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Past Highlights

  • NEW ARTICLE: Multi-modal analysis of aerosol robotic network size distributions for remote sensing applications: dominant aerosol type cases.

Citation: Taylor, M., Kazadzis, S., and Gerasopoulos, E.: Multi-modal analysis of aerosol robotic network size distributions for remote sensing applications: dominant aerosol type cases, Atmos. Meas. Tech., 7, 839-858, doi:10.5194/amt-7-839-2014, 2014.

Highlight Plot

Quick summary: Physical processes in the atmosphere often result in a bi-modal aerosol volume size distribution but the appearance of a third mode is also both realistic and likely. However, AERONET’s inversion algorithm currently only retrieves a 6 constant bi-lognormal fit via a fine and coarse mode separated at a point in the interval ≈ 0.5 - 1µm. By keeping the total volume constant and allowing the mode separation point to vary outside this narrow range - our “optimized equivalent volume” (OEV) method, we found we could significantly improve the bi-lognormal fit to size distributions of strong dust episodes in the Sahel. We then developed an automated Gaussian mixture model (GMM) with a statistical stopping condition to fit the size distribution with an optimal number n of lognormal distributions. We applied the GMM approach to size distributions corresponding to days of peak biomass burning at Mongu in Zambia, urban sulphate pollution at GSFC-Washington (USA) and sea salt aerosol at Lanai (Hawaii) as flagged up by the GOCART chemical model. In each of these cases, the GMM method found that the aerosol size distribution is best fit with 3 modes. We have applied this method to the temporal evolution of aerosol episodic events and are currently developing an online interface and API to facilitate its inclusion in operational algorithms that have lognormal size distributions as output.


  • LIVAS Web Portal has launched


"LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies" (LIVAS) Web Portal provides a global 3-dimensional aerosol and cloud optical climatology and a collection of case studies focused on atmospheric episodes related to specific aerosol/cloud types (extended atmospheric scenes, i.e. Saharan dust events, smoke and volcanic eruption events, polar-stratospheric clouds etc). In order to cover the different spectral domains for HSRL and IPDA lidars, the compiled database addresses the three harmonic operating wavelengths of Nd-YAG lasers (355 nm, 532 nm and 1064 nm) as well as typical wavelengths of IPDA lidars in the SWIR spectral domain (1570 nm and 2050 nm).


  • WWF action for informing people about wood burning and smog episodes.


Dr. Evangelos Gerasopoulos participates in a WWF campaign, for early informing people about what caused recent smog episodes in urban cities of Greece and which are the effects of such episodes on human health.

He exposes his opinion based on results obtained during a focused experimental campaign last winter under the framework of the NSRF THALES programme, entitled "Identification of sources and physicochemical properties of fine and ultrafine suspended particulate matter of atmospheric aerosol that affect the climate of Greece".




  • Participation in the European Aerosol Conference, Prague Czech Republic 1-6 September, 2013



 APCG members presented the following papers:  


  1. Athanasopoulou E., D. Rieger, C. Walter, H. Vogel, B. Vogel and E. Gerasopoulos: Modeling the chemical and radiative effects of aerosol during the wildfires of 2007 in Greece.
  2. Liakakou E., Gerasopoulos E., Paraskevopoulou D., Zarbas P., Theodosi C., Kalivitis N., Maneas G., Mihalopoulos N., Zerefos C.: Aerosol chemical composition at NEO (Eastern Mediterranean) during the ARGON 2012 summer campaign.
  3. Paraskevopoulou D., E. Liakakou, E. Gerasopoulos and N. Mihalopoulos: Long-term variability of elemental and organic carbon in aerosols over Athens, Greece.


  • How dangerous are episodes of smog?
During the period 10 January - 10 February 2013, detailed sampling of airborne particles was made with specific chemical analyzes in the five largest Greek cities. Sampling was conducted under the framework of the NSRF THALES programme, entitled "Identification of sources and physicochemical properties of fine and ultrafine suspended particulate matter of atmospheric aerosol that affect the climate of Greece". Sampling was done at Thisio, Aigia Paraskevi and Penteli in Athens (by the Foundation for Research and Technology, National Observatory of Athens (APCG members), NCSR Demokritos, and the Universities of Crete and the Aegean). In Thessaloniki (by the University of the Aegean), Patras (by the University of Patras), at Heraklion (by the University of Crete) and at Ioannina (by the Universites of Ioannina and Crete). In parallel, sampling was done at remote stations Finokalia, Lasithi ( by the University of Crete) and at the new-Navarino Environmental Observatory in Messinia (by the National Observatory of Athens and the Academy of Athens). In summary, the main results and conclusions from the first samplings are presented in the attached magazine (pp. 52-57).
  • Participation in the CERN Workshop on Innovations in Scholarly Communication (OA18)

APCG members presented the following poster:


  1. Perakakis, P., Taylor, M., 2013. Introducing LIBRE - a free online platform for open peer review.

  • The Marie-Curie Actions project AEROMAP now has an official website
The Researcher’s Gateway of the site contains links to key data sources and MATLAB code for loading and parsing data files. The Education Gateway has links to videos, Open CourseWare lecture courses and feature articles related to the atmospheric aerosols. A real-time monitor of global aerosols is under development and will go online in the next few months.


  • Participation in the European Geosciences Union, Vienna Austria 7-12 April, 2013.

APCG members will present the following papers:

  1. V. Amiridis, S. Kazadzis, E. Gerasopoulos, E. Marinou, A. Tsekeri and O. LeRille: 5-year CALIPSO observations of Saharan dust over North Africa and Europe.
  2. E. Gerasopoulos, M. Gratsea, V. Amiridis, C. Zerefos, M.O. Andreae: 1.5-year AOD observations at the Navarino Environmental Observatory (NEO), in Messinia-S. Greece (Eastern Mediterranean).
  3. S. Kazadzis, V. Amiridis, P. Kosmopoulos, E. Marinou, A. Tsekeri:  Impact of different aerosol types on the spectral solar radiation at different heights over the Mediterranean using the CALIPSO aerosol product.

  • Intensive campaign during winter 2012-2013 dedicated to the new emerging problem of smog due to wood burning in Athens and other Greek cities
    •   The campaign took place in the period 10 January – 10 February 2013, with the participation of groups from 3 Research Institutes (Foundation for Research and Technology-Hellas, National Observatory of Athens, NSCR Demokritos) and 5 Universities (Aegean/co-ordinator, Crete, Patras, Ioannina, Georgia Tech). The measurements were contacted within the frame of a THALIS-NSRF project entitled "Determination of sources and physicochemical properties of fine and ultrafine aerosols affecting the climate in Greece". The objective of the project is to identify the sources and to elucidate the processes by which aerosol particles and their precursors emitted in and transported to the region of our study affect local air quality and climate. In Athens, the main infrastructure operated at NOA's premises in Thissio (Athens center), but also at Agia Paraskevi (NCSR Demokritos premises) and Penteli (IERSD/NOA premises).

      The first results of the campaign were communicated to the media during an official Press Release that took place on 28/02/2013 at NCSR Demokritos premises.


      Experimental setup of the winter 2012-2013 THALIS intensive campaign

      Measurements site locations in Greece and Athens

      FORTH/ICE-HT mobile station operating at Thission
      Part of the infrastructure setup at NOA premises at Thission

      • NEW ARTICLE: Factors affecting O3 and NO2 photolysis frequencies measured in the eastern Mediterranean during the five-year period 2002–2006

      Citation: Gerasopoulos, E., S. Kazadzis, M. Vrekoussis, G. Kouvarakis, E. Liakakou, N. Kouremeti, D. Giannadaki, M. Kanakidou, B. Bohn, and N. Mihalopoulos (2012), Factors affecting O3 and NO2 photolysis frequencies measured in the eastern Mediterranean during the five-year period 2002–2006, J. Geophys. Res., 117, D22305, doi:10.1029/2012JD017622.

      Abstract: The photolysis frequencies of ozone (O3; to singlet oxygen, JO1D) and nitrogen dioxide (NO2; JNO2) were recorded at the remote coastal site Finokalia (35°20′N, 25°40′E), on the island of Crete, Greece, during the period 2002–2006. We present a study of their main climatological aspects and a quantification of the effect of aerosol and total ozone column on these frequencies. The 5-yr mean Aerosol Optical Depth (AOD) at 380 nm in the area is equal to 0.27 ± 0.13 and reduces JNO2 by 5%–14% at a solar zenith angle (sza) of 60°, compared to an aerosol-free atmosphere. It also leads to a similar reduction of JO1D by 5%–15% at the 60° sza, for an average total ozone column (300–320 Dobson units (DU)). The effect of regional background AOD (∼0.1) is a reduction of JNO2 and JO1D by up to 6% for sza in the range 15° to75°, respectively. During high aerosol loads (AOD 0.5–0.7) the percentage reduction of Js was found to be as much as 30%–40% at high sza. The day-to-day variability of total ozone column over the area, of the order of 20 DU, was found to result in a 12% change in JO1D at 60° sza as compared with zero AOD conditions. A reduction of Js corresponding to a 24% decrease in the local noon JO1D value and a 5% decrease in local noon JNO2 were found to result in a 12% reduction in the 24 h mean net chemical production of O3, using a chemical box model.

      Figure 4. Whole period averaged photolysis frequencies of (a) NO2 (JNO2) and (b) O3 (JO1D), versus the solar zenith angle (sza), for all-sky, clear-sky and cloudy (defined just subtracting cloudless from all-sky) conditions. Mean values of Js are calculated every 5 degrees of sza (0.5 degrees). (c, d) Js variability expressed as the ratio of the standard deviation of Js to their mean value, per 5 degree sza bin. Modeled values were derived from the radiative transfer model LibRadTran.

      Full article: http://apcg.space.noa.gr/upload/news/nId8_dt20121204_214436.pdf


      • Installation of a new MaxDOAS system at NOA premises in Penteli in collaboration with the DOAS-group, Institute of Environmental Physics (IUP), University of Bremen, Germany, 27 September -2 October, 2012

      The DOAS-group, Institute of Environmental Physics (IUP), University of Bremen, as part of a new collaboration with APCG/NOA, installed during 27/9 - 2/10 2012 a MaxDOAS system to retrieve atmospheric trace gas concentrations from UV/visible spectra of scattered sunlight over Athens, using the "Differential Optical Absorption Spectroscopy" technique. In particular, the MaxDOAS will be acquiring vertical profiles of nitrogen dioxide, glyoxal, formaldehyde and oxygen dimer (for aerosol extinction) at several azimuth angles (over the sea-east, the airport, Athens center, Piraeus port and Athens' suburbs-northwest), thus providing a 3D illustration of Athens pollution and internal transport patterns.


      MaxDOAS system at NOA premises in Penteli

      Scanning over Athens center

      Scanning over the airport
      Indoor single monochromator, CCD detector and cooling system
      Scanning during sunset

      The different viewing directions over Attica

      • Participation in the Researchers Night 2012, National Hellenic Research Foundation, Athens, Greece, 28 September, 2012




      • Participation in the 19th International Symposium on High-Power Laser Systems and  Applications,
      Istanbul, Turkey, 10-14 September 2012

      APCG members presented the following papers: 

      1. V. Amiridis: LIVAS: Lidar Climatology of Vertical Aerosol Structure





      • Participation in the ARGON intensive campaign, NEO premises in Costa Navarino, Messinia, Greece, 7 June – 12 July, 2012



      • Participation in the Euroscience Open Forum 2012, Dublin, Ireland 11-15 July, 2012 

      APCG members presented the following papers:

      1. M. Taylor AEROMAP: Global mapping of aerosol properties using neural network inversions of ground and satellite based data




      • Participation in the European Aerosol Conference, Granada Spain 2-7 September, 2012

      APCG members presented the following papers:

      1. A. Gkikas, N. Hatzianastassiou, S. Kazadzis, V. Amiridis, S. Basart, E. Marinou, J.M. Baldasano,  Optical and radiative properties of intense dust outflows, in the Mediterranean basin, based on a synergistic use of satellite, ground-based measurements and modeling
      2. M. Taylor , S. Kazantzis, A. Tsekeri, A. Gkikas and V. Amiridis Calculation of aerosol microphysical properties by neural network inversion of ground-based AERONET data
      3. D. Paraskevopoulou, S. Kazadzis, N. Mihalopoulos, A. Arola, K. Eleftheriadis, C. Theodosi, A. Bougiatioti, E. Diapouli and E. Gerasopoulos Evaluation of aerosol OC / BC estimations derived from AERONET data, using in-situ ground measurements.
      4. E. Athanasopoulou, E. Gerasopoulos, H. Vogel, S. Kazadzis, E. Liakakou, M. Gratsea, and B. Vogel Aerosol observations and predictions in the southeastern Europe during the extreme summer 2007



      • Participation in the International Radiation Symposium, Berlin Germany 6-10 August, 2012 

      APCG members presented the following papers:IRS 2012 logo


      1. A.V. Lindfors, A. Arola, S. Kazadzis, N. Kouremeti, and A. Bais: Effective aerosol optical depth from pyranometer measurements of global solar radiation at Thessaloniki, Greece
      2. O. Meinander, S. Kazadzis, A. Arola, R. Kivi, A. Kontu, H. Suokanerva, E. Kyrö, V.: Aaltonen, T. Manninen, A. Riihelä, J.-L. Roujean, and O. Hautecoeur, About UV Albedo of Seasonal Snow at Sodankylä
      3. S. Kazadzis, N. Kouremeti, A. Gkikas, A. Arola, I. Ialongo, A. Bais, A.M. Siani, T. Koskela, M. Janouch, J.M. Vilaplana, and C. Brogniez, Solar UV irradiance calculations with the use of satellite-based cloud, ozone and aerosol retrievals
      4. S. Kazadzis, V. Amiridis, N. Kouremeti, V. Gerasopoulos, and D. Kopania: Columnar aerosol absorption retrieval and effects on solar UV radiation
      5. K. Eleftheratos, S. Kazadzis, T. Koskela, K. Lakkala, C. Zerefos: Ozone and spectroradiometric UV changes in the past 20 years at high latitudes


      • Participation in the organisation of the 26th International Laser Radar Conference at Porto Heli, Greece, 25th - 29th June 2012

      APCG members participated in the organization of the ILRC2012.

      Moreover, they presented the following papers:

      1. Vassilis Amiridis, Alexandra Tsekeri, Franco Marenco, Eleni Marinou, Elina Giannakaki, Dimitrios Balis, Athanasios Nenes, James Allan, Hugh Coe, Validation of CALIPSO nighttime aerosol products using airborne lidar and in-situ observations.
      2. Eleni Marinou, Vassilis Amiridis, Alexandra Tsekeri, Sarah Basart, JoseMaria Baldasano, Stelios Kazadzis, Alexandros Papayannis, Comparison of Averaged Extinction Profiles from CALIPSO and BSC-DREAM8b Dust Model over Greece.
      3. Stelios Kazadzis, Natalia Kouremeti, Elina Giannakaki, Vassilis Amiridis, Rodelise Mamouri, Dimitrios Balis, Alexandros Papayannis, The effect of the aerosol vertical distribution on the solar radiation profiles.
      4. Alexandros Papayannis, Panayotis Kokkalis, Rodelise Mamouri, Vassilis Amiridis, Emmanouella Remoundaki, Georgios Tsaknakis, Stylianos Kazadzis, Alexandra Tsekeri, Eleni Marinou, Synergetic infrastructure for trace gas and aerosol measurements and characterization at the National Technical University of Athens and the National Observatory of Athens, Greece.
      5. Alexandros Papayannis, Dimitrios Balis, Panayotis Kokkalis, Rodelise Mamouri, Georgios Tsaknakis, Elina Giannakaki, Nikos Siomos, Vassilis Amiridis, ARIADNE: The greek lidar network.
      6. Elina Giannakaki, Dimitrios Balis, Vassilis Amiridis, Optical properties of anthropogenic aerosols over Thessaloniki, Greece, during SCOUT-O3 campaign.
      7. Vassilis Amiridis, Ulla Wandinger, Eleni Marinou, Olivier Le Rille, Stelios Kazadzis, Alexandra Tsekeri, Elina Giannakaki, Rodelise Mamouri, Panayotis Kokkalis, Natalia Kouremeti, Themistoklis Herekakis, Alexandros Papayannis, Dimitrios Balis, Gelsomina Pappalardo, LIVAS: Lidar Climatology of Vertical Aerosol Structure for Space-Based Lidar Simulation Studies.
      8. Alexandra Tsekeri, Vassilis Amiridis, Panayotis Kokkalis, Rodelise Mamouri, Alexandros Papayannis, Sarah Basart, Anatoli Chaikovsky, Oleg Dubovik, JoseMaria Baldasano, Evaluation of dust modelling using a synergetic algorithm of lidar and sunphotometer data.
      9. Panayotis Kokkalis, Alexandros Papayannis, Vassilis Amiridis, Rodelise Mamouri, Anatoli Chaikovsky, Oleg Dubovik, Alexandra Tsekeri, Evaluation of fine mode lidar concentration retrievals using airborne in-situ measurements.
      10. Rodelise Mamouri, Alexandros Papayannis, Detlef Muller,Georgios Tsaknakis, Panayotis Kokkalis, Vassilis Amiridis, Fresh smoke aerosol layers observations by a multi-wavelength Raman lidar over Athens, during hellenic wild fires.
      11. Panayotis Kokkalis, Alexandros Papayannis, Rodelise Mamouri, Georgios Tsaknakis, Vassilis Amiridis, The EOLE system of the National Technical University of Athens.




  Supporting Files
  1. Researchers_night2012_APCGposter (File size 1.42 MB)
  2. Amiridis, Livas HPLSA2012 (File size 3.42 MB)
  3. ARGON description (File size 79.02 KB)
  4. Taylor ESOF2012 (File size 1.05 MB)
  5. Athanasopoulou EAC2012 abstract (File size 105.27 KB)
  6. Athanasopoulou EAC2012 poster (File size 1.58 MB)
  7. Taylor EAC2012 abstract (File size 264.58 KB)
  8. Taylor EAC2012 poster (File size 1011.86 KB)
  9. IRS2012 Kazadzis (File size 106.91 KB)
  10. Amiridis, Livas ILRC abstract (File size 379.16 KB)
  11. Amiridis, ACEMED ILRC2012 (File size 241.51 KB)
  12. Kazadzis ILRC2012 (File size 138.52 KB)
  13. Marinou ILRC2012 poster (File size 1.7 MB)
  14. Taylor, AMT 2014 (File size 5.05 MB)
  15. Athanasopoulou EAC2013 poster (File size 1.41 MB)
  16. Liakakou EAC2013 poster (File size 923.35 KB)
  17. Paraskevopoulou EAC2013 oral (File size 1.93 MB)
  18. ET_March2013 (File size 3.92 MB)
  19. Taylor OAI8 poster (File size 1.86 MB)
  20. poster Gerasopoulos et al., 2013 (File size 1.47 MB)
  21. poster Amiridis et al., 2013 (File size 2.07 MB)
  22. poster Kazadzis et al., 2013 (File size 1.97 MB)
  23. First Results (parts of the Press Release) (File size 394.36 KB)
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