Evolution study of a water vapour plume using a mobile CO2 DIAL system

he DIAL system and the HYPACT model are two useful means to study plume evolution and dispersion. We developed a mobile DIAL system, mounted onto a truck. The DIAL is based on a single TEA CO2 laser source, able to switch between the "on" and "off' lines. This set-up allows rapid tuning of the two lines and keeps the misalignment within a range of 0.1 mrad, moderately below the beam divergence. The receiving system is a Newtonian telescope. All the instrumentation and the telescope are located inside the van. A large size scanning mirror, installed on the roof, sends the laser radiation into the atmosphere and, at the same time, it collects the backscattered light. To test all instrumentation, preliminary measurements have been completed to monitor a water vapour plume of a cement factory. The measurements are qualitatively compared against a dispersion plume model run initialially from climatological fields.