EARLINET: long term observations for aerosol study

L. Mona¹, U. Wandinger², H. Linnè³, A. Amodeo¹, A. Apituley⁴, L. Alados Arboledas⁵, D. Balis⁶, A. Chaikovsky⁷, A. Comeron⁸, V. Freudenthaler⁹, I. Grigorov¹⁰, O. Gustafsson¹¹, S. Kinne³, D. Nicolae¹², I. Mattis², V. Mitev¹³, A. Papayannis¹⁴, M.R. Perrone¹⁵, A. Pietruczuk¹⁶, M.Pujadas¹⁷, J.P. Putaud¹⁸, F. Ravetta¹⁹, V. Rizi²⁰, V. Simeonov²¹, N. Spinelli²², K. Stebel²³, T. Trickl²⁴, M. Wiegner⁹, G.Pappalardo¹

¹Istituto di Metodologie per l’Analisi Ambientale CNR-IMAA, Potenza, I-85050, Italy pappalardo@imaa.cnr.it

²Institut für Troposphärenforschung, Leipzig, Germany

³Max-Planck-Institut für Meteorologie, Hamburg, Germany

⁴Rijksinstituut voor Volksgezondheid en Milieu, Bilthoven, The Netherlands

⁵Universidad de Granada, Granada, Spain

⁶Aristoteleio Panepistimio, Thessalonikis, Greece

⁷Institute of Physics, National Academy of Sciences, Minsk, Bjelarus

⁸Universitat Politècnica de Catalunya, Barcelona, Spain

⁹Ludwig-Maximilians-Universität, München, Germany

¹⁰Institute of Electronics, Bulgarian Academy of Sciences, Sofia, Bulgaria

¹¹Swedish Defence Research Agency (FOI), Linköping, Sweden

¹²National Institute of R&D for Optoelectronics, Magurele-Bucharest, Romania

¹³CSEM, Centre Suisse d'Electronique et de Microtechnique SA, Neuchâtel, Switzerland

¹⁴National Technical University of Athens, Department of Physics, Athens, Greece

¹⁵Università del Salento, Department of Physics, Lecce, Italy

¹⁶Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland

¹⁷Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Madrid, Spain

¹⁸EC Joint Research Centre, Ispra (VA), Italy

¹⁹Université Pierre et Maris Curie-Institut Pierre Simon Laplace, Paris, France

²⁰Università degli Studi dell’Aquila - Dipartimento di Fisica - CETEMPS, L’Aquila, Italy

²¹Ecole Polytechnique Fédérale de Lausanne, Switzerland

²²Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Napoli, Italy

²³Norwegian Institute for Air Research (NILU), Kjeller, Norway

²⁴Forschungszentrum Karlsruhe IMK-IFU, Garmisch-Partenkirchen, Germany

The last IPCC scientific report (Forster et al., 2007) underlines that it is not actually possible to draw a conclusion about the effect of human activities on radiation budget because of the high uncertainty about aerosol direct and indirect effects. More observations, and in particular altitude resolved measurements, are needed in order to further reduce this uncertainty. Lidar techniques allow direct measurements of aerosol extinction (and therefore of the optical depth) without critical assumptions and allow the description of the aerosol vertical distribution. Therefore lidar measurements are an indispensable tool to study the vertical structure of aerosol field and to investigate aerosol optical properties. In order to study aerosol on large spatial scale and to investigate transport and modification phenomena taking into account the vertical mixing processes, observations performed by lidar networks are essentially needed. These are the motivations why EARLINET, the European Aerosol Research Lidar Network, was established in 2000, as a research program funded by the European Commission in the frame of the 5th framework program. After the end of the project, the network activity continued on the base of a voluntary association. On March 2006, the EC Project EARLINET-ASOS (Advanced Sustainable Observation System http://www.earlinetasos.org) started on the base of the EARLINET infrastructure. This infrastructure project will enhance the operation of the network.

At present, EARLINET consists of 25 lidar stations: 7 single backscatter lidar stations, 9 Raman lidar stations with the UV Raman channel for independent measurements of aerosol extinction and backscatter, and 9 multi-wavelength Raman lidar stations.

A long-term database of aerosol lidar measurements is collected within EARLINET since May 2000. In particular, measurement are performed, almost simultaneously by all EARLINET stations, 3 times per week following a regular schedule established within the network (Bosenberg et al., 2003). In addition to the routine measurements, further observations are devoted to monitor special events such as Saharan dust outbreaks, forest fires, photochemical smog and volcano eruptions.

Data quality is assured by intercomparisons of both instruments and retrieval algorithms for backscatter and Raman lidar data. Moreover, tools for the continuous quality check of the instruments and algorithms used have been developed within the network in order to assure that data provided within EARLINET are always of the highest possible quality level.

Thanks to the large amount of high quality data, EARLINET database can contribute significantly to the quantification of aerosol concentrations, radiative properties, long-range transport and budget, and prediction of future trends on European and global scale. It can also contribute to improve model treatment on a wide range of scales and to a better exploitation of present and future satellite data.

However, an accurate quantification of aerosol and cloud radiative forcing requires a synergistic approach of satellite and ground-based observations together with model calculations. In this context, EARLINET consortium is exploring possibilities about scientific study based on the integration with different datasets, like AERONET and EMEP data.

Moreover, since June 2006, EARLINET is involved in the validation and exploitation of lidar data provided within the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission (Mona et al., 2009; Pappalardo et al., 2009). This satellite mission provides a first unique opportunity to address the study the 4-dimensional distribution of aerosols and clouds on a global scale. Because of its geographic coverage and its high quality, the EARLINET network is an optimal instrument to increase and validate the accuracy of aerosol optical properties retrieved from the CALIPSO pure backscatter lidar, and to investigate the representativeness of CALIPSO observations.

Finally, EARLINET data will be used for aerosol models validation. First systematic quantitative comparisons with the DREAM (Dust REgional Atmospheric Model) dust forecast model have been carried out for selected stations with large number of dust observations.

The financial support by the European Commission for EARLINET (grant RICA-025991) and through GEOmon Integrated Project under the 6th Framework Programme (contract number FP6-2005-Global-4-036677) is gratefully acknowledged.

Bösenberg, J., V. Matthias, A. Amodeo, et al., (2003) EARLINET: A European Aerosol Research Lidar Network to Establish an Aerosol Climatology. Max-Planck-Institut Report No. 348.

Forster, P., et al. (2007), in Climate Change 2007: The Physical Science Basis, edited by S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor, and H. L. Miller, Cambridge Univ. Press, New York.

Mona, L., et al. (2009), One year of CNR-IMAA multi-wavelength Raman lidar measurements in coincidence with CALIPSO overpasses: Level 1 products comparison, in press on Atmos. Chem. And Phys.

Pappalardo, G., et al. (2009), EARLINET correlative measurements for CALIPSO: first intercomparison results, submitted to Jour. Geo. Res.