THE VERTICAL CHEMICAL AND METEOROLOGICAL STRUCTURE OF THE BOUNDARY-LAYER IN THE LOWER FRASER VALLEY DURING PACIFIC-93

Mixed layer depths were derived from potential temperature profiles fr om aircraft, high-altitude balloon sonde and tethersonde measurements taken during the Pacific'93 field study in the Lower Fraser Valley of southern British Columbia. In general, mixed layer depths derived from these different data sources were closely comparable. An airborne lid ar was used to map aerosol depth throughout the valley. These lidar-de rived aerosol depths compared well with the meteorologically derived m ixed layer depths. During one notable ozone episode, mixed layer depth s were low, and in the range 500-800m. Measurements of chemical pollut ants such as ozone and nitrogen oxides showed these to be generally we ll mixed below the top of the mixed layer during daytime. However, at times, layering within and above the inversion layer was observed. (C) 1997 Elsevier Science Ltd.