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Status: Confirmed |
Open to sharing: Yes |
Confidential: No |
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Transnational Access: Yes |
Open to training: No |
Grounded / Maintenance: No |
Aircraft name: BAe146 - FAAM
Airport: The aircraft will under-fly CALIPSO overpasses over Greece focusing also above the ground-based stations of Athens, Thessaloniki and Finokalia. CALIPSO overpasses to be followed are presented in Figure 2 along with the corresponding date and time information. 2 flights are requested, one during daytime and one during nighttime, either on 2nd or 9th of September 2011.
Project theme: The proposal aims at the evaluation of CALIPSO's algorithm for aerosol type classification using airborne and ground-based measurements over Eastern Mediterranean
Science context: The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), a joint U.S. (NASA) and French (CNES) satellite mission, is the first active sensor being in operation during the last four years, providing new insight into the role that clouds and aerosols play in regulating Earth's weather, climate, and air quality (Winker et al. 2007, 2009). CALIPSO's observations provide, for the first time, the vertical structure of aerosol distributions globally, along with aerosol type estimations, which however have not yet been evaluated. The identification of aerosol types is important, since different aerosol types have different effects on climate, visibility and health. We propose to evaluate CALIPSO's aerosol-type classification schemes over Greece, using high quality airborne aerosol measurements along with ground-based lidar, sunphotometric and in-situ observations. Aerosol backscatter and depolarization vertical profiles, size distributions, scattering coefficients, aerosol absorption and SSA airborne measurements will be used for the characterization of elevated aerosol layers. During the campaign, intensive ground-based measurements will be performed in Athens, Thessaloniki and Finokalia stations. These measurements will be used to classify the particular characteristics of diverse and mixed aerosol types and compare them with CALIPSO's aerosol-type classification scheme. The validation study will add to the efforts taken for aerosol characterization within the framework of the "Aerosols, Clouds and Trace gases Research InfraStructure network - ACTRIS" project. The results will also be valuable for the simulation studies currently performed at the European Space Agency (ESA) in anticipation of future lidar satellite missions (e.g. ADM-AEOLUS, EarthCARE, A-SCOPE).
Measurements to be made by aircraft: Identification and classification of aerosol types is important, since different aerosol types have different effects on climate, visibility and health. The space-borne lidar CALIOP on-board the CALIPSO satellite (Winker et al., 2007), provides information on layer-stratified types of aerosol that can be detected with this instrument. The CALIPSO Vertical Feature Mask (VFM) product (Vaughan et al. 2004), classifies aerosols and clouds based on their optical properties. With the scene-classification algorithm, the atmospheric features are classified as either clouds or aerosols, and then the clouds and aerosols are separated into different subclasses (Omar et al., 2009). The classification of features as clouds or aerosols by CALIOP has been previously validated, for example, by Kim et al. (2008) and Liu et al. (2009). They confirm that CALIPSO algorithms are able to discriminate between clouds and aerosols and detect the cloud top and base altitudes reliably. However, no previous work has been focused explicitly on the evaluation of the quality of CALIPSO's aerosol type classification scheme. In the aforementioned studies, misclassifications of CALIPSO VFM product have been reported. Among these misclassifications, the most prevalent were those associated with dust and smoke particles, over or close to the source regions (Liu et al., 2009). Moreover, the similarity of the optical properties of polluted continental and smoke aerosols, poses a challenge for CALIPSO's classification algorithm and is one of the limitations of the subtyping scheme (Omar et al., 2009). In the framework of ACEMED campaign, we propose to evaluate CALIPSO's aerosol-type classification schemes (Level 2, Version 3.01 products), using high quality airborne aerosol measurements along with ground-based lidar, sunphotometric and in-situ observations. The region selected to apply our study is the Eastern Mediterranean, recognized by the IPCC as one of the "hot" spots globally concerning climate change, since there, almost all aerosol types and related processes are met (e.g. Lelieveld et al., 2002). Specifically, Greece is year round affected by dust storms from desert or semi-arid areas in Africa, smoke from biomass burning, maritime aerosols, biogenic emissions and anthropogenic aerosols, the later produced either locally or transported mainly from continental Europe. It is, therefore, incontestable that such a complex mixture of different aerosol types, in a particularly variable environment, provides a setting of a unique natural laboratory for studying aerosol classification schemes. Special focus, within ACEMED will be put on the role of the absorbing aerosols in Eastern Mediterranean, which have a negative surface radiative forcing and large positive atmospheric forcing values, nearly identical to the highly absorbing south Asian haze observed over the Arabian Sea (Markowicz et al., 2002; Lelieveld et al., 2002; Sciare et al., 2003; Sciare et al., 2008). The effect of these fires on the aerosol budget over Greece is poorly assessed and based on ground-based measurements in Thessaloniki and Finokalia (Sciare et al., 2008; Amiridis et al., 2009). The contribution of these light absorbing particles is particularly important during the summer period when most of air masses over the Eastern Mediterranean originate from the Balkans, Turkey and Central/Eastern Europe (Vrekoussis et al., 2005; Bryant et al., 2006; Kazadzis et al., 2007; Sciare et al., 2008; Amiridis et al., 2009). During this period, extensive forest fires from Southern Europe are significantly contributing to large-scale aerosol emissions in the Mediterranean environment (Balis et al., 2003; Kazadzis et al., 2007; Amiridis et al., 2009; Sciare et al., 2008). The biomass burning regions contributing to the absorbing aerosol background over Greece are extended across Russia in the latitudinal belt between 45°N - 55°N, as well as in Eastern Europe (Baltic countries, Western Russia, Belarus, and the Ukraine). The highest frequency of agricultural fires occurs during summer, as depicted in Figure 1. In addition, the impact of dust in regional aerosol loads has been extensively studied during major Saharan dust outbreaks, and its role on radiative forcing has been depicted (Balis et al., 2004; Gerasopoulos et al., 2007; Kalivitis et al., 2007; Amiridis et al., 2009). Even though the maximum influence is encountered in spring, many studies highlight the presence of elevated dust layers over Greece during summer (e.g. Papayannis et al., 2009). Summer is also the season during which local processes of anthropogenic aerosol production are favored and transport from continental Europe is encountered due to the dominance of Northerly winds called Etesians. The challenge for the CALIPSO classification algorithm scheme, is to discriminate these diverse aerosol types, present in the Mediterranean environment, either as separated layers or external mixtures. The performance of CALIPSO will be evaluated within ACEMED in order to estimate the adequacy of these products for long-term climatological studies. In order to achieve the aim of ACEMED, aircraft lidar measurements of the vertical structure and in-situ aerosol measurements will be performed during under-flights of CALIPSO overpasses. Aerosol backscatter and depolarization vertical profiles, size distributions, scattering coefficients, aerosol absorption and SSA airborne measurements will be used for the characterization of elevated aerosol layers. Additional intensive ground-based measurements will be performed in Athens, Thessaloniki and Finokalia, including: - Multi-wavelength lidar measurements - Columnar sunphotometric measurements - Surface aerosol properties monitoring (optical, chemical, physical properties) Aerosol characterization will be established by ground-based active and passive remote sensing techniques. These measurements will be used to invert optical data into microphysical particle properties and to develop a high-sophisticated aerosol-type classification scheme. Direct surface measurements will be used for the speciation of particle samples and aerosols will be chemically classified by the predominant species (e.g., sulfates, black carbon, organic carbon, etc.). Overall, CALIPSO's aerosol classification schemes will be evaluated in elevated layers and surface against the detailed aircraft and ground-based retrievals. BENEFITS - OUTPUTS The validation study will add to the efforts taken for aerosol characterization using in-situ and remote sensing methods within the framework of the "Aerosols, Clouds and Trace gases Research InfraStructure network" (ACTRIS) project. The results will also be valuable for the simulation studies currently performed at the European Space Agency (ESA) in anticipation of future lidar satellite missions (e.g. ADM-AEOLUS, EarthCARE, A-SCOPE). Finally, the feasibility of long term aerosol studies will be assessed after the evaluation of CALIPSO's aerosol classification schemes. The results from the proposed experiments will be published in remote sensing and atmospheric chemistry/physics related science journals (e.g. Atmospheric Chemistry and Physics, Journal of Geophysical Research, Atmospheric Environment, Atmospheric Measurements and Techniques etc.). It is expected that several publications on aerosol characterization and satellite validation will be the outcome of this study. REFERENCES Amiridis, V., D. S. Balis, E. Giannakaki, A. Stohl, S. Kazadzis, M. E. Koukouli, and P. Zanis, Optical characteristics of biomass burning aerosols over Southeastern Europe determined from UV-Raman lidar measurements, Atmospheric Chemistry and Physics, 9, 2431-2440, 2009 Balis, D., V. Amiridis, C. Zerefos, E. Gerasopoulos, M. O. Andreae, P. Zanis, A. Kazantzidis, S. Kazadzis, and A. Papayannis, Raman lidar and sunphotometric measurements of aerosol optical properties over Thessaloniki, Greece, during a biomass burning episode, Atmospheric Environment, 37, 32, 4529-4538, 2003 Bryant, C., Eleftheriadis, K., Smolik, J., Zdimal, V., Mihalopoulos, N., and Colbeck, I., Optical properties of aerosols over the eastern Mediterranean, Atmos. Environ., 40, 6229–6244, 2006 Gerasopoulos, E., Koulouri, E., Kalivitis, N., Kouvarakis, G., Saarikoski, S., Makela, T., Hillamo, R., and Mihalopoulos, N.: Size-segregated mass distributions of aerosols over Eastern Mediterranean: seasonal variability and comparison with AERONET columnar size-distributions, Atmos. Chem. Phys., 7, 2551–2561, www.atmos-chem-phys.net/7/2551/2007, 2007 J. Sciare, K. Oikonomou, O. Favez, Z. Markaki, E. Liakakou, H. Cachier, and N.Mihalopoulos, Long-term measurements of carbonaceous aerosols in the Eastern Mediterranean: Evidence of long-range transport of biomass burning, Atmos. Chem. Phys., 8, 5551-5563, 2008 Kalivitis, N., Gerasopoulos, E., Vrekoussis, M., Kouvarakis, G., Kubilay, N., Hatzianastassiou, N., Vardavas, I., and Mihalopoulos, N.: Dust transport over the Eastern Mediterranean from TOMS, AERONET and surface measurements, J. Geophys. Res., 112, D03202, doi:10.1029/2006JD007510, 2007 Kazadzis, S., A. Bais, V. Amiridis, D. Balis, C. Meleti, N. Kouremeti, C. S. Zerefos, S. Rapsomanikis, M. Petrakakis, A. Kelesis, P. Tzoumaka, and K. Kelektsoglou, Nine years of UV aerosol optical depth measurements at Thessaloniki, Greece, Atmospheric Chemistry and Physics, 7, 2091-2101, 2007 Kim, S.-W., S. Berthier, J.-C. Raut, P. Chazette, F. Dulac, and S.-C. Yoon, Validation of aerosol and cloud layer structures from the spaceborne lidar CALIOP using a ground-based lidar in Seoul, Korea, Atmos. Chem. Phys., 8, 3705– 3720, 2008 Lelieveld , J. H. Berresheim, S. Borrmann, P. J. Crutzen, F. J. Dentener, H. Fischer, J. Feichter, P. J. Flatau, J. Heland, R. Holzinger, R. Korrmann, M. G. Lawrence, Z. Levin, K. M. Markowicz, N. Mihalopoulos, A. Minikin, V. Ramanathan, M. de Reus, G. J. Roelofs, H. A. Scheeren, J. Sciare, H. Schlager, M. Schultz, P. Siegmund, B. Steil, E. G. Stephanou, P. Stier, M. Traub, C. Warneke, J. Williams, H. Ziereis, Global Air Pollution Crossroads over the Mediterranean, Science, 298, 794-799, 2002. Markowicz, K.M., Flatau, P.J., Ramana, M.V., Crutzen, P.J., Ramanathan, V., Absorbing Mediterranean aerosols lead to a large reduction in the solar radiation at the surface, Geophys. Res. Lett., 10.1029/2002GL015767, 2002 Liu, Z., M. A. Vaughan, D. M. Winker, C. Kittaka, R. E. Kuehn, B. J. Getzewich, C. R. Trepte, and C. A. Hostetler, The CALIPSO lidar cloud and aerosol discrimination: Version 2 algorithm and initial assessment of performance, J. Atmos. Oceanic Technol., 26, 1198– 1213, doi:10.1175/2009JTECHA1229.1., 2009 Omar, A.H., David M. Winker, Mark A. Vaughan, Yongxiang Hu, Charles R. Trepte, Richard A. Ferrare, Kam-Pui Lee, Chris A. Hostetler, Chieko Kittaka, Raymond R. Rogers, Ralph E. Kuehn, Zhaoyan Liu., The CALIPSO Automated Aerosol Classification and Lidar Ratio Selection Algorithm. Journal of Atmospheric and Oceanic Technology 26:10, 1994-2014, 2009 Papayannis, A., R.E. Mamouri, V. Amiridis, S. Kazadzis, C. Perez, G. Tsaknakis, P. Kokkalis and J.M. Baldasano, Systematic lidar observations of Saharan dust layers over Athens, Greece in the frame of EARLINET project (2004-2006), Annales Geophysicae, 27, 3611-3620, 2009 Sciare, J., Bardouki, H., Moulin, C., and Mihalopoulos, N., Aerosol sources and their contribution to the chemical composition of aerosols in the Eastern Mediterranean Sea during summertime, Atmos. Chem. Phys., 3, 291-302, 2003 Vaughan, M., S. Young, D. Winker, K. Powell, A. Omar, Z. Liu, Y. Hu, and C. Hostetler, 2004: Fully automated analysis of space-based lidar data: An overview of the CALIPSO retrieval algorithms and data products. Proc. SPIE, 5575, 16-30. Vrekoussis, M., Liakakou, E., Koc¸ak, M., Kubilay, N., Oikonomou, K., Sciare, J., and Mihalopoulos, N., Seasonal variability of optical properties of aerosols in the Eastern Mediterranean, Atmos. Environ., 39, 7083-7094, 2005 Winker D. M., Hunt, W. H., McGill, M. J., et al., Initial performance assessment of CALIOP, Geophys. Res. Lett., 34, L19803, doi:10.1029/2007GL030135, 2007. Winker, D., M. Vaughan, A. Omar, Y. Hu, K. Powell, Z. Liu, W. Hunt, S. Young, Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms, J. Atm. Ocean. Tech., 26, 2310-2323, 2009
Season: 01/09/2011 – 10/09/2011
Weather constraints: Since the campaign is concentrated on aerosol characterization, cloud-free conditions are required during aircraft’s CALIPSO under-flights.
Time constraints: Periods during mid and late summer are preferable to include smoke aerosol background and possible Saharan dust advection over Greece. The proposed project is clustered with the AEGEAN_GAME2 EUFAR project. The preferred time window of the campaign is similar (01/09/2011 - 10/09/2011). ACEMED is an aerosol campaign focused on satellite validation and aerosol characterization, thus having completely different measurable objectives from AEGEAN_GAME2 which is concentrated on the study of physical and chemical processes of polluted air masses over the Aegean Sea for model evaluation.
Flights (number and patterns): The aircraft will under-fly CALIPSO overpasses over Greece. The overpasses that are closer to the ground-based stations are selected for this project, so the synergy between airborne and ground-based observations for satellite validation will be feasible. The maximum information will be used for aerosol characterization and evaluation of CALIPSO's retrievals. In Figure 2, CALIPSO overpasses for September of 2011 are presented. In total, a minimum of 10 flight hours are requested that correspond to approximately 2 aircraft missions. The aircraft is proposed to take off from Thessaloniki's or Chania's (near Finokalia station) airport (see Figure 2), measuring between 1-4 km. The flights should be performed during both daytime and nighttime. Two days are proposed for the flights, either the 2nd or 9th of September 2011.
Instruments: None
Other constraints: None
Name: AMIRIDIS Vassilis
PI email: vamoir@noa.gr