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Project Status: complete

Title: SODAR network support for LIRAQ utilization

Principal Investigator / Author(s): Russell, Philip B

Contractor: SRI International

Contract Number: A7-184-30

Research Program Area: Atmospheric Processes


The purpose of this project was to collect mixing depth data, convert it to an easily usable form, and distribute it to others for use in air quality and boundary layer studies. This collection, conversion, and distribution were accomplished satisfactorily. Thus the results of this project reinforce the conclusion reached in an earlier study (Russell and Uthe, 1978b) that sodar network measurements in the San Francisco Bay Area can provide long-term, hourly data on spatial variations of mixing depth and stability in a digital format readily usable in air quality simulation models.

The positive result is a direct consequence of the Bay area's special, marine-influenced meteorology, which is characterized by frequent low, strong, elevated inversions. These inversions are easily detected by commercial sodars of moderate power; moreover, they yield sodar facsimile records that are relatively easy to interpret. In general, at sites located progressively inland, the frequency, strength, and low altitude of these inversions are progressively moderated, and as a consequence an unambiguous mixing depth can be determined from sodar data a decreasing fraction of the time. This effect was evident in comparing the overall data sets from land-and marine influenced sites in the present study. Nevertheless, the digitized sodar data consistently gave quantitative measurements of the small mixing depths conducive to the development of air pollution episodes.

This study has also shown that automatic plotting routines can easily convert the digital sodar data to graphs of mixing depth and stability indicators. These graphs give an overview of large volumes of mixing information and are easier to comprehend than either the original facsimile records or listings of the digital data. Hence they facilitate rapid comparisons among different sites, days, and times of day.

Careful site selection and expert maintenance of sodar hardware continue to be of paramount importance in achieving satisfactory data quality and high data-capture fractions.


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

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