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Project at a Glance

Project Status: complete

Report Published May 1994:

Title: Multi-year observational study of atmospheric transport corridors and processes in California.

Principal Investigator / Author(s): Neff, William

Contractor: National Oceanic & Atmospheric Administration

Contract Number: A032-145

Research Program Area: Atmospheric Processes

Topic Areas: Monitoring, Transport


NOAA's Environmental Technology Laboratory (ETL, formerly the Wave Propagation Laboratory) used its network of boundary-layer 915-MHz radar wind profilers and supporting meteorological instrumentation to monitor and study major interbasin transport corridors for ozone and its precursors over two summer ozone seasons during 1991 and 1992. During this period wind profilers, some equipped with RASS temperature profiling, were deployed at 25 sites throughout California. Our goal was to provide data necessary to meet ARB needs to assess transport of ozone and its precursors in a number of transport couples throughout the State using wind and mixed layer depth determinations from profilers. In addition, we sought to provide a data base that could be used for future modeling exercises and to critically evaluate profiler technology for future applications in the State. In support of the study, we created a data base system and display software and installed a workstation for the Air Resources Board in Sacramento where data could be transferred in real-time over the Internet and again after reanalysis. In the course of the study we discovered contamination of the wind data by migrating birds. We found the effect to be significant along certain migratory paths in spring and early summer and again in late summer and early fall. Because of the seriousness of the problem, we redirected our internal resources and developed new editing methods to flag contaminated data after the fact and developed new signal processing routines that can now eliminate a substantial fraction of the contamination in real-time.

With the re-edited data, we carried out a number of analyses of meteorological conditions associated with high- and low-ozone periods in selected areas. In addition, a series of short term supplemental measurement campaigns suggested that the dynamics of the diurnal, thermally forced circulation along the major topographic boundaries of the Central Valley and the South Coast Basin play a significant role in the recirculation of pollutants in some cases and their transport into other air basins, in others. Analysis of profiler data adjacent to Banning and Cajon Passes in southern California suggest that such passes can be easily monitored with wind profilers so as to determine the direction and depth of transport from one basin to another.


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

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