18 research outputs found
Optical, microphysical, mass and geometrical properties of aged volcanic particles observed over Athens, Greece, during the Eyjafjallajokull eruption in April 2010 through synergy of Raman lidar and sunphotometer measurements
Six-month ground-based water vapour Raman lidar measurements over Athens, Greece and system validation
First water vapor measurement over Athens, Greece, obtained by a combined Raman-elastic backscatter lidar system
Three+two Raman lidar system configuration for space-borne active remote sensing system validation over Athens, Greece, in the frame of the EARLINET-ASOS and ESA-CALIPSO projects
Retrieval of the optical properties of tropospheric aerosols over Athens, Greece combining a 6-wavelength Raman-lidar and the CALIPSO VIS-NIR lidar system: Case-study analysis of a Saharan dust intrusion over the Eastern Mediterranean
Comparisons of aerosol backscatter using satellite and ground lidars: implications for calibrating and validating spaceborne lidar
Ground-, satellite- and simulation-based analysis of a strong dust event over Abastumani, Georgia, during May 2009
A strong dust event over Abastumani, Georgia, during May 2009 was studied using light detection and ranging (lidar), satellite and sun photometric measurements. High aerosol optical depth (AOD) values (0.45-0.57) at 500 nm were measured over the closest Aerosol Robotic Network (AERONET) site (Erdemli, Turkey), whereas over Georgia, the AOD measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) was about 0.9 at 550 nm. The AERONET data analysis showed a mean aerosol effective radius of about 2.5 μm, whereas the mean value of the Ångström exponent (α) (wavelength pair 440/870 nm) was smaller than 1, indicating the dominance of large aerosols. The aerosol lidar over Abastumani showed the existence of a strong particle load from the near ground up to a height of 3.5 km. The BSC-DREAM8b forecast model showed that the dust aerosols travelled from the Saharan and the Arabic deserts to the studied area, even reaching southern Russia, covering a total distance of about 5500 km, in the height region from about 2 to 11.5 km
Aerosol Lidar observations and model calculations of the Planetary Boundary Layer evolution over Greece, during the March 2006 Total Solar Eclipse
International audienceAn investigation of the Planetary Boundary Layer (PBL) height evolution over Greece, during the solar eclipse of 29 March 2006, is presented. Ground based observations were carried out using lidar detection and ranging devices and ground meteorological instruments, to estimate the height of the mixing layer (ML) before, during and after the solar eclipse in northern and southern parts of Greece exhibiting different sun obscuration. Data demonstrate that the solar eclipse has induced a decrease of the PBL height, indicating a suppression of turbulence activity similar to that during the sunset hours. The changes in PBL height were associated with a very shallow entrainment zone, indicating a significant weakening of the penetrative convection. Heat transfer was confined to a thinner layer above the ground. The thickness of the entrainment zone exhibited its minimum during the maximum of the eclipse, demonstrative of turbulence mechanisms suppression at that time. Model estimations of the PBL evolution were additionally conducted using the Comprehensive Air Quality Model with extensions (CAMx) coupled with the Weather Research and Forecasting model (WRF). Model-diagnosed PBL height decrease during the solar eclipse due to vertical transport decay, in agreement with the experimental findings; vertical profiles of atmospheric particles and gaseous species showed an important vertical mixing attenuation