Research Projects

Project at a Glance

Project Status: complete

Title: Ozone transport in the north central coast air basin

Principal Investigator / Author(s): Dabberdt, Walter

Contractor: SRI International

Contract Number: A9-143-31


Research Program Area: Atmospheric Processes

Topic Areas: Transport


Abstract:

SRI conducted an experimental study during the period 17 September to 8 October 1980 to examine the transport of air pollutants (principally ozone) into and within the North Central Coast Air Basin (NCCAB). Ozone conditions during the study were the highest ever recorded in the NCCAB. The study employed two inert, nontoxic gaseous tracers (sulfur hexafluoride and bromotrifluoromethane) released at different locations or times on each of eight test days. Up to 1000 measurements of each tracer were made on each test day using aircraft, vehicle, and stationary sampling. Aerometric measurements were made by the airplane and two surface monitoring stations. In addition to the tracer tests, two airborne ozone mapping tests were conducted off the coast from Monterey to San Francisco. The measurements documented significant ozone transport from San Francisco to the NCCAB over the coastal waters and onshore in Monterey Bay. Transport was also documented from San Jose to Hollister through the Santa Clara Valley, although less dramatic than the offshore transport. The Santa Clara Valley transport pattern is impeded and complicated by the complex terrain and meteorology. Significant ozone transport was not observed over the Santa Cruz Mountains between Los Gatos and Scotts Valley, although transport of the tracer did occur. The strong marine inversion over the cost on the two relevant test days inhibited elevated emissions from Moss landing from dispersing to the surface within the NCCAB. Other prevailing meteorological regimes may result in different impacts than those observed during the eight tests. Recommendations are provided for more quantitative and more detailed analyses of the data.


 

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