L. De Leo

Evolution study of smoke backscattering coefficients in a cell by means of a compact mobile Nd:YAG lidar system

Detection of smoke from forest fire is one of the practical applications of lidar. As it is well known, smoke contains a large number of small particles of ash or soot, leading to a large backscattering efficiency and consequently favourable conditions for lidar application. We have developed a compact mobile lidar system based on Nd:YAG Q-Switched laser source, operating at three wavelengths: 1064 nm, 532 nm and 355 nm, with emission rate of 10 Hz and pulse duration equal to 5 ns when the laser operate at the fundamental harmonic and 4 ns for the second and the third ones. The system has been tested by experimental measurements of the smoke backscattering coefficients carried out in an ad hoc cell. Since the spatial resolution of laser pulse is smaller than the cell length it has been possible to evaluate the profile of the smoke backscattering coefficients inside the cell itself. Moreover it has been developed a computational model for simulating the temporal and spatial evolution of smoke within the cell. These experimental and theoretical data have been used to optimize the theoretical already developed to study the smoke evolution into the atmosphere. In this paper measurements of smoke backscattering coefficients into a cell and simulations of smoke evolution will be presented.

Detection and monitoring of pollutant sources with Lidar/Dial techniques

Its well known that air pollution due to anthropogenic sources can have adverse effects on humans and the ecosystem. Therefore, in the last years, surveying large regions of the atmosphere in an automatic way has become a strategic objective of various public health organizations for early detection of pollutant sources in urban and industrial areas.The Lidar and Dial techniques have become well established laser based methods for the remote sensing of the atmosphere. They are often implemented to probe almost any level of the atmosphere and to acquire information to validate theoretical models about different topics of atmospheric physics. They can also be used for environment surveying by monitoring particles, aerosols and molecules.The aim of the present work is to demonstrate the potential of these methods to detect pollutants emitted from local sources (such as particulate and/or chemical compounds) and to evaluate their concentration. This is exemplified with the help of experimental data acquired in an industrial area in the south of Italy by mean of experimental campaign by use of pollutants simulated source. For this purpose, two mobile systems Lidar and Dial have been developed by the authors. In this paper there will be presented the operating principles of the system and the results of the experimental campaign.

Water vapour emission in vegetable fuel: absorption cell measurements and detection limits of our CO2 Dial system

Forest fires can be the cause of serious environmental and economic damages. For this reason a considerable effort has been directed toward the forest protection and fire fighting. In the early forest fire detection, Lidar technique present considerable advantages compared to the passive detection methods based on infrared cameras currently in common use, due its higher sensitivity and ability to accurately locate the fire. The combustion phase of the vegetable matter causes a great amount of water vapour emission, thus the water molecule behaviour will be studied to obtain a fire detection system ready and efficient also before the flame propagation. A first evaluation of increment of the water vapour concentration compared to standard one will be estimated by a numerical simulation. These results will be compared with the experimental measurements carried out into a cell with a CO2 Dial system, burning different kinds of vegetable fuel. Our results and their comparison will be reported in this paper.