VERTICAL NITROGEN-DIOXIDE AND OZONE CONCENTRATIONS MEASURED FROM A TETHERED BALLOON IN THE LOWER FRASER VALLEY

A series of vertical profiles of temperature, relative humidity, NO2 a nd O-3 were determined in the Lower Fraser Valley, British Columbia, a s part of the PACIFIC'93 held study. Data from one day show very struc tured vertical distributions of all parameters in the morning, as expe cted from the limited vertical mixing under the nocturnal inversion. N O2 concentrations of 20ppbv were observed 300m above the surface, whil e the surface concentrations were similar to 2ppbv. Ozone and nitrogen oxide chemistry were observed at all altitudes throughout the PBL. Ti tration of O-3 by NO to produce NO2 was observed in layers above the g round, under the influence of the NBL. An increase in odd oxygen throu ghout the PBL, during the morning and early afternoon, shows ''smog ch emistry'' is occurring even though the groundbased O-3 measurements su ggest this day was not particularly chemically active. However, once t he NBL has dissipated, the ground-based measurements seem representati ve of the entire PBL. (C) 1997 Elsevier Science Ltd.