Environmental Engineering and Management Journal January 2011, Vol.10, No. 1, 91-97 http://omicron.ch.tuiasi.ro/EEMJ/ ______________________________________________________________________________________________ ROMANIAN LIDAR INVESTIGATION OF THE EYJAFJALLAJOKULL VOLCANIC ASH Adrian Timofte 1,2 , Marius Mihai Cazacu 1 , Razvan Radulescu 3 , Livio Belegante 3 , Dan Gheorghe Dimitriu 1 , Silviu Gurlui 1∗ 1 Alexandru Ioan Cuza University of Iasi, Faculty of Physics, 11 Carol I Blvd., 700506 Iasi, Romania 2 National Meteorological Administration, Regional Forecast Center Bacau, Romania 3 National Institute of Research & Development for Optoelectronics, INOE, Bucharest, Romania Abstract The eruption of the Eyjafjallajokull volcano and its impact on the environment in Romania has been studied by means of different complementary tools. In order to characterize both various types of clouds, theirs dynamics, and the ash sulphates aerosols, different diagnosis type instruments have been deeply analyzed, too. Thus, the occurrence of the ash cloud over Romania, Bucharest city (lat: 44.4 N, long: 26.0 E), starting on the 17th of April 2010 when it covered this area, and also the weather conditions have been investigated. The HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) model, ECMWF (European Centre for Medium-Range Weather Forecasts) and satellite data were used as a complementary tool for the LIDAR measurement data. Key words: LIDAR, satellite data, synoptic, volcanic-ash Received: November, 2010; Revised final: January, 2011; Accepted: January, 2011 ∗ Author to whom all correspondence should be addressed: e-mail: sgurlui@uaic.ro; Phone: +40232201197; Fax: +40232201150 1. Introduction Situated in the north of Skógar and in the west of Mýrdalsjökull, Iceland, Eyjafjallajokull volcano has relatively frequently erupted since the last glacial period, most recently in 2010 and from 1821 to 1823 (Global Volcanism Program, 2010). The optically strongest volcanic ash plumes, ever measured over central Europe, reached the continent on the 16th of April 2010 and caused an almost complete disruption of the air traffic over western, central, and northern Europe for several days. Due to the favorable meteorological conditions, the free tropospheric ash clouds originating from strong eruptions of this volcano in southern Iceland on the 14 th of April 2010 were advected to Europe within less than two days. This major event can be regarded as a natural experiment to investigate the impact of fresh and aged volcanic ash on weather and climate, especially on the radiative transfer in the atmosphere and cloud processes as, e.g., the role of volcanic ash on cloud ice formation (Ansmann et al., 2010; Institute of Earth Sciences, 2010). Having this in view, our research focuses on the analysis of the physical phenomena in the atmosphere and the perturbations that occurred with the eruption of this volcano on the 14 th of April 2010, which gave off an ash cloud in the atmosphere. LIDAR (LIght Detection And Ranging) is an optical remote sensing technology that measures properties of scattered pulsed laser light Because of their short wavelengths range (IR-UV-VIS), the LIDAR systems can highlight atmospheric compounds (aerosols, different type of particles, etc). Depending on the output power and efficiency at the reception, the sounding distance can reach up to tens of kilometers, and the response time is about the order of minutes. The received signals are “the answer” of the atmosphere at the interaction with the optical beam, thus including information about the type, shape and density of the spreaders (Kovalev and Eichinger, 2004). “Gheorghe Asachi” Technical University of Iasi, Romania