using the differential absorption lidar (DIAL) technique in the Lintong district, about 35 km
northeast of Xi'an, the capital of the Shaanxi province, China. Concentrations ranging from 2
to 13 ng/m3 were observed. As uniquely enabled by the lidar technique, representative
average concentrations, integrated over a considerable volume, were recorded and put in
relation to weather conditions, and vertical concentration profiles were measured …