LIDAR

technology

LIDAR, short for LIght Detection and Ranging, is one of the keystone of the research field dealing with the characterization of the atmosphere and it is vastly contributing to our knowledge.

The technique uses the scattering properties of molecules, aerosols and hydrometeors to derive information on the atmospheric composition and/or thermodynamic state.

A LIDAR system consists of a transmitter and a receiver. The transmitter is a laser source, the receiver is a telescope followed by a spectral analysing system. The laser generates short, pulsed light at a specific wavelength that interacts with all the airborne particles. A small part of the emitted radiation is backscattered, collected by the telescope and sent to the spectral analyzing system, which selects specific wavelengths and polarization status. The selected radiation is directed onto a detector where the received optical signal is converted into an electrical signal. This is the LIDAR signals whose intensity depends on the properties of the atmosphere. The travel time of the laser pulse gives information on the distance of the particles; the polarization status on their shape.

Courtesy of A. Amodeo

Compared with the traditional method of air quality analysis, LIDARs assure:

– a continuous realtime monitoring

– the retrieve of

– space-time distribution and evolution of PM

– cloud dynamics

– PBL heigh

– PM structural properties: aerosol layer depth

– PM micro-physical properties: size distribution and refractive index

– PM optical properties: extinction and backscattering coefficients

– the possibility to localize pollutants sources

Applications

Air quality

The analysis of the airborne particulate matter has become a very high concern since it has been proved exposure to such particle can badly affect human health. Several research show that chronicle exposure reduce human life expectancy of more than 2 years in the most polluted regions. Since air pollution is not just a local problem (pollutants can be transported far away from its source by atmospheric motion) surveying large regions of the atmosphere and retrieving the space-time distribution of particulate matter can provide a valid help in the detection of pollutants sources and in the study of their transportation. Our LIDAR systems provide those information with great accuracy and security.

Climate changes

Climate change is a change in the statistical properties of the climate that affects all region around the world and persists for several decades. It is caused by both natural processes (changes in sun’s radiation, volcanoes eruptions, dust storms) and anthropic daily activities. Melting ice, rising seas, extreme weather, shifting rainfall are the most common effects. It negatively impacts human health, wildlife and economy (the poor developing countries are among the most affected). Our LIDAR systems can help to understand the complex interactions between clouds, anthropogenic aerosol the atmosphere and solar radiations.