**6. Conclusions**

Tropospheric lidars can provide impressive results: aerosol studies related to volcanic eruptions, tropospheric systems, biomass burning, and dust transport (both into and out of the continent) were conducted over the past 15 years. Pollutant dispersion studies in large cities of South America employing PBL dynamics, conducted in different sites, and with specific conditions, greatly aid local air quality authorities. More recently, studies on clouds and their impact on radiative transfer have been carried out. Given the geographical location of the lidar sites, essential comparisons can be carried on along a wide longitudinal interval, and tropospheric-stratospheric circulation experiments can be performed, as well as their climatological interpretation.
