Aerosols and climate
Atmospheric aerosols have large influence on Εarth’s radiation budget [Forster et al., 2007]. Recent estimations on the possible impact of aerosols (both direct and indirect effects) on the radiative forcing (cooling effect) in a global average are of the same order of magnitude as the CO2 effect (warming effect). However, high uncertainties still exist concerning the indirect and direct effects, which are connected with the aerosol influence on climate.
In addition, very little is known about the aerosol vertical distribution, the vertical distribution of the aerosol optical-chemical properties, the climatology and the transport processes of aerosols over the South-Eastern Europe
AQuA-GRO project
Air Quality assessment and study of transport processes along the axis Athens-Aegean sea (Greece) and Bucharest (Romania) using lidar techniques
AQuA-GRO project aims to create a statistical database of the spatio-temporal evolution of the vertical distribution of aerosols over Romania (region of Bucharest) and Greece (Athens/Evia island/Aegean Sea) using ground-based remote sensing techniques (lidar). Meteorological data will be also used to quantify the long-range transport and deposition mechanisms involved and to identify the major aerosol sources affecting air quality over Romania (region of Bucharest) and Athens, Evia island (Aegean Sea)(Greece).
Atmospheric Lidars
More than 35 years the lidar technique has been used for earth/atmospheric studies (clouds, aerosols, Planetary Boundary Layer), for the study of the vertical distribution of air pollutants (e.g. O3, NOx, SO2, Hg, toluene, benzene, etc.) and also for the retrieval of the vertical profile of the aerosol optical properties (Aerosol Optical Depth, backscatter and extinction coefficients).
The lidar technique is an active remote sensing method based on the emission of short light pulses (a few ns or ps duration) in the atmosphere. The laser wavelengths used in lidars, depend on the application and extend from about 250 nm to 11μm. In the case of the study of the vertical distribution of the aerosols, wavelengths from the ultraviolet to the mid-infrared are used (0.355-12μm). In the receiving part of a lidar system an optical telescope collects the laser photons backscattered from the atmosphere. An optical analyzing system (narrow band interference filters or spectrometers) are used to separate the various signals received which are later detected by various detectors [photomultipliers (PMTs) for the UV and the visible part of the spectrum or photodiodes (APDs) for the near infrared spectral region] .