Research Projects

Project at a Glance

Project Status: complete

Title: Summary of SCAQS upper air measurements performed by the STI aircraft

Principal Investigator / Author(s): Anderson, J A

Contractor: Sonoma Technology, Inc.

Contract Number: A6-098-32

Research Program Area: Atmospheric Processes

Topic Areas: Ecosystem Impacts, Impacts, Monitoring


During the summer and fall on 1987, the Southern California Air Quality Study (SCAQS) was performed in the Los Angeles Basin. Extensive ground level and airborne sampling was performed on a total of 17 intensive study days during two summer and one fall study periods. The summer sampling periods were June 15 to July 24, 1987 and August 18 to September 4, 1987. The fall study period began November 9 and continued to November 18. After a break for Thanksgiving, the program resumed December 2 and continued until December 12, 1987.

Airborne sampling described in this report was performed by Sonoma Technology, Inc. (STI). The STI aircraft sampled during all three study periods. The aircrafts used by STI was instrumented to make real time measurements of various meterological and air quality parameters and to collect integrated filter samples as well as various grab samples.

The objectives of the aircraft measurements were:

-To document, on study days, the three dimensional distribution of ozone, aerosols, and their precursors throughout the study area, and

-To document the chemical composition of the aerosol, hydrocarbons, and selected other species which required integrated sampling at selected location aloft.

During the three study periods, the STI aircraft flew a total of 267 spirals and 35 orbits during 37 flights on 16 of the 17 intensive study days. A spiral is a vertical sounding flown over a fixed ground location during a climb or descent of the aircraft. A series of spirals during each flight were used to characterize the spatial and temporal distribution of pollutants at various locations around the Basin. Orbits were flown for the purpose of collecting integrated samples. During an orbit, the aircraft would circle a fixed ground location at a constant altitude while samples were being collected.

During sampling, 35 sets of integrated filter samples were exposed. The filters were analyzed for organic, elemental, and total carbon, PAN, nitrate-nitric acid, sulfate (for SO2), aerosol mass, sulfate, nitrate, chloride, ammonium (for NH3), and aldehydes. In addition to the integrated filter sets, 67 canister samples (for hydrocarbons), 116 bag samples (for perfluorocarbon tracers), and 148 syringe samples (for SF6 tracer) were collected.

This report documents the sampling activities of the STI aircraft and summarizes the sampling that was performed and samples collected.


For questions regarding research reports, contact: Heather Choi at (916) 322-3893

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