Project at a Glance
Title: Development of a vertical mixing data base in the San Francisco Bay and delta region
Principal Investigator / Author(s): Russell, Philip B.
Contractor: Stanford Research Institute
Contract Number: A6-066-80
Research Program Area: Atmospheric Processes
The objective of this project was to produce a smog-season database on mixing depth and stability patterns in the San Francisco Bay and Delta Region, for input to air quality simulation models.
To meet this objective a network of 13 sodars (acoustic radars) was operated from mid-August to early November 1976. Ancillary measurements of temperature and humidity profiles, haze and cloud layering, and 10-mile winds were made by airplane, lidar and anemometer.
Techniques of filming and manual digitization were developed to convert the continuous sodar data to hourly digital parameters describing mixing depth and near-surface echo type (a stability indicator). The sodar-inferred mixing depths were compared to those inferred from the ancillary measurements. These and previous tests show good overall agreement and demonstrate that sodar measurements compare very favorably with alternate techniques for determining mixing depth in the Bay Area. To illustrate the use of the data, time-dependent maps of mixing depth are derived for a two-day period. These maps show spatial patterns of mixing layer growth caused by solar heating of land surfaces, compensating downward motions over the bays, and the inland progression of a sudden lifting that marked the end of an air pollution incident.
Appendices include the digitized sodar, airplane, and wind data. The sodar and wind data are also available on computer cards.
This report was submitted in fulfillment of Contract A6-066-80 by SRI International under sponsorship of the California Air Resources Board. Work was completed as of 25 August 1977.
For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893
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