Research Projects

Project at a Glance

Project Status: complete

Report Published June 1977:

Title: Atmospheric tracer studies to characterize the transport and dispersion of pollutants in the California delta region

Principal Investigator / Author(s): Lamb, Brian K

Contractor: Division of Chemistry and Chemical Engineering, California Institute of Technology

Contract Number: A5-065-87

Research Program Area: Atmospheric Processes

Topic Areas: Transport


Eight atmospheric tracer studies, utilizing CBrF3 and/or SF6, were conducted from August 31, 1976, through September 14, 1976, within the California Delta Region during four designated meteorological periods. The purpose of these tests was to quantitatively determine the transport and dispersion characteristics of the air passing over the Montezuma Hills. The data base was comprehensive enough to permit accurate mass balances of the tracer; essentially all of the tracer was accounted for by this analysis. Due to the steadiness of the winds, the plume trajectories at 10 km and 50 km downwind of the Montezuma Hills were found to be quite similar. On the average, plumes emitted from the Montezuma Hills during the test periods were transported southeast over Stockton. As a result of the steady nature of the winds, the commonly used Hino correction was found to grossly underestimate the hourly-averaged tracer concentrations computed from 10-second averaged concentrations. A comparison of experimentally determined dispersion parameters with those associated with Pasquill atmospheric stability classes indicated that atmospheric stability generally decreases with increasing distance downwind from the Montezuma Hills. In spite of the complex meteorology and terrain, estimates of tracer concentrations based upon the Gaussian plume model were found to be reasonably accurate. A nomograph was developed to permit rapid calculation of non-reactive pollutant concentrations from tracer data and pollutant emission rates; in the case of NO2, the oxidation of NO to NO2 was assumed to be rapid relative to the transport time.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

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