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Dr. NIKOLAOS SIOMOS
Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Greece

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0 Aerosol
0 Photometry
0 machine learning
0 LiDAR Remote Sensing
0 Satellite applications

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Aerosol
machine learning

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Preprint content
Published: 04 March 2021
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In this study, we present a comparison of the AEOLUS satellite L2A product with the retrievals of the ground-based lidar systems of EARLINET (European Aerosol Research Lidar Network), part the European Research Infrastructure for the observation of Aerosol, Clouds and Trace Gases (ACTRIS). Dedicated ground‐based measurements during AEOLUS overpasses have been performed among the 29 member stations since the beginning of the mission, however, we have included only the stations that have gathered a significant number of collocations in the analysis. The satellite timeseries we deployed covers the period 2019-2020 that correspond to the best available version of the satellite processing algorithms. We harvest the collocations using the following spacio-temporal criteria. Only overpasses that fall within a radius less than 100km around the station are included. Using this criterion, the AEOLUS L2A climatology is generated per station independently of the ground-based measurements. To isolate collocated data we reject all AEOLUS data with a time interval between the overpass and the central time of the ground-based measurement that is greater than 3 hours. The ground based lidar climatology is also computed per station. AEOLUS L2A products include aerosol extinction coefficient profiles and aerosol co-polar backscatter coefficient profiles from circularly polarized light emission. While the extinction profiles are directly comparable with the ground-based lidars, this is not the case for the backscatter profiles since AEOLUS cannot measure the cross polar component of the aerosol backscatter. The co-polar backscatter is close to the total backscatter only in the absence of depolarizing scatterers such as dust, pollen, volcanic ash, and cirrus ice crystals. Ground-based measurements are divided in two categories for the evaluation depending on whether aerosol depolarization measurements have been performed. If the particle linear depolarization ratio (PLDR) is available, it can be applied to convert the lidar total backscatter to an AOLUS-like co-polar backscatter coefficient. This category is applied for the direct evaluation of the satellite product. Cases that lack PLDR information assist to quantify the uncertainties introduced by using the AEOLUS co-polar backscatter as a substitute for the total backscatter. The analysis includes both an indirect climatological comparison and a direct collocation comparison between the ground based and satellite datasets. Via the collocation comparison, random and systematic uncertainties in the satellite product are identified and quantified. A climatological comparison can show the potential of AEOLUS to capture annual cycles despite its intrinsic random errors. In the future, the analysis will be further supported with auxiliary data such as sunphotometer measurements, aerosol classification flags, modeled backward trajectories, and satellite cloud fraction data.

ACS Style

Nikolaos Siomos; Antonis Gkikas; Holger Baars; Ulla Wandinger; Vasilis Amiridis; Peristera Paschou; EARLINET consortium. Investigating the performance of AEOLUS L2A products over Europe with EARLINET ground-based lidars. 2021, 1 .

AMA Style

Nikolaos Siomos, Antonis Gkikas, Holger Baars, Ulla Wandinger, Vasilis Amiridis, Peristera Paschou, EARLINET consortium. Investigating the performance of AEOLUS L2A products over Europe with EARLINET ground-based lidars. . 2021; ():1.

Chicago/Turabian Style

Nikolaos Siomos; Antonis Gkikas; Holger Baars; Ulla Wandinger; Vasilis Amiridis; Peristera Paschou; EARLINET consortium. 2021. "Investigating the performance of AEOLUS L2A products over Europe with EARLINET ground-based lidars." , no. : 1.

Journal article
Published: 03 March 2021 in Atmospheric Chemistry and Physics
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The aim of this study is to investigate the potential of the Global Ozone Monitoring Experiment-2 (GOME-2) instruments, aboard the Meteorological Operational (MetOp)-A, MetOp-B and MetOp-C satellite programme platforms, to deliver accurate geometrical features of lofted aerosol layers. For this purpose, we use archived ground-based lidar data from stations available from the European Aerosol Research Lidar Network (EARLINET) database. The data are post-processed using the wavelet covariance transform (WCT) method in order to extract geometrical features such as the planetary boundary layer (PBL) height and the cloud boundaries. To obtain a significant number of collocated and coincident GOME-2 – EARLINET cases for the period between January 2007 and September 2019, 13 lidar stations, distributed over different European latitudes, contributed to this validation. For the 172 carefully screened collocations, the mean bias was found to be −0.18 ± 1.68 km, with a near-Gaussian distribution. On a station basis, and with a couple of exceptions where very few collocations were found, their mean biases fall in the ± 1 km range with an associated standard deviation between 0.5 and 1.5 km. Considering the differences, mainly due to the temporal collocation and the difference, between the satellite pixel size and the point view of the ground-based observations, these results can be quite promising and demonstrate that stable and extended aerosol layers as captured by the satellite sensors are verified by the ground-based data. We further present an in-depth analysis of a strong and long-lasting Saharan dust intrusion over the Iberian Peninsula. We show that, for this well-developed and spatially well-spread aerosol layer, most GOME-2 retrievals fall within 1 km of the exact temporally collocated lidar observation for the entire range of 0 to 150 km radii. This finding further testifies for the capabilities of the MetOp-borne instruments to sense the atmospheric aerosol layer heights.

ACS Style

Konstantinos Michailidis; Maria-Elissavet Koukouli; Nikolaos Siomos; Dimitris Balis; Olaf Tuinder; L. Gijsbert Tilstra; Lucia Mona; Gelsomina Pappalardo; Daniele Bortoli. First validation of GOME-2/MetOp absorbing aerosol height using EARLINET lidar observations. Atmospheric Chemistry and Physics 2021, 21, 3193 -3213.

AMA Style

Konstantinos Michailidis, Maria-Elissavet Koukouli, Nikolaos Siomos, Dimitris Balis, Olaf Tuinder, L. Gijsbert Tilstra, Lucia Mona, Gelsomina Pappalardo, Daniele Bortoli. First validation of GOME-2/MetOp absorbing aerosol height using EARLINET lidar observations. Atmospheric Chemistry and Physics. 2021; 21 (4):3193-3213.

Chicago/Turabian Style

Konstantinos Michailidis; Maria-Elissavet Koukouli; Nikolaos Siomos; Dimitris Balis; Olaf Tuinder; L. Gijsbert Tilstra; Lucia Mona; Gelsomina Pappalardo; Daniele Bortoli. 2021. "First validation of GOME-2/MetOp absorbing aerosol height using EARLINET lidar observations." Atmospheric Chemistry and Physics 21, no. 4: 3193-3213.

Journal article
Published: 04 December 2020 in Remote Sensing
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A long-term analysis and climatology of aerosol backscatter and extinction coefficients profiles using a five-year study period lidar dataset derived from a multiwavelenth Raman lidar at Thessaloniki station is presented. All measurements have been processed with the latest version of the Single Calculus Chain (SCCv5.1.6) fully automated algorithm, which has been developed to provide a common lidar processing tool, within EARLINET (European Aerosol Research Lidar NETwork) stations. The optical products delivered by the SCC tool have already been compared with the optical products derived from the operational algorithm of Thessaloniki (THessaloniki Aerosol LIdar Algorithm-THALIA) and discussed in terms of inhomogeneities. In this contribution, we analyze these products for climatological purposes, in order to investigate the aerosol columnar properties over Thessaloniki lidar station, drawing conclusions about the issues to be considered when switching from the current operational algorithm to the SCCv5. The SCCv5 algorithm is evaluated for the AOD both for 355 and 532 nm. The agreement with THALIA algorithm seems promising with correlations of 0.89 and 0.84, respectively, and absolute deviations within the range of the EARLINET quality requirements. Time series of the AOD at 355 nm denote a decrease of 0.017 per year in the free troposphere, a trend that is also shown in the AOD values derived from the operational algorithm (0.014). A decrease of 0.01 per year in the lower troposphere is also noted from the SCC, whereas the corresponding AOD values derived from the operational algorithm denote a decrease of 0.017.

ACS Style

Kalliopi Voudouri; Nikolaos Siomos; Konstantinos Michailidis; Giuseppe D’Amico; Ina Mattis; Dimitris Balis. Consistency of the Single Calculus Chain Optical Products with Archived Measurements from an EARLINET Lidar Station. Remote Sensing 2020, 12, 3969 .

AMA Style

Kalliopi Voudouri, Nikolaos Siomos, Konstantinos Michailidis, Giuseppe D’Amico, Ina Mattis, Dimitris Balis. Consistency of the Single Calculus Chain Optical Products with Archived Measurements from an EARLINET Lidar Station. Remote Sensing. 2020; 12 (23):3969.

Chicago/Turabian Style

Kalliopi Voudouri; Nikolaos Siomos; Konstantinos Michailidis; Giuseppe D’Amico; Ina Mattis; Dimitris Balis. 2020. "Consistency of the Single Calculus Chain Optical Products with Archived Measurements from an EARLINET Lidar Station." Remote Sensing 12, no. 23: 3969.

Preprint content
Published: 08 July 2020
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The aim of this study is to investigate the potential of GOME-2 instruments on board the MetOpA, MetOpB and MetOpC platforms, to deliver accurate geometrical features of lofted aerosol layers. For this purpose, we use archived ground-based lidar data from lidar stations available fromEuropean Aerosol Research Lidar Network (EARLINET) database. The data are post-processed with the wavelet covariance transform (WCT) method in order to extract geometrical features such as the Planetary Boundary Layer, PBL, height and the cloud boundaries. To obtain a significant number of collocated and coincident GOME-2 – EARLINET cases for the period between January 2007 and September 2019, fourteenlidar stations, distributed over different European latitudes, contributed to this validation. For the 172 carefully screened collocations, the mean bias was found to be −0.18 ± 1.68 km, with a near Gaussian distribution. On a station-basis, and with a couple of exceptions where very few collocations were found, their mean biases fall in the ± 1 km range with an associated standard deviation between 0.5 and 1.5 km. Considering the differences, mainly due to the temporal collocation and the difference between the satellite pixel size and the point view of the ground-based observations, these results are quite promising and demonstrating that stable and extended aerosol layers as captured by the satellite sensors, are verified by the ground-based data. We further present an in-depth analysis of a strong and long-lasting Saharan dust intrusion over the Iberian Peninsula. We show that for, this well-developed and spatially well-spread aerosol layer, most GOME-2 retrievals fall within 1 km of the exactly temporally collocated lidar observation for the entire range of 0 to 150 km radii. This finding further testifies to the capabilities of the MetOp-born instruments to sense the atmospheric aerosol layer height.

ACS Style

Konstantinos Michailidis; Maria-Elissavet Koukouli; Nikolaos Siomos; Dimitrios Balis; Olaf Tuinder; L. Gijsbert Tilstra; Lucia Mona; Gelsomina Pappalardo; Daniele Bortoli. First validation of GOME-2/MetOp Absorbing Aerosol Height using EARLINET lidar observations. 2020, 2020, 1 -31.

AMA Style

Konstantinos Michailidis, Maria-Elissavet Koukouli, Nikolaos Siomos, Dimitrios Balis, Olaf Tuinder, L. Gijsbert Tilstra, Lucia Mona, Gelsomina Pappalardo, Daniele Bortoli. First validation of GOME-2/MetOp Absorbing Aerosol Height using EARLINET lidar observations. . 2020; 2020 ():1-31.

Chicago/Turabian Style

Konstantinos Michailidis; Maria-Elissavet Koukouli; Nikolaos Siomos; Dimitrios Balis; Olaf Tuinder; L. Gijsbert Tilstra; Lucia Mona; Gelsomina Pappalardo; Daniele Bortoli. 2020. "First validation of GOME-2/MetOp Absorbing Aerosol Height using EARLINET lidar observations." 2020, no. : 1-31.

Journal article
Published: 17 March 2020 in Remote Sensing
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In this study, we present an aerosol classification technique based on measurements of a double monochromator Brewer spectrophotometer during the period 1998–2017 in Thessaloniki, Greece. A machine learning clustering procedure was applied based on the Mahalanobis distance metric. The classification process utilizes the UV Single Scattering Albedo (SSA) at 340 nm and the Extinction Angstrom Exponent (EAE) at 320–360 nm that are obtained from the spectrophotometer. The analysis is supported by measurements from a CIMEL sunphotometer that were deployed in order to establish the training dataset of Brewer measurements. By applying the Mahalanobis distance algorithm to the Brewer timeseries, we automatically assigned measurements in one of the following clusters: Fine Non Absorbing Mixtures (FNA): 64.7%, Black Carbon Mixtures (BC): 17.4%, Dust Mixtures (DUST): 8.1%, and Mixed: 9.8%. We examined the clustering potential of the algorithm by reclassifying the training dataset and comparing it with the original one and also by using manually classified cases. The typing score of the Mahalanobis algorithm is high for all predominant clusters FNA: 77.0%, BC: 63.9%, and DUST: 80.3% when compared with the training dataset. We obtained high scores as well FNA: 100.0%, BC: 66.7%, and DUST: 83.3% when comparing it with the manually classified dataset. The flags obtained here were applied in the timeseries of the Aerosol Optical Depth (AOD) at 340 nm of the Brewer and the CIMEL in order to compare between the two and also stress the future impact of the proposed clustering technique in climatological studies of the station.

ACS Style

Nikolaos Siomos; Ilias Fountoulakis; Athanasios Natsis; Theano Drosoglou; Alkiviadis Bais. Automated Aerosol Classification from Spectral UV Measurements Using Machine Learning Clustering. Remote Sensing 2020, 12, 965 .

AMA Style

Nikolaos Siomos, Ilias Fountoulakis, Athanasios Natsis, Theano Drosoglou, Alkiviadis Bais. Automated Aerosol Classification from Spectral UV Measurements Using Machine Learning Clustering. Remote Sensing. 2020; 12 (6):965.

Chicago/Turabian Style

Nikolaos Siomos; Ilias Fountoulakis; Athanasios Natsis; Theano Drosoglou; Alkiviadis Bais. 2020. "Automated Aerosol Classification from Spectral UV Measurements Using Machine Learning Clustering." Remote Sensing 12, no. 6: 965.

Conference paper
Published: 09 October 2019 in Remote Sensing of Clouds and the Atmosphere XXIV
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The irregular shape of mineral dust provides a strong signature on active and passive polarimetric remote sensing observations. Nowadays, advanced lidar systems operating in the framework of ACTRIS are capable of providing quality assured, calibrated multi-wavelength linear particle depolarization ratio measurements, while new developments will provide us more polarimetric measurements in the near future. Passive polarimeters are already part of ACTRIS and their integration in operational algorithms is expected in the near future. This wealth of new information combined with updated scattering databases and sophisticated inversion schemes provide the means towards an improved characterization of desert dust in the future. We present here some examples from the ACTRIS journey on dust research during the last decade, aiming to demonstrate the progress on issues such as: (a) the discrimination of desert dust in external mixtures, (b) the separation and estimation of the fine and coarse particle modes, (c) the synergy of passive and active remote sensing for the derivation of dust concentration profiles, (d) the provision of dust-related CCN and IN particle concentrations for aerosol-cloud interaction studies, (e) the development of new scattering databases based on realistic particle shapes, (e) the application of these techniques on spaceborne lidar retrievals for the provision of global and regional climatological datasets. Future plans within ACTRIS for the evaluation and advancement of the methodologies and retrievals are also discussed, combined with new developments within the framework of the D-TECT ERC Grant.

ACS Style

Vassilis Amiridis; Alexandra Tsekeri; Eleni Marinou; Emmanouil Proestakis; Antonis Gkikas; Anna Gialitaki; Vasiliki Daskalopoulou; Peristera Paschou; Nikolaos Siomos; Ioannis Binietoglou; Josef Gasteiger; Volker Freudenthaler; Rodanthi-Elisavet Mamouri; Albert Ansmann; Lucia Mona. Advancing the remote sensing of desert dust. Remote Sensing of Clouds and the Atmosphere XXIV 2019, 11152, 1115206 .

AMA Style

Vassilis Amiridis, Alexandra Tsekeri, Eleni Marinou, Emmanouil Proestakis, Antonis Gkikas, Anna Gialitaki, Vasiliki Daskalopoulou, Peristera Paschou, Nikolaos Siomos, Ioannis Binietoglou, Josef Gasteiger, Volker Freudenthaler, Rodanthi-Elisavet Mamouri, Albert Ansmann, Lucia Mona. Advancing the remote sensing of desert dust. Remote Sensing of Clouds and the Atmosphere XXIV. 2019; 11152 ():1115206.

Chicago/Turabian Style

Vassilis Amiridis; Alexandra Tsekeri; Eleni Marinou; Emmanouil Proestakis; Antonis Gkikas; Anna Gialitaki; Vasiliki Daskalopoulou; Peristera Paschou; Nikolaos Siomos; Ioannis Binietoglou; Josef Gasteiger; Volker Freudenthaler; Rodanthi-Elisavet Mamouri; Albert Ansmann; Lucia Mona. 2019. "Advancing the remote sensing of desert dust." Remote Sensing of Clouds and the Atmosphere XXIV 11152, no. : 1115206.

Journal article
Published: 23 September 2019 in Atmospheric Chemistry and Physics
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We present the evaluation activity of the European Aerosol Research Lidar Network (EARLINET) for the quantitative assessment of the Level 2 aerosol backscatter coefficient product derived by the Cloud-Aerosol Transport System (CATS) aboard the International Space Station (ISS; Rodier et al., 2015). The study employs correlative CATS and EARLINET backscatter measurements within a 50 km distance between the ground station and the ISS overpass and as close in time as possible, typically with the starting time or stopping time of the EARLINET performed measurement time window within 90 min of the ISS overpass, for the period from February 2015 to September 2016. The results demonstrate the good agreement of the CATS Level 2 backscatter coefficient and EARLINET. Three ISS overpasses close to the EARLINET stations of Leipzig, Germany; Évora, Portugal; and Dushanbe, Tajikistan, are analyzed here to demonstrate the performance of the CATS lidar system under different conditions. The results show that under cloud-free, relative homogeneous aerosol conditions, CATS is in good agreement with EARLINET, independent of daytime and nighttime conditions. CATS low negative biases are observed, partially attributed to the deficiency of lidar systems to detect tenuous aerosol layers of backscatter signal below the minimum detection thresholds; these are biases which may lead to systematic deviations and slight underestimations of the total aerosol optical depth (AOD) in climate studies. In addition, CATS misclassification of aerosol layers as clouds, and vice versa, in cases of coexistent and/or adjacent aerosol and cloud features, occasionally leads to non-representative, unrealistic, and cloud-contaminated aerosol profiles. Regarding solar illumination conditions, low negative biases in CATS backscatter coefficient profiles, of the order of 6.1 %, indicate the good nighttime performance of CATS. During daytime, a reduced signal-to-noise ratio by solar background illumination prevents retrievals of weakly scattering atmospheric layers that would otherwise be detectable during nighttime, leading to higher negative biases, of the order of 22.3 %.

ACS Style

Emmanouil Proestakis; Vassilis Amiridis; Eleni Marinou; Ioannis Binietoglou; Albert Ansmann; Ulla Wandinger; Julian Hofer; John Yorks; Edward Nowottnick; Abduvosit Makhmudov; Alexandros Papayannis; Aleksander Pietruczuk; Anna Gialitaki; Arnoud Apituley; Artur Szkop; Constantino Muñoz Porcar; Daniele Bortoli; Davide Dionisi; Dietrich Althausen; Dimitra Mamali; Dimitris Balis; Doina Nicolae; Eleni Tetoni; Gian Luigi Liberti; Holger Baars; Ina Mattis; Iwona Sylwia Stachlewska; Kalliopi Artemis Voudouri; Lucia Mona; Maria Mylonaki; Maria Rita Perrone; Maria João Costa; Michael Sicard; Nikolaos Papagiannopoulos; Nikolaos Siomos; Pasquale Burlizzi; Rebecca Pauly; Ronny Engelmann; Sabur Abdullaev; Gelsomina Pappalardo. EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product. Atmospheric Chemistry and Physics 2019, 19, 11743 -11764.

AMA Style

Emmanouil Proestakis, Vassilis Amiridis, Eleni Marinou, Ioannis Binietoglou, Albert Ansmann, Ulla Wandinger, Julian Hofer, John Yorks, Edward Nowottnick, Abduvosit Makhmudov, Alexandros Papayannis, Aleksander Pietruczuk, Anna Gialitaki, Arnoud Apituley, Artur Szkop, Constantino Muñoz Porcar, Daniele Bortoli, Davide Dionisi, Dietrich Althausen, Dimitra Mamali, Dimitris Balis, Doina Nicolae, Eleni Tetoni, Gian Luigi Liberti, Holger Baars, Ina Mattis, Iwona Sylwia Stachlewska, Kalliopi Artemis Voudouri, Lucia Mona, Maria Mylonaki, Maria Rita Perrone, Maria João Costa, Michael Sicard, Nikolaos Papagiannopoulos, Nikolaos Siomos, Pasquale Burlizzi, Rebecca Pauly, Ronny Engelmann, Sabur Abdullaev, Gelsomina Pappalardo. EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product. Atmospheric Chemistry and Physics. 2019; 19 (18):11743-11764.

Chicago/Turabian Style

Emmanouil Proestakis; Vassilis Amiridis; Eleni Marinou; Ioannis Binietoglou; Albert Ansmann; Ulla Wandinger; Julian Hofer; John Yorks; Edward Nowottnick; Abduvosit Makhmudov; Alexandros Papayannis; Aleksander Pietruczuk; Anna Gialitaki; Arnoud Apituley; Artur Szkop; Constantino Muñoz Porcar; Daniele Bortoli; Davide Dionisi; Dietrich Althausen; Dimitra Mamali; Dimitris Balis; Doina Nicolae; Eleni Tetoni; Gian Luigi Liberti; Holger Baars; Ina Mattis; Iwona Sylwia Stachlewska; Kalliopi Artemis Voudouri; Lucia Mona; Maria Mylonaki; Maria Rita Perrone; Maria João Costa; Michael Sicard; Nikolaos Papagiannopoulos; Nikolaos Siomos; Pasquale Burlizzi; Rebecca Pauly; Ronny Engelmann; Sabur Abdullaev; Gelsomina Pappalardo. 2019. "EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product." Atmospheric Chemistry and Physics 19, no. 18: 11743-11764.

Journal article
Published: 19 September 2019 in Remote Sensing
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The gap in knowledge regarding the radiative effects of aerosols in the UV region of the solar spectrum is large, mainly due to the lack of systematic measurements of the aerosol single scattering albedo (SSA) and absorption optical depth (AAOD). In the present study, spectral UV measurements performed in Thessaloniki, Greece by a double monochromator Brewer spectrophotometer in the period 1998–2017 are used for the calculation of the aforementioned optical properties. The main uncertainty factors have been described and there is an effort to quantify the overall uncertainties in SSA and AAOD. Analysis of the results suggests that the absorption by aerosols is much stronger in the UV relative to the visible. SSA follows a clear annual pattern ranging from ~0.7 in winter to ~0.85 in summer at wavelengths 320–360 nm, while AAOD peaks in summer and winter. The average AAOD for 2009–2011 is ~50% above the 2003–2006 average, possibly due to increased emissions of absorbing aerosols related to the economic crisis and the metro-railway construction works in the city center.

ACS Style

Ilias Fountoulakis; Athanasios Natsis; Nikolaos Siomos; Theano Drosoglou; Alkiviadis F. Bais. Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece. Remote Sensing 2019, 11, 2179 .

AMA Style

Ilias Fountoulakis, Athanasios Natsis, Nikolaos Siomos, Theano Drosoglou, Alkiviadis F. Bais. Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece. Remote Sensing. 2019; 11 (18):2179.

Chicago/Turabian Style

Ilias Fountoulakis; Athanasios Natsis; Nikolaos Siomos; Theano Drosoglou; Alkiviadis F. Bais. 2019. "Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece." Remote Sensing 11, no. 18: 2179.

Preprint
Published: 04 September 2019
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The gap in knowledge regarding the radiative effects of aerosols in the UV region of the solar spectrum is large, mainly due to the lack of systematic measurements of the aerosol single scattering albedo (SSA) and absorption optical depth (AAOD). In the present study, spectral UV measurements performed in Thessaloniki, Greece by a double monochromator Brewer spectrophotometer in the period 1998 - 2017 are used for the calculation of the aforementioned optical properties. The main uncertainty factors have been described and there is an effort to quantify the overall uncertainties in SSA and AAOD. Analysis of the results suggests that the absorption by aerosols is much stronger in the UV relative to the visible. SSA follows a clear annual pattern ranging from ~0.7 in winter to ~0.85 in summer at wavelengths 320 – 360 nm, while AAOD peaks in summer and winter. The average AAOD for 2009 – 2011 is ~50% above the 2003 – 2006 average, possibly due to increased emissions of absorbing aerosols related to the economical crisis and the metro-railway construction works in the city center. A detailed analysis of the uncertainties in the retrieval of the SSA and the AAOD from the Brewer spectrophotometer has been also performed.

ACS Style

Ilias Fountoulakis; Athanasios Natsis; Nikolaos Siomos; Theano Drosoglou; Alkiviadis F. Bais. Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece. 2019, 1 .

AMA Style

Ilias Fountoulakis, Athanasios Natsis, Nikolaos Siomos, Theano Drosoglou, Alkiviadis F. Bais. Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece. . 2019; ():1.

Chicago/Turabian Style

Ilias Fountoulakis; Athanasios Natsis; Nikolaos Siomos; Theano Drosoglou; Alkiviadis F. Bais. 2019. "Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece." , no. : 1.

Journal article
Published: 29 August 2019 in Atmospheric Chemistry and Physics
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In this study we apply and compare two algorithms for the automated aerosol-type characterization of the aerosol layers derived from Raman lidar measurements over the EARLINET station of Thessaloniki, Greece. Both automated aerosol-type characterization methods base their typing on lidar-derived aerosol-intensive properties. The methodologies are briefly described and their application to three distinct cases is demonstrated and evaluated. Then the two classification schemes were applied in the automatic mode to a more extensive dataset. The dataset analyzed corresponds to ACTRIS/EARLINET (European Aerosol Research Lidar NETwork) Thessaloniki data acquired during the period 2012–2015. Seventy-one layers out of 110 (percentage of 65 %) were typed by both techniques, and 56 of these 71 layers (percentage of 79 %) were attributed to the same aerosol type. However, as shown, the identification rate of both typing algorithms can be changed regarding the selection of appropriate threshold criteria. Four major types of aerosols are considered in this study: Dust, Maritime, PollutedSmoke and CleanContinental. The analysis showed that the two algorithms, when applied to real atmospheric conditions, provide typing results that are in good agreement regarding the automatic characterization of PollutedSmoke, while there are some differences between the two methods regarding the characterization of Dust and CleanContinental. These disagreements are mainly attributed to differences in the definitions of the aerosol types between the two methods, regarding the intensive properties used and their range.

ACS Style

Kalliopi Artemis Voudouri; Nikolaos Siomos; Konstantinos Michailidis; Nikolaos Papagiannopoulos; Lucia Mona; Carmela Cornacchia; Doina Nicolae; Dimitris Balis. Comparison of two automated aerosol typing methods and their application to an EARLINET station. Atmospheric Chemistry and Physics 2019, 19, 10961 -10980.

AMA Style

Kalliopi Artemis Voudouri, Nikolaos Siomos, Konstantinos Michailidis, Nikolaos Papagiannopoulos, Lucia Mona, Carmela Cornacchia, Doina Nicolae, Dimitris Balis. Comparison of two automated aerosol typing methods and their application to an EARLINET station. Atmospheric Chemistry and Physics. 2019; 19 (16):10961-10980.

Chicago/Turabian Style

Kalliopi Artemis Voudouri; Nikolaos Siomos; Konstantinos Michailidis; Nikolaos Papagiannopoulos; Lucia Mona; Carmela Cornacchia; Doina Nicolae; Dimitris Balis. 2019. "Comparison of two automated aerosol typing methods and their application to an EARLINET station." Atmospheric Chemistry and Physics 19, no. 16: 10961-10980.

Original paper
Published: 12 February 2019 in Theoretical and Applied Climatology
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Monitoring of aerosols and their temporal evolution is very important for climate and air quality studies. In this study, we present a climatology of aerosol optical and microphysical properties over a continental southeastern European area based on 9 years of observations from a Cimel sun-photometer operating at Magurele (Romania) in the framework of AErosol RObotic NETwork (AERONET). The site is characterized by high intra-annual and inter-annual variability of the total aerosol optical depth (AOD), which has two peaks, during March and August. For half year, from May to November, Magurele is affected by the transport of aerosols from the nearby city of Bucharest, since the dominant winds are from this direction. Thus, the predominant is the fine mode of aerosols. The high inter-annual and intra-annual variability of Angstrom exponent (440–870 nm) indicates the presence of aerosols of different sizes. Negative statistically significant trends at all AOD wavelengths, the order of 20–40% per decade, have been calculated for the 9-year period of study (2007–2016). These trends are mostly attributed to the reduction of the fine mode particles, showing that the implementation of the EU regulations for the decrease of particulate matter emissions in Bucharest has been beneficial.

ACS Style

Emil Carstea; Konstantinos Fragkos; Nikolaos Siomos; Bogdan Antonescu; Livio Belegante. Columnar aerosol measurements in a continental southeastern Europe site: climatology and trends. Theoretical and Applied Climatology 2019, 137, 3149 -3159.

AMA Style

Emil Carstea, Konstantinos Fragkos, Nikolaos Siomos, Bogdan Antonescu, Livio Belegante. Columnar aerosol measurements in a continental southeastern Europe site: climatology and trends. Theoretical and Applied Climatology. 2019; 137 (3-4):3149-3159.

Chicago/Turabian Style

Emil Carstea; Konstantinos Fragkos; Nikolaos Siomos; Bogdan Antonescu; Livio Belegante. 2019. "Columnar aerosol measurements in a continental southeastern Europe site: climatology and trends." Theoretical and Applied Climatology 137, no. 3-4: 3149-3159.

Journal article
Published: 21 August 2018 in Atmospheric Chemistry and Physics
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In this study we investigate the climatological behavior of the aerosol optical properties over Thessaloniki during the years 2003–2017. For this purpose, measurements of two independent instruments, a lidar and a sunphotometer, were used. These two instruments represent two individual networks, the European Lidar Aerosol Network (EARLINET) and the Aerosol Robotic Network (AERONET). They include different measurement schedules. Fourteen years of lidar and sunphotometer measurements were analyzed, independently of each other, in order to obtain the annual cycles and trends of various optical and geometrical aerosol properties in the boundary layer, in the free troposphere, and for the whole atmospheric column. The analysis resulted in consistent statistically significant and decreasing trends of aerosol optical depth (AOD) at 355 nm of −23.2 and −22.3 % per decade in the study period over Thessaloniki for the EARLINET and the AERONET datasets, respectively. Therefore, the analysis indicates that the EARLINET sampling schedule can be quite effective in producing data that can be applied to long-term climatological studies. It is also shown that the observed decreasing trend is mainly attributed to changes in the aerosol load inside the boundary layer. Seasonal profiles of the most dominant aerosol mixture types observed over Thessaloniki have been generated from the lidar data. The higher values of the vertically resolved extinction coefficient at 355 nm appear in summer, while the lower ones appear in winter. The dust component is more dominant in the free troposphere than in the boundary layer during summer. The biomass burning layers tend to arrive in the free troposphere during spring and summer. This kind of information can be quite useful for applications that require a priori aerosol profiles. For instance, they can be utilized in models that require aerosol climatological data as input, in the development of algorithms for satellite products, and also in passive remote-sensing techniques that require knowledge of the aerosol vertical distribution.

ACS Style

Nikolaos Siomos; Dimitris S. Balis; Kalliopi A. Voudouri; Eleni Giannakaki; Maria Filioglou; Vassilis Amiridis; Alexandros Papayannis; Konstantinos Fragkos. Are EARLINET and AERONET climatologies consistent? The case of Thessaloniki, Greece. Atmospheric Chemistry and Physics 2018, 18, 11885 -11903.

AMA Style

Nikolaos Siomos, Dimitris S. Balis, Kalliopi A. Voudouri, Eleni Giannakaki, Maria Filioglou, Vassilis Amiridis, Alexandros Papayannis, Konstantinos Fragkos. Are EARLINET and AERONET climatologies consistent? The case of Thessaloniki, Greece. Atmospheric Chemistry and Physics. 2018; 18 (16):11885-11903.

Chicago/Turabian Style

Nikolaos Siomos; Dimitris S. Balis; Kalliopi A. Voudouri; Eleni Giannakaki; Maria Filioglou; Vassilis Amiridis; Alexandros Papayannis; Konstantinos Fragkos. 2018. "Are EARLINET and AERONET climatologies consistent? The case of Thessaloniki, Greece." Atmospheric Chemistry and Physics 18, no. 16: 11885-11903.

Conference paper
Published: 13 April 2018 in EPJ Web of Conferences
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In this study we present some first results on the potential of 15 years of lidar measurements over the lidar station of Thessaloniki to compile a climatology of the aerosol properties for the period 2001-2015. This is examined on a monthly, seasonal and annual basis. Both the profile structure and the columnar properties of the aerosol extinction and backscatter products are examined. The results are compared for consistency against co-located sunphotometer measurements.

ACS Style

Nikolaos Siomos; Kalliopi A. Voudouri; Eleni Giannakaki; Vasilis Amiridis; Maria Filioglou; Alexandros Papayannis; Dimitris S. Balis. Long term lidar measurements of aerosol properties over thessaloniki. EPJ Web of Conferences 2018, 176, 05033 .

AMA Style

Nikolaos Siomos, Kalliopi A. Voudouri, Eleni Giannakaki, Vasilis Amiridis, Maria Filioglou, Alexandros Papayannis, Dimitris S. Balis. Long term lidar measurements of aerosol properties over thessaloniki. EPJ Web of Conferences. 2018; 176 ():05033.

Chicago/Turabian Style

Nikolaos Siomos; Kalliopi A. Voudouri; Eleni Giannakaki; Vasilis Amiridis; Maria Filioglou; Alexandros Papayannis; Dimitris S. Balis. 2018. "Long term lidar measurements of aerosol properties over thessaloniki." EPJ Web of Conferences 176, no. : 05033.

Conference paper
Published: 13 April 2018 in EPJ Web of Conferences
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The long term analysis of 15 years of lidar data derived from a Raman lidar at Thessaloniki is presented here. All measurements have been processed with the latest version 4 of the EARLINET Single Calculus Chain algorithm and are compared with the results from the current operational retrieval algorithm. In this paper we investigate the consistency between the EARLINET database and SCC for the case of Thessaloniki and we identify the issues to be considered when switching from current operations to SCC.

ACS Style

Nikolaos Siomos; Kalliopi A. Voudouri; Maria Filioglou; Eleni Giannakaki; Vasilis Amiridis; Giuseppe D’Amico; Dimitris S. Balis. Consistency of the single calculus chain for climatological studies using long-term measurements from thessaloniki lidar station. EPJ Web of Conferences 2018, 176, 09007 .

AMA Style

Nikolaos Siomos, Kalliopi A. Voudouri, Maria Filioglou, Eleni Giannakaki, Vasilis Amiridis, Giuseppe D’Amico, Dimitris S. Balis. Consistency of the single calculus chain for climatological studies using long-term measurements from thessaloniki lidar station. EPJ Web of Conferences. 2018; 176 ():09007.

Chicago/Turabian Style

Nikolaos Siomos; Kalliopi A. Voudouri; Maria Filioglou; Eleni Giannakaki; Vasilis Amiridis; Giuseppe D’Amico; Dimitris S. Balis. 2018. "Consistency of the single calculus chain for climatological studies using long-term measurements from thessaloniki lidar station." EPJ Web of Conferences 176, no. : 09007.

Conference paper
Published: 13 April 2018 in EPJ Web of Conferences
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The Cloud-Aerosol Transport System (CATS) onboard the International Space Station (ISS), is a lidar system providing vertically resolved aerosol and cloud profiles since February 2015. In this study, the CATS aerosol product is validated against the aerosol profiles provided by the European Aerosol Research Lidar Network (EARLINET). This validation activity is based on collocated CATS-EARLINET measurements and the comparison of the particle backscatter coefficient at 1064nm.

ACS Style

Emmanouil Proestakis; Vassilis Amiridis; Michael Kottas; Eleni Marinou; Ioannis Binietoglou; Albert Ansmann; Ulla Wandinger; John Yorks; Edward Nowottnick; Abduvosit Makhmudov; Alexandros Papayannis; Aleksander Pietruczuk; Anna Gialitaki; Arnoud Apituley; Constantino Muñoz-Porcar; Daniele Bortoli; Davide Dionisi; Dietrich Althausen; Dimitra Mamali; Dimitris Balis; Doina Nicolae; Eleni Tetoni; Gian Luigi Liberti; Holger Baars; Iwona S. Stachlewska; Kalliopi-Artemis Voudouri; Lucia Mona; Maria Mylonaki; Maria Rita Perrone; Maria João Costa; Michael Sicard; Nikolaos Papagiannopoulos; Nikolaos Siomos; Pasquale Burlizzi; Ronny Engelmann; Sabur F. Abdullaev; Julian Hofer; Gelsomina Pappalardo. Earlinet validation of CATS L2 product. EPJ Web of Conferences 2018, 176, 02005 .

AMA Style

Emmanouil Proestakis, Vassilis Amiridis, Michael Kottas, Eleni Marinou, Ioannis Binietoglou, Albert Ansmann, Ulla Wandinger, John Yorks, Edward Nowottnick, Abduvosit Makhmudov, Alexandros Papayannis, Aleksander Pietruczuk, Anna Gialitaki, Arnoud Apituley, Constantino Muñoz-Porcar, Daniele Bortoli, Davide Dionisi, Dietrich Althausen, Dimitra Mamali, Dimitris Balis, Doina Nicolae, Eleni Tetoni, Gian Luigi Liberti, Holger Baars, Iwona S. Stachlewska, Kalliopi-Artemis Voudouri, Lucia Mona, Maria Mylonaki, Maria Rita Perrone, Maria João Costa, Michael Sicard, Nikolaos Papagiannopoulos, Nikolaos Siomos, Pasquale Burlizzi, Ronny Engelmann, Sabur F. Abdullaev, Julian Hofer, Gelsomina Pappalardo. Earlinet validation of CATS L2 product. EPJ Web of Conferences. 2018; 176 ():02005.

Chicago/Turabian Style

Emmanouil Proestakis; Vassilis Amiridis; Michael Kottas; Eleni Marinou; Ioannis Binietoglou; Albert Ansmann; Ulla Wandinger; John Yorks; Edward Nowottnick; Abduvosit Makhmudov; Alexandros Papayannis; Aleksander Pietruczuk; Anna Gialitaki; Arnoud Apituley; Constantino Muñoz-Porcar; Daniele Bortoli; Davide Dionisi; Dietrich Althausen; Dimitra Mamali; Dimitris Balis; Doina Nicolae; Eleni Tetoni; Gian Luigi Liberti; Holger Baars; Iwona S. Stachlewska; Kalliopi-Artemis Voudouri; Lucia Mona; Maria Mylonaki; Maria Rita Perrone; Maria João Costa; Michael Sicard; Nikolaos Papagiannopoulos; Nikolaos Siomos; Pasquale Burlizzi; Ronny Engelmann; Sabur F. Abdullaev; Julian Hofer; Gelsomina Pappalardo. 2018. "Earlinet validation of CATS L2 product." EPJ Web of Conferences 176, no. : 02005.

Journal article
Published: 07 March 2018 in Remote Sensing
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During August 2016, a quasi-stationary high-pressure system spreading over Central and North-Eastern Europe, caused weather conditions that allowed for 24/7 observations of aerosol optical properties by using a complex multi-wavelength PollyXT lidar system with Raman, polarization and water vapour capabilities, based at the European Aerosol Research Lidar Network (EARLINET network) urban site in Warsaw, Poland. During 24–30 August 2016, the lidar-derived products (boundary layer height, aerosol optical depth, Ångström exponent, lidar ratio, depolarization ratio) were analysed in terms of air mass transport (HYSPLIT model), aerosol load (CAMS data) and type (NAAPS model) and confronted with active and passive remote sensing at the ground level (PolandAOD, AERONET, WIOS-AQ networks) and aboard satellites (SEVIRI, MODIS, CATS sensors). Optical properties for less than a day-old fresh biomass burning aerosol, advected into Warsaw’s boundary layer from over Ukraine, were compared with the properties of long-range transported 3–5 day-old aged biomass burning aerosol detected in the free troposphere over Warsaw. Analyses of temporal changes of aerosol properties within the boundary layer, revealed an increase of aerosol optical depth and Ångström exponent accompanied by an increase of surface PM10 and PM2.5. Intrusions of advected biomass burning particles into the urban boundary layer seem to affect not only the optical properties observed but also the top height of the boundary layer, by moderating its increase.

ACS Style

Iwona S. Stachlewska; Mateusz Samson; Olga Zawadzka; Kamila M. Harenda; Lucja Janicka; Patryk Poczta; Dominika Szczepanik; Birgit Heese; Dongxiang Wang; Karolina Borek; Eleni Tetoni; Emmanouil Proestakis; Nikolaos Siomos; Anca Nemuc; Bogdan H. Chojnicki; Krzysztof M. Markowicz; Aleksander Pietruczuk; Artur Szkop; Dietrich Althausen; Kerstin Stebel; Dirk Schuettemeyer; Claus Zehner. Modification of Local Urban Aerosol Properties by Long-Range Transport of Biomass Burning Aerosol. Remote Sensing 2018, 10, 412 .

AMA Style

Iwona S. Stachlewska, Mateusz Samson, Olga Zawadzka, Kamila M. Harenda, Lucja Janicka, Patryk Poczta, Dominika Szczepanik, Birgit Heese, Dongxiang Wang, Karolina Borek, Eleni Tetoni, Emmanouil Proestakis, Nikolaos Siomos, Anca Nemuc, Bogdan H. Chojnicki, Krzysztof M. Markowicz, Aleksander Pietruczuk, Artur Szkop, Dietrich Althausen, Kerstin Stebel, Dirk Schuettemeyer, Claus Zehner. Modification of Local Urban Aerosol Properties by Long-Range Transport of Biomass Burning Aerosol. Remote Sensing. 2018; 10 (3):412.

Chicago/Turabian Style

Iwona S. Stachlewska; Mateusz Samson; Olga Zawadzka; Kamila M. Harenda; Lucja Janicka; Patryk Poczta; Dominika Szczepanik; Birgit Heese; Dongxiang Wang; Karolina Borek; Eleni Tetoni; Emmanouil Proestakis; Nikolaos Siomos; Anca Nemuc; Bogdan H. Chojnicki; Krzysztof M. Markowicz; Aleksander Pietruczuk; Artur Szkop; Dietrich Althausen; Kerstin Stebel; Dirk Schuettemeyer; Claus Zehner. 2018. "Modification of Local Urban Aerosol Properties by Long-Range Transport of Biomass Burning Aerosol." Remote Sensing 10, no. 3: 412.

Research article
Published: 20 December 2017 in Atmospheric Measurement Techniques
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The Generalized Aerosol Retrieval from Radiometer and Lidar Combined data algorithm (GARRLiC) and the LIdar-Radiometer Inversion Code (LIRIC) provide the opportunity to study the aerosol vertical distribution by combining ground-based lidar and sun-photometric measurements. Here, we utilize the capabilities of both algorithms for the characterization of Saharan dust and marine particles, along with their mixtures, in the south-eastern Mediterranean during the CHARacterization of Aerosol mixtures of Dust and Marine origin Experiment (CHARADMExp). Three case studies are presented, focusing on dust-dominated, marine-dominated and dust–marine mixing conditions. GARRLiC and LIRIC achieve a satisfactory characterization for the dust-dominated case in terms of particle microphysical properties and concentration profiles. The marine-dominated and the mixture cases are more challenging for both algorithms, although GARRLiC manages to provide more detailed microphysical retrievals compared to AERONET, while LIRIC effectively discriminates dust and marine particles in its concentration profile retrievals. The results are also compared with modelled dust and marine concentration profiles and surface in situ measurements.

ACS Style

Alexandra Tsekeri; Anton Lopatin; Vassilis Amiridis; Eleni Marinou; Julia Igloffstein; Nikolaos Siomos; Stavros Solomos; Panagiotis Kokkalis; Ronny Engelmann; Holger Baars; Myrto Gratsea; Panagiotis I. Raptis; Ioannis Binietoglou; Nikolaos Mihalopoulos; Nikolaos Kalivitis; Giorgos Kouvarakis; Nikolaos Bartsotas; George Kallos; Sara Basart; Dirk Schuettemeyer; Ulla Wandinger; Albert Ansmann; Anatoli P. Chaikovsky; Oleg Dubovik. GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures. Atmospheric Measurement Techniques 2017, 10, 4995 -5016.

AMA Style

Alexandra Tsekeri, Anton Lopatin, Vassilis Amiridis, Eleni Marinou, Julia Igloffstein, Nikolaos Siomos, Stavros Solomos, Panagiotis Kokkalis, Ronny Engelmann, Holger Baars, Myrto Gratsea, Panagiotis I. Raptis, Ioannis Binietoglou, Nikolaos Mihalopoulos, Nikolaos Kalivitis, Giorgos Kouvarakis, Nikolaos Bartsotas, George Kallos, Sara Basart, Dirk Schuettemeyer, Ulla Wandinger, Albert Ansmann, Anatoli P. Chaikovsky, Oleg Dubovik. GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures. Atmospheric Measurement Techniques. 2017; 10 (12):4995-5016.

Chicago/Turabian Style

Alexandra Tsekeri; Anton Lopatin; Vassilis Amiridis; Eleni Marinou; Julia Igloffstein; Nikolaos Siomos; Stavros Solomos; Panagiotis Kokkalis; Ronny Engelmann; Holger Baars; Myrto Gratsea; Panagiotis I. Raptis; Ioannis Binietoglou; Nikolaos Mihalopoulos; Nikolaos Kalivitis; Giorgos Kouvarakis; Nikolaos Bartsotas; George Kallos; Sara Basart; Dirk Schuettemeyer; Ulla Wandinger; Albert Ansmann; Anatoli P. Chaikovsky; Oleg Dubovik. 2017. "GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures." Atmospheric Measurement Techniques 10, no. 12: 4995-5016.

Articles
Published: 01 October 2017 in International Journal of Remote Sensing
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We investigate the uncertainty introduced to the optical and microphysical properties estimated with the lidar radiometer inversion code (LIRIC) by user-defined input parameters based on measurements carried out with a multi-wavelength Raman lidar and a sun photometer located at Thessaloniki, Greece (40.6° N, 22.9° E, 60 m above sea level). The sensitivity study involves three tests. We first evaluate the selection of the regularization parameters needed for the algorithm to initialize the iteration process. The latter two tests consider the impact of the boundary limits at the top/bottom (upper/lower limit) of the signal to the derived concentration profiles. The aforementioned tests were applied to two different cases, a Saharan dust event and a continental pollution case. We concluded that the largest uncertainties are introduced when varying the lower limit (more than 35%) regardless of the aerosol type or mode (fine/coarse). Varying the regularization parameters resulted in an uncertainty of 20%, and the selection of upper limit led to discrepancies of less than 3%. In conclusion, this sensitivity study indicates that future LIRIC users should apply an overlap function to the lidar signals before applying the methodology for minimizing the uncertainties in the near range.

ACS Style

M. Filioglou; Nikolaos Siomos; A. Poupkou; S. Dimopoulos; A. Chaikovsky; D. Balis. A sensitivity study of the LIdar-Radiometer Inversion Code (LIRIC) using selected cases from Thessaloniki, Greece database. International Journal of Remote Sensing 2017, 39, 315 -333.

AMA Style

M. Filioglou, Nikolaos Siomos, A. Poupkou, S. Dimopoulos, A. Chaikovsky, D. Balis. A sensitivity study of the LIdar-Radiometer Inversion Code (LIRIC) using selected cases from Thessaloniki, Greece database. International Journal of Remote Sensing. 2017; 39 (2):315-333.

Chicago/Turabian Style

M. Filioglou; Nikolaos Siomos; A. Poupkou; S. Dimopoulos; A. Chaikovsky; D. Balis. 2017. "A sensitivity study of the LIdar-Radiometer Inversion Code (LIRIC) using selected cases from Thessaloniki, Greece database." International Journal of Remote Sensing 39, no. 2: 315-333.

Preprint content
Published: 17 July 2017
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The Generalized Aerosol Retrieval from Radiometer and Lidar Combined data algorithm (GARRLiC) and the LIdar-Radiometer Inversion Code (LIRIC) provide the opportunity to study the aerosol vertical distribution by combining ground-based lidar and sun-photometric measurements. Here, we utilize the capabilities of both algorithms for the characterization of Saharan dust and marine particles, along with their mixtures, in the South-Eastern Mediterranean during the CHARacterization of Aerosol mixtures of Dust and Marine origin Experiment (CHARADMExp). Three case studies are presented, focusing on dust-dominated, marine-dominated and dust/marine mixing conditions. GARRLiC and LIRIC achieve a satisfactory characterization for the first case in terms of particle microphysical properties and concentration profiles. Τhe marine-dominated and the mixture cases are more challenging for both algorithms, although GARRLiC manages to provide more detailed microphysical retrievals compared to AERONET, while LIRIC effectively discriminates dust and marine in its concentration profile retrievals.

ACS Style

Alexandra Tsekeri; Anton Lopatin; Vassilis Amiridis; Eleni Marinou; Julia Igloffstein; Nikolaos Siomos; Stavros Solomos; Panagiotis Kokkalis; Ronny Engelmann; Holger Baars; Myrto Gratsea; Panagiotis I. Raptis; Ioannis Binietoglou; Nikolaos Mihalopoulos; Nikolaos Kalivitis; Giorgos Kouvarakis; Nikolaos Bartsotas; George Kallos; Sara Basart; Dirk Schuettemeyer; Ulla Wandinger; Albert Ansmann; Anatoli P. Chaikovsky; Oleg Dubovik. GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures. 2017, 10, 4995 -5016.

AMA Style

Alexandra Tsekeri, Anton Lopatin, Vassilis Amiridis, Eleni Marinou, Julia Igloffstein, Nikolaos Siomos, Stavros Solomos, Panagiotis Kokkalis, Ronny Engelmann, Holger Baars, Myrto Gratsea, Panagiotis I. Raptis, Ioannis Binietoglou, Nikolaos Mihalopoulos, Nikolaos Kalivitis, Giorgos Kouvarakis, Nikolaos Bartsotas, George Kallos, Sara Basart, Dirk Schuettemeyer, Ulla Wandinger, Albert Ansmann, Anatoli P. Chaikovsky, Oleg Dubovik. GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures. . 2017; 10 (12):4995-5016.

Chicago/Turabian Style

Alexandra Tsekeri; Anton Lopatin; Vassilis Amiridis; Eleni Marinou; Julia Igloffstein; Nikolaos Siomos; Stavros Solomos; Panagiotis Kokkalis; Ronny Engelmann; Holger Baars; Myrto Gratsea; Panagiotis I. Raptis; Ioannis Binietoglou; Nikolaos Mihalopoulos; Nikolaos Kalivitis; Giorgos Kouvarakis; Nikolaos Bartsotas; George Kallos; Sara Basart; Dirk Schuettemeyer; Ulla Wandinger; Albert Ansmann; Anatoli P. Chaikovsky; Oleg Dubovik. 2017. "GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures." 10, no. 12: 4995-5016.

Journal article
Published: 14 June 2017 in Atmospheric Chemistry and Physics
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In this study we present an evaluation of the Comprehensive Air Quality Model with extensions (CAMx) for Thessaloniki using radiometric and lidar data. The aerosol mass concentration profiles of CAMx are compared against the PM2.5 and PM2. 5−10 concentration profiles retrieved by the Lidar-Radiometer Inversion Code (LIRIC). The CAMx model and the LIRIC algorithm results were compared in terms of mean mass concentration profiles, center of mass and integrated mass concentration in the boundary layer and the free troposphere. The mean mass concentration comparison resulted in profiles within the same order of magnitude and similar vertical structure for the PM2. 5 particles. The mean centers of mass values are also close, with a mean bias of 0.57 km. On the opposite side, there are larger differences for the PM2. 5−10 mode, both in the boundary layer and in the free troposphere. In order to grasp the reasons behind the discrepancies, we investigate the effect of aerosol sources that are not properly included in the model's emission inventory and in the boundary conditions such as the wildfires and the desert dust component. The identification of the cases that are affected by wildfires is performed using wind backward trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model in conjunction with satellite fire pixel data from MODerate-resolution Imaging Spectroradiometer (MODIS) Terra and Aqua global monthly fire location product MCD14ML. By removing those cases the correlation coefficient improves from 0.69 to 0.87 for the PM2. 5 integrated mass in the boundary layer and from 0.72 to 0.89 in the free troposphere. The PM2.5 center of mass fractional bias also decreases to 0.38 km. Concerning the analysis of the desert dust component, the simulations from the Dust Regional Atmospheric Model (BSC-DREAM8b) were deployed. When only the Saharan dust cases are taken into account, BSC-DREAM8b generally outperforms CAMx when compared with LIRIC, achieving a correlation of 0.91 and a mean bias of −29.1 % for the integrated mass in the free troposphere and a correlation of 0.57 for the center of mass. CAMx, on the other hand, underestimates the integrated mass in the free troposphere. Consequently, the accuracy of CAMx is limited concerning the transported Saharan dust cases. We conclude that the performance of CAMx appears to be best for the PM2.5 particles, both in the boundary layer and in the free troposphere. Sources of particles not properly taken into account by the model are confirmed to negatively affect its performance, especially for the PM2. 5−10 particles.

ACS Style

Nikolaos Siomos; Dimitris S. Balis; Anastasia Poupkou; Natalia Liora; Spyridon Dimopoulos; Dimitris Melas; Eleni Giannakaki; Maria Filioglou; Sara Basart; Anatoli Chaikovsky. Investigating the quality of modeled aerosol profiles based on combined lidar and sunphotometer data. Atmospheric Chemistry and Physics 2017, 17, 7003 -7023.

AMA Style

Nikolaos Siomos, Dimitris S. Balis, Anastasia Poupkou, Natalia Liora, Spyridon Dimopoulos, Dimitris Melas, Eleni Giannakaki, Maria Filioglou, Sara Basart, Anatoli Chaikovsky. Investigating the quality of modeled aerosol profiles based on combined lidar and sunphotometer data. Atmospheric Chemistry and Physics. 2017; 17 (11):7003-7023.

Chicago/Turabian Style

Nikolaos Siomos; Dimitris S. Balis; Anastasia Poupkou; Natalia Liora; Spyridon Dimopoulos; Dimitris Melas; Eleni Giannakaki; Maria Filioglou; Sara Basart; Anatoli Chaikovsky. 2017. "Investigating the quality of modeled aerosol profiles based on combined lidar and sunphotometer data." Atmospheric Chemistry and Physics 17, no. 11: 7003-7023.