Research Projects

This report describes the ozone lidar experiments conducted by NOAA's Environmental Technology Laboratory (ETL) in California in 1993. These experiments were sponsored by the California Air Resources Board. The main objectives of the experiments were: (1) to verify the capability of the ETL ozone lidar for remotely sensing ozone and aerosol profiles in the lower troposphere, (2) to test the integrity of the lidar system and the mobile laboratory for further system improvements, (3) to improve the data retrieval algorithm and processing techniques for better accuracy of ozone observations and (4) to test the performance of this lidar in a very polluted environment like the Los Angeles air basin, and obtain first-hand information about ozone and aerosol vertical distribution in this region. The two experiments using NOAA's lidar demonstrate that the ozone lidar can be a powerful tool for air quality monitoring and research.

The intercomparison experiment in Davis showed that the lidar and airborne DASIBI measurements of ozone mixing ratio agreed with each other within 10 parts per billion (ppb) from near the surface up to 3 km in most cases. This good agreement occurred even though the lidar was installed in a mobile laboratory just prior to its shipment. This late installation prevented any significant test of the lidar's performance in its new environment (thus some hardware problems were initially found during the field experiments and later during the data processing; the problems were corrected through data processing).

The experiment in Los Angeles (Claremont) included the day with the highest ozone concentration of the year. The lidar observations revealed large amounts of ozone trapped in the marine boundary layer below 400 m during the high ozone episode. The polluted air mass arrived at the site like a front, with a sudden increase in concentrations at all heights in the boundary layer. Aerosol profiles revealed two layers of aerosol-laden air (the boundary layer and the layer from about 1 krn to 4.5 km) separated by a thin layer of clean air just above the top of an inversion. The lidar provided unique information on the vertical distribution of the pollution and allowed data analysts to better interpret the processes involved.