Horizontal Lidar Measurements of Near-surface Ozone

Small-scale, horizontal ozone gradients result from inhomogeneous air-pollution emissions, varying surface vegetation, in conjunction with complicated physical mixing and chemical reactions. High-resolution horizontal ozone measurements are critical for urban-scale air-quality models, but are rarely conducted. We are developing a scanning ozone lidar that currently measures ozone profiles from 1 to 7 km with adjustable elevation and azimuth angles. The horizontal lidar measurements at 20 m AGL reveal noticeable ozone horizontal gradients up to 2 ppbv/km during daytime. The observed horizontal ozone gradients show structure at much finer scales than the three EPA stations closest to the lidar site. Our final objective is to make scanning ozone lidar measurements to evaluate high-resolution atmospheric numerical models and improve our understanding of small-scale air-quality processes.