellite measurements. . 2020; 2020 ():1-35.
Chicago/Turabian StyleNick Schutgens; Oleg Dubovik; Otto Hasekamp; Omar Torres; Hiren Jethva; Peter J. T. Leonard; Pavel Litvinov; Jens Redemann; Yohei Shinozuka; Gerrit de Leeuw; Stefan Kinne; Thomas Popp; Michael Schulz; Philip Stier. 2020. "AEROCOM/AEROSAT AAOT & SSA study, part I: evaluation and intercomparison of satellite measurements." 2020, no. : 1-35.
We examine the capability of near-spherical-shaped particles to reproduce the triple-wavelength particle linear depolarization ratio (PLDR) and lidar ratio (LR) values measured over Europe for stratospheric smoke originating from Canadian wildfires. The smoke layers were detected both in the troposphere and the stratosphere, though in the latter case the particles presented PLDR values of almost 18 % at 532 nm as well as a strong spectral dependence from the UV to the near-IR wavelength. Although recent simulation studies of rather complicated smoke particle morphologies have shown that heavily coated smoke aggregates can produce large PLDR, herein we propose a much simpler model of compact near-spherical smoke particles. This assumption allows for the reproduction of the observed intensive optical properties of stratospheric smoke, as well as their spectral dependence. We further examine whether an extension of the current Aerosol Robotic Network (AERONET) scattering model to include the near-spherical shapes could be of benefit to the AERONET retrieval for stratospheric smoke cases associated with enhanced PLDR. Results of our study illustrate the fact that triple-wavelength PLDR and LR lidar measurements can provide us with additional insight when it comes to particle characterization.
Anna Gialitaki; Alexandra Tsekeri; Vassilis Amiridis; Romain Ceolato; Lucas Paulien; Anna Kampouri; Antonis Gkikas; Stavros Solomos; Eleni Marinou; Moritz Haarig; Holger Baars; Albert Ansmann; Tatyana Lapyonok; Anton Lopatin; Oleg Dubovik; Silke Groß; Martin Wirth; Maria Tsichla; Ioanna Tsikoudi; Dimitris Balis. Is the near-spherical shape the “new black” for smoke? Atmospheric Chemistry and Physics 2020, 20, 14005 -14021.
AMA StyleAnna Gialitaki, Alexandra Tsekeri, Vassilis Amiridis, Romain Ceolato, Lucas Paulien, Anna Kampouri, Antonis Gkikas, Stavros Solomos, Eleni Marinou, Moritz Haarig, Holger Baars, Albert Ansmann, Tatyana Lapyonok, Anton Lopatin, Oleg Dubovik, Silke Groß, Martin Wirth, Maria Tsichla, Ioanna Tsikoudi, Dimitris Balis. Is the near-spherical shape the “new black” for smoke? Atmospheric Chemistry and Physics. 2020; 20 (22):14005-14021.
Chicago/Turabian StyleAnna Gialitaki; Alexandra Tsekeri; Vassilis Amiridis; Romain Ceolato; Lucas Paulien; Anna Kampouri; Antonis Gkikas; Stavros Solomos; Eleni Marinou; Moritz Haarig; Holger Baars; Albert Ansmann; Tatyana Lapyonok; Anton Lopatin; Oleg Dubovik; Silke Groß; Martin Wirth; Maria Tsichla; Ioanna Tsikoudi; Dimitris Balis. 2020. "Is the near-spherical shape the “new black” for smoke?" Atmospheric Chemistry and Physics 20, no. 22: 14005-14021.
The exploration of aerosol retrieval synergies from diverse combinations of ground-based passive sun-photometric measurements with co-located active lidar ground-based and radiosonde observations using versatile GRASP algorithm is presented. Several potentially fruitful aspects of observation synergy were considered. First, a set of passive and active ground-based observations collected during both day and night time were inverted simultaneously under the assumption of temporal continuity of aerosol properties. Such approach explores the complementarity of the information in different observations and results in a robust and consistent processing of all observations. For example, the interpretation of the night-time active observations usually suffers from the lack of information about aerosol particles sizes, shapes and complex refractive index. In the realized synergy retrievals, the information propagating from the close-by sun-photometric observations provides sufficient constraints for reliable interpretation of both day- and night- time lidar observations. Second, the synergetic processing of such complementary observations with enhanced information content allows for optimizing the aerosol model used in the retrieval. Specifically, the external mixture of several aerosol components with predetermined sizes, shapes and composition has been identified as an efficient approach for achieving reliable retrieval of aerosol properties in several situations. This approach allows for achieving consistent and accurate aerosol retrievals from processing stand-alone advanced lidar observations with reduced information content about aerosol columnar properties. Third, the potential of synergy processing of the ground-based sun–photometric and lidar observations, with the in situ backscatter sonde measurements was explored using the data from KAUST.15 and KAUST.16 field campaigns held at King Abdullah University of Science and Technology (KAUST) in the August of 2015 and 2016. The inclusion of radiosonde data has been demonstrated to provide significant additional constraints to validate and improve the accuracy and scope of aerosol profiling. The results of all retrieval set-ups used for processing both synergy and stand-alone observation data sets are discussed and inter-compared.
Anton Lopatin; Oleg Dubovik; David Fuertes; Georgiy Stenchikov; Tatyana Lapyonok; Igor Veselovskii; Frank G. Wienhold; Illia Shevchenko; Qiaoyun Hu; Sagar Parajuli. Synergy processing of diverse ground-based remote sensing and in situ data using GRASP algorithm: applications to radiometer, lidar and radiosonde observations. 2020, 2020, 1 -50.
AMA StyleAnton Lopatin, Oleg Dubovik, David Fuertes, Georgiy Stenchikov, Tatyana Lapyonok, Igor Veselovskii, Frank G. Wienhold, Illia Shevchenko, Qiaoyun Hu, Sagar Parajuli. Synergy processing of diverse ground-based remote sensing and in situ data using GRASP algorithm: applications to radiometer, lidar and radiosonde observations. . 2020; 2020 ():1-50.
Chicago/Turabian StyleAnton Lopatin; Oleg Dubovik; David Fuertes; Georgiy Stenchikov; Tatyana Lapyonok; Igor Veselovskii; Frank G. Wienhold; Illia Shevchenko; Qiaoyun Hu; Sagar Parajuli. 2020. "Synergy processing of diverse ground-based remote sensing and in situ data using GRASP algorithm: applications to radiometer, lidar and radiosonde observations." 2020, no. : 1-50.
We analyse of the airborne measurements of above-cloud aerosols from the AEROCLO-sA field campaign performed in Namibia during August and September 2017. To improve the retrieval of the aerosol and cloud properties, the airborne demonstrator of the Multi-viewing, Multi-channel, Multi-polarization (3MI) satellite instrument, called OSIRIS, was deployed on-board the Safire Falcon 20 aircraft during 10 flights performed over land, over the ocean and along the Namibian coast. The airborne instrument OSIRIS provides observations at high temporal and spatial resolutions for AAC and cloud properties, with well-defined uncertainties. OSIRIS was supplemented with the airborne multi-wavelength sun-photometer PLASMA2. The application of the algorithm developed for the POLDER spaceborne instrument in the visible range to the OSIRIS measurements allowed to characterise the Aerosol Above Cloud (AAC) properties. The variations of the aerosol properties are consistent with the different atmospheric circulation regimes observed during the deployment. Airborne observations typically a show strong Aerosol Optical Depth (AOD, up to 1.2 at 550 nm) of fine mode particles from biomass burning (extinction Angström exponent varying between 1.6 and 2.2), transported above a stratocumulus deck (cloud top around 1 km above mean sea level) with Cloud Optical Thickness (COT) up to 35 at 550 nm. The above-cloud visible AOD retrieved with OSIRIS agrees within 10 % with the PLASMA2 sun-photometer measured in the same environment. The AEROCLO-sA campaign-average Single Scattering Albedo (SSA) obtained by OSIRIS at 550 nm is 0.87. The strong absorption of the biomass burning plumes in the visible is consistent with the observations from the AERONET ground-based sun-photometers. The latter indicate a significant increase of the absorption at 440 nm, showing possible additional presence of absorbing organic species within the smoke plumes. Biomass burning aerosols are also vertically collocated with significant amounts of water content up to the top of the plume around 6 km height. The average AAC Direct Radiative Effect (DRE) calculated from the airborne measurements in the visible range is +85 W m−2 (standard deviation of 26 W m−2) with instantaneous values up to +200 W m−2 during intense events. Combination between water vapour and the strong positive aerosol forcing over the region explains possible feedbacks on cloud development. This new set of data represents a new opportunity to better constrain climate models and to study aerosol–cloud–radiation interactions over the South-East Atlantic region.
Aurélien Chauvigné; Fabien Waquet; Frédérique Auriol; Luc Blarel; Cyril Delegove; Oleg Dubovik; Cyrille Flamant; Marco Gaetani; Philippe Goloub; Rodrigue Loisil; Marc Mallet; Jean-Marc Nicolas; Frédéric Parol; Fanny Peers; Benjamin Torres; Paola Formenti. Aerosol and cloud properties in the Namibian region during AEROCLO-sA field campaign: 3MI airborne simulator and sun-photometer measurements. 2020, 1 -21.
AMA StyleAurélien Chauvigné, Fabien Waquet, Frédérique Auriol, Luc Blarel, Cyril Delegove, Oleg Dubovik, Cyrille Flamant, Marco Gaetani, Philippe Goloub, Rodrigue Loisil, Marc Mallet, Jean-Marc Nicolas, Frédéric Parol, Fanny Peers, Benjamin Torres, Paola Formenti. Aerosol and cloud properties in the Namibian region during AEROCLO-sA field campaign: 3MI airborne simulator and sun-photometer measurements. . 2020; ():1-21.
Chicago/Turabian StyleAurélien Chauvigné; Fabien Waquet; Frédérique Auriol; Luc Blarel; Cyril Delegove; Oleg Dubovik; Cyrille Flamant; Marco Gaetani; Philippe Goloub; Rodrigue Loisil; Marc Mallet; Jean-Marc Nicolas; Frédéric Parol; Fanny Peers; Benjamin Torres; Paola Formenti. 2020. "Aerosol and cloud properties in the Namibian region during AEROCLO-sA field campaign: 3MI airborne simulator and sun-photometer measurements." , no. : 1-21.
Multi-angle polarimetric (MAP) imaging of Earth scenes can be used for the retrieval of microphysical and optical parameters of aerosols and clouds. The Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) is an aircraft MAP instrument with a hyper-angular imaging capability of 60 along-track viewing angles at 670 nm and 20 along-track viewing angles at other wavelengths – 440, 550, and 870 nm – across the full 114∘ (94∘) along-track (cross-track) field of view. Here we report the retrieval of aerosol properties using the Generalized Retrieval of Aerosols and Surface Properties (GRASP) algorithm applied to AirHARP observations collected during the NASA Aerosol Characterization from Polarimeter and Lidar (ACEPOL) campaign in October–November 2017. The retrieved aerosol properties include spherical fraction (SF), aerosol column concentration in multiple size distribution modes, and, with sufficient aerosol loading, complex aerosol refractive index. From these primary retrievals, we derive aerosol optical depth (AOD), Angstrom exponent (AE), and single scattering albedo (SSA). AODs retrieved from AirHARP measurements are compared with the High Spectral Resolution LiDAR-2 (HSRL2) AOD measurements at 532 nm and validated with measurements from collocated Aerosol Robotic NETwork (AERONET) stations. A good agreement with HSRL2 (ρ=0.940, |BIAS|=0.062, mean absolute error (MAE) = 0.122) and AERONET AOD (0.010≤MAE≤0.015, 0.002≤|BIAS|≤0.009) measurements is observed for the collocated points. There was a mismatch between the HSRL2- and AirHARP-retrieved AOD for the pixels close to the forest fire smoke source and to the edges of the plume due to spatial mismatch in the sampling. This resulted in a higher BIAS and MAE for the HSRL2 AOD comparison. For the case of AERONET AOD comparison, two different approaches are used in the GRASP retrievals, and the simplified aerosol component-based GRASP/Models kernel which retrieves fewer number of aerosol parameter performed well compared to a more generous GRASP/Five mode approach in the low aerosol loading cases. Forest fire smoke intercepted during ACEPOL provided a situation with homogenous plume and sufficient aerosol loading to retrieve the real part of the refractive index (RRI) of 1.55 and the imaginary part of the refractive index (IRI) of 0.024. The derived SSAs for this case are 0.87, 0.86, 0.84, and 0.81 at wavelengths of 440, 550, 670, and 870 nm, respectively. Finer particles with an average AE of 1.53, a volume median radius of 0.157 µm, and a standard deviation (SD) of 0.55 for fine mode is observed for the same smoke plume. These results serve as a proxy for the scale and detail of aerosol retrievals that are anticipated from future space mission data, as HARP CubeSat (mission begins 2020) and HARP2 (aboard the NASA PACE mission with launch in 2023) are near duplicates of AirHARP and are expected to provide the same level of aerosol characterization.
Anin Puthukkudy; J. Vanderlei Martins; Lorraine A. Remer; Xiaoguang Xu; Oleg Dubovik; Pavel Litvinov; Brent McBride; Sharon Burton; Henrique M. J. Barbosa. Retrieval of aerosol properties from Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) observations during ACEPOL 2017. Atmospheric Measurement Techniques 2020, 13, 5207 -5236.
AMA StyleAnin Puthukkudy, J. Vanderlei Martins, Lorraine A. Remer, Xiaoguang Xu, Oleg Dubovik, Pavel Litvinov, Brent McBride, Sharon Burton, Henrique M. J. Barbosa. Retrieval of aerosol properties from Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) observations during ACEPOL 2017. Atmospheric Measurement Techniques. 2020; 13 (10):5207-5236.
Chicago/Turabian StyleAnin Puthukkudy; J. Vanderlei Martins; Lorraine A. Remer; Xiaoguang Xu; Oleg Dubovik; Pavel Litvinov; Brent McBride; Sharon Burton; Henrique M. J. Barbosa. 2020. "Retrieval of aerosol properties from Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) observations during ACEPOL 2017." Atmospheric Measurement Techniques 13, no. 10: 5207-5236.
The climatological characteristics of total aerosol optical thickness (AOT) together with fine and coarse mode AOT (fAOT, cAOT), and fine mode fraction (FMF= fAOT/AOT) over East and South Asia are presented here for the period March 2005 to October 2013. The characteristics are retrieved from POLDER/PARASOL measurements using recently developed aerosol component module of GRASP algorithm. The satellite retrievals were validated and presented a good agreement with the AERONET products (e.g., R of ~ 0.8 – 0.9 for AOT, fAOT, Ångström Exponent and FMF). The results show a seasonal cycle and strong relation to the emission sources. For example, FMF has a peak of nearly 1.0 in March in the Indo‐China Peninsula region, reaches a minimum of about 0.4 in April in Northwestern China region. These patterns can be explained by dominance of anthropogenic pollution or desert dust emissions. Maps of fine, coarse, and total AOT, as well as of FMF for the East and South Asia region are presented and analyzed in scope of seasonal and interannual variabilities.
Lei Li; Huizheng Che; Yevgeny Derimian; Oleg Dubovik; QingZu Luan; Qiuyue Li; Xueying Huang; Hujia Zhao; Ke Gui; Yu Zheng; Linchang An; Tianze Sun; Yuanxin Liang. Climatology of Fine and Coarse Mode Aerosol Optical Thickness Over East and South Asia Derived From POLDER/PARASOL Satellite. Journal of Geophysical Research: Atmospheres 2020, 125, 1 .
AMA StyleLei Li, Huizheng Che, Yevgeny Derimian, Oleg Dubovik, QingZu Luan, Qiuyue Li, Xueying Huang, Hujia Zhao, Ke Gui, Yu Zheng, Linchang An, Tianze Sun, Yuanxin Liang. Climatology of Fine and Coarse Mode Aerosol Optical Thickness Over East and South Asia Derived From POLDER/PARASOL Satellite. Journal of Geophysical Research: Atmospheres. 2020; 125 (16):1.
Chicago/Turabian StyleLei Li; Huizheng Che; Yevgeny Derimian; Oleg Dubovik; QingZu Luan; Qiuyue Li; Xueying Huang; Hujia Zhao; Ke Gui; Yu Zheng; Linchang An; Tianze Sun; Yuanxin Liang. 2020. "Climatology of Fine and Coarse Mode Aerosol Optical Thickness Over East and South Asia Derived From POLDER/PARASOL Satellite." Journal of Geophysical Research: Atmospheres 125, no. 16: 1.